Neonatal Hyperbilirubinemia and Cholestasis.

Abstract

A male infant is born via vaginal delivery at 29 weeks’ estimated gestation with a birthweight of 1,490 g to a 22-year-old gravida 1, para 1 woman who presented with preterm labor. No maternal risk factors are identified; all maternal prenatal laboratory findings are negative. Group B Streptococcus carrier status is unknown and no intrapartum antibiotic prophylaxis or betamethasone had been administered because it was a precipitous delivery. The infant’s Apgar scores are 8 and 9 at 1 and 5 minutes, respectively. Physical examination findings are normal, with mild retractions. The infant initially undergoes intubation for surfactant therapy and is started on broad-spectrum antibiotics to rule out sepsis and total parental nutrition (TPN). One day after birth, he is weaned to continuous positive airway pressure and gradually to room air.Routine echocardiography shows a large patent ductus arteriosus which is treated with acetaminophen with subsequent closure and trivial aortic insufficiency on repeat follow-up echocardiography. The infant continues to receive TPN and partial oral feedings until 18 days after birth, when he starts having bloody regurgitation. Because of a concern for necrotizing enterocolitis (NEC), broad-spectrum antibiotics are initiated and oral feeds are suspended. Feedings are then restarted, with resolution of NEC. Shortly after, at about 1 month of age, he develops generalized edema with hypoalbuminemia of 3.1 g/dL (31 g/L), which improves with a high protein diet and furosemide. He receives 3 packed red blood cell infusions for anemia, with a hematocrit below 28%, after which he develops cellulitis from an intravenous infiltrate that resolves with a course of vancomycin. Concurrently, the total and direct bilirubin levels are increased at 5.41 mg/dL (92.5 μmol/L) and 0.4 mg/dL (6.8 μmol/L), respectively. Bilirubin level trends are observed and are shown in Table 1. No jaundice or acholic stools are seen nor is any dark-colored urine noted.Because of the elevated direct hyperbilirubinemia, abdominal ultrasonography is performed, which reveals mild hepatosplenomegaly and a normal-appearing gallbladder. The total and direct bilirubin are 6.21 mg/dL (106.2 μmol/L) and 2.8 mg/dL (47.8 μmol/L), respectively. A presumptive diagnosis of TPN cholestasis is made. TPN is then discontinued and the patient is started on ursodeoxycholic acid (ursodiol). However, it did not lead to any improvement in hyperbilirubinemia. Hepatic function enzymes—alanine transaminase and aspartate transaminase—show an upward trend, as do the γ-glutamyltransferase (GGT) levels—197 U/L (3.2 μkat/L), 286 U/L (4.7 μkat/L), and 324 U/L (5.5 μkat/L), respectively. Additional diagnostic laboratory tests were performed (Table 2).Blood cultures do not show any growth, but C-reactive protein concentration is elevated to 0.6 mg/dL (6.02 mg/L). Infectious serologies for hepatitis B, C, and toxoplasmosis, other infections, rubella, cytomegalovirus (CMV) infection, and herpes simplex (TORCH) IgM are ordered. While awaiting the results, further evaluation is recommended by the gastroenterology consulting service. The metabolic evaluation includes an acylcarnitine panel that is within normal limits; uric acid of 1.5 mg/dL (0.09 mmol/L); and amino acids showing nonspecific mild elevation, organic acids with nonspecific glutaric acid elevation, and α1-antitrypsin serum level of 165 mg/dL (30.3 μmol/L), which is within normal range. The coagulation panel shows a prothrombin of 12.7 seconds and partial thromboplastin time of 30.8 seconds. Thyroid function tests performed to exclude thyroid disorders show a thyroid-stimulating hormone of 1.91 μIU/mL (1.91 mIU/L) and free thyroxine of 1.2 ng/dL (15.4 pmol/L). Thereafter, urine polymerase chain reaction (PCR) testing for CMV showed 45,700 IU/mL, and the TORCH panel revealed a CMV IgM level of 70.8 AU/ml. Maternal breast milk CMV PCR result is positive. Treatment with ganciclovir is initiated, and ursodiol is continued along with water-soluble vitamins ADEK. Auditory brainstem response (ABR) indicates no response in the left ear with a normal ABR on follow-up testing 2 weeks later. The ophthalmologic findings are negative for chorioretinitis and head ultrasonography findings are normal with no periventricular calcifications.Because the direct bilirubin concentration does not come down with ganciclovir and ursodiol, the infant is evaluated for biliary atresia with a cholecystography hepatobiliary iminodiacetic