Effect of phenobarbital on serial ultrasonic examination in the evaluation of neonatal jaundice.

The diagnosis of some cases of neonatal jaundice is complicated because of inability to identify the gallbladder, which makes it very difficult to differentiate biliary atresia from neonatal hepatitis even by serial ultrasonic (US) examination. Serial (US) examination after the administration of phenobarbital as a cholagogue at a dosage of 5 mg/kg/day for 5 days was performed to evaluate nine patients with neonatal jaundice. In five of the nine patients, the gallbladder was identified by a change in size following oral feeding. These patients were diagnosed as having neonatal hepatitis. The gallbladders of the other four patients were not identified before, during, or after feeding. They were diagnosed as having biliary atresia and the diagnoses were confirmed by surgery. Administration of phenobarbital for 5 days before serial US examination is very useful in the diagnosis of neonatal hepatitis when differentiation between neonatal hepatitis and biliary atresia is impossible because of inability to identify the gallbladder by US alone.