Abstract
Background and Aims
Retrograde enteroscopy for evaluation of the small bowel can be performed using through-the-scope balloon-assisted enteroscopy (TTSE). TTSE consists of a balloon catheter designed for anchoring in the small bowel, inserted through the instrument channel of a standard colonoscope. We aimed to assess the ability of TTSE to improve the depth of maximal ileal insertion (DMI) compared with the colonoscope alone (C1).
Methods
We performed a prospective, randomized, crossover study to compare the DMI between TTSE and enteroscopy using the adult colonoscope alone. After measuring the DMI by the randomized sequence, the endoscopist switched the technique and measured the DMI again. The primary end point of the study was a comparison of DMI (centimeters) between the colonoscope with TTSE (DMI-N) and the colonoscope alone (DMI-C).
Results
A total of 18 subjects were enrolled, with 9 randomized to colonoscope alone first (C1) followed by TTSE (N2) and 9 to TTSE first (N1) followed by colonoscope alone (C2). The mean (standard deviation) of DMI was DMI-C1: 69.4 (40.3), DMI-N2: 107.2 (62.4), DMI-N1: 92.2 (31.3), and DMI-C2: 102.8 (29.1). Overall, TTSE showed a trend toward an increased DMI compared with the colonoscope alone (difference = 13.61; 95% confidence interval, −3.12 to 30.34; P = .06). In the stratified analyses by the randomization sequence (ie, C1N2), TTSE produced a significant increase in DMI (difference = 37.8; 95% confidence interval, 14.08-61.48; P = .006) compared with the colonoscope alone.
Conclusions
As per design-based analysis, the TTSE technique produced an increased DMI ranging between 13.6 and 37.8 cm more than with the standard colonoscope, which trended toward significance. Retrograde enteroscopy using TTSE may help improve DMI compared with colonoscope alone.
Introduction
The small bowel begins distal to the pylorus and ends at the ileocecal valve. It is a tubular structure with a length of 7 m (22 feet) in the average adult.1 This makes the small bowel the longest structure within the gastrointestinal (GI) tract. Because of its length, complex loops, and depth, complete visualization of the small bowel often is limited and inaccessible. Examination and management of small-bowel pathologies were historically limited to imaging and surgical management via laparotomy with intraoperative enteroscopy.2 The advent of video capsule endoscopy (VCE) transformed the landscape of small-bowel endoscopic evaluation as a result tof its noninvasive nature with minimal risk to the patient. However, VCE is limited to being a diagnostic modality only.3
Current guidelines from the American College of Gastroenterology recommend initial upper and lower endoscopy before assessment for small-bowel bleeding, with VCE as the first diagnostic modality followed by deep enteroscopy if indicated.4 In cases of suspected small-bowel GI bleed with unremarkable upper and lower endoscopies, antegrade deep balloon-assisted enteroscopy is the recommended study of choice if a bleeding source is not identified on VCE.5,6 Balloon-assisted enteroscopy uses an overtube with a balloon at the tip.3 Deep enteroscopy can be performed antegrade or retrograde through the ileocecal valve.
NaviAid (Smart Medical Systems, Ra'anana, Israel) uses a novel through-the-scope balloon that is introduced through the instrument channel of a standard endoscope (minimum working channel diameter needed is 3.7 mm) and through a series of inflation and deflation, the endoscope is advanced to evaluate deeper structures.7 This system can be used for both antegrade and retrograde enteroscopy and provides the option of on-demand enteroscopy.
Retrograde enteroscopy is less commonly performed than antegrade because of limited diagnostic and therapeutic yield and because of technical difficulty. The estimated maximal depth of insertion during retrograde enteroscopy is variable and depends on the level of expertise, method of depth estimation, and technique used. It can range from approximately 70 to 200 cm proximal to the ileocecal valve.8
Through-the-scope balloon-assisted enteroscopy (TTSE) was found to have a shorter procedure time, fewer training requirements, no need for additional special equipment, and a similar safety profile when compared with traditional enteroscopy techniques.9 We conducted this prospective study to compare the depth of maximal insertion (DMI) using TTSE with that of retrograde enteroscopy with the standard adult-sized colonoscope. To eliminate confounding effects, observational bias, and optimize sample size, we tested the effect of TTSE on DMI compared with the standard colonoscope alone using a crossover trial design.
