How does anorectal manometry aid in fecal incontinence evaluation?

How does anorectal manometry aid in fecal incontinence evaluation?

• A. Measures urinary flow rate.
• B. Visualizes rectal mucosa.
• C. Provides histology of rectal tissue.
• D. Measures anal sphincter pressures and rectal sensation.

Answer: (D)

Anorectal manometry focuses on how the anal sphincters work and how the rectum senses stool, which is exactly what drives many cases of fecal incontinence. By measuring resting anal canal pressure, we learn about the base tone maintained by the internal anal sphincter. By measuring the maximum squeeze pressure, we assess the voluntary external anal sphincter and the pelvic floor’s ability to tighten. Rectal sensation thresholds—first sensation, urge, and maximum tolerable volume—tell us how well the rectum communicates its contents to the brain and when a person feels the need to void. The test may also evaluate reflexes between the rectum and anal canal. These data help distinguish contributing factors: low resting or reduced squeeze pressures point to external sphincter or pelvic floor weakness; diminished rectal sensation suggests sensory impairment contributing to leakage; normal pressures with incontinence symptoms may indicate other mechanisms or guide non-surgical therapies. This information is directly used to tailor treatment, such as biofeedback for dysfunction in sensation or pelvic floor strengthening or surgical/neuromodulation options for sphincter weakness. Note that the test does not visualize the rectal mucosa, provide tissue histology, or measure urinary flow—those require endoscopy, biopsy, or urodynamics, respectively.

Anorectal manometry focuses on how the anal sphincters work and how the rectum senses stool, which is exactly what drives many cases of fecal incontinence. By measuring resting anal canal pressure, we learn about the base tone maintained by the internal anal sphincter. By measuring the maximum squeeze pressure, we assess the voluntary external anal sphincter and the pelvic floor’s ability to tighten. Rectal sensation thresholds—first sensation, urge, and maximum tolerable volume—tell us how well the rectum communicates its contents to the brain and when a person feels the need to void. The test may also evaluate reflexes between the rectum and anal canal.

These data help distinguish contributing factors: low resting or reduced squeeze pressures point to external sphincter or pelvic floor weakness; diminished rectal sensation suggests sensory impairment contributing to leakage; normal pressures with incontinence symptoms may indicate other mechanisms or guide non-surgical therapies. This information is directly used to tailor treatment, such as biofeedback for dysfunction in sensation or pelvic floor strengthening or surgical/neuromodulation options for sphincter weakness.

Note that the test does not visualize the rectal mucosa, provide tissue histology, or measure urinary flow—those require endoscopy, biopsy, or urodynamics, respectively.