Remedial colon hydrotherapy device enema as a salvage strategy for inadequate bowel preparation for colonoscopy: A retrospective cohort study

Dongxuan Zhang; Chunxia Zhao; Yuan Tao; Jiao Zhang; Qisheng Zhang; Da Li; Ping Ye; Xiaobo Yu; Chao Chen

doi:10.1371/journal.pone.0319493

. 2025 Mar 19;20(3):e0319493. doi: 10.1371/journal.pone.0319493

Remedial colon hydrotherapy device enema as a salvage strategy for inadequate bowel preparation for colonoscopy: A retrospective cohort study

Dongxuan Zhang ^1,^*,^#, Chunxia Zhao ^2,^#, Yuan Tao ¹, Jiao Zhang ¹, Qisheng Zhang ¹, Da Li ¹, Ping Ye ¹, Xiaobo Yu ¹, Chao Chen ¹

Editor: Chih-Wei Tseng³

PMCID: PMC11922272 PMID: 40106477

Abstract

Objective

Colon hydrotherapy devices serve as a physiotherapeutic modality to manage colonic disorders by promoting intestinal peristalsis and enhancing gastrointestinal functionality. This study aims to assess and compare the effectiveness, safety, and tolerability of two remedial strategies for inadequate bowel preparation: colon hydrotherapy device enema and oral polyethylene glycol electrolyte powder.

Methods

A retrospective analysis was performed on 109 patients who failed to adequately prepare for colonoscopy. These patients received remedial bowel preparation on the same day as their procedure, with 55 undergoing colon hydrotherapy enema and 54 receiving oral polyethylene glycol electrolyte powder. Patient satisfaction and tolerance were evaluated through telephone follow-up. Key metrics included the Boston Bowel Preparation Scale scores, preparation time, incidence of adverse reactions, and patient tolerance and satisfaction.

Results

No significant differences were observed in baseline characteristics between groups (P > 0.05). The Boston Bowel Preparation Scale scores for the entire colon were 7 (3) in the hydrotherapy group and 6.5 (1) in the oral group (z = -2.075, P = 0.038). Notably, scores for the left colon were significantly higher in the hydrotherapy group [3 (1) vs. 2 (0), z = -5.586, P < 0.001]. The hydrotherapy group also exhibited a shorter preparation time [80 (20) min vs. 92.5 (20) min, z = -3.961, P < 0.001] and a lower incidence of adverse effects (36.4% vs. 88.9%, χ² = 32.035, P < 0.001). Patient satisfaction metrics, including re-selection rates and tolerance of side effects, were significantly higher in the hydrotherapy group.

Conclusions

The colon hydrotherapy device enema is an effective, efficient, and well-tolerated method for bowel cleansing, demonstrating a low incidence of adverse events. It is recommended as an effective and safe remedial therapy for patients with inadequate bowel preparation prior to colonoscopy.

Introduction

Colonoscopy is an essential tool for the screening, diagnosis, and treating colonic lesions. Inadequate bowel preparation can result in prolonged operating time, increased difficulty during the procedure, incomplete examination, a higher risk of missed lesions, and an elevated risk of complications. Numerous studies have identified various factors that may affect the effectiveness of bowel preparation, including constipation, high body mass index (BMI), male gender, advanced age, a history of colon surgery, and other underlying medical conditions such as diabetes mellitus, Parkinson’s disease, stroke, or spinal cord injury, as well as the use of medications like antidepressants [1,2]. Given the evolving socio-economic structure, the growing elderly population, and the rising popularity of colonoscopy, the proportion of patients with risk factors for inadequate bowel preparation is increasing. With the aging population growing, individuals increasingly suffer from multiple chronic diseases simultaneously, necessitating the use of various medications for treatment. Some of these medications can induce adverse reactions in the digestive tract, leading to symptoms such as nausea and vomiting and alterations in intestinal transit. Common drugs that can cause such reactions include calcium antagonists, non-steroidal anti-inflammatory drugs (NSAIDs), anxiolytics, antidepressants, diuretics, statins, metformin, and glycosidase inhibitors [3–7]. It is therefore crucial to emphasize the assessment of inadequate bowel preparation and the development of effective and safe remedial measures, while simultaneously enhancing routine bowel preparation programme. Currently, neither domestic nor international guidelines explicitly outline the optimal remedial measures for inadequate bowel preparation without canceling the same-day examination. In clinical practice, an additional 2 liters of low-dose polyethylene glycol (PEG) electrolyte powder is frequently used as a remedial approach. Several clinical studies suggest that utilizing additional oral PEG electrolytes and routine cleansing enemas may enhance bowel cleansing [8–11]. However, the quality of the existing literature is low, and comprehensive comparisons between different regimens are lacking.

The colon hydrotherapy device is primarily used in clinical settings to treat colon-related disorders such as functional constipation, colonic drug dialysis, chronic colitis, and bowel cleansing. In clinical practice, it is also employed for remedial bowel preparation. In certain cases, colon hydrotherapy devices have shown efficacy, efficiency, and safety in this role. However, there is a lack of systematic and standardized clinical studies examining the impact of remedial enemas using colon hydrotherapy devices on bowel cleanliness. The study is a retrospective cohort analysis comparing the effect of two different remedies: a colon hydrotherapy device enema and re-administration of oral polyethylene glycol (PEG) electrolyte powder. The study focuses on the improvement on colon cleanliness, the time required for remedial consumption, and patient tolerance and satisfaction among those without canceling the same-day examination.

Materials and methods

General information

At our endoscopy center, the standard bowel preparation protocol prior to colonoscopy involves the administration of 3 liters of polyethylene glycol (PEG). This protocol is divided into a single-dose or a split-dose regimen. Based on both national and international literature, as well as the characteristics of our population, risk factors for inadequate bowel preparation in China include chronic constipation, a body mass index (BMI) greater than 25 kg/m², age over 70 years, a history of colon surgery, and the presence of comorbidities such as diabetes mellitus, Parkinson’s disease, stroke, or spinal cord injury. The use of tricyclic antidepressants or narcotic analgesics, such as opioids, also increases this associated risks. For patients with these risk factors, we recommend administering 1 liter of PEG 6 to 10 hours before the examination and an additional 2 liters 4 to 6 hours before the procedure on the same day. For patients without clear risk factors, we advise the consumption of 3 liters of PEG 4 to 6 hours before the examination on the day of the procedure. In our daily clinical practice at the Gastroenterology Department and Endoscopy Centre, we conduct an initial assessment of bowel cleanliness for patients scheduled for colonoscopy on the day of their examination. This evaluation is based on the patient’s most recent bowel movement, and the findings are documented in the patient’s medical record. The assessment is categorized into four grades: Grade 1 indicated very poor bowel preparation with brown fecal water and a large amount of waste material; Grade 2 indicated relatively poor preparation with dark yellow fecal water and a small amount of waste; Grade 3 was considered good, characterized by yellowish clear watery stool; and Grade 4 was very good, defined by colorless clear watery stool. Grades 1 and 2 are considered indicative of inadequate bowel preparation [12]. For patients assessed with Grades 1 and 2, we inform them of the potential adverse effects of insufficient bowel preparation and suggest remedial measures while ultimately respecting the patient’s decision.

The study included 121 patients who exhibited inadequate bowel preparation following routine administration of either a single or divided oral intake of polyethylene glycol electrolyte solution for colonoscopy at Beijing Changping Hospital of Traditional Chinese Medicine from April 2019 to June 2022. Among these, 3 patients did not complete the colonoscopy due to scope access difficulties or intolerable abdominal pain, and 9 patients declined to participate in telephone follow-ups. Consequently, 109 patients were included in the final analysis. Of these, 55 patients received treatment with an enema utilizing a colon hydrotherapy machine (DJS-C, Hangzhou Hercules Medical Instrument Co., Ltd., in China), while 54 patients underment re-administration of the oral polyethylene glycol electrolyte solution (Fig 1). The clinical case information was obtained from the medical records (S1 File). The clinical data were collected retrospectively between October 2022 and December 2023. Telephone follow-up interviews (S2 File) were also conducted from October 2022 to December 2023, with verbal consent obtained from patients in compliance with ethical standards. The study was approved by the Medical Ethics Committee of Changping Hospital of Traditional Chinese Medicine (ethics approval number: 2022-04-01).

