Hemolytic Disease of the Fetus and Newborn
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About Hemolytic Disease of the Fetus and Newborn
Hemolytic disease of the fetus and newborn (HDFN) is a rare and potentially life-threatening condition that affects approximately 4,000 – 8,000 United States (US) pregnancies per year. The disease is caused by antibodies from the mother which target proteins (also called antigens) on the fetal red blood cells (a process known as red cell alloimmunization). The most common antigen is RhD, although other antigens, such as Rhc, RhE, and Kell, may also be involved in the process.
During pregnancy, antibodies can cross the placenta and bind to the antigens on the surface of the fetus’ red blood cells, leading to fetal red blood cell destruction (hemolysis) and anemia (low red blood cell count). Anemia causes less oxygen to be delivered to all the fetal tissues and can lead to organ damage and ultimately lead to fetal heart failure and even fetal death. In addition, sometimes fetuses that have suffered anemia during pregnancy may have significant consequences like cerebral palsy.
In the case of RhD antigen incompatibility, this antibody formation is typically preventable. However, it is not always 100% effective. Moreover, HDFN can occur with other antigen incompatibilities where there is no preventative treatment.
Although current screening and management of HDFN have significantly improved perinatal outcomes, some of these treatments, such as transfusing blood to the fetus during pregnancy, may be associated with significant complications. Thus, non-invasive, safe, and effective treatment alternatives are needed.
Most Western countries have implemented screening programs for detection of RBC alloimmunization in pregnancy; however, the frequency and timing of those screening programs vary.
To properly diagnose HDFN, the physician will conduct a detailed review of the mother’s past medical history including any past blood transfusions and past pregnancies. In addition, the physician may conduct a number of tests and assessments, such as:
Free Fetal DNA
To check the antigen status of the fetus by looking for fetal DNA in the mother’s bloodstream.
To determine the antigen status of the fetus. In this test, a needle is put into the mother's amniotic sac and a sample of amniotic fluid is collected for analysis.
To look for the amount and type of red blood cell antibodies in the mother’s blood.
To detect fetal anemia by measuring the speed of blood moving through the fetal brain. The type of ultrasound is called Doppler. Doppler measures the speed of blood in a specific vessel in the brain called the middle cerebral artery (MCA).
To determine the degree of fetal anemia. In this test, a fetal blood sample is taken from the umbilical cord under ultrasound guidance. If the fetus is found to be anemic, an intrauterine blood transfusion may be performed at the same setting.
Disease Management Strategies
Depending on the stage of pregnancy and severity of the condition, as well as in consultation with a physician, HDFN may be managed in a number of ways.
Depending on the health status of the newborn, the newborn may require supportive management and close monitoring in the neonatal intensive care unit.
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