Refractory Chronic Constipation in an Adolescent Female Later Diagnosed With Internal Anal Sphincter Achalasia.

Internal anal sphincter achalasia (IASA) is a rare anorectal disorder that presents as chronic refractory constipation in pediatrics. With a poor response to conventional constipation-based therapy, it is often misdiagnosed as other conditions, such as ultra-short-segment Hirschsprung disease. This case report describes a rare case of IASA in an adolescent female, emphasizing the importance of ruling out other differentials, including Hirschsprung disease, via rectal biopsy and thus allowing for earlier targeted therapy to improve lifestyle conditions.