Inclusion criteria

Patient bowel preparation prior to colonoscopy was deemed inadequate. The degree of intestinal cleansing before the remedial bowel preparation was evaluated based on the characteristics of the last bowel movement before the intended colonoscopy. This assessment was categorized into four grades. Grades 1 and 2 were classified as inadequate bowel preparation.
The patients were required to undergo remedial bowel preparation on the day of their scheduled colonoscopy, utilizing either a colon hydrotherapy device enema or consuming 2 liters of polyethylene glycol electrolyte solution.
Patients who consent to and complete a telephone follow-up are eligible for inclusion in the study.

Exclusion criteria

Patients who used two or more remedial options in combination (different combinations of the three remedial bowel preparation methods: colon hydrotherapy device enema, oral polyethylene glycol electrolyte powder, and plain cleansing enema).
Patients with missing or incomplete case information.
Patients with incomplete telephone follow-ups.

Remedial measures

For patients assessed as having inadequate bowel preparation after the routine bowel preparation program, remedial bowel preparation was implemented via colon hydrotherapy enema or a low-dose oral PEG program (2 L) on the same day without cancelling the examination.

The colon hydrotherapy enema procedures were conducted in the enema room (S3 File). Before commencing the procedure, patients was informed about the general operation of the colon hydrotherapy instrument. Understanding and cooperation were obtained from each patient. The patients were instructed to lie on the left side. Following the standard operating procedures of colon hydrotherapy, after necessary adjustments such as water temperature and flow rate were made and pipeline connections completed, the rectal catheter was inserted into the anus under pressure monitoring. The process of flushing and discharge continued until the colon was irrigated with the recycled liquid, resulting in either watery stools or yellowish transparent liquid.

Patients in the oral medication group were administered a low-dose PEG solution (2 L). This compound preparation consists of two doses: Dose A and Dose B. Dose A contains 13.125 grams of polyethylene glycol 4000, while Dose B contains 0.1785 grams of sodium bicarbonate, 0.3507 grams of sodium chloride, and 0.0466 grams of potassium chloride. One packet of each dose (A and B) was dissolved in 125 ml of warm water to form a solution. Patients were instructed to consume 250 milliliters every ten minutes. Once patients had passed a further number of stools, the colonoscopy procedure was initiated anew.

Collection indicators

Demographic characteristics and baseline information include: gender, age, body mass index (BMI), underlying diseases, history of pelvic and abdominal surgery, Activities of Daily Living (ADL) scores, renal function evaluation, medication history, the initial bowel preparation protocol, initial bowel preparation evaluation before remedial bowel preparation.
Quality of remedial bowel preparation: The Boston Bowel Preparation Scale (BBPS) for the whole colon and each segment of the colon (S4 File). The BBPS is a standardized 9-point scale for assessing the colon, which is divided into three segments: right colon (cecum and ascending colon segment), transverse colon (transverse colon), and left colon (descending, sigmoid, and rectal segments). Each segment is rated from 0 to 3 based on the degree of cleanliness. The total score, which ranges from 0 to 9, indicates the level of bowel preparation: ≤ 5 points indicates poor preparation, 6–7 points indicates good preparation, and ≥ 8 points indicates very good preparation. A BBPS score of ≥ 6 was considered satisfactory. The success rate was defined as the proportion of patients in each group achieving a BBPS score of ≥ 6.
Remedial bowel preparation time: This refers to the interval between the initiation of remedial bowel cleansing measures and the start of the post-remedial colonoscopy. After stool assessment, patients with inadequate bowel preparation were given additional preparation, contingent upon their consent. The timing assessment was primarily based on medical records and time data from the endoscopy information system. During data collection and analysis, we extracted information from patients’ medical records and recorded the start time of the post-remedial colonoscopy to evaluate the timing of remedial bowel preparation.
The safety of remedial bowel preparation involves documenting any adverse reactions experienced by the patient, such as nausea, vomiting, abdominal distension, abdominal pain, dizziness, or anal itching, as noted in the medical records and reported during telephone follow-up visits.
Remedial bowel preparation tolerance and acceptability were evaluated by contacting patients via telephone to determine their willingness to undergo the same bowel preparation procedure for a future colonoscopy if needed. The Likert scale was used during the telephone follow-up to assess patient satisfaction with the bowel preparation process. It examined three areas: (a) satisfaction with the duration of the bowel preparation; (b) tolerance of discomfort during the procedure; and (c) satisfaction with the service attitude of the medical staff. Satisfaction was rated on a numerical scale from 0 (very dissatisfied) to 10 (very satisfied) (S2 File).

Statistical methods

The data were analyzed using SPSS 25.0 statistical software. For data conforming to a normal distribution, results were presented as the mean ± standard deviation, and an independent samples t-test was utilized for intergroup comparisons. Non-normally distributed data were reported as the median (M) and interquartile range (IQR), with a rank-sum test applied for intergroup comparisons. Categorical data were summarized as the number of cases and corresponding percentages. The chi-square, Fisher’s exact test and rank-sum test were used for group comparisons, with a P-value of less than 0.05 serving as the threshold for statistical significance.

Results

Comparison of general information of patients in both groups

A total of 109 patients with inadequate bowel preparation following routine administration of polyethylene glycol electrolyte solution, either as a single or divided oral intake, were included in the final analysis. Of these, 55 patients were treated with an enema using a colon hydrotherapy machine, while 54 patients received a re-administration of the oral polyethylene glycol electrolyte solution. Evaluating the general characteristics of patients in both groups was crucial for assessing comparability. The analyzed demographic and clinical features included age, gender distribution, body mass index (BMI), Activities of Daily Living (ADL) scores, prevalent underlying diseases, history of pelvic and abdominal surgeries (specifically colorectal, gallbladder, uterine and adnexal, and appendix surgeries), medications, serum creatinine levels, endogenous creatinine clearance (Ccr), the initial bowel preparation protocol and bowel preparation evaluation before remedial bowel preparation. No statistically significant differences were observed between the two groups concerning these characteristics (Table 1).

Table 1. General characteristics of patients in both groups.

Variables	Total (n = 109)	Hydrotherapy device enema group (n = 55)	Oral medication group (n = 54)	Statistic	P
Age, Mean ± SD^a	66.29 ± 9.93	67.09 ± 9.669	65.48 ± 10.21	t^b = 0.845	0.400
Sex, (m/^f)	59/50	27/29	32/22	χ²^c = 1.135	0.287
BMI, Mean ± SD	23.99 ± 3.25	23.89 ± 3.44	24.08 ± 3.08	t = -0.303	0.763
ADL, M^d (IQR)^e	95.00 (5)	95.00 (5)	95.00 (1)	z^f = -0.298	0.765
Diabetes, n(%)	42 (38.5)	25(45.5)	17(31.5)	χ² = 2.246	0.134
Constipation, n(%)	49 (45.0)	25(45.5)	24 (44.4)	χ² = 0.011	0.916
Stroke, n(%)	29 (26.6)	13 (23.6)	16 (29.6)	χ² = 0.501	0.479
History of pelvic-abdominal surgery, n(%)	13 (11.9)	6 (10.9)	7 (13.0)	χ² = 0.109	0.741
Colorectal surgery, n(%)	3 (2.8)	2(3.6)	1(1.9)		1^g
Gallbladder surgery, n(%)	2(1.8)	1(1.8)	1(1.9)		1^g
Uterus and adnexa, n(%)	5(4.6)	2(3.6)	3(5.6)		0.679^g
Appendix surgeries, n(%)	5(4.6)	1(1.8)	4(7.4)		0.206^g
Renal function evaluation
Serum creatinine	72.35 ± 18.97	70.85 ± 19.95	73.87 ± 17.97	t = -0.827	0.409
Endogenous Creatinine Clearance (Ccr)	79.55 ± 22.27	79.19 ± 20.98	79.92 ± 23.71	t = -0.172	0.863
Medication history, n(%)
Calcium antagonists	34(31.1)	18(32.7)	16(29.6)	χ² = 0.122	0.837
NSAIDs	22(20.2)	8(14.5)	14(25.9)	χ² = 2.191	0.159
Anxiolytic and antidepressant drugs	10(9.2)	6(10.9)	4(7.4)	χ² = 0.401	0.742
Diuretics	20(18.3)	7(12.7)	13(24.1)	χ² = 2.342	0.144
Statins	24(22.0)	11(20.0)	13(24.1)	χ² = 0.263	0.650
Metformin	17(15.6)	8(14.5)	9(16.7)	χ² = 0.093	0.797
Glycosidase inhibitors	20(18.3)	12(21.8)	8(14.8)	χ² = 0.892	0.459
The initial bowel preparation protocol (single dose/ split dose)	19/90	8/47	11/43	χ² = 0.642	0.423
Bowel preparation evaluation(Grade 1/ Grade 2) before remedial bowel preparation	55/54	26/29	29/25	χ² = 0.451	0.502

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^aStandard deviation.

