Endoflip vs high-definition manometry in the assessment of fecal incontinence: A data-driven unsupervised comparison

A comparison of function lumen imaging probe measurements of anal sphincter function in fecal incontinence

BACKGROUND

The functional lumen imaging probe (FLIP) is a test of anal sphincter distensibility under evaluation by specialist centers. Two measurement protocols termed "stepwise" and "ramp" are used, risking a lack of standardization. This study aims to compare the performance of these protocols to establish if there are differences between them.

METHODS

Patients with fecal incontinence were recruited and underwent measurement with both protocols at a tertiary pelvic floor referral unit. Differences in minimum diameter, FLIP bag pressure, and distensibility index (DI) at rest and during squeeze were calculated at various FLIP bag volumes.

KEY RESULTS

Twenty patients (19 female, mean age 61 [range: 38-78]) were included. The resting minimum diameter at 30 and 40 mL bag volumes were less in the stepwise protocol (mean bias: -0.55 mm and -1.18 mm, p < 0.05) along with the DI at the same bag volumes (mean bias: -0.37 mm2/mmHg and -0.55 mm2/mmHg, p < 0.05). There was also a trend towards greater bag pressures at 30 mL (mean bias: +2.08 mmHg, p = 0.114) and 40 mL (mean bias: +2.81 mmHg, p = 0.129) volumes in the stepwise protocol. There were no differences between protocols in measurements of minimum diameter, maximum bag pressure, or DI during voluntary squeeze (p > 0.05).

CONCLUSION AND INFERENCES

There are differences between the two commonly described FLIP measurement protocols at rest, although there are no differences in the assessment of squeeze function. Consensus agreement is required to agree the most appropriate FLIP measurement protocol in assessing anal sphincter function.

Current Status and Role of Artificial Intelligence in Anorectal Diseases and Pelvic Floor Disorders

Background

Anorectal diseases and pelvic floor disorders are prevalent among the general population. Patients may present with overlapping symptoms, delaying diagnosis, and lowering quality of life. Treating physicians encounter numerous challenges attributed to the complex nature of pelvic anatomy, limitations of diagnostic techniques, and lack of available resources. This article is an overview of the current state of artificial intelligence (AI) in tackling the difficulties of managing benign anorectal disorders and pelvic floor disorders.

Methods

A systematic literature review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched the PubMed database to identify all potentially relevant studies published from January 2000 to August 2023. Search queries were built using the following terms: AI, machine learning, deep learning, benign anorectal disease, pelvic floor disorder, fecal incontinence, obstructive defecation, anal fistula, rectal prolapse, and anorectal manometry. Malignant anorectal articles and abstracts were excluded. Data from selected articles were analyzed.

Results

139 articles were found, 15 of which met our inclusion and exclusion criteria. The most common AI module was convolutional neural network. researchers were able to develop AI modules to optimize imaging studies for pelvis, fistula, and abscess anatomy, facilitated anorectal manometry interpretation, and improved high-definition anoscope use. None of the modules were validated in an external cohort.

Conclusion

There is potential for AI to enhance the management of pelvic floor and benign anorectal diseases. Ongoing research necessitates the use of multidisciplinary approaches and collaboration between physicians and AI programmers to tackle pressing challenges.

Use of endolumenal functional lumen imaging probe in investigating paediatric gastrointestinal motility disorders

Investigating gastrointestinal (GI) motility disorders relies on diagnostic tools to assess muscular contractions, peristalsis propagation and the integrity and coordination of various sphincters. Manometries are the gold standard to study the GI motor function but it is increasingly acknowledged that manometries do not provide a complete picture in relation to sphincters competencies and muscle fibrosis. Endolumenal functional lumen imaging probe (EndoFLIP) an emerging technology, uses impedance planimetry to measure hollow organs cross sectional area, distensibility and compliance. It has been successfully used as a complementary tool in the assessment of the upper and lower oesophageal sphincters, oesophageal body, the pylorus and the anal canal. In this article, we aim to review the uses of EndoFLIP as a tool to investigate GI motility disorders with a special focus on paediatric practice. The majority of EndoFLIP studies were conducted in adult patients but the uptake of the technology in paediatrics is increasing. EndoFLIP can provide a useful complementary data to the existing GI motility investigation in both children and adults.

