# The Clinical Relevance of the Rectosigmoid Brake in Surgical Disorders and Therapies: A Systematic Review of Colonic Manometry Studies

## TL;DR

The rectosigmoid brake in the colon helps control stool flow and its dysfunction is linked to several colorectal disorders, offering a new target for diagnosis and treatment.

## Contribution

This systematic review identifies the rectosigmoid brake as a unifying physiological mechanism in multiple surgical and functional colorectal conditions.

## Key findings

- Altered rectosigmoid brake activity is consistently observed in postoperative ileus, low anterior resection syndrome, fecal incontinence, and acute colonic pseudo-obstruction.
- High-resolution manometry reveals hyperactive postoperative activity in ileus and suppressed activity in fecal incontinence.
- Sacral nerve stimulation can enhance rectosigmoid brake activity, improving symptoms in fecal incontinence.

## Abstract

The rectosigmoid brake (RSB) regulates rectal filling via retrograde cyclic motor patterns in the distal colon. Disruption has been linked to postoperative ileus (POI), low anterior resection syndrome (LARS), fecal incontinence (FI), and acute colonic pseudo‐obstruction (ACPO). We synthesized manometric evidence to clarify the RSB's clinical relevance.

A systematic search of Ovid MEDLINE and Embase (March 2025) for studies assessing distal colonic motility in adults with surgical or functional colorectal conditions. Thirty‐four studies met the inclusion criteria, including nine using high‐resolution manometry. Data were qualitatively synthesized by condition.

Altered RSB activity was a consistent finding. In POI (7 studies; 2 HRM), the HRM studies showed immediate postoperative hyperactive distal cyclic activity (~2–4 cycles/min) correlating with delayed return of bowel function, contradicting older low‐resolution reports of quiescence. In LARS (4 studies; 3 HRM), post‐prandial cyclic patterns and propagating sequences were blunted after rectosigmoid resection. In FI (5 studies; 2 HRM), the brake was suppressed; sacral nerve stimulation increased distal retrograde contractions with parallel symptom gains. In ACPO (1 HRM case study), recordings showed disordered, non‐propagating hyperactive activity consistent with distal functional obstruction rather than hypoactivity.

Across POI, LARS, FI, and ACPO, the RSB appears to be a unifying physiological mechanism and a promising physiological biomarker with diagnostic and therapeutic potential. Priorities include standardizing manometric definitions, establishing normative reference metrics, and advancing non‐invasive assessment (e.g., body‐surface colonic mapping) to enable RSB‐guided care and translation to practice.

The distal colon has a natural “brake” (the rectosigmoid brake) that controls how quickly stool enters the rectum, helping prevent urgency and maintain continence.When this brake misfires, different problems can result: after colorectal surgery it may become overactive and delay recovery; when weakened or removed it can lead to urgency or incontinence.This brake is a promising, measurable sign to guide care: it can be boosted by sacral nerve stimulation, and new non‐invasive tests may help doctors track it to predict recovery and tailor treatment.

The distal colon has a natural “brake” (the rectosigmoid brake) that controls how quickly stool enters the rectum, helping prevent urgency and maintain continence.

When this brake misfires, different problems can result: after colorectal surgery it may become overactive and delay recovery; when weakened or removed it can lead to urgency or incontinence.

This brake is a promising, measurable sign to guide care: it can be boosted by sacral nerve stimulation, and new non‐invasive tests may help doctors track it to predict recovery and tailor treatment.

Colonic motility mapping reveals a meal‐induced rectosigmoid brake in healthy individuals that is disrupted, disorganized, or exaggerated following surgery and in motility disorders. These alterations underlie conditions such as ileus, pseudo‐obstruction, and fecal incontinence, and may be modulated by sacral neuromodulation.