^bt-test.

^cChi-square test.

^dMedian.

^eInterquartile range.

^fMann–Whitney test.

^gFisher’s exact test.

Comparison of bowel cleansing quality following remedial bowel preparation between two patient groups

The median total Boston Bowel Preparation Scale (BBPS) score was 7 (3) in the hydrotherapy device group, compared to 6.5 (1) in the oral group, indicating a statistically significant difference in score distribution [median difference (95% CI): 1 (0-1.0), z = -2.075, P = 0.038]. In the left colon, the hydrotherapy device group achieved a BBPS score of 3 (1), which was statistically higher than the oral group, which scored 2 (0) [median difference (95% CI): 1 (0–1), z = -5.586, P < 0.001]. No statistically significant difference was found in the BBPS score distribution for the right colon, where both groups scored 2 (1), z = -0.692, P = 0.489, or for the transverse colon, where both groups scored 2 (1), z = -0.805, P = 0.421 (Table 2).

Table 2. Comparison of the BBPS score after remedial bowel preparation between two patient groups.

	Hydrotherapy device enema group (n = 55)	Oral medication group (n = 54)	Median difference (95%CI)	Z^a	P
Whole colon M^b (IQR^c)	7(3)	6.5(1)	1(0-1.0)	-2.075	0.038
The right colon M (IQR)	2(1)	2(1)	0(0)	-0.692	0.489
The transverse colon M (IQR)	2(1)	2(1)	0(0)	-0.805	0.421
The left colon M (IQR)	3(1)	2(0)	1(0-1.0)	-5.586	<0.001

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^a Mann–Whitney test.

^b Median.

^c Interquartile range.

Comparison of success rates of remedial bowel preparation procedures between two patient groups

The success rate of bowel preparation was 80% in the hydrotherapy device group and 87% in the oral group. There was no statistically significant difference in the success rates between the two groups (χ² = 0.979, P = 0.323) (Table 3).

Table 3. Comparison of success rates of remedial bowel preparation between the two groups.

Groups	Total (cases)	Pass [cases(%)]	Failed [cases(%)]	Chi-Square test
Groups	Total (cases)	Pass [cases(%)]	Failed [cases(%)]	χ²	P
Hydrotherapy device enema group	55	44(80.0)	11(20.0)	0.979	0.323
Oral medication group	54	47(87.0)	7(13.0)	0.979	0.323

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Comparison of remedial bowel preparation time between two groups

The median remedial bowel preparation time, with the interquartile range (IQR) was 80 [20] minutes in the hydrotherapy device group and 92.5 [20] minutes in the oral medication group. There was a statistically significant difference in the distribution of remedial bowel preparation time between the two groups (median difference -15, 95% CI: -20 to -10, z = -3.961, P < 0.001) (Table 4).

Table 4. Comparison of remedial bowel preparation time between two groups.

Groups	M(IQR)(min)	Median difference (95%CI)	Wildcoxon two-sample rank sum test
Groups	M(IQR)(min)	Median difference (95%CI)	Z	P
Hydrotherapy device enema group	80 [20]	-15(-20- -10)	-3.961	<0.001
Oral medication group	92.5 [20]	-15(-20- -10)	-3.961	<0.001

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Comparison of adverse reaction incidence in remedial bowel preparation between two patients groups

The overall incidence of adverse reactions during remedial bowel preparation was 36.4% in the hydrotherapy device group and 88.9% in the oral group. There was a statistically significant difference in the overall incidence of adverse reactions between the two groups (χ² = 32.035, P < 0.001). Specific adverse reactions, such as nausea (0% vs. 77.8%, χ² = 69.594, P < 0.001), vomiting (0% vs. 31.5%, χ² = 20.514, P < 0.001), abdominal distension (12.7% vs. 40.7%, χ² = 10.95, P = 0.001), and abdominal pain (7.3% vs. 24.1%, χ² = 5.843, P = 0.016), were significantly less frequent in the hydrotherapy group compared to the oral group. However, the incidence of dizziness (9.1% vs. 5.6%, χ² = 0.501, P = 0.479) and anal itching and discomfort (14.5% vs. 3.7%, χ² = 3.844, P = 0.093) did not differ significantly between the two groups (Table 5, Fig 2).

Table 5. Comparison of adverse reaction incidence in remedial bowel preparation between two patient groups.

	Hydrotherapy device enema group (n = 55)	Oral medication group (n = 54)	χ²	P
Overall Adverse Reactions n(%)	20(36.4)	48(88.9)	32.035	<0.001
Nausea n(%)	0(0)	42(77.8)	69.594	<0.001
Vomiting n(%)	0(0)	17(31.5)	20.514	<0.001
Bloating n(%)	7(12.7)	22(40.7)	10.95	0.001
Abdominal pain n(%)	4(7.3)	13(24.1)	5.843	0.016
Dizziness n(%)	5(9.1)	3(5.6)	0.501	0.479
Anal itching n(%)	8(14.5)	2(3.7)	3.844	0.093

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Comparison of satisfaction and tolerance of remedial bowel preparation between two patients groups

A total of 72.7% of patients in the hydrotherapy device group indicated that they would opt for the same remedy if remedial bowel preparation was needed for another colonoscopy. In contrast, 5.5% would refuse to the procedure, while 21.8% were undecided during telephone follow-up interviews. In the oral group, 31.5% expressed willingness to choose the same remedy again, 38.9% would refuse, and 31.5% were undecided. There was a statistically significant difference in the rates of choice between the two groups (χ² = 23.345, P < 0.001) (Table 6).

Table 6. Comparison of the acceptance of remedial bowel preparation in two patients groups.

Groups	Total (cases)	Select again[cases(%)]	Rejected[cases(%)]	Unable to select[cases(%)]	Chi-Square test
Groups	Total (cases)	Select again[cases(%)]	Rejected[cases(%)]	Unable to select[cases(%)]	χ²	P
Hydrotherapy device enema group	55	40(72.7)	3(5.5)	12 (21.8)	23.345	<0.001
Oral medication group	54	17(31.5)	21(38.9)	17(31.5)	23.345	<0.001

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The median satisfaction with the time consumed for remedial bowel preparation was 9 (2) in the hydrotherapy device group and 7.5 (3) in the oral medication group. This difference was statistically significant [Median difference (95%CI) 1 (1–2), z = -5.155, P < 0.001]. The median tolerance for discomfort symptoms was 10 (2) in the hydrotherapy group and 6.5 (4) in the oral group. A statistically significant difference was observed between the two groups [Median difference (95%CI) 2 (2–3), z = -5.677, P < 0.001]. The median satisfaction with healthcare professionals was 10 (0) in the hydrotherapy group and 8 (4) in the oral group. The two groups were statistically different [Median difference (95%CI) 1 (0–2), z = -5.14, P < 0.001] (Table 7).

Table 7. Comparison of the satisfaction and tolerance of remedial bowel preparation in two groups of patients.

	Hydrotherapy device enema group (n = 55)	Oral medication group (n = 54)	Median difference (95%CI)	Z	P
Time Consumption Satisfaction M (IQR)	9(2)	7.5(3)	1(1–2)	-5.155	<0.001
Tolerance of discomfort symptomsM (IQR)	10(1)	6.5(4)	2(2–3)	-5.677	<0.001
Satisfaction with healthcare staff M (IQR)	10(0)	8(4)	1(0-2)	-5.140	<0.001

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The grouping of patients based on their decisions showed no significant differences in age, gender, or success rates of remedial bowel preparation among the three groups. However, significant differences were observed in the incidence of adverse reactions (χ² = 38.177, P < 0.001), Boston Bowel Preparation Scale (BBPS) scores after remedial preparation (z = 8.747, P = 0.013), time consumption satisfaction scores (z = 38.78, P < 0.001), tolerance of discomfort symptoms scores (z = 75.436, P < 0.001), and satisfaction with healthcare staff scores (z = 41.915, P < 0.001). The “inability to choose” group had an overall adverse reaction incidence rate of 89%, which was significantly higher than that of the “re-choice” group. Additionally, scores for time consumption satisfaction, tolerance of discomfort, and satisfaction with healthcare staff were higher in the “re-choice” group compared to both the “refusal” and “inability to choose” groups (Table 8).