Methods
Subjects
This was a prospective, randomized, crossover, single-center study conducted from September 1, 2020, to July 31, 2023, at Texas Tech University Health Sciences El Paso/University Medical Center of El Paso. The trial was prospectively registered at ClinicalTrials.gov (NCT04646083) (https://clinicaltrials.gov/study/NCT04646083). We adopted a crossover design approach in which after randomization to the endoscopy sequence, the endoscopist proceeded with the examination of the ileum either with an adult colonoscope alone first or with the use of TTSE. After measuring the DMI by the randomized sequence, the endoscopist switched the technique and measured the DMI again. We collected data from 18 adult patients (>18 years of age) in whom retrograde enteroscopy was indicated for any of the following: obscure GI bleeding, iron deficiency anemia, abnormal VCE, and abnormal findings on computed tomography. We excluded patients with the following characteristics: inability to sign informed consent, pregnant or breastfeeding, previous colonic resection, history of known strictures, altered anatomy, inadequate bowel preparation, and high preoperative risk assessment in which anesthesia time should be minimized. The study was approved by the Texas Tech University Health Sciences Center El Paso Institutional Review Board.
Randomization
A randomization envelope was selected for each patient, and accordingly the patient was allocated to the chosen sequence: Sequence A, colonoscopy with TTSE followed by colonoscopy with an adult-sized colonoscope alone, or sequence B, colonoscopy with an adult-sized colonoscope alone followed by colonoscopy with TTSE.
Procedure
On the basis of randomization and sequence assigned, the endoscopist proceeded with ileal intubation either with an adult-sized colonoscope or with the use of TTSE. For colonoscope alone, the terminal ileum was intubated with the standard adult-sized colonoscope (Olympus, Center Valley, Pa, USA) and advanced in the ileum to the maximal extent. The TTSE (NaviAid; Smart Medical Systems) device has a working length of 350 cm with a 40-mm balloon diameter. The balloon is controlled by an air supply unit (NaviAid SPARK) (Fig. 1).8 For the colonoscope with TTSE, the terminal ileum was intubated with the standard colonoscope, and the balloon catheter was inserted through the instrument channel of the colonoscope, and the deflated balloon then advanced ahead of the colonoscope by approximately 20 to 30 cm. The balloon was then inflated to a pressure of 6 kilopascals, which acts as an anchor in the small bowel. The colonoscope was then carefully advanced while the balloon catheter was under light traction. The balloon was then deflated and advanced further into the small bowel. Using this repetitive push-pull technique, we advanced the endoscope deep into the small bowel.8
Figure 1.
Standard colonoscope with through-the-scope balloon enteroscopy device inflated. The associated air supply unit is shown below the colonoscope.
If a patient was assigned to sequence A (adult-sized colonoscope alone then TTSE), once the DMI had been achieved with the adult-sized colonoscope, the colonoscope was withdrawn back to the ileocecal valve. The endoscopist then proceeded with the use of TTSE. If a patient was assigned to sequence B (TTSE then adult-sized colonoscope alone), once the DMI had been achieved with TTSE, the colonoscope was withdrawn to the ileocecal valve, and the endoscopist proceeded with the adult-sized colonoscope alone. All cases were performed with patients under monitored anesthesia care. A tattoo at the point of maximal insertion was placed using a suspension containing carbon particles (Spot, GI Supply, Camp Hill, Pa) after the first insertion (C1 or N1) as a reference point.8,10 All cases were performed by 1 of 2 board-certified gastroenterologists experienced in balloon-assisted enteroscopy and TTSE with NaviAid (M.J.Z. and I.A-B.).
End points and definitions
Outcome measures included DMI (centimeters), diagnostic yield, and adverse events. The DMI from the ileocecal valve was estimated with 2 operators present. Depth of insertion was estimated on withdrawal by counting 10-cm intervals as the endoscope was slowly withdrawn.11,12 The primary end point of the study was a comparison of DMI. Secondary end points included diagnostic yield and adverse events (adverse events were assessed throughout the study during every procedure and with a follow-up phone call within 1 week of the procedure).
