Rectal Sensory and Compliance Testing: A Method Comparison Study between High-Resolution Anorectal Manometry and Barostat Investigations

Abstract

Abnormal visceral perception and motor function are often observed in patients with fecal incontinence, evacuation disorders and irritable bowel syndrome. The international anorectal physiology working group has proposed a standardization for anorectal function assessment, where rectal sensitivity testing is performed using an elastic balloon attached to a high-resolution anorectal manometry (HRAM) catheter. Rectal compliance, another component of rectal function evaluation, is a pressure-volume relationship that refers to the rectum's ability to stretch and expand as it receives and holds fecal matter. There are no data available regarding the possibility of compliance testing using HRAM, although this is theoretically possible by correcting for the elastic balloon's intrinsic properties. The gold standard for measurement of visceral sensitivity and compliance is the rectal barostat, according to the procedure described by the European COST action GENIEUR group. Data on the agreement between the two different procedures are scarce. Hence, we performed a comparative study of the HRAM and barostat investigations in 26 healthy individuals. We hypothesized that by inflating the balloon before the examination, rectal compliance can be measured with HRAM investigations, and we examined correlations and levels of agreement between the methods. Our results demonstrate that assessing rectal compliance with HRAM is technically possible; however, a strong correlation with the rectal barostat was only observed at the maximum tolerable volume (Spearman's rho = 0.7, p = 0.02). We only found moderate correlations (Spearman's rho = 0.562, p = 0.019) for compliance according to the barostat methodology and for rectal sensibility testing (Spearman's rho = 0.57, p = 0.03 for maximum tolerable volume). Bland-Altman plots showed poor levels of agreement between the methods. We conclude that HRAM and the rectal barostat cannot be used interchangeably for compliance or sensitivity assessments. We suggest the development of a non-elastic balloon with a fixed size and shape to assess rectal sensory function and compliance in HRAM testing.

Keywords: high-resolution anorectal manometry; rectal barostat; rectal compliance; rectal sensory function.

Figure 1

The protocols used for the HRAM and rectal barostat testing.

Figure 2

Median compliance values at 50%, 75% and 100% of the maximum tolerable volume (MTV) using uncorrected HRAM pressure (U), group-level corrected HRAM pressures (GC), individual-corrected HRAM (IC), barostat (B) and barostat investigations in the individual correction group (BI).

Figure 3

HRAM-based compliance at 100% MTV using the group-level correction plotted against the barostat-based compliance at 100% MTV. The black line represents the line of equality.

Figure 4

Bland–Altman plots for compliance data using (a) general correction at 100% MTV; (b) individual correction at 75% MTV and (c) 100% MTV. CB and CH: barostat- and HRAM-based compliance.

Figure 5

Median sensory threshold volumes with quartiles. FS: first sensation; FU: first urge; IU: intense urge; MTV: maximum tolerable volume.

Figure 6

HRAM-based MTV plotted against barostat-based MTV. The black line represents the line of equality.

Figure 7

Bland–Altman Plot of HRAM-based MTV and barostat-based MTV (N = 25) (a) and HRAM-based U at first and second inflations (N = 17) (b), illustrating the difference in scale for the 95% limits of agreement. U1, U2: urgency on first and second inflations.