Anorectal Manometry in Defecatory Disorders: A Comparative Analysis of High-resolution Pressure Topography and Waveform Manometry

BACKGROUND/AIMS: Whether high-resolution anorectal pressure topography (HRPT), having better fidelity and spatio-temporal resolution is comparable to waveform manometry (WM) in the diagnosis and characterization of defecatory disorders (DD) is not known. METHODS: Patients with chronic constipation (Rome III) were evaluated for DD with HRPT and WM during bearing-down “on-bed” without inflated rectal balloon and “on-commode (toilet)” with 60-mL inflated rectal balloon. Eleven healthy volunteers were also evaluated. RESULTS: Ninety-three of 117 screened participants (F/M = 77/16) were included. Balloon expulsion time was abnormal (> 60 seconds) in 56% (mean 214.4 seconds). A modest correlation between HRPT and WM was observed for sphincter length (R = 0.4) and likewise agreement between dyssynergic subtypes (κ = 0.4). During bearing down, 2 or more anal pressure-segments (distal and proximal) could be appreciated and their expansion measured with HRPT but not WM. In constipated vs healthy participants, the proximal segment was more expanded (2.0 cm vs 1.0 cm, P = 0.003) and of greater pressure (94.8 mmHg vs 54.0 mmHg, P = 0.010) during bearing down on-commode but not on-bed. CONCLUSIONS: Because of its better resolution, HRPT may identify more structural and functional abnormalities including puborectal dysfunction (proximal expansion) than WM. Bearing down on-commode with an inflated rectal balloon may provide additional dimension in characterizing DD.