Evaluation of ability to defecate using saline evacuation from the rectum.

Purpose: The purpose of this study is to establish a simple technique to evaluate anorectal motility and the dynamics of defecation.
Methods: Pressure fluctuations in the rectum and anal canal during 500 ml of saline infusion in the rectum and then a saline evacuation curve were recorded using manometer and uroflowmeter.
Results: This study consisted of 37 patients with a mean age of 49.6 years. All patients without problems with defecation showed periodic relaxation of the anal canal, which was synchronized with rectal contractions during saline infusion. The saline evacuation curves of these patients were characterized by short evacuation time and high-peak flow. Of the 13 patients with constipation, 9 showed no rectoanal synchronization and had segmental evacuation curves. The patients with incontinence tended to have poor ability for holding saline in the rectum, resulting in low-peaked evacuation curves.
Conclusions: This simple and noninvasive technique for recording anorectal pressure fluctuations and dynamics of saline evacuation from the rectum enables quantitative and qualitative evaluation of the ability to defecate.