The gastrorectal reflex in women with obstructed defecation

This study evaluated the tonic response of the rectum to a meal in women with obstructed defecation. Fifteen control subjects and 60 women with obstructed defecation were studied. Total colonic transit time was normal in 30 patients (group I) and prolonged in the other 30 (group II). After over-night fasting an "infinitely compliant" polyethylene bag was inserted into the rectum. Rectal tone was assessed by measuring variations in bag volume with a computerized electromechanical air injection system. After an adaptation period of 30 min all subjects consumed a 450-kcal liquid meal. Postprandial recordings were continued for 3 h. In a second recording session we investigated the tonic response of the rectum to an evoked urge to defecate. In a third session rectal sensory perception was assessed. Following the meal all controls showed an increase in rectal tone (mean 74.8±17%). Patients in whom colonic transit time was normal showed a similar tonic response. In group II the increase in rectal tone was significantly lower (mean 27.8±10%; P<0.001). Three patients of this group showed no response to a meal at all. All controls showed an increase in rectal tone during an evoked urge to defecate (mean 39.2±9%). In both groups this tonic response was absent or significantly blunted (mean 15.3±6%) and 16.4±5%, respectively; P<0.001). In both groups rectal sensory perception was significantly impaired. In conclusion, patients with obstructed defecation in whom colonic transit time is normal have an intact gastrorectal reflex. The increase in rectal tone after a meal is absent or blunted in patients with obstructed defecation in whom transit time is prolonged. The tonic response of the rectum to an evoked urge to defecate as well as rectal sensory perception are significantly impaired both in patients with a normal and in those with a prolonged transit time.

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