Validation of the digital rectal examination as an estimate of anal sphincter squeeze pressure.

Although digital examination is commonly used to assess anal sphincter tone and maximal squeeze pressure, the accuracy of this test has never been adequately validated. A total of 27 patients with a spectrum of subjectively assessed anal sphincter tones were studied. Simultaneous subjective (digital) and objective (manometric) determinations of maximal anal squeeze pressures were made. Subjective digital assessment revealed the following: three patients, absent squeeze pressure (grade 0); two patients, markedly reduced (grade +1); six patients, reduced (grade +2); and the remaining 16 patients had normal maximal squeeze pressure (grade +3). Simultaneous objective anal sphincter pressure measurements, when compared with these subjective values, revealed a correlation coefficient of 0.97 (p less than 0.05). Therefore, the clinician can reliably use the digital rectal examination to judge anal sphincter strength.