Diagnostic Accuracy of Anorectal Manometry in Identifying Dyssynergic Defecation among Chronic Constipation Patients

Abstract

Background:

Dyssynergic defecation (DD) is a common yet underdiagnosed subtype of chronic constipation, often refractory to conventional treatment. Anorectal manometry (ARM) is a valuable physiological tool for identifying neuromuscular abnormalities contributing to DD.

Objective:

This study aimed to assess the diagnostic accuracy of ARM in detecting DD among patients with chronic constipation.

Materials and Methods:

A prospective observational study was conducted at Dr. D. Y. Patil Medical College, Pune, between January 2023 and February 2025, involving 102 patients with chronic constipation unresponsive to laxatives and lifestyle changes. Patients underwent high-resolution ARM and balloon expulsion test (BET). Dyssynergic patterns were classified using Rao’s criteria. Data were analyzed using SPSS v26.0.

Results:

Among the participants (mean age 45.53 ± 13.3 years), 75.5% were diagnosed with DD via ARM. The most prevalent manometric subtype was Type IV (28.4%), followed by Type I (21.6%). ARM demonstrated high diagnostic accuracy with a sensitivity of 97.4%, specificity of 88.5%, and overall accuracy of 95.1% when compared with BET.

Conclusion:

ARM is a reliable diagnostic modality for evaluating functional defecatory disorders. Incorporating ARM into routine evaluation of chronic constipation, especially when empirical therapies fail, can significantly enhance diagnostic precision and guide targeted interventions such as biofeedback therapy.

INTRODUCTION

Chronic constipation is a common gastrointestinal disorder characterized by infrequent and/or difficult passage of stools. Its prevalence varies widely, ranging from 1% to 80%, due to differences in diagnostic criteria and study populations.[1] Multiple factors contribute to its pathogenesis, including dietary habits, genetic predisposition, intestinal motility, nutrient absorption, socioeconomic conditions, lifestyle factors, and biological and pharmacological influences.[2]

According to the Rome IV criteria, functional constipation is diagnosed when 25% of bowel movements are associated with at least two of the following symptoms: straining, hard or lumpy stools, sensation of incomplete evacuation, anorectal obstruction, need for manual maneuvers, or fewer than three defecations per week over the past 3 months, with symptom onset exceeding 6 months. Chronic constipation can be categorized into four subtypes: normal transit constipation, slow transit constipation, dyssynergic defecation (DD), and a combination of slow transit and DD.[3,4]

DD is a prevalent subtype, affecting up to 50% of patients with chronic constipation[5] which results from impaired neuromuscular coordination of the abdominal, recto anal, and pelvic floor muscles, leading to inadequate rectal propulsive forces and/or increased resistance to stool passage. Unlike slow transit constipation, which often responds to laxatives, DD typically requires targeted interventions such as biofeedback therapy and pelvic floor rehabilitation.[6] Given this distinction, clinical guidelines recommend physiological anorectal testing for patients with constipation who do not respond to empirical laxative treatment.[7]

Anorectal manometry (ARM) is a widely used diagnostic tool for evaluating functional anorectal disorders, including fecal incontinence and constipation. It assesses the mechanical function of the anal sphincters and rectum by measuring intraluminal pressures during voluntary and involuntary actions, providing insights into striated and smooth muscle function, reflexes, recto anal coordination, rectal sensation, and compliance. ARM plays a crucial role in diagnosing DD, and facilitating targeted management strategies for affected patients.[8]

This study aims to evaluate the role of ARM in diagnosing chronic constipation due to DD.

MATERIALS AND METHODS

A prospective, observational study was conducted in the Department of General Surgery at Dr. D. Y. Patil Medical College and Research Centre, Pimpri, Pune, from January 2023 to February 2025. The study included 102 patients with chronic constipation who met the eligibility criteria. A consecutive, nonprobability sampling technique was used for participant selection. This study was approved by the Institutional Ethical Committee (IESC/PGS/2023/75), and written informed consent was obtained from all participants before enrollment.

Inclusion criteria

Patients included in the study were those with chronic constipation who remained refractory to regular laxative therapy or had not responded to lifestyle and dietary modifications. In addition, patients diagnosed with constipation-predominant irritable bowel syndrome and those meeting at least two criteria of the ROME IV diagnostic criteria for functional constipation were also included.

