Megarectum Surgery in the management of constipation in children

Constipation is a symptom rather than a diagnosis, and megarectum is a descriptive anatomical and physiological phenotype rather than a single disease. The distinction matters because a markedly enlarged rectum may be secondary to prolonged faecal retention, may represent primary rectal ectasia or idiopathic megarectum, may form part of a congenital segmental dilatation, or may occur in association with anorectal malformation or more extensive colonic dysmotility. The principal clinical error is to treat all such children as though they have the same disorder. The original version of this review argued that the decision to operate should be based on the pathology and the likelihood of benefit rather than on an arbitrary duration of unsuccessful medical treatment (Dewan 2025). The literature published subsequently strengthens this position while providing a more structured framework for defining refractory constipation and selecting investigations. The 2025 NASPGHAN position paper defines paediatric refractory constipation as persistent Rome IV functional constipation despite at least three months of appropriate conventional therapy, including stimulant laxatives and behavioural/biomechanical measures, together with ongoing symptoms and impaired quality of life (Kilgore et al. 2025). Contemporary evidence also supports selective use of contrast enema, anorectal physiology and colonic manometry rather than indiscriminate investigation. Colonic manometry can help distinguish segmental from pancolonic dysmotility and may guide diversion, antegrade continence enemas (ACE) and resection (Gupta et al. 2020; Chanpong et al. 2025). Surgery remains appropriate for a small but important group. ACE is an established treatment for severe refractory constipation, but recent systematic-review and long-term outcome data demonstrate wide variation in success and significant stomal morbidity (Baaleman et al. 2023; Jonker et al. 2025; Tervahartiala et al. 2026). Conversely, series of children with true megarectum or megarectosigmoid demonstrate that resection can provide durable improvement in carefully selected patients (Glasser et al. 2018; Kirgizov et al. 2019). The appropriate operation depends on whether the principal abnormality is the rectum, rectosigmoid, or more extensive colonic dysmotility. This review updates the original discussion and incorporates the 2025-2026 literature (Dewan 2025). The central proposition remains that children should be treated according to the anatomy and physiology of their bowel, not simply according to the label of constipation.