Tag Archives: anorectal manometry

You Can Do Anorectal Manometry in Your Sleep, But Should You?

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DF Baaleman et al. JPGN 2023; 76: 731-736. Open Access! Accuracy of Anorectal Manometry to Detect the Rectoanal Inhibitory Reflex in Children: Awake Versus Under General Anesthesia

In this retrospective review from a tertiary referral center with 34 children.

Background: “The RAIR is an involuntary anal reflex mediated by a complex intramural neuronal plexus that results in a decrease of the internal anal sphincter (IAS) pressure following distension of the rectum. Such distension can be caused by gas, feces, or an inflated balloon during ARM testing (3). In patients with Hirschsprung disease, the RAIR is absent due to an abnormal development of the enteric nervous system resulting in the absence of ganglion cells (4). Additionally, the RAIR is occasionally found to be absent in children with normal presence of ganglion cells who are then diagnosed with internal anal sphincter achalasia (IASA) (5,6). The clinical significance of this diagnosis is still unclear (5).”

Key findings:

  • In 9 of 34 (26%) children the RAIR was solely identified during ARM under general anesthesia (GA) and not during ARM while awake.
  • In 4 of 34 (12%) children, assessment of the RAIR was inconclusive during ARM under GA due to too low, or loss of anal canal pressure.  In 2 of those children, ARMs while awake showed presence of a RAIR.
  • In the entire cohort, 2 children were diagnosed with Hirschsprung disease. 1 had an inconclusive study while awake and absence of RAIR while under GA. 1 had absence of RAIR while awake and under GA.
  • Other findings among the 34 children: 13 (38%) were diagnosed with pelvic floor dyssynergia, 3 (9%) were diagnosed with IASA, 2 (6%) were diagnosed with IASA and pelvic floor dyssynergia

Discussion:

The authors note that in patients with absent RAIR while awake but present while under GA, could result in “incorrect identification of an absent RAIR [and] may result in the unnecessary performance of rectal biopsies and the incorrect diagnosis of IASA…. Still, the ARM while awake more likely represents what they experience when they try to defecate during the day. Therefore, one could argue that these children may experience obstructive symptoms in daily life similar to a child diagnosed with IASA… In our sample, 9 children would have been misdiagnosed with IASA if they would not have undergone a repeat ARM (5).”

My take: It is interesting that about a quarter of children had RAIR identified only while under GA. Given the uncertainty regarding the clinical significance of a IASA diagnosis, in many centers the next step would be arranging a rectal biopsy rather than repeating a study under GA.

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