Exclusion criteria

Patients were excluded if their constipation was secondary to organic or systemic diseases or resulted from medication use. Immunocompromised individuals and females with a history of normal vaginal delivery with episiotomy were also excluded. Furthermore, patients with a history of major pelvic floor surgeries, spinal cord injuries, or fractures of the pelvic or lower limb long bones were not considered for the study.

Procedure

Patients presenting to the general surgery and medical gastroenterology outpatient department with chronic constipation were screened based on the inclusion and exclusion criteria. A detailed history and clinical and laboratory data were conducted, and data were recorded in a structured pro forma.

Comprehensive clinical assessment included demographic details, symptom duration, comorbidities, previous gastrointestinal or anorectal surgeries, stool frequency and consistency, rectal evacuation difficulty, sensation of incomplete evacuation, straining, rectal obstruction, need for digital evacuation, vaginal or perineal support during defecation, abdominal massage, unsuccessful defecation attempts, abdominal pain, bloating, pain during evacuation, enterocele, or cystocele. In addition, dietary habits, fluid intake, physical activity, symptoms of bladder or gynecological disorders, psychiatric history, and history of physical abuse were documented.

Physical examination included abdominal palpation to exclude masses, digital rectal examination at rest to rule out tumors, and digital examination during attempted defecation to assess pelvic floor contraction. To exclude colonic malignancy, ulcerative colitis, and rectal ulcerations, all patients underwent flexible sigmoidoscopy or full-length colonoscopy, either at the study center or at an external facility.

Anorectal manometry

All patients underwent ARM to assess anorectal function and identify DD patterns. All patients underwent ARM using the high-resolution system developed by The Royal Melbourne Hospital, incorporating a 16-channel water-perfusion manometry setup. The catheter employed for the procedure measured 4.2 mm in diameter and featured 16 radial pressure ports. A latex balloon affixed to the distal tip of the catheter was used for the balloon expulsion test (BET) and rectal sensory evaluations.

Bowel preparation was not required prior to the procedure. Examinations were conducted with patients positioned in the left lateral decubitus position, with hips and knees flexed. Prior to catheter insertion, the procedure – including resting, squeeze, and bear-down maneuvers – was explained to each patient. The catheter was inserted into the rectum and gradually withdrawn to accurately locate the anal sphincter zone, identified as a high-pressure segment situated between the lower-pressure zones of the rectum and the external environment. The length of this high-pressure zone, along with basal anal sphincter pressure, was documented.

All recordings were performed in accordance with established international minimum standards and followed a previously published and validated protocol.[4,9] After a 5-min rest period to allow for patient acclimatization, basal anal pressure – reflective of internal anal sphincter tone – was recorded. Patients were then instructed to voluntarily contract their anal sphincter to assess external sphincter function, and the corresponding squeeze pressure was measured. Finally, patients were asked to perform a bearing-down maneuver to simulate defecation.

Rao’s classification of defecation disorder (dyssynergic defecation)

Type	Description[9,10]
Normal	An adequate increase in rectal pressure (≥40 mmHg) accompanied by a simultaneous reduction in anal pressure
Type I	An increased intra-rectal pressure (≥40 mmHg) with a paradoxical increase in the intra-anal pressure
Type II	An inadequate increase in rectal pressure of (≤40 mmHg, poor propulsive force) and paradoxical simultaneous increase anal pressure
Type III	An increase in rectal pressure (≥40 mmHg) and failure of reduction in anal pressure (≤20% baseline pressure)
Type IV	An inadequate increase in rectal pressure of (≤40 mmHg, poor propulsive force) and failure of reduction in anal pressure (≤20% baseline pressure)

Analysis of manometry signal

ARM signal was analyzed using Trace 2.1 software from GS Hebbard (Australia). Normal manometry values considered were as follows.[11]

Balloon expulsion test

BET was done in all patients. Patients underwent rectal cleansing with enemas before the procedure. Patients were positioned in the left lateral decubitus position with knees and hips flexed. A lubricated deflated balloon connected to a plastic catheter was inserted into the rectum and inflated with 50 mL of warm water or until the patient felt an urgency to defecate. If the patient was unable to evacuate in 1–2 min, then gradually increase in weight at another end of catheter to support evacuation was done. Patient was also asked to report about feel for the first time sensation, urge or desire to defecate, and at that point maximum tolerable limit was measured.

