FORT LAUDERDALE, FLA. — Anal manometry is a useful tool for the evaluation of patients with abnormal anorectal physiology, including those presenting with constipation, fecal incontinence, proctalgia, or rectal prolapse, according to Dana R. Sands, M.D.
Manometry provides information about the functional status of the anal sphincter and distal rectum, and often is used with other tests such as anal ultrasound, anal sphincter EMG, pudendal nerve terminal motor latency assessment, and defecography, said Dr. Sands of the Cleveland Clinic Florida, Weston.
In patients with fecal incontinence, for example, anal ultrasound is the cornerstone of treatment, but anal manometry, EMG, and pudendal nerve assessment “round out the evaluation,” she said at a symposium on pelvic floor disorders sponsored by the Cleveland Clinic Florida.
Anal manometry, however, is not well standardized, Dr. Sands said, noting that different facilities have different protocols and normal values.
Some manometry devices include a microtransducer, some use air-filled balloon systems, and still others use continuously perfused probes. The Cleveland Clinic uses a balloon-tip catheter system that is perfused with water. The device measures rectal sensation, resting and squeezing pressures at different levels in the anal canal, and rectal compliance, all of which can play a role in fecal incontinence.
Although some surgeons say their index finger is the best device for identifying anal sphincter pathology, manometry provides a higher level of information than that achieved via digital rectal exam, she said.
In one study of 64 patients, digital rectal exam performed by an experienced colorectal surgeon yielded 63% sensitivity and 57% specificity for internal anal sphincter pathology, and 84% sensitivity and 57% specificity for external anal sphincter pathology.
“I think we can be a little more sophisticated than that with the manometry machine,” she said, adding that manometry also provides insight into the etiology of conditions such as fecal incontinence and can aid in discussions with patients about expected outcomes and prognosis.