Accuracy of Anorectal Manometry to Detect the Rectoanal Inhibitory Reflex in Children: Awake Versus Under General Anesthesia

Objectives: Our objective was to investigate if there is a difference in the detection of the rectoanal inhibitory reflex (RAIR) when an anorectal manometry (ARM) is performed awake or under general anesthesia. Methods: A retrospective review of ARM studies was performed to identify children who had undergone ARMs both while awake and under general anesthesia. We compared ARM outcomes including the detection of the RAIR and anal canal resting pressure. Results: Thirty-four children had received ARMs both while awake and under general anesthesia (53% female, median age at first ARM 7.5 years [range 3-18 years]). In 9 of 34 (26%) children the RAIR was solely identified during ARM under general anesthesia and not during ARM while awake. In 6 of 9 (66%) this was unrelated to the balloon volumes used during balloon inflations. In 4 of 34 (12%) children, assessment of the RAIR was inconclusive during ARM under general anesthesia due to too low, or loss of anal canal pressure. In 2 of those children, ARMs while awake showed presence of a RAIR. Anal canal resting pressures were higher during ARM while awake versus ARM under general anesthesia (median 70 [interquartile range, IQR 59-85] vs 46 mmHg [IQR 36-65] respectively, P < 0.001). Conclusions: General anesthesia may affect the detection of a RAIR in 2 ways. On the one hand, it may facilitate better visualization in children in whom a RAIR could not be visualized while awake. On the other hand, it may cause a loss of anal canal pressure resulting in an inconclusive test result.