Audit of the diagnosis of rectal evacuation disorders in chronic constipation

Background: Balloon expulsion test (BET) and high-resolution anorectal manometry (HRM) are used in diagnosis of rectal evacuation disorders (REDs); their performance characteristics are suboptimal. Methods: We audited records of 449 consecutive patients with chronic constipation (CC). We documented anal sphincter tone and contraction, puborectalis tenderness, and perineal descent on digital rectal exam (DRE); maximum resting and squeeze pressures, and rectoanal pressure gradient on HRM; weight or time to balloon expulsion; colonic transit, and area of rectal area on radiograph (RASF). We based the diagnosis of RED on ≥2 abnormalities on both DRE and HRM, excluding results of BET, as the performance of BET is being investigated. Results of RED vs non-RED and results obtained using tbBET vs wbBET groups were compared. We used multivariate logistic regressions to identify predictors of RED using different diagnostic modalities. Key Results: Among 449 individuals, 276 were included (74 RED and 202 non-RED). Predominant exclusions were for no HRM (n = 79) or use of low resolution anorectal manometry (n = 77). Logistic regression models for abnormal tbBET showed time >60 seconds, RASF and age-predicted RED. For tbBET, the current cutoff of 60 seconds had sensitivity of 39.0% and specificity 93.0% to diagnose RED; on the other hand, applying the cutoff at 22 seconds, the sensitivity was 77.8% and specificity 69.8%. Conclusions & Inferences: The clinical diagnosis of RED in patients with CC is achieved with combination of DRE, HRM and an optimized, time-based BET. Prospective studies are necessary to confirm the proposed 22 second cutoff for tbBET.