Value of anorectal manometry in patients with impaired defecation

Several guidelines recommend anorectal manometry in patients with functional anorectal disorders, eg. fecal incontinence and chronic constipation caused by outlet obstruction. We retrospectively reviewed tracings obtained between March 2005 and November 2008. A total of 189 patients (80% women; average age 56 years) were included. The main indications were fecal incontinence (21%) and constipation (79%). Patients suffering from incontinence were older (68±6 vs. 52±8 years) and had lower resting (35±8mmHg vs. 63±5mmHg P≤0.01) and squeeze pressure (54±7mmHg vs. 112±9mmHg P≤0.01) compared to continent patients, the perceptual thresholds were significantly lower in patients with fecal incontinence (urge: 50±4ml), compaired to those with constipation (137±18ml, P≤0.001). However, the sensitivity and specificity of manometric data seems to be low. An abnormal straining pattern suggesting dyssynergic defecation was seen in 51% of constipated patients compared to 85% of patients with fecal incontinence. Because of the low sensitivity and specificity of manometric parameters endoanal ultrasonography, defecography, balloon expulsion test are suggested to be performed in all patients with defecation disorders in order to make accurate diagnosis.