acid (HIDA) scan. The HIDA scan findings are significant and do not show uptake of radioactive isotope in the gallbladder or excretion into the gut (Fig 1). The infant is transferred to a tertiary center for intraoperative cholangiography and liver biopsy. On cholangiography, a thin gallbladder is visualized with uptake of tracer in the intrahepatic biliary tree, common bile duct, and cystic duct (Fig 2). The biopsy reveals lobular and cannalicular cholestasis, extramedullary hematopoiesis, and paucity of native bile ducts with proliferation of extrahepatic bile ducts and none of the typical features of biliary atresia.Direct or conjugated hyperbilirubinemia has either extrahepatic causes such as obstruction of the bile flow or is related to an intrahepatic condition causing hepatocellular injury. This accumulation of biliary substances in the blood is referred to as neonatal cholestasis and affects about 1 in 2,500 births. (1) Direct hyperbilirubinemia, with levels greater than 1.0 mg/dL (>17 mmol/L) or greater than 15% of total bilirubin, is never physiologic and should be investigated. (2)(3) Common presenting symptoms include jaundice, acholic stools, dark urine, hepatomegaly, and poor feeding or poor weight gain. (4) In severe cases, infants may have deficits in fat-soluble vitamins, coagulopathy, encephalopathy caused by hyperammonemia, splenomegaly, and signs of increased portal pressure. (3)The differential diagnosis for direct hyperbilirubinemia is vast and includes extrahepatic obstruction such as biliary atresia, choledochal cysts, or tumors; infectious etiologies such as viruses, bacteria, and toxoplasmosis; metabolic disorders of carbohydrate, amino acid, and lipid or bile acid metabolism; liver enzyme defects such as α1-antitrypsin deficiency; inherited causes including Alagille syndrome, cystic fibrosis, and progressive familial intrahepatic cholestasis (PFIC); endocrine disorders such as hypothyroidism; hematologic causes such as alloimmune neonatal hemochromatosis; and other causes including drug toxicity, TPN, hypovolemic shock, idiopathic neonatal hepatitis, or nonsyndromic paucity of interlobar bile ducts.Initial laboratory tests in addition to total and fractionated serum bilirubin include evaluation of transaminases for hepatocyte damage, a coagulation profile, GGT for biliary epithelial damage, a complete metabolic panel which may suggest metabolic disease, hypoalbuminemia, or other electrolyte disturbances. A complete blood cell count with differential, inflammatory markers, and blood and urine cultures are essential to rule out sepsis and urinary tract infections. (3) Initial diagnostic imaging must include abdominal ultrasonography, which can identify anatomic or obstructive lesions, such as choledochal cysts, which require surgery as well as a screen for portal hypertension if indicated by hepatosplenomegaly. (3)If the ultrasound scan is normal, additional laboratory evaluation to consider includes serologic testing for TORCH infections, toxoplasmosis, syphilis, varicella-zoster, parvovirus B19, rubella, CMV, and herpes infections, as well as metabolic and endocrine screening with laboratory values for thyroid-stimulating hormone, thyroxine, and α1-antitrypsin concentration. Additional tests for metabolic disorders such as galactosemia or tyrosinemia may include tests for succinylacetone and galactose transferase enzymes as well as levels of galactose, amino acids tyrosine and methionine, organic acids, reducing substances, and acylcarnitine. Of note, genetic studies for JAG1 in Alagille syndrome and CFTR membrane transporter in cystic fibrosis are common with direct hyperbilirubinemia. Importantly, a HIDA scan should be obtained to evaluate for the presence of intrahepatic and extrahepatic bile ducts. If no clear etiology is found or when the HIDA scan is concerning for biliary atresia, a liver biopsy and intraoperative cholangiography are warranted. (2)(3) If biliary atresia is confirmed on cholangiography, the operative management is with a Kasai procedure which should immediately be done, preferably before 2 months of age. (5)In this case, several of the usual causative etiologies for direct hyperbilirubinemia could be considered. First, this infant received TPN for almost 4 weeks at the time direct hyperbilirubinemia was noted. Cholestasis is a known side effect and affects about 18% to 25% of infants receiving TPN, with the highest rates among premature infants and those with longer duration of TPN. Second, our patient had been treated for necrotizing