Pediatric High-Resolution Anorectal Manometry: Reference Ranges in 998 Children With Defecatory Disorders

Anorectal manometry (ARM) is a commonly performed motility test in pediatrics. Currently, adult ARM normative data are extrapolated to pediatric assessments due to few validated pediatric studies. We share a single center experience of ARM performed in children with defecatory disorders across all age groups to highlight differences in measurements.

This retrospective study reviewed 1001 ARM studies performed at Children's Hospital Los Angeles (CHLA) GI Motility Lab from 2012 to 2019, of which 998 studies met criteria for evaluation. They were stratified by gender (male, female) and age. Fifty-four patients with anorectal malformations were assessed independently. All studies were performed using high-resolution solid-state manometry catheters.

The mean anal sphincter resting pressure (ASRP) for 944 patients without anorectal malformations was 75.6 ± 21.3 mmHg, with a statistically significant difference between male and female patients (male: 74.0 ± 20.9; female: 77.6 ± 21.3; p = 0.007). For each year of age, there is an estimated 0.23 mmHg increase in ASRP, but the result is not statistically significant (p = 0.082, CI: -0.03 to 0.49). In the subset of patients with anorectal malformations (n = 54), mean ASRP was 45.3 + 19.2 mmHg, without a significant difference between male or female.

This is the largest pediatric study in patients with defecatory disorders demonstrating that mean ASRP does not vary with age from newborns to adolescents and is similar to adult values. Specific quantitative RAIR parameters such as latency, recovery, and duration require further studies in pediatrics.