Predicting Obstructive Defecation: Symptoms and Physiologic Tests

Abstract

Purpose: Constipation can be from a variety of disorders including obstructive defecation (OD) and delayed colonic transit. Prior studies have not shown predictive value of symptoms in identifying patients with OD. AIM. To determine which physiologic tests and specific questions of the Rome Pelvic Floor Dyssynergia questionnaire can be used to suggest OD or delayed colonic transit. Methods: A retrospective analysis of patients from May to January 2007 was conducted. Each patient underwent anorectal manometry (ARM), anal electromyography (EMG), balloon expulsion, and whole gut transit scintigraphy. OD was defined by the presence of 2 of the following 3 criteria: 1) inadequate relaxation of the internal anal sphincter (IAS) on ARM; 2) paradoxical increase in EMG activity on bearing down (simulated defecation); 3) inability to expel a 50 cc rectally placed balloon within 3 minutes. The manometric defecation index (DI) was defined as the ratio of intrarectal pressure to external anal sphincter pressure during simulated defecation. Patients were asked questions from the Rome Pelvic Floor Dyssynergia questionnaire: A) straining during movements; B) feeling of incomplete evacuation; C) sensation of blocked stools; D) manual maneuvers to facilitate defecation; E) difficulty relaxing to allow defecation. Results: Of 76 patients, OD was identified in 55 and nonobstructive constipation (NOC) was present in 21 patients. Abnormal DI ( < 1.2) was present in 47/55 (85%) OD patients and 9/21 (43%) NOC patients. Paradoxical EMG response was present in 38/55 (69%) OD patients and only 1/21 (5%) NOC patients. Abnormal IAS relaxation ( < 75%) was present in 32/55 (58%) OD patients and 14/21 (67%) NOC patients. Prolonged balloon expulsion (>3 minutes) was present in 16/55 (29%) OD patients and 3/21 (14%) NOC patients. Question A was associated with OD (P= 0.054); B was associated with both OD (P= 0.035) and with delayed colonic transit (P= 0.032); C was associated with OD (P= 0.060); D was associated with delayed colonic transit (P= 0.056); E was not associated with either OD or delayed colonic transit. Conclusion: The manometric defecation index was sensitive and EMG paradoxical response was specific in identifying patients with obstructive defecation whereas balloon expulsion did not appear to be useful. Questions A (straining during bowel movements) and C (sensation of blocked stools) were associated with obstructive defecation but not delayed colonic transit whereas D (manual maneuvers to facilitate defecation) was associated with delayed colonic transit but not obstructive defecation.