Table 8. Comparison of characteristics between patients with three different options.

Variables	Select again (n = 57)	Rejected (n = 24)	Unable to select (n = 28)	Statistic	P
Age, Mean ± SDa	66.30 ± 10.41	64.54 ± 9.80	67.79 ± 9.07	F = 0.686	0.506
Sex, (m/f)	30/27	12/12	17/11	χ² = 0.705	0.739
BBPS	7(2)	6(3)*	6.5(2)	Z = 8.747	0.013
The success rates of remedial bowel preparation	87.8%	70.8%	85.7%	χ² = 3.403	0.217
Overall Adverse Reactions	35.1%	95.8%	89.3%	χ² = 38.177	< 0.001
Time Consumption Satisfaction M (IQR)	9 (1.5)	6(3)*	8(1)*	Z = 38.78	< 0.001
Tolerance of discomfort symptomsM (IQR)	10 (1)	5(1)*	7 (1)*	Z = 75.436	< 0.001
Satisfaction with healthcare staff M (IQR)	10 (2)	7 (4)*	10 (2)*	Z = 41.915	< 0.001

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* Statistically different compared to the Select again group.

Discussion

Adequate bowel preparation is crucial for high-quality colonoscopy, as it significantly affects diagnostic accuracy and therapeutic safety during the procedure. Despite routine bowel preparation, inadequate bowel preparation remains a common clinical problem. A meta-analysis of 67 studies reported that the failure rate of bowel preparation quality after routine bowel preparation ranged from 5% to 67%, with a median of 26% [1]. Inadequate bowel preparation can lead to prolonged operation times, increased difficulty in colonoscopy, incomplete examinations, a higher risk of missed lesions, and an increased risk of complications [13-16]. Another meta-analysis of eight studies demonstrated that there was no significant difference in adenoma detection rates between moderate- and high-quality bowel preparation [15]. However, low-quality bowel preparation was associated with significantly lower adenoma detection rates. Patients must schedule their colonoscopy appointments in advance and complete blood tests and electrocardiograms to assess overall health prior to the procedure. Some patients may also need to discontinue anticoagulant and antiplatelet medications, as directed by the referring physician. For inadequate bowel preparation (insufficient to detect polyps larger than 5 mm), it is recommended to either terminate and reschedule the colonoscopy or attempt additional cleansing without canceling the examination [17]. Imagine a scenario where a patient, on the day of their colonoscopy, completes the procedure after opting for remedial bowel preparation due to inadequate initial preparation. This streamlined approach helps avoid re-booking or repeating pre-colonoscopy assessments and bowel preparation, thereby reducing repeat visits and associated costs, and ensuring timely, high-quality examinations. Considering successful clinical outcomes, patient preferences and other relevant economical factors, it is vital to identify a remedial bowel preparation solution that is effective, safe, and well-tolerated for same-day administration.

Polyethylene glycol (PEG) electrolytes are the most commonly used bowel cleanser [16]. Re-administration of oral PEG electrolytes is also common as a remedial measure [18]. In a study of 131 patients, it was observed that those on a 2L oral PEG regimen achieved superior bowel preparation quality, with an adequate bowel preparation rate of 81.5% [8]. However, clinical observations indicate that if the initial bowel preparation with oral PEG electrolytes results in poor cleanliness, the incidence of adverse reactions—such as nausea, vomiting, abdominal distension, and abdominal pain—tends to be higher during remedial preparation. This leads to poor patient adherence and tolerance. Therefore, there is a need for a more efficient, safe, and well-tolerated remedial bowel preparation regimen.

Colon hydrotherapy is a physical therapy device that utilizes water impact and massage to stimulate the colon, resulting in therapeutic benefits. The device is known for its straightforward operation, safety, and reliability. It can be calibrated to meet the specific needs of the patient, allowing for adjustments in water temperature, pressure, and flow to suit diverse treatment requirements. Additionally, it features an automatic cleaning mechanism to ensure the equipment’s hygiene and safety. In clinical practice, colon hydrotherapy is used to manage colon-related disorders, including functional constipation, colon dialysis, chronic colitis, bowel cleansing, and other conditions.

In this study, the Boston Bowel Preparation Scale [19–21] for the entire colon as well as the left colon, were higher in the group using the colon hydrotherapy device enema compared to the oral medication group after remedial bowel preparation. This indicated that colon cleansing was more effective in the former group, with a particularly notable improvement in the left colon cleansing. Additionally, a comparison of the time required for remedial bowel preparation showed that the colon hydrotherapy device enema group required significantly less time than the oral medication group. This suggests that colon hydrotherapy device enemas are faster and more efficient than oral medication for remedial bowel cleansing.

During the course of remedial bowel preparation, no serious complications were observed in either group. However, the overall incidence of adverse reactions in the colon hydrotherapy device enema group was significantly lower than in the oral medication group. Specifically, adverse reactions such as nausea, vomiting, abdominal pain, and abdominal distension occurred less frequently in the hydrotherapy device group. The incidence of other adverse reactions, including dizziness and anal itching, was comparable between the two groups, suggesting that colon hydrotherapy device enemas may be a safer alternative to oral medication for remedial bowel preparation.

In the oral medication group, the most frequent adverse reactions were nausea, vomiting, and bloating. In some instances, these reactions led to patients not consuming the entire bowel cleansing agent or experiencing prolonged bowel preparation times. Among those who underwent hydrotherapy, the most commonly observed adverse reactions were anal itching, bloating, and dizziness. Most patients who experienced dizziness during remedial bowel preparation were of advanced age and presented with conditions such as carotid atherosclerosis, hypertension, cerebral infarction, and other cardiovascular and cerebrovascular diseases (S5 File). Although the incidence of dizziness was slightly higher in the hydrotherapy group compared to the oral medication group, this difference was not statistically significant. Such a reaction could potentially lead to dangerous situations, such as falls. A prospective study should be conducted to further clarify the incidence and risk factors associated with dizziness as an adverse reaction during remedial bowel preparation.

Patients in the colon hydrotherapy device group demonstrated significantly higher tolerance and satisfaction scores compared to the oral medication group. Additionally, a larger proportion of patients in the hydrotherapy group opted to use the same remedy again, indicating greater tolerance and compliance with colon hydrotherapy device enemas for remedial bowel preparation. This finding contrasts with previous studies comparing regular cleansing enemas to oral bowel cleansers [22]. Previous studies have suggested that regular cleansing enemas are less tolerated and accepted than oral cleansers. However, this study attributes the high tolerance and compliance with colon hydrotherapy to several factors:

1) The adjustable temperature and flow rate of the water stream in the colon hydrotherapy device provide greater comfort while ensuring effective cleaning.
2) The device performs repeated flushing and discharging while the patient remains in the lateral position, simplifying the procedure by eliminating the need for the patient to repeatedly get up for discharging.
3) In this study, patients initially underwent bowel preparation with oral compound polyethylene glycol electrolyte powder and were subsequently transitioned to remedial bowel preparation. It seems that the patients lacked confidence in repeating the same initial bowel preparation method. However, the different approach for remedial preparation appeared to boost their confidence and alleviate anxiety.

The endoscopy center in our hospital is currently integrated with the gastroenterology ward, which includes a dedicated enema room equipped with a hydrotherapy device. This retrospective study involved inpatients scheduled for colonoscopy due to various indications. A nurse operates the colon hydrotherapy machine daily. This machine is used for bowel cleansing and often for treating chronic constipation and administering medication retention enemas. When a colonic hydrotherapy enema is needed, the attending physician coordinates with the nurse to ensure the procedure is conducted promptly.

In this retrospective cohort study, colon hydrotherapy device enemas for remedial bowel preparation demonstrated superiority in bowel cleansing, safety, and tolerability. However, the study was limited by its non-randomised controlled trial design, small sample size, and potential recall bias. Further validation is needed through multicentre, large-sample, prospective randomised controlled trials. Additionally, as the remedial bowel cleansing program is implemented in clinical practice, further investigation into the coordination among attending physicians, the endoscopy center, nursing staff, and patients is necessary. In our healthcare system, the cost of administering 2 liters of Compound Polyethylene Glycol Electrolyte Powder orally is RMB 69.3, whereas a hydrotherapy enema costs RMB 56. Thus, hydrotherapy enema for bowel preparation is less expensive for patients compared to the oral administration of Compound Polyethylene Glycol Electrolyte Powder. Further studies will be conducted to compare the cost-effectiveness of these two methods. This will enhance the program’s adaptability and facilitate its broader adoption.

