Chronic Megacolon Presenting in Adolescents or Adults: Clinical Manifestations, Diagnosis, and Genetic Associations

Objective: Chronic megacolon is rarely encountered in clinical practice beyond infancy or early childhood. Most cases are sporadic, and some are familial megacolon and present during adolescence or adulthood. There is a need for diagnostic criteria and identifying genetic variants reported in non-Hirschsprung’s megacolon. Methods: PubMed search was conducted using specific key words. Results: This article reviews the clinical manifestations, current diagnostic criteria, and intraluminal measurements of colonic compliance to confirm the diagnosis when the radiological imaging is not conclusive. Normal ranges of colonic compliance at 20, 30, and 44 mmHg distension are provided. The diverse genetic associations with chronic acquired megacolon beyond childhood are reviewed, including the potential association of SEMA3F gene in a family with megacolon. Conclusions: Measuring colonic compliance could be standardized and simplified by measuring volume at 20, 30, and 44 mmHg distension to identify megacolon when radiology is inconclusive. Diverse genetic associations with chronic acquired megacolon beyond childhood have been identified.