Closure mechanism of the anal canal in women: assessed by three-dimensional ultrasound imaging.

Purpose: To describe the functional correlates of anal canal anatomy using 3 dimensional ultrasound imaging.

Methods: Ten nulliparous women were studied by using a 10-cm bag of 20-mm diameter. The bag was placed along the anal canal and inflated with 20 to 45 ml water, in 5-ml increments.

Effects of pelvic floor muscle contraction on anal canal pressure.

The role of pelvic floor muscle contraction in the genesis of anal canal pressure is not clear. Recent studies have suggested that vaginal distension increases pelvic floor muscle contraction. We studied the effects of vaginal distension on anal canal pressure in 15 nullipara asymptomatic women.