How Useful Is Digital Rectal Examination in the Diagnosis of Dyssynergia?

Abstract

Purpose: In patients with constipation and difficult defecation, anorectal manometry (ARM) is regarded as a gold standard for the diagnosis of dyssynergic defecation. However, it is not widely available and lacks standardization. Digital rectal examination (DRE) may provide vital clues regarding anorectal structure and function that could suggest dyssynergia. However, DRE is not systematically performed, and its clinical utility in the evaluation of dyssynergia is not known. Aim: To examine the diagnostic yield of DRE in pts with constipation and difficult defecation. Methods: Patients presenting to a single gastroenterologist with constipation and difficult defecation (Rome II) were enrolled. All pts completed a constipation questionnaire and had clinical assessment, including a detailed DRE: anocutaneous reflex, resting and squeeze anal sphincter tone, perineal descent, and anal relaxation with straining. A clinical impression of dyssynergia was noted in the chart. Subsequently, all patients had ARM with a solid state, 6-sensor probe. Anal sphincter and intrarectal pressures were analyzed at rest, squeeze and during attempted defecation, and these data were used to identify dyssynergia. A balloon expulsion test (BET) was also performed. The diagnostic yield of DRE was compared with ARM, using manometry as the gold standard. Results: We examined 100 pts (F/M: 94/6, mean age: 41 ± 15.3 yrs) with constipation. Excessive straining, hard stools, incomplete evacuation, ≤ 3 BM/wk and use of digital maneuvers were reported by 84%, 88%, 80%, 75% and 40% of patients respectively. Based on DRE (impaired perineal descent or paradoxical anal contraction or impaired push effort), 76 (76%) had dyssynergia. Subsequently, ARM identified 95 pts (95%) with dyssynergia. DRE had as sensitivity of 81% and positive predictive value (PPV) of 99% for diagnosis of dyssynergic defecation. Normal resting tone on DRE had a sensitivity of 81% and PPV of 69% but a weak sphincter had a sensitivity of 25% and PPV of 28%. Normal squeeze tone had a sensitivity of 78% and PPV of 69% whereas a weak squeeze pressure had sensitivity of 31% and PPV of 40%. Anocutaneous reflex was normal in 73%, and absent in 27%. BET had a sensitivity of 49% and PPV of 100%. Conclusion: In patients presenting with constipation in a tertiary care center, DRE has a high sensitivity and PPV in identifying pts with dyssynergic defecation. DRE has good sensitivity and PPV for detecting a normal but not an abnormal resting or squeeze sphincter tone. A prolonged balloon expulsion test is diagnostic but a normal test does not exclude dyssynergia.