Current and future perspectives on the utility of provocative tests of anal sphincter function: A state-of-the-art summary

BACKGROUND

The maintenance of fecal continence depends upon coordinated interactions between the pelvic floor, anorectum, and anal sphincter complex orchestrated by central and peripheral neural activities. The current techniques to objectively measure anorectal function rely on fixed diameter catheters placed inside the anal canal with a rectal balloon to obtain measurements of anal resting and squeeze function, and rectal compliance. Until recently it had not been possible to measure the distensibility of the anal canal, or in other words its ability to resist opening against an increasing pressure, which has been proposed as the main determinant of a biological sphincter's function. Anal acoustic reflectometry (AAR) and the functional lumen imaging probe (FLIP) are two novel, provocative techniques that dynamically assess the anal sphincter complex under volume-controlled distension. In doing so, both provide information on the viscoelastic properties of the anal canal and offer new insights into its function.

PURPOSE

This review details the current and potential future applications of AAR and FLIP and highlights the unanswered questions relevant to these new technologies.

Low-cost gastrointestinal manometry via silicone-liquid-metal pressure transducers resembling a quipu

The evaluation of the tone and contractile patterns of the gastrointestinal (GI) tract via manometry is essential for the diagnosis of GI motility disorders. However, manometry is expensive and relies on complex and bulky instrumentation. Here we report the development and performance of an inexpensive and easy-to-manufacture catheter-like device for capturing manometric data across the dynamic range observed in the human GI tract. The device, which we designed to resemble the quipu-knotted strings used by Andean civilizations for the capture and transmission of information-consists of knotted piezoresistive pressure sensors made by infusing a liquid metal (eutectic gallium-indium) through thin silicone tubing. By exploring a range of knotting configurations, we identified optimal design schemes that led to sensing performances comparable to those of commercial devices for GI manometry, as we show for the sensing of GI motility in multiple anatomic sites of the GI tract of anaesthetized pigs. Disposable and customizable piezoresistive catheters may broaden the use of GI manometry in low-resource settings.

Review of the indications, methods, and clinical utility of anorectal manometry and the rectal balloon expulsion test

BACKGROUND

Anorectal manometry (ARM) comprehensively assesses anorectal sensorimotor functions.

PURPOSE

This review examines the indications, techniques, interpretation, strengths, and weaknesses of high-resolution ARM (HR-ARM), 3-dimensional high-resolution anorectal manometry (3D-HR-ARM), and portable ARM, and other assessments (i.e., rectal sensation and rectal balloon expulsion test) that are performed alongside manometry. It is based on a literature search of articles related to ARM in adults. HR-ARM and 3D-HR-ARM are useful for diagnosing defecatory disorders (DD), to identify anorectal sensorimotor dysfunction and guide management in patients with fecal incontinence (FI), constipation, megacolon, and megarectum; and to screen for anorectal structural (e.g., rectal intussusception) abnormalities. The rectal balloon expulsion test is a useful, low-cost, radiation-free, outpatient assessment tool for impaired evacuation that is performed and interpreted in conjunction with ARM. The anorectal function tests should be interpreted with reference to age- and sex-matched normal values, clinical features, and results of other tests. A larger database of technique-specific normal values and newer paradigms of analyzing anorectal pressure profiles will increase the precision and diagnostic utility of HR-ARM for identifying abnormal mechanisms of defecation and continence.

Long-term anorectal function in rectal cancer patients treated with chemoradiotherapy and endorectal brachytherapy

AIM

The aim was to study anorectal function in long-term survivors after combined, curatively intended, chemoradiotherapy and endorectal brachytherapy for low rectal cancer.

METHODS

This was a case-control design. We compared anorectal function by anal manometry, anal functional lumen imaging probe (EndoFLIP) and rectal bag distension in rectal cancer patients (RCPs) and healthy, normal subjects (NSs). Symptoms were assessed by the low anterior resection syndrome (LARS) and Wexner faecal incontinence scores.

RESULTS

Thirteen RCPs (12 men, median age 68 years, range 52-92) after 60 Gy radiotherapy, 5 Gy endorectal brachytherapy and oral tegafur-uracil with complete clinical response (median time since treatment 2.8 years, range 2.2-5.6) were compared to 15 NSs (14 men, median age 64 years, range 47-75). RCPs had lower than normal anal resting pressure, 38.6 mmHg (range 8.8-67.7) versus 58.8 mmHg (25.7-105.2) (P < 0.003), and squeeze pressure, 117 mmHg (55.2-203) versus 188 mmHg (103-248) (P < 0.01). Squeeze-induced pressure increase recorded by EndoFLIP was also lower in RCPs (q > 7.56, P < 0.001) as was the anal canal resistance to increasing distension (q = 3.13, P < 0.05). No differences in median rectal volume at first sensation (72 [22-158] vs. 82 [36-190] ml, P = 0.4) or at urge to defaecate (107 [42-227] vs. 132 [59-334] ml, P = 0.2) were found. However, maximum tolerable rectal volume was lower in RCPs (145 [59-319] vs. 222 [106-447] ml, P < 0.02). The median (range) low anterior resection syndrome score was 27 (0-39) for RCPs and 7 (0-23) for NSs (P < 0.001), while the Wexner score was 0 (0-5) versus 0 (0-4) (P = 0.56).

