atresia

Atresia is a medical term for congenital absence or complete closure of a normal body passage or opening, or the cutting off of a tubular structure. It most often refers to congenital conditions present at birth, though atresia can be acquired in some contexts.

Common forms include intestinal atresia, biliary atresia, choanal atresia, and anorectal (imperforate anus) atresia. Intestinal atresia involves closure or narrowing of a segment of the intestine and may present with bilious vomiting and abdominal distension in newborns; it is usually diagnosed by radiographic findings and managed with surgical repair, such as resection of the affected segment and anastomosis. Biliary atresia is the progressive obstruction of the extrahepatic biliary system in infancy, leading to cholestasis and jaundice; diagnosis uses ultrasound, hepatobiliary scintigraphy, and liver biopsy, and treatment typically begins with a Kasai portoenterostomy, with liver transplantation considered if liver function deteriorates. Choanal atresia is blockage of the nasal passage behind the nostrils, causing respiratory distress in newborns, often noticed when feeding and relieved by crying; it is corrected surgically. Anorectal atresia refers to an absent or closed anal opening, often associated with other anomalies; management usually involves staged surgical repair, sometimes starting with a diverting colostomy.

Etiology is generally developmental, arising from failed recanalization, vascular events, or abnormal embryologic development, and may be isolated or part of a syndrome with other congenital anomalies. Diagnosis relies on clinical presentation and targeted imaging or endoscopic evaluation. Treatment centers on surgical correction and supportive care, with prognosis varying by type, extent, timing of intervention, and associated conditions.