Comparison of ultrasound and manometric sphincter length and incontinence scores

Fecal incontinence can be assessed by a wide variety of means that vary in their clinical relevance. This study assesses the correlation between two methods of recording sphincter length and incontinence scores.

A retrospective review of results from 1999 to 2001 of 137 patients with fecal incontinence was undertaken on patients who had both ultrasound and manometric assessment. Incontinence scores, ultrasonic sphincter length, and manometrically derived sphincter length were recorded. The data were analyzed using the Spearman rank correlation coefficient (r(s)) for nonparametric data.

There was negative correlation between incontinence scores and manometric sphincter length (r(s) = -0.27; P = 0.002) but not with ultrasonic length (r(s) = -0.08; P = 0.38). There was correlation between manometric and ultrasonic lengths (r(s) = 0.21; P = 0.02). In males, all three correlated but none of the values were significant (n = 12). Internal and external sphincter defects had no effect on correlation coefficients.

Given that all measurements include a degree of subjectivity, manometry more closely correlates with the fecal incontinence scores than ultrasound measurements. There seems to be little benefit in measuring the sphincter length with ultrasound. Manometric sphincter length measurement seems to have a role in assessing patients with fecal incontinence.