Sample size
A previous study reported greater mean (standard deviation [SD]) DMI in double-balloon enteroscopy compared with single-balloon enteroscopy (108.1 [84.1] cm vs 73.3 [63.4] cm). Using this input and other supporting data,13,14 we anticipated observing at least 10-cm greater DMI with TTSE compared with the standard colonoscope with SDs of the period differences of 5 to 7 cm. On the basis of this information, a total sample size of 18 with a 2 × 2 crossover design with an equal number in each sequence was required to detect at least a 10-cm difference between procedures using a 2-sided paired t test with a sufficient power (>80%) at a significance level of 0.05. In addition, the proposed sample size was also found to be sufficiently powered to detect an effect size of 0.7 or greater with more than 80% power at 5% alpha using a paired t test. Therefore, we enrolled a total of 18 patients in this study. Considering the short duration (time from consent to the end of procedures), we did not account for patient dropout. However, 2 patients in whom we did not enter the terminal ileum and perform the procedure (1 had a poor prep and 1 had a colon mass) were excluded from the study.
Data analysis
Continuous data are described with mean and SD, whereas categorical data are described with frequencies and percentages. After data collection, subjects were assigned a subject number, and patient-protected health information was deleted from the data-collection sheet. This information is stored in an encrypted drive and available upon reasonable request. All baseline data including demographics and clinical characteristics were compared between randomized groups (colonoscope alone first and TTSE second: C1N2 vs TTSE first and colonoscope alone second: C2N1) using either unpaired t tests or Fisher exact tests. After the crossover design-based analysis,15,16 the overall difference in DMI measurement was compared between the 2 groups using a 2-sided paired t test after inducing normality using a log transformation. As per the crossover design, we evaluated (1) procedure effect, (2) sequence effect, and (3) interaction between procedure and sequence effect. Accordingly, a linear mixed-effects model was used to determine the interaction between the time (first procedure vs second procedure) and the procedure (colonoscopy vs TTSE) on DMI. In the presence of an interaction effect, the effect of the procedure on DMI was evaluated separately for each randomized sequence using a paired t test. These findings were further validated by conducting a nonparametric Wilcoxon signed rank test. The effect size was summarized with a mean difference and a 95% confidence interval (CI). The results of nonparametric analyses were summarized with a median and interquartile range. Statistical analyses were carried out using Stata 17 (StataCorp LLC, College Station, Tex, USA). A P value less than 5% alpha was considered a statistically significant finding.
Results
A total of 18 retrograde enteroscopy procedures were performed during the study period. The mean age of patients included was 59 years (SD, 13.29), 38.89% of the patients were male, and 77.78% of the patients had Hispanic ethnicity. Main indications for retrograde enteroscopy included obscure GI bleed in 16.67%, iron deficiency anemia in 61.11%, and abnormal abdominal imaging in 16.67%. All patients underwent previous VCE, which showed angioectasias in 38.89% and erosions in 61.11%. The sequence of retrograde enteroscopy method was randomized before the procedure, and 9 patients underwent retrograde enteroscopy with standard colonoscope alone first followed by TTSE. No baseline differences were observed between randomized sequences. The procedure was technically successful in all of the patients included in the study. There were significant findings (diagnostic yield) in 6 (33%) patients on retrograde enteroscopy, which was followed by an intervention (biopsy) for further evaluation—ileitis in 2 patients (1 with increased stromal fibrosis suggestive of radiation enteritis and the other with chronic inflammation and surface erosions), ileal erosion or ulcer in 2 (1 with superficial erosion and surrounding acute and chronic inflammation and the other was normal), stricture in 1 (stromal edema and granulation-like changes), and segmental bleed in 1 (normal mucosa). There were no differences between the 2 groups. No adverse events were noted in any of the patients (Table 1).
Table 1.
Patient characteristics and colonoscope findings in the entire group and by randomization sequence
| Factor | Value (n = 18) | Colonoscope alone first and TTSE second (n = 9) | TTSE first and colonoscope alone second (n = 9) | P value |
|---|---|---|---|---|
| Age, years, mean (SD) | 59.00 (13.29) | 55.22 (14.30) (n = 9) | 62.78 (11.79) (n = 9) | .24 |
| Sex | .15 | |||
| Male | 7 (38.89%) | 2 (22.22%) | 5 (55.56%) | |
| Female | 11 (61.11%) | 7 (77.78%) | 4 (44.44%) | |
| Ethnicity | .26 | |||
| Hispanic | 14 (77.78%) | 6 (66.67%) | 8 (88.89%) | |
| Non-Hispanic | 4 (22.22%) | 3 (33.33%) | 1 (11.11%) | |
| Indication | .62 | |||
| Obscure gastrointestinal bleed | 3 (16.67%) | 1 (11.11%) | 2 (22.22%) | |
| IDA | 11 (61.11%) | 5 (55.56%) | 6 (66.67%) | |
| Abnormal imaging | 3 (16.67%) | 2 (22.22%) | 1 (11.11%) | |
| Other | 1 (5.56%) | 1 (11.11%) | 0 (0.00%) | |
| Previous VCE | .15 | |||
| AVM | 7 (38.89%) | 2 (22.22%) | 5 (55.56%) | |
| Erosion | 11 (61.11%) | 7 (77.78%) | 4 (44.44%) | |
| Significant finding (DY) | 6 (33.33%) | 2 (22.22%) | 4 (44.44%) | .32 |
| Ileitis | 2 | 0 | 2 | |
| Erosions/ulcer | 2 | 1 | 1 | |
| Stricture | 1 | 0 | 1 | |
| Blood | 1 | 1 | 0 | |
| Intervention performed/biopsy | 6 (33.33%) | 2 (25.00%) | 4 (44.44%) | .40 |
| Adverse events | 0 (0%) | 0 (0%) | 0 (0%) | NA |
AVM, Arteriovenous malformation; DY, diagnostic yield; IDA, iron deficiency anemia; NA, not applicable; SD, standard deviation; TTSE, through-the-scope balloon-assisted enteroscopy; VCE, video capsule endoscopy.
