Anorectal physiological testing in defecatory disorders: a prospective study.

A prospective study of anorectal physiological testing in 26 patients with obstructed defecation and 20 patients with faecal incontinence was performed. There were overlaps in individual test parameters between the two groups of patients. However, patients with severely blunted rectal sensation (maximum tolerated volume > 300 mL) and anismus were more likely to have obstructed defecation. Patients with very low anal canal pressures, a short (< 2.0 cm) anal canal, bilaterally prolonged (> 2.1 ms) pudendal nerve terminal motor latency and a grossly distorted and canal (vector symmetry index < or = to 0.75) were more likely to have faecal incontinence. Thus, patterns of anorectal physiological test results together with clinical evaluation, rather than individual test measurements, are more valuable in defining the underlying defecatory disorders and providing guidance on therapy.