Biliary atresia with splenic malformation syndrome

Biliary atresia with splenic malformation syndrome (BASM), also known as biliary atresia splenic malformation syndrome or the syndromic form of biliary atresia, is a rare congenital condition that combines biliary atresia — a progressive obliterative cholangiopathy affecting the bile ducts — with laterality defects and splenic abnormalities. Unlike isolated (non-syndromic) biliary atresia, BASM is present from birth and is thought to arise from disrupted embryonic development of laterality during early gestation. The condition primarily affects the hepatobiliary system and the spleen, but may also involve the cardiovascular system and abdominal organ positioning. Key clinical features include neonatal jaundice (due to obstructed bile flow), acholic (pale) stools, dark urine, and hepatomegaly. Splenic malformations may include polysplenia (multiple small spleens), asplenia (absent spleen), or a double spleen. Associated anomalies can include situs inversus or situs ambiguus (abnormal positioning of abdominal and thoracic organs), preduodenal portal vein, interrupted inferior vena cava, cardiac defects (such as atrial or ventricular septal defects), and intestinal malrotation. The hepatobiliary obstruction leads to progressive liver damage, fibrosis, and eventually biliary cirrhosis if untreated. The primary surgical treatment is the Kasai portoenterostomy (hepatoportoenterostomy), which aims to restore bile flow by connecting the liver directly to the small intestine. However, outcomes of the Kasai procedure in BASM patients tend to be less favorable compared to those with isolated biliary atresia, with a higher rate of failure to clear jaundice. Liver transplantation remains the definitive treatment for patients who develop end-stage liver disease. Early diagnosis and referral to a specialized pediatric hepatobiliary center are critical for optimizing outcomes. The presence of associated cardiac and vascular anomalies may complicate surgical management and requires careful preoperative evaluation.

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