Anal inspection and digital rectal examination compared to anorectal physiology tests and endoanal ultrasonography in evaluating fecal incontinence

Abstract

Background: Anal inspection and digital rectal examination are routinely performed in fecal incontinent patients but it is not clear to what extent they contribute to the diagnostic work-up. We examined if and how findings of anal inspection and rectal examination are associated with anorectal function tests and endoanal ultrasonography.

Methods: A cohort of fecal incontinent patients (n=312, 90% females; mean age 59) prospectively underwent anal inspection and rectal examination. Findings were compared with results of anorectal function tests and endoanal ultrasonography.

Results: Absent, decreased and normal resting and squeeze pressures at rectal examination correlated to some extent with mean (+/-SD) manometric findings: mean resting pressure 41.3 (+/-20), 43.8 (+/-20) and 61.6 (+/-23) Hg (p<0.001); incremental squeeze pressure 20.6 (+/-20), 38.4 (+/-31) and 62.4 (+/-34) Hg (p<0.001). External anal sphincter defects at rectal examination were confirmed with endoanal ultrasonography for defects <90 degrees in 36% (37/103); for defects between 90-150 degrees in 61% (20/33); for defects between 150-270 degrees in 100% (6/6). Patients with anal scar tissue at anal inspection had lower incremental squeeze pressures (p=0.04); patients with a gaping anus had lower resting pressures (p=0.013) at anorectal manometry. All other findings were not related to any anorectal function test or endoanal ultrasonography.

Conclusions: Anal inspection and digital rectal examination can give accurate information about internal and external anal sphincter function but are inaccurate for determining external anal sphincter defects <90 degrees. Therefore, a sufficient diagnostic work-up should comprise at least rectal examination, anal inspection and endoanal ultrasonography.