Statistical analysis

All data were recorded in a pre-designed study pro forma. Qualitative variables were analyzed using frequency and percentages, and associations between qualitative variables were assessed using the Chi-Square test. Quantitative data were presented as mean ± standard deviation. P < 0.05 was taken as a level of significance. The results we graphically presented were deemed necessary. Statistical analysis was performed using SPSS version 26.0 (IBM Corp, Armonk, New York, USA).

RESULTS

The mean age of cases with chronic constipation was 45.53 ± 13.3 years, with over one-third of cases between 31 and 50 years (35.3%) followed by 51–70 years (39.2%) [Table 1].

Table 1.

Age distribution (n=102)

Age group (years)	n (%)
≤30	18 (17.6)
31–50	36 (35.3)
51–70	40 (39.2)
>70	8 (7.8)
Total	102 (100)

Data expressed in frequency (n) and percentage (%)

Out of the total 102 cases of chronic constipation, there was a slight male preponderance (53.9%) [Table 2].

Table 2.

Gender distribution (n=102)

Gender	n (%)
Female	47 (46.1)
Male	55 (53.9)
Total	102 (100)

Data expressed in frequency (n) and percentage (%)

Major associated comorbidities among cases with chronic constipation were diabetes (13.7%), followed by hypertension (7.8%) and COPD (6.9%) [Table 3].

Table 3.

Distribution based on comorbidities (n=102)

Co-morbidity	n (%)
Diabetes mellitus	14 (13.7)
Hypertension	8 (7.8)
COPD	7 (6.9)
CKD	3 (2.9)

Data expressed in frequency (n) and percentage (%). CKD=Chronic kidney disease, COPD=Chronic obstructive pulmonary disease

In most cases of chronic constipation, the duration of symptoms was between 3 and 6 months (60.8%), while in 20.6% of cases, the symptoms lasted more than 6 months [Table 4].

Table 4.

Distribution of study groups as per duration of symptoms

Duration of symptoms (months)	n (%)
≤3	19 (18.6)
3–6	62 (60.8)
>6	21 (20.6)
Total	102 (100)

Data expressed in frequency (n) and percentage (%)

The most common symptoms observed among cases of chronic constipation were: straining (94.1%), feeling of incomplete evacuation (60.8%), abdominal pain (56.9%), and bloating (47.1%). More than one unsuccessful defecation attempt per day was reported in over half of the cases (53.9%), while bowel frequency of <3 per week was seen in 20.6% of cases, respectively [Table 5].

Table 5.

Distribution of study groups as per presenting complaints (n=102)

Symptoms	n (%)
Bowel frequency <3/weeks	21 (20.6)
Straining	96 (94.1)
Feeling of incomplete evacuation	62 (60.8)
Abdominal pain	58 (56.9)
Bloating	48 (47.1)
>1 unsuccessful defecation attempt/day	55 (53.9)
Feeling of anorectal obstruction	9 (8.8)
Manual manoeuvers	5 (4.9)
Loose stools without laxatives	4 (3.9)

Data expressed in frequency (n) and percentage (%)

On manometry, the prevalence of DD in cases of chronic constipation was seen as 76.5% cases. The most common pressure profile observed was Type IV (28.4%), followed by Type I (21.6%). Type II and III were seen in 6.9% and 19.6% of cases, respectively [Table 6].

Table 6.

Distribution of dyssynergic pattern in anorectal manometry (n=102)

Manometry results (pressure profile)	n (%)
Normal	24 (23.5)
Type 1	22 (21.6)
Type 2	7 (6.9)
Type 3	20 (19.6)
Type 4	29 (28.4)
Total	102 (100)

Data expressed in frequency (n) and percentage (%)

Diagnosis of DD as per ARM was made in 75.5% of cases of chronic constipation [Table 7].

Table 7.

Dyssynergic defecation as per anorectal manometry findings

DD as per manometry	n (%)
No	25 (24.5)
Yes	77 (75.5)
Total	102 (100)

Data expressed in frequency (n) and percentage (%). DD=Dyssynergic defecation

Diagnosis of DD as per Balloon expulsion test was made in 75.5% of cases with chronic constipation [Table 8].

Table 8.

Dyssynergic defecation as per balloon expulsion test results (n=102)

DD as per BET	n (%)
No	26 (25.5)
Yes	76 (74.5)
Total	102 (100)

Data expressed in frequency (n) and percentage (%). DD=Dyssynergic defecation, BET=Balloon expulsion test

The sensitivity and specificity of ARM in diagnosing DD among cases of chronic constipation were 97.4% and 88.5%, respectively, with a diagnostic accuracy of 95.1% [Table 9].