The mean (SD) DMI (centimeters) was estimated in 4 groups as DMI-C1: 69.4 (40.3), DMI-N2: 107.2 (62.4), DMI-N1: 92.2 (31.3), and DMI-C2: 102.8 (29.1). Although TTSE showed an increased DMI (n = 9, 92.2 [31.3]) compared with colonoscope alone (n = 9, 69.4 [40.3]) when used as the initial technique, the difference was not statistically significant (difference = 22.8; 95% CI, −13.14 to 58.7; P = .11). The overall mean DMI (SD) was estimated to be 99.7 (48.5) cm in the TTSE group (n = 18) compared with 86.1 (38) cm in the colonoscope alone group (n = 18). This difference showed a trend toward an increased DMI compared with the colonoscope alone (difference = 13.61; 95% CI, −3.12 to 30.34; P = .06) indicating a greater DMI may be associated with TTSE compared with the standard colonoscope alone method (Table 2).
Table 2.
Distribution and comparison of depth of maximal ileal insertion (centimeters) between procedures (colonoscope alone and TTSE)
| Procedures | Mean (SD) |
|---|---|
| Colonoscope alone first | 69.44 (40.03) |
| Colonoscope alone second | 102.78 (29.06) |
| Overall colonoscope alone | 86.11 (38.02) |
| TTSE first | 92.22 (31.34) |
| TTSE second | 107.22 (62.41) |
| Overall TTSE | 99.72 (48.52) |
| Overall difference between TTSE and colonoscope alone | 13.61 (95% CI, −3.12 to 30.34; P = .06) |
CI, Confidence interval; TTSE, through-the-scope balloon-assisted enteroscopy; SD, standard deviation.
The significant interaction between procedure and sequence indicated a differential effect on DMI depending on the sequence. Although there was greater DMI with TTSE followed by colonoscope alone compared with colonoscope alone followed by TTSE, the difference was not statistically significant (P = .115). In addition, TTSE yielded significantly greater DMI compared with colonoscope alone (P < .001), depending on the randomized sequence (P < .001). Considering a significant interaction between the procedure (colonoscope alone vs colonoscope with TTSE) and sequence of the procedure implemented (first vs second) (Supplementary Table 1, available online at www.igiejournal.org), a stratified analysis was conducted. In the stratified analysis by sequence (ie, C1N2), we found a significant increase in DMI with TTSE (difference = 37.8; 95% CI, 14.08-61.48; P = .006) than colonoscope alone (difference=10.6; 95% CI, 1.45-19.66; P = .028) (Table 3). These results were unchanged in the nonparametric analysis (Supplementary Table 2, available online at www.igiejournal.org). These findings indicate that the DMI was greater in the TTSE group compared with the colonoscope alone group.
Table 3.
Comparison of depth of maximal ileal insertion (centimeters) between colonoscope alone and TTSE in different sequences
| Procedures | Mean (SD) | Difference (95% CI) | P value |
|---|---|---|---|
| Colonoscope alone first vs TTSE second | 69.44 (40.03) vs. 107.22 (62.41) | 37.8 (14.08-61.48) | .006 |
| TTSE first vs colonoscope alone second | 92.22 (31.34) vs. 102.78 (29.06) | −10.6 (−19.66 to −1.45) | .028 |
CI, Confidence interval; TTSE, through-the-scope balloon-assisted enteroscopy; SD, standard deviation.