CONCLUSION

Radiotherapy combined with endorectal brachytherapy for rectal cancer causes long-term anorectal symptoms, impaired anal sphincter function and reduced rectal capacity.

Teaching EndoFLIP Impedance Planimetry to Practicing Endoscopists: An "Into the Fire" Approach to Simulation

Background. There are growing interests from practicing endoscopists to implement the functional lumen imaging probe (FLIP) impedance planimetry system. We present a simulation-based curriculum using an "into the fire" approach with hands-on pre- and post-tests to teach the use of this technology. Methods. The curriculum consists of a series of pre-tests, didactic content, mentored hands-on instructions, and post-tests. Pre- and post-testing included a knowledge-based written test, a confidence survey, and an assessment form specific to the hands-on performance of FLIP. Result. Twenty-two practicing physicians completed the curriculum. After course completion, participants had improved knowledge-based written test scores from 6.8±1.7 to 8.9±0.9 (P<0.001), confidence scores from 10.0±5.9 to 22.1±2.6 (P<0.001), and hands-on performance score from 11.4±3.4 to 23.1±2.0 (P<0.001) with significant improvement in all components of the hands-on skills. Conclusion. Our simulation curriculum is effective in improving confidence, knowledge, and technical proficiency when teaching the use of FLIP to practicing physicians.

A new method for assessing anal distensibility with a barostat and magnetic resonance imaging in healthy and constipated women

OBJECTIVES

Defecation requires relaxation of the internal and external anal sphincters. High anal resting pressure is associated with painful constipation, defecatory disorders, and increased healthcare utilization in constipated patients; the mechanisms are unclear. Perhaps patients with a high anal resting pressure have a less distensible canal, which impedes defecation.

METHODS

In 50 of 64 participants (33 healthy and 17 constipated women), anal pressures and distensibility were measured, respectively, with manometry and balloon distention combined with magnetic resonance imaging; rectal balloon expulsion time (BET) was also studied.

RESULTS

The BET (P = .006) was longer, and the mean (SD) rectoanal pressure gradient (-58[40] vs -34[26] mm Hg, P = .03) was more negative in constipated than healthy women; anal resting pressure was not different. During anal distention, the balloon expanded rapidly at an opening pressure of 49 (18) mm Hg, which was lower (P < .0001) than resting pressure (90 [25] mm Hg). The resting pressure was correlated with the opening pressure (r = 0.57, P < .0001) and inversely (r = -0.38, P = .007) with maximum volume but not with anal distensibility (volume-pressure slope). In healthy women, the difference (opening-resting pressure) was correlated with anal relaxation during evacuation (r = 0.35, P = .04). Anal distensibility and sensory thresholds were not different between constipated and healthy women.

CONCLUSIONS

Among healthy and constipated women, a greater anal resting pressure is correlated with greater opening pressure and lower maximum volume during distention, and, hence, provides a surrogate marker of anal distensibility. The difference (opening-resting pressure), which reflects anal relaxation during distention, is correlated with anal relaxation during evacuation. Anal resting pressure and distensibility were comparable in healthy and constipated women.

Assessing Anorectal Function in Constipation and Fecal Incontinence

Constipation and fecal incontinence are commonly encountered complaints in the gastrointestinal clinic. Assessment of anorectal function includes comprehensive history, rectal examination, and prospective stool diary or electronic App diary that accurately captures bowel symptoms, evaluation of severity, and quality of life of measure. Evaluation of a suspected patient with dyssynergic constipation includes anorectal manometry, balloon expulsion test, and defecography. Investigation of a suspected patient with fecal incontinence includes high-resolution anorectal manometry; anal ultrasound or MRI; and neurophysiology tests, such as translumbosacral anorectal magnetic stimulation or pudendal nerve latency. This article provides an approach to the assessment of anorectal function.

