A 1-month-old girl presents to her pediatrician with her mother. The patient was born at 38 weeks gestation via Caesarean section for cervical incompetence. The patient’s mother has no complaints. The child had a runny nose and cough for a few days last week. The patient’s mother endorses decreased appetite during the aforementioned illness which has now returned to baseline. The patient’s family history is significant for an older brother with glucose-6-phosphate dehydrogenase (G6PD) deficiency and a maternal uncle with cirrhosis secondary to chronic hepatitis B. On physical exam, the patient has scleral icterus and dark urine staining her diaper. Laboratory testing reveals the following: Serum: Na+: 137 mEq/L Cl-: 102 mEq/L K+: 4.2 mEq/L HCO3-: 24 mEq/L Urea nitrogen: 12 mg/dL Glucose: 96 mg/dL Creatinine: 0.36 mg/dL Alkaline phosphatase: 146 U/L Aspartate aminotransferase (AST): 86 U/L Alanine aminotransferase (ALT): 76 U/L Total bilirubin: 4.6 mg/dL Direct bilirubin: 3.8 mg/dL Which of the following is the most likely diagnosis?
Decreased metabolism of bilirubin
Increased enterohepatic circulation of bilirubin
Obstruction of the extrahepatic biliary tree
Obstruction of the intrahepatic biliary tree
Obstruction of the extrahepatic biliary tree
This 2-month-old patient presents with jaundice, dark urine, mild transaminitis, and conjugated hyperbilirubinemia, which suggests the diagnosis of biliary atresia. Biliary atresia is characterized by obstruction of the extrahepatic biliary tree.

Biliary atresia is a progressive, obliterative disease of the extrahepatic biliary tree. It presents in the first 8 weeks of life with jaundice, acholic stools, dark urine, hepatomegaly, mild transaminitis, and conjugated hyperbilirubinemia. The definitive diagnosis is made by a cholangiogram that will demonstrate the obliteration of these ducts. Patients who are untreated experience fatal neurological defects due to kernicterus and accumulation of bilirubin in the brain. Treatment usually involves hepatoportoenterostomy (Kasai procedure), in which the duodenum is directly anastomosed to the liver. Most patients also eventually require a liver transplant.

Hartley et al. review the evidence regarding the diagnosis and treatment of patients with biliary atresia. They discuss how researchers are trying to reverse the liver fibrosis associated with this disease. They recommend early referral for a Kasai procedure or liver transplant as needed.

Incorrect Answers:
Answer A: Decreased metabolism of bilirubin occurs with enzymatic deficiencies such as those seen in Crigler-Najjar or Gilbert syndrome. Both Crigler-Najjar and Gilbert syndromes lead to unconjugated hyperbilirubinemia (much more severe in Crigler-Najjar syndrome) rather than the conjugated hyperbilirubinemia seen in this patient.

Answer B: Increased enterohepatic circulation describes the pathophysiology underlying breast milk jaundice. Breast milk jaundice classically peaks in the first 2 weeks of life and leads to unconjugated rather than conjugated hyperbilirubinemia. Treatment is usually supportive and patients can typically continue to breastfeed.

Answer C: Increased production of bilirubin can occur in hemolytic diseases such as G6PD deficiency or hereditary spherocytosis. These conditions would similarly lead to an unconjugated hyperbilirubinemia. Treatment is with addressing the underlying anemia with possible transfusion or splenectomy.

Answer E: Obstruction of the intrahepatic biliary tree describes Alagille syndrome, in which patients have a paucity of interlobular bile ducts. Alagille syndrome is less common than biliary atresia and usually presents with other associated features, such as short stature, dysmorphic facies, ocular findings, and cardiac or renal anomalies. Treatment is with ursodiol.

Bullet Summary:
Biliary atresia presents in the first 8 weeks of life with jaundice and conjugated hyperbilirubinemia.