Discussion
In this study, we evaluated the utility of retrograde TTSE compared with standard colonoscope-based retrograde enteroscopy. To our knowledge, this is the first study comparing the DMI in retrograde enteroscopy between standard colonoscope alone and TTSE. Retrograde TTSE had a greater mean DMI when performed first compared with the standard colonoscope (92.2 cm and 69.4 cm, respectively), however, without statistical significance (P = .197). In contrast, TTSE yielded 37.8-cm greater DMI after colonoscope alone, whereas colonoscope alone yielded 10.6-cm greater DMI after TTSE, indicating that the maximum DMI could be achieved by using TTSE. In addition, we found that both techniques had a similar safety profile in our small sample.
A multicenter retrospective study previously evaluated the use of TTSE for assessment of the small bowel (antegrade and retrograde). Retrograde enteroscopy with TTSE was performed in one-third of the patients included with a mean DMI of 89 cm beyond the ileocecal valve (range, 20-150 cm).17 A prospective study assessing retrograde double-balloon enteroscopy utility in small-bowel examination reported a mean DMI of 124 cm.18
Several studies emphasize the consideration of retrograde TTSE due to shorter procedure times, faster learning curve, less specialized equipment, and similar safety profile.14,17, 18, 19 The retrograde enteroscopy technique involves inflation of the balloon after advancement in a blind fashion, which could pose a theoretical potential risk of rupture during inflation in a stricture or a diverticulum proximally. However, no such adverse events were noted in our study or studies evaluating retrograde TTSE.17,18 We did not assess the procedure time because of the tandem nature of the study and possible interaction and sequence effects.
Single- and double-balloon—assisted enteroscopy are much more commonly used in clinical practice than TTSE, so it is valuable to compare results between TTSE and these procedures. However, studies evaluating the use of retrograde TTSE compared with single- or double-balloon–assisted retrograde enteroscopy are limited. In a retrospective study at our institution, Jia et al20 evaluated the diagnostic and therapeutic utility of single-balloon–assisted retrograde enteroscopy compared with retrograde TTSE. The authors compared the depth of insertion, procedure duration, and diagnostic yield. Single-balloon–assisted retrograde enteroscopy achieved greater DMI compared with TTSE technique but without statistical significance (mean DMI 92.5 cm and 64.6 cm, respectively, P = .08). However, single-balloon–assisted retrograde enteroscopy procedure duration was longer compared with TTSE technique (91.9 minutes and 70.5 minutes, respectively, P = .04) with similar diagnostic yield between the 2 techniques.20
It is interesting that we observed significant DMI into the ileum with the standard colonoscope alone. There are multiple studies evaluating ileoscopy during colonoscopy, however, with emphasis on indications, diagnostic, and therapeutic yield rather than depth of insertion with standard colonoscope.21, 22, 23 To our knowledge, there are no studies evaluating the depth of maximal insertion with the standard colonoscope alone. With the standard colonoscope, we had a mean DMI of 69.4 cm, which is comparable with some studies evaluating the DMI of retrograde single-balloon–assisted enteroscopy.24 A study on utility of single-balloon–assisted enteroscopy found that the retrograde approach was performed in 29 patients with a mean DMI of 73.3 cm.24
It is important to note that DMI varies among different studies, and DMI can reach up to 199 cm with single-balloon–assisted retrograde TTSE.25 The study by Jia et al20 in which they evaluated retrograde TTSE and single-balloon–assisted enteroscopy found that that the DMI using the TTSE technique was 64.6 cm. This observation highlights the expertise of the endoscopist with ileoscopy in general in achieving greater depth of insertion into the ileum.
To our knowledge, there have been no previous studies with a tandem approach in the retrograde examination of the small bowel. In our study, we found that a tandem approach can result in deeper small-bowel examination, which could be a result of operator learning effect, or due to shortening of the small bowel and further reduction of the colonoscope, which can result in deeper small-bowel examination. Note that the tandem approach was used to address a research question. Regardless of the technique performed, we found that the second ileocecal intubation had deeper mean small-bowel intubations (DMI-N1 92.2 cm followed by DMI-C2 102.8 cm, and DMI-C1 69.4 cm followed by DMI-N2 107.2 cm).