The use of impedance planimetry (Endoscopic Functional Lumen Imaging Probe, EndoFLIP® ) in the gastrointestinal tract: A systematic review

BACKGROUND AND PURPOSE

The EndoFLIP® system is a method of delineating impedance and was first designed to investigate the characteristics of the esophago-gastric junction. In the last decade, its use was widened to investigate other sphincteric and non-sphincteric systems of the gastrointestinal tract. The objective of the present systematic review was to summarize the available data in literature on the use of the EndoFLIP® system in the gastrointestinal tract, including sphincteric and non-sphincteric regions. We performed a systematic review in accordance with recommendations for systematic review using PRISMA guidelines without date restriction, until June 2020, using MEDLINE-PubMed, Cochrane Library, and Google Scholar databases. Only articles written in English were included in the present review. Five hundred and six unique citations were identified from all database combined. Of those, 95 met the inclusion criteria. There was a lack of standardization among studies in terms of anesthetic drugs use, probe placement, and inflation protocol. In most cases, only small cohorts of patients were included. Most studies investigated the EGJ, with a potential use of the EndoFLIP® to identify a subgroup of patients with achalasia and for intraoperative assessment of treatment efficacy in achalasia. However, the use of EndoFLIP® in the esophageal body (esophageal panometry), other esophageal diseases (gastro-esophageal reflux disease, eosinophilic esophagitis), and other sphincter regions (anal canal, pylorus) will need further confirmatory studies. The EndoFLIP® system provides detailed geometric data of the gastrointestinal lumen but further works are needed to determine its use in clinical practice.

Esophageal Functional Lumen Imaging Probe (FLIP): How Can FLIP Enhance Your Clinical Practice?

Recent innovations in esophageal diagnostic testing have enhanced gastroenterology clinical practice by facilitating more nuanced and advanced evaluation of esophageal symptoms. Among these pivotal advances is the FDA-approved functional lumen imaging probe (FLIP), which utilizes impedance planimetry via volumetric distension of a catheter-mounted balloon at the time of sedated upper endoscopy, to acquire esophageal dimensions and pressures. In real time, FLIP can display cross-sectional areas (CSA) and distensibility indices (ratios of CSA to intra-balloon pressures) throughout the esophagus, most notably at the esophagogastric junction, as well as secondary peristaltic esophageal body contractile patterns. As the use of FLIP has progressively spread and permeated into the practice of clinical gastroenterology since its introduction, increasing data on and experiences with its applications have accumulated to guide its utility in clinical practice. In this current review developed for gastroenterologists and foregut surgeons across clinical practice, we provide an introduction to FLIP technology and metrics and discuss the clinical scenarios in which performance of or referral for FLIP may be helpful in the evaluation and management of patients with commonly encountered esophageal symptoms and disorders. Specifically, we discuss the potential applications and limitations of FLIP as a complementary diagnostic modality in patients with non-obstructive dysphagia, established or suspected achalasia spectrum disorders, eosinophilic esophagitis, gastroesophageal reflux disease and those undergoing esophageal surgery.

Initial Experience with Endoscopic Pyloromyotomy, with Description and Video of Technique

BACKGROUND

Gastric per oral endoscopic myotomy (G-POEM) is a recently developed incisionless procedure to address gastroparesis. It has been previously described to treat medical and postsurgical gastroparesis. The present study is a case series of patients undergoing G-POEM for a variety of indications, both elective and urgent.

METHODS

IRB approval was obtained for retrospective review of a prospectively collected database including patients who underwent G-POEM during a 1.5-year period. Using an upper endoscope, a mucosotomy is made 2 cm proximal to the pylorus on the anterior surface of the stomach. A submucosal tunnel is made to the pylorus muscle, which is completed incised. When possible, Endoflip® was used to evaluate pyloric distensibility before and after the myotomy. Patient demographic factors, additional procedures, and other follow-up were collected by chart review. Elective cases were offered repeat gastric emptying study at 6 months.

RESULTS

There were 17 patients available for review. The procedure was technically completed in all cases. There was one gastric perforation recognized on postoperative day two that was addressed with laparoscopy and omental patch. Median length of stay was zero days, and 13/17 (76%) of patients experienced symptomatic relief. Pyloric distensibility significantly decreased intraoperatively from 5.6 (± 1.7) to 10.8 (± 5.0) cm²/mmHg (p = 0.002).

CONCLUSION

This limited case series demonstrates G-POEM to be a versatile procedure able to address gastroparesis in a variety of settings. Success rates are congruent with previously published reports, and one serious complication was able to be addressed laparoscopically. Endoflip® was able to verify a successful myotomy intraoperatively. This procedure is an attractive alternative to less effective non-invasive treatments and a more invasive laparoscopic pyloroplasty.