Conclusions

The proportion of patients with risk factors for inadequate bowel preparation is increasing in clinical practice. To address this issue, it is essential to continue improving the routine bowel preparation plan [23], effectively educate patients [17, 19, 23], and enhance the assessment of bowel cleanliness before and during colonoscopy [24]. Additionally, implementing efficient, safe, and well-tolerated remedial bowel preparation measures is crucial for ensuring high-quality colonoscopy examinations. In conclusion, the colon hydrotherapy device enema is a highly effective method for bowel cleansing, characterized by a short preparation time, a low incidence of adverse events, and high tolerability. Consequently, it is an effective and safe remedial therapy for patients with inadequate bowel preparation prior to colonoscopy.

Supporting information

S1 File. All data underlying the findings.

(XLSX)

pone.0319493.s001.xlsx^{(60.7KB, xlsx)}

S2 File. Telephone Follow-up Survey.

(DOCX)

pone.0319493.s002.docx^{(16.5KB, docx)}

S3 File. Colonic hydrotherapy device operation procedure.

(DOCX)

pone.0319493.s003.docx^{(11.6KB, docx)}

S4 File. The boston bowel preparation scale.

(DOCX)

pone.0319493.s004.docx^{(12.2KB, docx)}

S5 File. Information on 8 patients with dizziness symptoms.

(XLSX)

pone.0319493.s005.xlsx^{(13.8KB, xlsx)}

Data Availability

All relevant data are within the paper and its Supporting Information files.

Funding Statement

The author(s) received no specific funding for this work.

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PLoS One. 2025 Mar 19;20(3):e0319493. doi: 10.1371/journal.pone.0319493.r001

Author response to Decision Letter 0

19 Aug 2024

PLoS One. doi: 10.1371/journal.pone.0319493.r002

Decision Letter 0

Chih-Wei Tseng

14 Nov 2024

PONE-D-24-32926Remedial colon hydrotherapy device enema as a salvage strategy for inadequate bowel preparation for colonoscopy: A retrospective cohort studyPLOS ONE

Dear Dr. Zhang,

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5. Review Comments to the Author

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Reviewer #1: This retrospective study aims to compare the effectiveness of hydrotherapy and oral polyethylene glycol (PEG) as alternative methods for bowel preparation in salvage cleaning for colonoscopy. There are several concerns to this paper as the following:

Major concerns:

1. Line 111: The extended time between the colonoscopy exam and the follow-up phone call may affect the patient's ability to recall details of the preparation and procedure. What were the phone call questionnaires?

2. Line 123 -130: The BBPS score or stool assessment prior to salvage cleansing should be presented.

3. Line 128-130: Is the BBPS score assessed during the first colonoscopy view, and if BBPS score <6 or <2 in any segment, is salvage cleaning then applied? Please clarify this point.

4. Line 142: The timing and method for assessing bowel cleanliness before the salvage cleaning preparation were not provided in the article.

5. Line 184, 363-364: What are the questionnaires consisted in the phone calls?? Please provide the questionnaires and chart as supplement data. How is the patient satisfaction score graded? Is the Leaker Score used?

6. Line 213: The difference between BBPS scores of 7 and 6.5 is minimal, especially given the study's small sample size. Hydrotherapy appears to be most effective in cleaning the descending colon, as shown in Table 2, but it seems to have limited impact on the ascending and transverse colons. Therefore, it is recommended to increase the sample size to enhance the reliability of the observed differences.

7. Line 229: How is the success rate defined? Was cleanliness graded and compared before and after salvage cleaning? What is the average experience in years of the colonoscopists? Please provide the actual data in chart or supplementary data.

8. It would be interesting to compare the ADR between the two groups.

9. Line 358-360: The supplement data or chart did not provide information on conditions such as carotid atherosclerosis, hypertension, cerebral infarction, and numerous other cardiovascular and cerebrovascular diseases. On what basis was this conclusion made?

10. The BBPS score shown in the S1 file assessed after applying salvage strategy?

Minor concerns:

1. English writing skills should be improved.

2. The make and model of the hydrotherapy machine should be included in the method or supplementary S2 file.

3. The labels in Table 2 are unclear. “Hepatic, transverse and splenic flexure” is confusing.

4. Line 342-343: redundant, repeated and unclear statement.

5. Reduce the use of long sentences. For example in line 394 to 399.

6. In S1 file, cases number 25, 71, and 82: The “colonoscopy” column indicates “poor bowel preparation”, yet the BBPS score is still 6. Please clarify.

6. Please review all the punctuation.

Reviewer #2: It has been my pleasure to review the manuscript titled “Remedial colon hydrotherapy device enema as a salvage strategy for inadequate bowel preparation for colonoscopy: A retrospective cohort study”. As authors say, it is a priority to guarantee a correct preparation before colonoscopy to improve the rates of diagnosis during the procedure. Preparation protocols may fail due to bad tolerance, mistakes during the performance, patients’ features, etc.; so it is necessary to have alternative possibilities. It is also very important that patients do not have poor experiences during the preparation so they agree to continue controls when needed.

Authors make with this article a very interesting proposal. However there are many points I recommend further development before accepting this manuscript for publication.

Comments about the preparation:

· There is a detailed explanation about second preparations, but not about the main protocol of colon preparation. All patients followed a standard protocol? Could there be differences?

· Was there any evaluation of previous experience in colonoscopy?

· If I understand correctly, patients with inadequate colon preparation have to do a second treatment after a colonoscopy. So after sedation, they are informed and make a choice between hydrotherapy and oral medication. How much time passes between they awake and start the second preparation?

Comments about the patients, selection criteria and potential bias:

· How many patients were excluded of the final evaluation? Criteria is explained, but there is no further information.

· It is a very important limitation the N of patients and do not allow subgroups. As we see in the S1 file, their baseline characteristics in medical antecedents are very different. For example, there are patients that have incomplete intestinal obstruction, but no information of the level is given. Further, history of abdominal surgery is a very vague term. As we can see in the file, there are included in a same group colorectal tumor surgeries, gynecological surgeries, etc. without differentiation. They are important details for colonic transit and preparation results.

· No information about baseline medications is given, and they may influence on final results of preparations.

· Hydrotherapy or oral medication were personal choices, although there are some that said they were unable to make a choice. What was the reason in these cases? Was there any evaluation of preparation failure in previous studies? This may influence on personal preferences and experience of the patient.

· Follow-up interviews were done after one year or more. Recall bias is a huge limitation here.

Comments about adverse effects:

· I understand after reading S1 file that some patients were hospitalized. Was there any evaluation of kidneys function after double preparation?

· Colon hydrotherapy may cause rectal ulcers or other lesions, even if performed by a well-experienced nurse. Were there any lesions?

Comments about the conclusions of the Authors:

· The first sentence (lines 393-394) is not well expressed. The increase of colonoscopies do not exactly increase the number of inadequate preparations. But it is true that having correct protocols and alternatives for colon preparation is a main step.

I have some suggestions about economical details to add in the Discussion Section, if it is possible, to give some more context to the article.

· What is the difference between repeating the colonoscopy the same day or another day?

· I assume there is an extra agenda in the Endoscopy Unit to repeat a patient with poor / inadequate colon preparation. How is it managed? The goal is to avoid cancellation, but as care pressure is increasing and agendas are commonly tight, it is very difficult to me to understand how it is done.

· What is the extra cost to have every day a trained nurse to perform colonic hydrotherapy, just in case it is needed?

Reviewer #3: Thank you for the opportunity to review the manuscript, "Remedial colon hydrotherapy device enema as a salvage strategy for inadequate bowel preparation for colonoscopy: A retrospective cohort study." Please find my comments below:

1. I am not familiar with the term "electronic colonoscopy" is this just a standard colonoscopy or is this a variant?

2. How did you select who received which intervention?

3. Were any of your satisfaction assessments validated tools?

4. Can you expand on how many patients were sent for remedial therapy solely based on the passage of stool just prior to their scheduled procedure vs how many had the scope placed and the BBPS evaluated? For those where the scope was placed and the BBPS was evaluated for at least 1 segment was there a difference in the change in prep quality adjustment between the 2 interventions?