Depth of insertion remains an estimate provided by the endoscopists in both antegrade and retrograde enteroscopy and is complicated by possible scope slippage. Multiple techniques have been proposed in the past regarding depth of insertion estimation during enteroscopy, which can either be done on insertion or during withdrawal. In our study, we assessed DMI using the withdrawal method, which was described by Efthymiou et al.11 This was done by the counting of the number of 5-cm segments on withdrawal.11 This method was also used by Christian et al12 in their study evaluating DMI of retrograde single-balloon–assisted enteroscopy. The studies evaluating the different techniques of insertion depth estimation primarily evaluate single- and double-balloon–assisted enteroscopy, which we extrapolated for use in our study with TTSE and the standard colonoscope. Other methods of insertion depth estimation include counting of individual folds on withdrawal, addition of the net advancements of the enteroscope through the overtube, or overtube insertion depth.26
Our study has some limitations. These include small sample size attributable to the use of the tandem approach that we used in the study, the inherently approximate nature of distance assessment on withdrawal, and limited number of operators. It would have been potentially helpful if we performed the standard colonoscope technique in a tandem approach to assess its potential use in cases in which retrograde enteroscopy is needed and with limited equipment available.
Note that this study focused only on the DMI and that diagnostic yield and technical success of TTSE were not fully evaluated. The tandem approach design was used to evaluate how much increase in DMI is actually achieved with the use of TTSE, but it does not correspond to real clinical practice. This study was designed using a crossover trial to estimate efficient effect sizes by removing confounding effects, observational bias, and optimizing sample size.
The association between the DMI and diagnostic and therapeutic yield remains a matter of debate. A randomized prospective study evaluating achieving complete enteroscopy with single- compared with double-balloon–assisted enteroscopy found that the latter had a greater likelihood of complete enteroscopy (66% vs 22%, P < .0001) with greater therapeutic yield in the double-balloon–assisted enteroscopy cohort (72% vs 48%, P = .025).27 Another randomized prospective study evaluating double-balloon–assisted enteroscopy to a novel motorized spiral enteroscopy found a greater rate of total enteroscopy with the novel technique. This was accompanied by a higher diagnostic yield in the novel technique group (80% vs 62.1%).28
On the contrary, several studies evaluating DMI in different enteroscopy techniques show that greater DMI is not necessarily associated with improved diagnostic and therapeutic yield. A study comparing retrograde single-balloon–assisted enteroscopy to retrograde double-balloon–assisted enteroscopy found that although the DMI was greater in double-balloon–assisted enteroscopy (108.1 [84.1] cm vs 73.3 [63.4] cm, P = .001), the diagnostic and therapeutic yield were similar (40.9% vs 40.8%, P = .95 and 17.1% vs 19.1%, P = .61 respectively).14 Another study evaluating the DMI between single-balloon and double-balloon–assisted enteroscopy found greater DMI in the antegrade approach with double balloon (234.1 cm vs 203.8 cm) and similar DMI in the retrograde approach (75.2 cm vs 72.1 cm). However, diagnostic and therapeutic yield was similar in both techniques.11
It is important to note that studies evaluating the diagnostic and therapeutic yield in retrograde enteroscopy are scarce because the retrograde approach is less commonly performed compared with the antegrade approach. In addition, the diagnostic and therapeutic yield of antegrade and retrograde enteroscopy was evaluated in the past, and the researchers concluded that the diagnostic and therapeutic yield is greater in the antegrade approach for small-bowel pathology evaluation overall.29 Moreover, evaluating studies that assess DMI in small-bowel examination remains difficult because of the heterogeneity in the results secondary to the estimation of the DMI being operator-dependent. Our study suggests the use of TTSE may result in a greater depth of insertion into the ileum than the colonoscope alone. We are not suggesting the use of a tandem approach in clinical practice (we used this design to test our hypothesis in the study), but we have shown an advantage of using TTSE for retrograde enteroscopy.
In conclusion, after the crossover design-based analysis, the colonoscope with TTSE procedure produced an increased DMI ranging between 13.6 to 37.8 cm more than the colonoscope-alone procedure. Retrograde enteroscopy using TTSE yields a modestly greater mean DMI than with the colonoscope alone. Future studies evaluating retrograde endoscopic techniques for small-bowel examination with emphasis on diagnostic and therapeutic yield are needed.
Patient Consent
The patients in this article have given written informed consent to publication of their case details.
Disclosure
All authors disclosed no financial relationships.
Footnotes
The preliminary results of this project were presented at Digestive Disease Week, May 18-21, 2024, Washington, DC.
Supplementary data
References
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