enterocolitis shortly before and had cellulitis at the time of cholestasis. Although blood cultures were negative in this case, severe infections and sepsis are associated with the development of cholestasis. Third, CMV IgM and urine CMV PCR results were positive, as was maternal breast milk CMV PCR, suggesting a neonatal CMV infection or a postnatal CMV infection through breast milk. Fourth, the HIDA scan was concerning for biliary atresia because the gallbladder was not visualized up to 24 hours and there was lack of excretion of radioisotope in the intestine. Further investigation with an intraoperative cholangiography and liver biopsy refuted biliary atresia, but paucity of intrahepatic bile ducts was seen. This finding is often seen in PFIC; however, the lack of a family history and the elevated GGT levels refuted this diagnosis. A final diagnosis of postnatal CMV hepatitis was confirmed.CMV infections are classified as congenital, that is, acquired during pregnancy, neonatal infections acquired at delivery, and postnatal infections acquired after delivery. Congenital CMV infection affects less than 1% of infants, and the overall prevalence of symptomatic congenital CMV is 0.07%. (6) Symptoms may include brain abnormalities, sensorineural hearing loss, intrauterine growth restriction, petechial rash, chorioretinitis, hepatosplenomegaly, and thrombocytopenia, and can result in long-term sequelae in about 25% of cases. (7) To prevent adverse consequences of undiagnosed congenital CMV, many neonatal units routinely screen for CMV with a salivary swab; however, treatment without symptoms still remains controversial.Neonatal infections are acquired during the time of delivery and present at about 4 weeks of age. Postnatal infection is linked to breast milk in about 38% of premature infants, of whom approximately half are symptomatic and 12% show a sepsislike picture. (8) Postnatal infections are more common in the preterm infant because they are usually related to maternal seroconversion and the infant does not have adequate maternal antibodies to CMV. The incubation time of 42 days corresponds to the timeframe when our patient presented with hepatitis. Another potential source of postnatal CMV infections are blood transfusions. This is a rare phenomenon because administration of blood products to neonates requires CMV-negative and leukoreduced blood products. Horizontal transmission has been reported, though it is very rare. Both neonatal and postnatal infections require a high index of suspicion and CMV testing should be performed with direct hyperbilirubinemia before initiating further studies.Postnatal CMV infection can cause severe illness, including pneumonitis, hepatitis, chorioretinitis, multiorgan failure, developmental delay, and hearing loss. (9) CMV infection can present solely as cholestatic hepatitis, however, investigation should include imaging of the brain to exclude calcifications, an ophthalmology consultation to evaluate for chorioretinitis, and hearing tests.Prevention of transmission through handwashing practices and freezing and thawing of breast milk may prevent infection. Although few studies in neonates have been performed, treatment with ganciclovir is often initiated for more severe cases, including those presenting with hepatitis. (9) In these small studies, positive effects of treatment include reduced bilirubin and transaminase values and reduction of CMV viral load without reduction of chronic liver disease. (9) Side effects of ganciclovir are typically neutropenia and kidney injury which should be monitored. To increase bile excretion, ursodiol is the preferred medical treatment over phenobarbital. Despite the low risk of hearing loss and cognitive problems reported in long-term follow-up studies of postnatal infections, the severe possible sequelae warrant a high clinical suspicion and early diagnosis and treatment. (10)Our patient continues to be treated with ursodiol and ganciclovir. He is feeding medium-chain fatty acid–based formula supplemented with vitamins ADEK. The infant is doing well clinically and was discharged from the hospital with total and direct bilirubin levels of 7.4 mg/dL (126.5 μmol/L) and 5.1 mg/dL (87.2 μmol/L), respectively. He has close follow-up with both gastroenterology and infectious disease specialists. Results of his hearing tests and brain ultrasonography were within normal limits and his follow-up with ophthalmology showed no evidence of retinitis. Repeat assessments are scheduled for possible development delay.