5. How do you define preprocedureal constipation for the purposes of this study?

6. What is the definition for this study of "success rate" of the bowel preparation?

7. What is the difference in cost between these two measures?

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Reviewer #3: No

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PLoS One. 2025 Mar 19;20(3):e0319493. doi: 10.1371/journal.pone.0319493.r003

Author response to Decision Letter 1

26 Dec 2024

Dear Reviewers:

We are writing to express our sincere appreciation for your insightful comments and suggestions regarding our article entitled “Remedial colon hydrotherapy device enema as a salvage strategy for inadequate bowel preparation for colonoscopy: A retrospective cohort study” (Manuscript No: PONE-D-24-32926). This study explores remedial strategies to improve bowel preparation for colonoscopy, a critical aspect of effective diagnostic procedures. The constructive feedback provided by the reviewers has been invaluable in enhancing the quality of our manuscript. We have made extensive modifications and supplemented additional data to strengthen our findings and ensure the robustness of our results. All changes in the revised manuscript are highlighted in red text for your convenience. Below this letter, you will find point-by-point responses to the comments from the three reviewers. We believe these revisions have significantly improved our manuscript, and we are grateful for the opportunity to address these important issues.

Reviewer #1

Major concerns:

The author's answer: Thank you for your valuable comments. We apologize for not uploading the telephone questionnaire as an attachment when the manuscript was first submitted. The telephone questionnaire in this study consisted of three parts.

The first part was the Introduction, which explained the purpose and content of the telephone follow-up to the respondents and obtained their consent to proceed with the questionnaire. The second part aimed to confirm the respondent's basic personal information, including name, age, and gender. The third part consisted of seven main questions designed to gather detailed insights relevant to our study. These questions were as follows:

① Do you still clearly recall the process of your colonoscopy examination conducted at our endoscopy center in [Time]?

② Given that you underwent remedial bowel preparation for a previous colonoscopy due to inadequate preparation, would you prefer the same remedial preparation method for any future colonoscopies where bowel preparation is suboptimal? (Select again, Rejected, Unable to select)

③ On a scale from 0 to 10, where 0 is very dissatisfied and 10 is very satisfied, how would you rate the time consumed in the remedial bowel preparation process?

④ On a scale from 0 to 10, where 0 is very dissatisfied and 10 is very satisfied, how satisfied were you with the level of discomfort you experienced from the various symptoms during the remedial bowel preparation process?

⑤ On a scale from 0 to 10, where 0 is very dissatisfied and 10 is very satisfied, how satisfied were you with the service attitude of the medical staff during the remedial bowel preparation process?

⑥ Could you please detail the discomfort you encountered during your remedial bowel preparation?

⑦ Have you encountered any issues or difficulties that you would like to share?

These questions were designed to assess the respondents' experiences and satisfaction with the remedial bowel preparation process. We uploaded the telephone questionnaire as supplementary data, as S2 File. Meanwhile we have a statement in the manuscript at lines 218 to 225.

In conducting this retrospective study, we included patients who underwent remedial bowel preparation between April 2019 and June 2022 to ensure an adequate sample size for inclusion. The telephone questionnaire was conducted between October 2022 and December 2023, which introduced the potential for recall bias in the results.To minimize recall bias, our team members reviewed the patients' inpatient medical records to identify any discrepancies with the telephone questionnaire responses. This cross-verification helped ensure the accuracy of the data collected. To further address recall bias, we are planning a prospective study. This study will aim to collect information from patients immediately after they have received bowel preparation, thereby reducing the reliance on long-term memory and improving data accuracy.

2.Line 123 -130: The BBPS score or stool assessment prior to salvage cleansing should be presented.

The author's answer: We appreciate your valuable comments. In this retrospective study, the degree of bowel cleansing prior to remedial bowel preparation was assessed based on the fecal characteristics of the last bowel movement before the proposed colonoscopy. The assessment was graded into four categories:

Grade 1: Very poor bowel preparation (brown fecal water with a large amount of waste material).

Grade 2: Relatively poor (dark yellow fecal water with a small amount of fecal waste material).

Grade 3: Good (yellowish clear watery stool).

Grade 4: Very good (colorless clear watery stool).

Grades 1 and 2 were considered inadequate bowel preparation. We have revised and clarified lines 125-135 of the article to better explain this grading system. The results of the stool assessment prior to bowel preparation for each patient are provided in the S1 file.

In the manuscript, we conducted a statistical analysis of the pre-remedial bowel preparation fecal assessment results for both groups. The overall distribution was similar, with no statistical difference observed (χ² = 0.451, P = 0.502). This analysis is presented in lines 248-251 of the manuscript, and the statistical results are detailed in Table 1.

3.Line 128-130: Is the BBPS score assessed during the first colonoscopy view, and if BBPS score <6 or <2 in any segment, is salvage cleaning then applied? Please clarify this point.

The author's answer: We thank you for your helpful comments and apologize for not explaining this issue clearly in the article. In our daily clinical practice at the Gastroenterology Department and Endoscopy Centre, we perform an initial assessment of bowel cleanliness for patients undergoing colonoscopy on the day of the scheduled examination. This assessment is based on the patient's last bowel movement, and the results are recorded in the patient's medical record. For patients assessed as Grade 1 or Grade 2, we inform them of the potential adverse effects of poor bowel preparation and recommend remedial bowel preparation, while ultimately respecting the patient's choice.

In this retrospective study, we did not use the Boston Bowel Preparation Scale (BBPS) score to decide whether a patient should undergo remedial bowel preparation. During data collection, we found that only 3 of 121 patients with a left hemicolon BBPS score of less than 2 at the start of the colonoscopy were withdrawn and underwent remedial bowel preparation at the end of the procedure. The final 109 patients included in the study were judged to have failed bowel preparation based solely on their final bowel movement after routine preparation. We apologize for not detailing this in the article and are correcting and clarifying this information on lines 125-135 and lines 155-159.

4.Line 142: The timing and method for assessing bowel cleanliness before the salvage cleaning preparation were not provided in the article.

The author's answer: Thank you for pointing out this issue in the manuscript. We apologize for not explicitly stating the timing and method for assessing bowel cleanliness prior to the salvage cleaning preparation in the manuscript. We have now detailed and revised this information in lines 125-135. In our daily clinical practice at the Gastroenterology Department and Endoscopy Centre, we perform an initial assessment of bowel cleanliness for patients undergoing colonoscopy on the day of the scheduled examination. This assessment is based on the patient's last bowel movement, and the results are recorded in the patient's medical record. For patients assessed as Grade 1 or Grade 2, we inform them of the potential adverse effects of poor bowel preparation and recommend remedial bowel preparation, while ultimately respecting the patient's choice.

5.Line 184, 363-364: What are the questionnaires consisted in the phone calls? Please provide the questionnaires and chart as supplement data. How is the patient satisfaction score graded? Is the Leaker Score used?

The author's answer: We appreciate your pointing out these issues in the manuscript, and we sincerely apologize for not addressing the issues you raised in the manuscript. We uploaded the telephone questionnaire as supplementary data, as S2 File. The telephone questionnaire consisted of seven questions. The tool used for the satisfaction assessment part of the telephone follow-up was the Likert scale, which assessed patients' satisfaction with the bowel preparation process by rating the following three areas: (a) satisfaction with the time taken for the bowel preparation process; (b) tolerance of discomfort during the bowel preparation process; and (c) satisfaction with the service attitude of the medical staff during the bowel preparation process. Satisfaction was rated on a numerical scale from 0 (very dissatisfied) to 10 (very satisfied).

6.Line 213: The difference between BBPS scores of 7 and 6.5 is minimal, especially given the study's small sample size. Hydrotherapy appears to be most effective in cleaning the descending colon, as shown in Table 2, but it seems to have limited impact on the ascending and transverse colons. Therefore, it is recommended to increase the sample size to enhance the reliability of the observed differences.

The author's answer: Thank you for your valuable comments. We fully understand your concerns. The sample size of this retrospective study is indeed small, and there are unavoidable issues such as recall bias and incomplete data. To improve the reliability of the observed differences and to reduce these common issues in retrospective studies, our team is continuing to conduct relevant prospective studies. We aim to collect more subjects with complete data to support our research findings.

7.Line 229: How is the success rate defined? Was cleanliness graded and compared before and after salvage cleaning? What is the average experience in years of the colonoscopists? Please provide the actual data in chart or supplementary data.

