Functional anal canal length measurement using high‐resolution anorectal manometry to investigate anal sphincter dysfunction in patients with fecal incontinence or constipation

Abstract

Background Using high‐resolution anorectal manometry, we aimed to evaluate the: (a) optimal threshold to measure functional anal canal length (FACL) with intra‐ and inter‐observer variability; (b) relationship between abnormal FACL and other phenotypic findings; and (c) utility of FACL measurement to discriminate between healthy volunteers (HV) and patients with fecal incontinence (FI) or chronic constipation (CC). Methods Consecutive patients referred for investigation of FI or CC in isolation were included. FACL was calculated at 5, 10, 20, 30, and 50 mm Hg above rectal pressure. 5th‐95th percentile in HV defined limits of normality. Key Results FACL was analyzed in 192 patients with FI (154 females), 204 patients with CC (175 females), and 134 HV (101 females). The optimal threshold for measurement of FACL was 20 mm Hg. Using this threshold, observer reproducibility was very high (ICC 0.99, P < 0.0001). FACL was shorter in females with FI and longer in females with CC compared to HV (2.3 vs 2.9 cm; and 3.4 cm vs 2.9 cm; both P < 0.0001). Twenty percent of females and 13% males with FI had a short FACL, associated with older age, anal hypotonia or hypocontractility, and a atrophic internal anal sphincter. However, abnormal FACL in isolation was only found in 1/190 FI (0.5%) and 2/201 CC (1%) patients; all other patients had other abnormal manometric findings. Conclusions and Inferences Considering overlap with other routinely evaluated manometric parameters, FACL measurement does not provide additional information in the diagnostic assessment of FI or CC.

Improving the utility of high‐resolution manometry for the diagnosis of defecatory disorders in women with chronic constipation

“…Sensors 5 and 6 may be located either in the rectum or in the anal canal. In a prior study, sensors that recorded pressures, which were 20 mmHg greater than rectal pressure, were considered to be in the anal canal 25 . At rest, the rectal pressure is approximately 10 mmHg.…”

“…In a prior study, sensors that recorded pressures, which were 20 mmHg greater than rectal pressure, were considered to be in the anal canal. 25 At rest, the rectal pressure is approximately 10 mmHg. Hence, in this study, sensors that recorded a resting pressure of 30 mmHg or greater were considered to be in the functional anal canal.…”

The London Classification: Improving Characterization and Classification of Anorectal Function with Anorectal Manometry

“…Nevertheless, recent 3D HD-ARM studies have shown that sustained voluntary contraction (long squeeze) is the most discriminant parameter to differentiate constipated and incontinent patients [32]. Similarly, other measures, consistently reported using conventional manometry studies, have not been considered essential by the IAPWG [10••], including functional anal canal length [33], anal relaxation during push and sustained urgency volume during the rectal sensory test. Further, the recto-anal pressure gradient (RAPG) during push has not been incorporated.…”

Normal values and associated factors in high-resolution anorectal manometry in healthy Vietnamese adults

“…We did nd a signi cant difference in the functional anal canal length between participants with BMI < 25 and those with BMI ≥ 25, suggesting that BMI variation could affect the functional anal canal length. In the study conducted by Paul et al, functional anal canal length was used to evaluate anal sphincter dysfunction in patients with fecal incontinence or constipation, using baseline values collected from a healthy volunteer control group [18]. However, functional anal canal length did not help diagnosis of fecal incontinence or constipation in that study.…”