A 20-year-old woman, G3, P2, has a screening ultrasound at 18 weeks' gestation that shows hydrops fetalis but no malformations. The woman's two previous pregnancies ended at term in live births. The current pregnancy results in a live birth at 36 weeks. Physical examination shows marked hydrops of the neonate and placenta. Laboratory studies show a cord blood hemoglobin level of 9.2 g/dL and total bilirubin concentration of 20.2 mg/dL. Which of the following laboratory findings is most likely to be present in this case?
This infant has erythroblastosis fetalis, which results when prior sensitization to a fetal blood cell antigen leads to alloantibodies in maternal blood that can cross the placenta. The Rh blood group system is most often implicated. The maternal antibody coats fetal RBCs, causing hemolysis. The Coombs test is positive. The fetal anemia leads to congestive heart failure and hydrops. Hemolysis results in a very high bilirubin level. A high maternal serum level of a-fetoprotein suggests a fetal neural tube defect; such defects are not associated with hydrops. Viral hepatitis is not a perinatal infection. Diminished glucocerebrosidase activity causes Gaucher disease, and this condition does not lead to perinatal liver failure or anemia. Listeriosis or other congenital infections may produce fetal hydrops and anemia, although not of the severity described in this case.
Diminished glucocerebrosidase activity in fetal cells
Elevated maternal serum a-fetoprotein level
Positive Coombs test result on cord blood
Positive maternal hepatitis B surface antigen
Disease of Infancy & Childhood