The author's answer: Thank you for your question. We sincerely apologize for not defining "success rate" within the manuscript. In this study, the Boston Bowel Preparation Scale (BBPS) was utilized to evaluate the quality of bowel preparation in patients undergoing salvage bowel preparation. The BBPS is a standardized 9-point scale for assessing the colon, which is divided into three segments: right colon, transverse colon, and left colon. Each segment is rated from 0 to 3 based on the degree of cleanliness. The total score, which ranges from 0 to 9, indicates the level of bowel preparation: ≤5 points indicates poor preparation, 6–7 points indicates good preparation, and ≥8 points indicates very good preparation. A BBPS score of ≥6 was considered satisfactory. The success rate was defined as the proportion of patients in each group achieving a BBPS score of ≥6. Additionally, differences in BBPS scores across bowel segments and overall scores were compared between the two groups. The definition of success rate has been added to the manuscript at lines 204-205. To facilitate understanding of the scale content, we have uploaded the BBPS as supplementary data, designated as S4 File.

In this retrospective study, BBPS scores for patients were not recorded before remedial bowel preparation. the degree of bowel cleansing prior to remedial bowel preparation was assessed based on the fecal characteristics of the last bowel movement before the proposed colonoscopy. The assessment was graded into four categories:

Grade 1: Very poor bowel preparation (brown fecal water with a large amount of waste material).

Grade 2: Relatively poor (dark yellow fecal water with a small amount of fecal waste material).

Grade 3: Good (yellowish clear watery stool).

Grade 4: Very good (colorless clear watery stool).

Grades 1 and 2 were considered indicative of inadequate bowel preparation. For patients assessed with these grades, we inform them of the potential adverse effects of insufficient bowel preparation and recommend remedial measures, while ultimately respecting the patient's decision. The results of the stool assessment prior to bowel preparation for each patient are provided in the S1 file. In the manuscript, we conducted a statistical analysis of the pre-remedial bowel preparation fecal assessment results for both groups. The overall distribution was similar, with no statistical difference observed (χ² = 0.451, P = 0.502). This analysis is presented in lines 249-251 of the manuscript, and the statistical results are detailed in Table 1.

Our endoscopy center currently employs five endoscopists. One has 20 years of experience, while the remaining four have 7, 8, 10, and 4 years of experience, respectively.

8.It would be interesting to compare the ADR between the two groups.

The author's answer: Thank you for your valuable comments. We have compared the ADR between the two groups in the results section (line 291-303). The statistics are presented in Table 5, along with Fig 2, which provides a more visual comparison of the ADR between the two groups.

Fig 2. Adverse reaction incidence in remedial bowel preparation between two patient groups ns, no significance; *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001

9.Line 358-360: The supplement data or chart did not provide information on conditions such as carotid atherosclerosis, hypertension, cerebral infarction, and numerous other cardiovascular and cerebrovascular diseases. On what basis was this conclusion made?

The author's answer: Thank you for your valuable comments. In this retrospective study, we observed that 5 patients in the hydropathy enema group and 3 in the oral medication group experienced dizziness. Such reactions could lead to dangerous situations like falls, prompting further analysis of these patients' case records to identify common characteristics. We found that the average age of these 8 patients was 74.25±5.6 years, and all had a history of cardiovascular and cerebrovascular diseases. Therefore, we reported in the article, "The majority of patients who experienced dizziness during remedial bowel preparation were of advanced age and presented with a combination of carotid atherosclerosis, hypertension, cerebral infarction, and several other cardiovascular and cerebrovascular diseases." The clinical diagnoses of all patients are detailed in S1 file, and we compiled the clinical information of these 8 patients into S5 file. We will continue prospective studies to clarify the incidence and risk factors associated with dizziness as an adverse reaction during remedial bowel preparation.

10.The BBPS score shown in the S1 file assessed after applying salvage strategy?

The author's answer: Thank you for your question. Yes. After remedial bowel preparation, the patient's bowel cleanliness was assessed using the Boston Bowel Preparation Scale (BBPS).

Minor concerns:

1. English writing skills should be improved.

The author's answer: Firstly, I would like to express my sincere gratitude for the feedback you have provided. We value your comments on improving our English writing skills. We recognize that there are deficiencies in the English expression in this submission, which may have impacted the clarity and professionalism of the paper. We sincerely apologize for this and promise to take steps to improve. To enhance the quality of the paper, we have engaged a professional English editor to conduct a thorough language review of the entire text. Additionally, we plan to use advanced language correction software to aid future writing efforts, ensuring that submitted papers meet the highest linguistic standards. And here we did not list the changes but marked in red in the revised paper. We are committed to continuously improving our English writing skills in future research and writing, ensuring that our work meets the standards of the journal.

Thank you again for your feedback and support.

2.The make and model of the hydrotherapy machine should be included in the meth

Attachment

Submitted filename: A rebuttal letter.docx

pone.0319493.s007.docx^{(150.3KB, docx)}

PLoS One. doi: 10.1371/journal.pone.0319493.r004

Decision Letter 1

Chih-Wei Tseng

12 Jan 2025

PONE-D-24-32926R1Remedial colon hydrotherapy device enema as a salvage strategy for inadequate bowel preparation for colonoscopy: A retrospective cohort studyPLOS ONE

Dear Dr. Zhang,

Please submit your revised manuscript by Feb 26 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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We look forward to receiving your revised manuscript.

Kind regards,

Chih-Wei Tseng

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Reviewer #1: (No Response)

Reviewer #2: Thank for allowing to review this manuscript. The Authors have gone through all points expressed by the Reviewers very carefully.

I have some minor comments to give:

· Lines 82-83: these medications can induce secondary effects in the digestive tract, such as nausea, vomiting and (add) “alterations in intestinal transit”4.

· Lines 118-119: I am confused with the sentence “The use of tryciclic antidepressants or anesthesia also increases this risk”. Is “anesthesia” referring to analgesia / pain killers?

· Line 182: I would separate in different paragraphs these sentences: one paragraph for hydrotherapy, and one for oral medication.

· Line 446: I would separate in different paragraphs these sentences: one paragraph for the hospital organization, one for comments about the study.

· In my opinion, the conclusion given is too aggressive. The results of this retrospective study lead to think that colon hydrotherapy is a good and safe remedial therapy for patients with inadequate bowel preparation, but there is no strength in data to say that “it is recommended as the optimal remedial strategy”. I would be more cautious with this sentence.

Reviewer #3: Thank you for the opportunity to review the revised manuscript, "Remedial colon hydrotherapy device enema as a salvage strategy for inadequate bowel preparation for colonoscopy: A retrospective cohort study." Please find my comments below:

1. You list as exclusion criteria "Patients who used two or more remedial options in combination." Could you be more clear here. I agree that if they used both techniques without an evaluation between each technique it would be appropriate to exclude. However, if they used one method and had an inadequate prep necessitating use of the other technique, then they should be included as a treatment failure.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

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Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

**********

PLoS One. 2025 Mar 19;20(3):e0319493. doi: 10.1371/journal.pone.0319493.r005

Author response to Decision Letter 2

17 Jan 2025

Dear Editors and Reviewers,

We would like to express our sincere gratitude to the editors and reviewers for their thorough examination of our manuscript and for providing valuable and constructive feedback. We deeply appreciate the time and effort invested in reviewing our work, and we are confident their insights will substantially enhance the quality of our study.

Our article, titled "Remedial Colon Hydrotherapy Device Enema as a Salvage Strategy for Inadequate Bowel Preparation for Colonoscopy: A Retrospective Cohort Study" (Manuscript No: PONE-D-24-32926), explores strategies to improve bowel preparation—a crucial component of effective diagnostic procedures for colonoscopy. We are pleased that the reviewers have acknowledged the significance and novelty of our research. Their suggestions have been instrumental in refining and clarifying our findings. We have carefully considered each of their comments and made the necessary revisions to address the issues raised. For your convenience, all changes in the revised manuscript are highlighted in red text. We have rechecked the reference list of the manuscript to ensure its completeness and accuracy. The 13th and 22nd references in the article are in Chinese, and we have labeled them in the reference list according to ICMJE recommendations（line 520 and line 551）.

Below this letter, you will find point-by-point responses to the reviewers' comments.

We believe these revisions have significantly strengthened our manuscript, and we appreciate the opportunity to address these important concerns.

Reviewer #1: (No Response)

Reviewer #2: Thank for allowing to review this manuscript. The Authors have gone through all points expressed by the Reviewers very carefully.

