212 Obstetrics and Gynecology Board Review •••
❍ Do the lungs of an infant with Rh sensitization mature more quickly or more slowly than an infant of the
same gestational age?
More slowly. Hydropic changes in the placenta may increase insulin production leading to delayed lung maturation
as seen in diabetics.
❍ What ultrasound findings are suggestive of prehydropic fetal anemia?
Polyhydramnios.
Placental thickness >4 cm.
Pericardial effusion.
Dilation of cardiac chambers.
Enlargement of spleen and liver.
Visualization of both sides of fetal bowel wall.
Dilation of the umbilical vein.
❍ For a fetus with evidence of hemolysis based on MCA Dopplers or amniotic fluid bilirubin analysis, what is
the next best test to perform?
Percutaneous umbilical blood sampling to determine fetal hematocrit.
❍ What routine tests, besides assessment of amniotic fluid bilirubin or umbilical cord hematocrit, are
undertaken in cases of Rh alloimmunization?
Antepartum fetal surveillance by nonstress test or biophysical profile is begun at 32 weeks’ gestation.
❍ What are the two types of fetal transfusions?
Intrauterine intraperitoneal (needle into peritoneal cavity of fetus).
Intrauterine intravascular (needle into umbilical vein).
❍ What are the advantages of intraperitoneal transfusions^.^.^.^ intravascular?
Intraperitoneal: Ease of placement and decreased dislodgement.
Intravascular: Ability to obtain fetal hematocrit prior to transfusion and after direct placement of red cells
intravascularly.
Intravascular transfusion is generally preferred. However, intraperitoneal transfusion is considered if vascular access
is difficult because of early gestational age or fetal position.
❍ What are the complications of transfusions, and which is the most common?
Fetal bradycardia, infection, premature rupture of membranes, fetal death (4–9%), and need for emergent delivery
secondary to fetal status (ie, fetal bradycardia).
Fetal bradycardia is the most common complication of fetal transfusion.
❍ What is the purpose of intrauterine transfusion?
To correct fetal anemia that improves fetal oxygenation.
❍ What type of blood is used for the transfusion?
Type O, leukocyte reduced, cytomegalovirus negative, and gamma irradiated packed erythrocytes that are
cross-matched to a maternal blood sample.