gynecology and obstetrics
Hemolytic Disease of the Fetus and Neonate
Prevention of Hemolytic Disease of the Fetus and Neonate
Prevention involves giving Rh-negative mothers Rho(D) immune globulin at the following times: At 28 weeks gestation Within 72 hours of pregnancy termination After any episode of vaginal bleeding After amniocentesis or chorionic villus sampling Manual removal of the placenta should be avoided because it may force fetal cells into maternal circulation. Maternal sensitization and antibody production due to Rh incompatibility can be prevented by giving the woman Rho(D) immune globulin. This preparation contains high titers of anti-Rh antibodies, which neutralize Rh-positive fetal RBCs. Because fetomaternal transfer and likelihood of sensitization is greatest at termination of pregnancy, the preparation is given within 72 hours after termination of each pregnancy, whether by delivery, abortion, or treatment of ectopic pregnancy. The standard dose is 300 mcg IM. A rosette test can be used to rule out significant fetomaternal hemorrhage, and if results are positive, a Kleihauer-Betke (acid elution) test can measure the amount of fetal blood in the maternal circulation. If test results indicate fetomaternal hemorrhage is massive (>30 mL whole blood), additional injections (300 mcg for every 30 mL of fetal whole blood, up to 5 doses within 24 hours) are necessary. If given only after delivery or termination of pregnancy, treatment is occasionally ineffective because sensitization can occur earlier during pregnancy. Therefore, at about 28 weeks, all pregnant women with Rh-negative blood and no known prior sensitization are given a dose of Rho(D) immune globulin. Some experts recommend a 2nd dose if delivery has not occurred by 40 weeks. Rho(D) immune globulin should also be given after any episode of vaginal bleeding and after amniocentesis or chorionic villus sampling. Anti-Rh antibodies persist for>3 months after one dose. 