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

Abstract

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.

Keywords: anal sphincter; biofeedback therapy; constipation; high-resolution anorectal manometry.

Figure 1.

Configuration of selected anorectal catheters.

Figure 2.

Representative examples of pressure topography assessed with 3D-HR-ARM. (A) At rest, observe the high pressure zones representing the puborectalis (green) and the internal (IAS) and external anal sphincters (EAS) in red. (B) During squeeze, observe increased pressure generated by the puborectalis and EAS, which are now respectively colored red and magenta. During evacuation, there was normal relaxation (C) or paradoxical contraction (D) of the puborectalis and external anal sphincter.

Figure 3.

Representative images and summary data (median and interquartile values) of rectoanal pressures at rest and during evacuation in the seated position in the 4 patterns. Rectoanal pressures were measured by a 12-sensor catheter depicted in the vertical black bar, upper right corner. Note the transmission of pressure from the rectal balloon throughout the anal canal in the transmission pattern. Footnotes indicate comparison of rectal or anal pressure during evacuation in patients with normal versus prolonged BET in the same pattern. ^a P<.05. ^b P≤.01. ^c P≤.001. Reproduced with permission from Sharma M, Muthyala A, Feuerhak K, Puthanmadhom Narayanan S, Bailey KR, Bharucha AE. Improving the utility of high-resolution manometry for the diagnosis of defecatory disorders in women with chronic constipation. Neurogastroenterology & Motility. 2020;e13910.