Table 9.

Diagnostic accuracy of anorectal manometry to diagnose Dyssynergic defecation

DD - ARM	DD - BET		Total
	No	Yes
No	23	2	25
Yes	3	74	77
Total	26	76	102
Parameters	Percentage
Sensitivity	97.4
Specificity	88.5
PPV	96.1
NPV	92.0
Accuracy	95.1

DD=Dyssynergic defecation, ARM=Anorectal manometry, PPV=Positive predictive value, NPV=Negative predictive value, BET=Balloon expulsion test

DISCUSSION

This study aimed to evaluate the utility of ARM in diagnosing DD among patients with chronic constipation and to determine the prevalence of dyssynergic patterns. A total of 102 patients with chronic constipation were included, all of whom underwent detailed clinical evaluation, ARM, and BET for confirmation of DD.

The mean age of the patients in this study was 45.53 years, with the majority being in the age groups of 31–50 years (35.3%) and 51–70 years (39.2%). A slight male predominance was observed, with 53.9% males and 46.1% females. These findings are comparable to previous studies. Kulkarni et al.[12] reported a higher mean age of 66.5 ± 3.2 years, with a male predominance (70%), while Goyal et al.[13] observed a median age of 47 years with 87.8% male participants. Similarly, Zhao et al.[14] found the mean age to be 49.87 years among 60 patients with functional defecation disorder.

The predominant symptoms in our cohort were straining during defecation (94.1%), sensation of incomplete evacuation (60.8%), abdominal pain (56.9%), and bloating (47.1%). More than half the patients (53.9%) reported more than one unsuccessful defecation attempt per day, and 20.6% had a bowel movement frequency of fewer than three per week. These findings are in alignment with previous reports. Kulkarni et al.[12] and Goyal et al.[13] both observed that straining was the most frequent complaint, followed by other symptoms such as hard stools, sensation of obstruction, and bloating.

Globally, DD is considered a major subtype of functional constipation, reported in approximately 27%–59% of chronically constipated patients.[15,16] In the present study, DD was diagnosed in 74.5% of cases via BET and in 75.5% via ARM. This is higher than the prevalence reported by Kulkarni et al.[12] (46%), Goyal et al.[13] (55.3%), and Jat et al.[17] (46%). Jain et al.[18] similarly found a prevalence of 58.4% in a cohort of 178 patients with anorectal disorders. The relatively high prevalence in our cohort might reflect referral bias or greater sensitivity of the diagnostic approach used.

ARM revealed dyssynergic patterns in 76.5% of cases. Type IV dyssynergia (inadequate propulsive pressure with impaired anal relaxation) was the most common subtype (28.4%), followed by type I (adequate propulsive pressure with paradoxical anal contraction) in 21.6%. Type III and type II were observed in 19.6% and 6.9% of cases, respectively. Our findings differ slightly from those of Kulkarni et al.,[12] who found type I to be the most prevalent (20%), followed by type IV (14%), type II (8%), and type III (4%). Similarly, Jat et al.[17] and Zhao et al.[14] also reported type I as the most common subtype.

In this study, ARM demonstrated a sensitivity of 97.4%, specificity of 88.5%, and diagnostic accuracy of 95.1% for identifying DD. These findings suggest that ARM is highly reliable for evaluating functional defecation disorders. In contrast, Ortengren et al.,[19] through a meta-analysis of 15 studies (n = 2140), reported pooled sensitivity and specificity of 79% and 64%, respectively, with an AUC of 0.78. Meanwhile, Blackett et al.[20] observed a lower sensitivity of 36% but a high specificity of 85% for ARM when correlated with prolonged BET.

CONCLUSION

This study highlights the significant diagnostic value of ARM in evaluating chronic constipation due to DD. Approximately three-fourths of patients with chronic constipation were found to have DD, with Type I and Type IV dysfunctions being the most prevalent patterns. ARM demonstrated high diagnostic accuracy in identifying these functional defecatory disorders. Based on these findings, ARM should be considered an essential component in the diagnostic workup of patients with chronic constipation, particularly when conventional therapies fail to provide relief.

Limitations

This study is important in a clinical perspective but has a few limitations, such as it is conducted in a single tertiary center, did not include healthy subject for ARM test as a control group. Another limitation of our study is the lack of data on defecatory index in all patients.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.