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

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.