High-resolution anorectal manometry for defecation function evaluation in children following surgical repair of congenital anorectal malformations

Abstract

Objective To assess the application of high-resolution anorectal manometry (HRAM) for evaluating postoperative defecation function in children following surgical repair of congenital anorectal malformations (ARMs). Methods A total of 77 children undergoing surgeries for ARMs in our hospital. from 2014 to 2017 were enrolled in this study. The patients' postoperative defecation function was evaluated based on Kelly scores at 6 to 12 months after the surgeries. The results of HRAM for measuring the resting and maximum pressures, effective length of the anal canal, and rectoanal inhibitory reflex recovery were compared among the patients with different positions of ARM and with different postoperative defecation functions. Of the 77 children included, 32 were found to have low ARM (with a distance < 1.5 cm between the blind rectal pouch and the anal crypt) and 45 had high ARM (≥1.5 cm); 72 of the children had good postoperative defecation function (Kelly score of 3-6) and 5 had poor defecation function (Kelly score of 0-2). Results We compared the HRAM findings between the 32 children having low ARM and the 40 children with high ARM in the 72 children with good postoperative defecation function, and the results showed significantly higher mean resting pressure (38.00±12.33 vs 32.27±11.86 mmHg) and maximum resting pressure (42.65± 14.23 vs 36.67±12.10 mmHg), a longer effective length of the anal canal (2.43±0.30 vs 2.18±0.33 cm), and a higher recovery rate of rectoanal inhibitory reflex (90.63% vs 17.50%) in the former children (all P < 0.05). In the 45 children with high ARMs, the children with poor defecation function had a significantly mean higher resting pressure than those with good defecation function (32.27±11.86 vs 26.08±2.36 mmHg, P < 0.05) and had also a higher maximum resting pressure (36.67±12.10 vs 29.96±2.55 mmHg, P < 0.05). Three-dimensional image analysis highlighted the presence of a low pressure band or a pressure loss zone in the images in the children with poor postoperative defecation function. Conclusion Children with low ARMs have significantly higher mean resting pressure and maximum resting pressure, a longer effective anal canal length, and a higher rectoanal inhibitory reflex recovery rate than those with high ARMs. The anal sphincter function can be evaluated based on the three-dimensional images, and HRAM can be used for assessing postoperative defecation function in children with ARMs.

Keywords

• congenital anorectal malformations
• high resolution anorectal manometry
• defecation function