I have some minor comments to give:

· Lines 82-83: these medications can induce secondary effects in the digestive tract, such as nausea, vomiting and (add) “alterations in intestinal transit”.

The author's answer: Thank you for your valuable comments. Your revision has made this statement more comprehensive and precise. We have incorporated this change into the manuscript (lines 83-84).

· Lines 118-119: I am confused with the sentence “The use of tryciclic antidepressants or anesthesia also increases this risk”. Is “anesthesia” referring to analgesia / pain killers?

The author's answer: We thank you for your helpful comments and apologize for not explaining this issue clearly in the article. In the manuscript, “anesthesia” is referring to narcotic analgesics, such as opioids. For greater clarity and to avoid misunderstandings, we have revised this line in the manuscript to read: "The use of tricyclic antidepressants or narcotic analgesics, such as opioids, also increases the associated risks." (lines 118-119)

· Line 182: I would separate in different paragraphs these sentences: one paragraph for hydrotherapy, and one for oral medication.

The author's answer: Thank you for your valuable advice. This revision enhances the article's structure. We have reorganized this section of the manuscript into two paragraphs: one focused on hydrotherapy and the other on oral medication. (lines 178-195)

· Line 446: I would separate in different paragraphs these sentences: one paragraph for the hospital organization, one for comments about the study.

The author's answer: Thanks again for your valuable comment. We have reorganized this section of the manuscript into two paragraphs: one focused on the hospital organization and the other on comments about the study. (lines 446-467)

The author's answer: Thank you for your valuable comments. We fully understand your concerns. Indeed, in this retrospective study, the conclusions were initially expressed too assertively. Based on the current study results, we recognize the need to conduct further prospective studies to validate our conclusions. Following your comments, we have revised the abstract and conclusion sections of the manuscript, which now state: "It is recommended as an effective and safe remedial therapy for patients with inadequate bowel preparation prior to colonoscopy." (lines 64-65) and "Consequently, it is an effective and safe remedial therapy for patients with inadequate bowel preparation prior to colonoscopy." (lines 477-478).

The author's answer: Thank you for your valuable comments, and we apologize for not clearly presenting this in the manuscript. In this retrospective clinical study, we included "patients with a combination of two or more remedies" as an exclusion criterion. In clinical practice, the specifics of combining two or more therapeutic regimens include the following scenarios:

1.After routine bowel preparation, if a patient is initially assessed as having inadequate bowel preparation, the treating clinician may first administer a low dose of polyethylene glycol (PEG) electrolyte powder orally. If the patient is unable to continue oral intake due to severe nausea, vomiting, or other adverse reactions, or if there is no bowel movement post-intake, the clinician may communicate with the patient to proceed with either a plain cleansing enema or a colon hydrotherapy device enema to continue the bowel preparation.

2.Patients evaluated as having poor bowel preparation via fecal assessment, who did not respond to a plain cleansing enema, might receive a colon hydrotherapy device enema.

These patients undergo colonoscopy following a complex combination of bowel preparation methods, with cleanliness assessed using the BBPS scale. We determined that it was challenging to ascertain whether the bowel cleanliness was due to a specific bowel preparation regimen or the combined effect of different regimens. Therefore, we excluded patients who used combinations of two or more bowel cleansing regimens in this retrospective clinical trial. This explanation is provided in lines 167-170 of the manuscript.

Thank you again for your suggestion, which has highlighted the need to further investigate and validate the scope of colon hydrotherapy device enema as a remedial bowel preparation method. This includes not only its use for inadequate bowel preparation following conventional regimens but also exploring its value after other remedial preparation regimens.

Once again, we thank the reviewers for their support and for their role in helping us to improve our manuscript. We look forward to the opportunity to further discuss our work with you.

Yours sincerely,

Dongxuan Zhang

17 January 2025

Attachment

Submitted filename: A_rebuttal_letter_auresp_2.docx

pone.0319493.s008.docx^{(16.7KB, docx)}

PLoS One. doi: 10.1371/journal.pone.0319493.r006

Decision Letter 2

Chih-Wei Tseng

4 Feb 2025

Remedial colon hydrotherapy device enema as a salvage strategy for inadequate bowel preparation for colonoscopy: A retrospective cohort study

PONE-D-24-32926R2

Dear Dr. Zhang,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Chih-Wei Tseng

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

All comments have been addressed

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #2: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #2: No

Reviewer #3: No

**********

PLoS One. doi: 10.1371/journal.pone.0319493.r007

Acceptance letter

Chih-Wei Tseng

PONE-D-24-32926R2

PLOS ONE

Dear Dr. Zhang,

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team.

At this stage, our production department will prepare your paper for publication. This includes ensuring the following:

* All references, tables, and figures are properly cited

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If revisions are needed, the production department will contact you directly to resolve them. If no revisions are needed, you will receive an email when the publication date has been set. At this time, we do not offer pre-publication proofs to authors during production of the accepted work. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few weeks to review your paper and let you know the next and final steps.

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on behalf of

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PLOS ONE

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

S1 File. All data underlying the findings.

(XLSX)

pone.0319493.s001.xlsx^{(60.7KB, xlsx)}

S2 File. Telephone Follow-up Survey.

(DOCX)

pone.0319493.s002.docx^{(16.5KB, docx)}

S3 File. Colonic hydrotherapy device operation procedure.

(DOCX)

pone.0319493.s003.docx^{(11.6KB, docx)}

S4 File. The boston bowel preparation scale.

(DOCX)

pone.0319493.s004.docx^{(12.2KB, docx)}

S5 File. Information on 8 patients with dizziness symptoms.

(XLSX)

pone.0319493.s005.xlsx^{(13.8KB, xlsx)}

Attachment

Submitted filename: A rebuttal letter.docx

pone.0319493.s007.docx^{(150.3KB, docx)}

Attachment

Submitted filename: A_rebuttal_letter_auresp_2.docx

pone.0319493.s008.docx^{(16.7KB, docx)}

Data Availability Statement

All relevant data are within the paper and its Supporting Information files.

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PERMALINK

Remedial colon hydrotherapy device enema as a salvage strategy for inadequate bowel preparation for colonoscopy: A retrospective cohort study

Dongxuan Zhang

Chunxia Zhao

Yuan Tao

Jiao Zhang

Qisheng Zhang

Da Li

Ping Ye

Xiaobo Yu

Chao Chen

Roles

Abstract

Objective

Methods

Results

Conclusions

Introduction

Materials and methods

General information

Fig 1. The flow chart.

Inclusion criteria

Exclusion criteria

Remedial measures

Collection indicators

Statistical methods

Results

Comparison of general information of patients in both groups

Table 1. General characteristics of patients in both groups.

Comparison of bowel cleansing quality following remedial bowel preparation between two patient groups

Table 2. Comparison of the BBPS score after remedial bowel preparation between two patient groups.

Comparison of success rates of remedial bowel preparation procedures between two patient groups

Table 3. Comparison of success rates of remedial bowel preparation between the two groups.

Comparison of remedial bowel preparation time between two groups

Table 4. Comparison of remedial bowel preparation time between two groups.

Comparison of adverse reaction incidence in remedial bowel preparation between two patients groups

Table 5. Comparison of adverse reaction incidence in remedial bowel preparation between two patient groups.

Fig 2. Adverse reaction incidence in remedial bowel preparation between two patient groups ns, no significance; * , P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001.

Comparison of satisfaction and tolerance of remedial bowel preparation between two patients groups

Table 6. Comparison of the acceptance of remedial bowel preparation in two patients groups.

Table 7. Comparison of the satisfaction and tolerance of remedial bowel preparation in two groups of patients.

Table 8. Comparison of characteristics between patients with three different options.

Discussion

Conclusions

Supporting information

Data Availability

Funding Statement

References

Author response to Decision Letter 0

Decision Letter 0

Chih-Wei Tseng

Roles

Author response to Decision Letter 1

Decision Letter 1

Chih-Wei Tseng

Roles

Author response to Decision Letter 2

Decision Letter 2

Chih-Wei Tseng

Roles

Acceptance letter

Chih-Wei Tseng

Roles

Associated Data

Supplementary Materials

Data Availability Statement

ACTIONS

PERMALINK

RESOURCES

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Cited by other articles

Links to NCBI Databases

Fig 2. Adverse reaction incidence in remedial bowel preparation between two patient groups ns, no significance; * , P ≤ 0.05; , P ≤ 0.01; *, P ≤ 0.001.