Comparing Diagnostic Tests in Dyssynergic Defecation-Constipation

Abstract

Introduction: Idiopathic chronic constipation is a common medical problem, with an average reported prevalence of 15% in North America. The prevalence of constipation is higher in women. Normal transit constipation, colonic inertia, and dyssynergic defecation (DD) are subtypes of idiopathic chronic constipation. There is limited agreement among tests to diagnose dyssynergic defecation. Dyssynergic defecatory symptoms, failure to expel a 60-mL balloon during a balloon expulsion test, and anal sphincter dyssynergic pattern on manometry testing are frequently used for diagnosing pelvic floor dyssynergia. The aim of this study is to compare the result of different studies in predicting DD. Methods: From January 2013 to May 2014, 143 consecutive constipated patients referred for pelvic floor testing were included in the study and the results of their work-ups were collected. Detailed questionnaires regarding patients’ defecatory symptoms, pertinent medical and surgical history, medication use, and digital rectal exam by gastroenterologists with motility expertise were collected prior to anorectal high-resolution manometry testing. Results: Our study includes 143 patients with constipation who were referred by their primary physician or gastroenterologist to our tertiary care center for pelvic floor testing. The mean age of the patients was 50 years with the majority of the patients being female (87%). Mean resting pressures were 62±6 mm Hg, mean squeeze pressures 143±13 mm Hg, and maximum tolerated volume was 201±63 mL; 111 patients (78%) had symptoms on questionnaire suggestive of DD. While 80 patients (56%) had an expert-performed digital rectal exam suggestive of DD, high-resolution manometry diagnosed dyssynergic pattern in 83 patients (58%). Expert-performed digital rectal exam is 87% sensitive and 85% specific for diagnosing DD versus dyssynergia documented by high-resolution manometry as the gold standard. Balloon expulsion test was abnormal (more than 2 minutes) in 57 subjects (40%). Among 32 patients with DD on manometry test who had normal balloon expulsion test (<2 min), 14 (43%) patients had resting anal pressure less than 45 mm Hg. Conclusion: Defecation is a complex process, influenced by stool consistency and pelvic floor neuromuscular sensation and function. While, there is no single criterion in diagnosing dyssynergic defecation (DD), the ability to expel a 60-mL balloon does not exclude the presence of pelvic floor dyssynergia. Therefore, a careful interpretation of the test results is important in making the correct diagnosis.