Megarectum after surgery for anorectal malformations

Area of Science:

• Pediatric Surgery
• Gastroenterology
• Developmental Biology

Background:

• Megarectum is a complication of anorectal malformation (ARM) surgery impacting long-term continence.
• Factors influencing continence include rectal reservoir, anorectal muscle complex innervation, the anorectal inhibitory reflex (AIR), and anal margin sensation.

Purpose of the Study:

• To investigate outcomes after ARM surgery, focusing on megarectum.
• To determine if sacrococcygeal anomalies affect megarectum incidence due to altered rectal proprioception.
• To assess if an abnormal AIR can cause passive rectal dilatation without mechanical obstruction.

Main Methods:

• Retrospective analysis of 86 infants with ARM over 20 years.
• Comparison of sacrococcygeal malformation incidence in children with and without megarectum.
• Evaluation of manometry results for AIR integrity and correlation with megarectum.

Main Results:

• 16% of ARM patients developed megarectum; sacrovertebral anomalies were significantly more common in those with megarectum (57% vs 7%).
• Preoperative manometry in 5 patients showed an intact AIR; colonic manometry revealed hyperactive colons in 2.
• Constipation was the primary preoperative symptom; 3 patients experienced incontinence post-resection.

Conclusions:

• Sacral anomalies, more frequent in megarectum cases, may impair rectal proprioception, contributing to megarectum development.
• While innervation anomalies may coexist, preoperative manometries indicated normal AIRs.
• Rectal dysmotility and diffuse colonic hypermotility might lead to stool retention and rectal dilatation, necessitating further research.