Rh Negative Disease
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From WikiParentingRh disease of the newborn is caused by incompatibility between the blood of a mother and the baby inutero. It is a hemolytic disease, which means that the disease causes destruction of fetal red blood cells. Untreated, Rh disease can result in stillbirth. Rh disease can also result in jaundice, anemia, brain damage, heart failure and death of newborns but it does not affect the mother’s health. Since 1968, early detection of Rh disease risk and corresponding treatment that usually can prevent the disease has caused a dramatic decline in the illness. However, not all women who need the treatment receive it, and a small number of women cannot benefit from it.
Most people are Rh-positive, which means that their blood has the Rh factor, an inherited protein found on the surface of red blood cells. Roughly 15 percent of the white population, 5 to 8 percent of the African-American and Hispanic populations, and 1 to 2 percent of the Asian and Native American populations are Rh-negative. Rh-negative blood does not affect its carriers in any way. However, an Rh-negative woman is at risk of having a baby with Rh disease, which can bring serious and fatal complications to the child. When an Rh-negative mother and an Rh-positive father conceive an Rh-positive baby, there is then a danger that, during pregnancy and especially during labor and delivery, some of the fetus’s Rh-positive red blood cells may get into the mother’s bloodstream. When this occurs, the mother’s body attempts to fight them off by producing antibodies against them. This fight against the invading blood cells is called sensitization.
After the mother has become sensitized, her Rh antibodies can cross the placenta and destroy some of an Rh-positive fetus’s red blood cells, which results in Rh disease in the baby. In a first pregnancy with an Rh-positive baby, there usually are no serious complications because the baby often is born before the mother is sensitized, or before the mother produces substantial Rh antibodies. Each successive Rh-positive baby of a sensitized mother is at greater risk for more severe Rh disease because the mother will continue to produce antibodies as part of her blood throughout her life.
A simple blood test can detect Rh-negative blood in the mother. Every pregnant woman should be tested at her first prenatal visit to find out if she is Rh-negative. A blood test also can determine if an Rh-negative woman has become sensitized.
 Treatment to Prevent Sensitization of the Mother
An unsensitized Rh-negative mother can be treated during pregnancy with injections of a purified blood product called Rh immune globulin (RhIg) to prevent sensitization. RhIg contains antibodies to the Rh factor, which attach to and may help mask any Rh-positive fetal cells in the mother’s bloodstream. Consequently, the mother’s body does not recognize these Rh-positive fetal blood cells as foreign and does not produce antibodies to fight them. RhIg protection lasts about 12 weeks.
The mother's health care provider will most likely recommend that she begin receiving RhIg injections first at 28 weeks of pregnancy and again within 72 hours of delivery, if a blood test shows that her baby is Rh-positive. Occasionally, health care providers also recommend an additional RhIg injection when an Rh-negative woman goes past her delivery due date. The mother will not require another injection after delivery if her baby is Rh-negative. Additionally, an Rh-negative mother should be treated with RhIg after any situation in which the fetal red blood cells can mix with her blood, including after a miscarriage, an ectopic pregnancy, an induced abortion, or a blood transfusion with Rh-positive blood. RhIg treatment also is recommended after certain prenatal tests, such as amniocentesis and chorionic villus sampling (CVS).
An Rh-negative woman does not need RhIg treatment if blood tests reveal that the baby’s father is Rh-negative because this means that the baby will also be Rh-negative. An Rh-negative baby will not develop Rh disease.
RhIg treatment can prevent sensitization in nearly all unsensitized Rh-negative women. However, RhIg treatment will be ineffective in an Rh-negative woman who already is sensitized. Rh-negative women become sensitized when they do not receive the treatment when they need it, such as after an unrecognized miscarriage.
 Prenatal Monitoring
There is no way to unsensitize a sensitized mother. If the father is Rh-positive (or if his Rh status is unknown), the health care provider will usually offers a sensitized pregnant woman a test called amniocentesis to determine whether the baby is Rh-positive or Rh-negative. Even if the father is Rh-positive, he may carry an Rh-negative gene, which the baby has a 50 percent chance of inheriting.
If the fetus is Rh-positive has unknown Rh status, the health care provider will measure the levels of antibodies in the mother’s blood as pregnancy progresses. If the mother develops high levels of antibodies, the health care provider will recommended tests that can help determine if the baby is developing Rh disease. Some doctors prefer to administer amniocentesis every ten days to two weeks to determine if a fetus is developing anemia and how severe it may be. Amniocentesis poses a small risk of miscarriage.
In addition to amniocentesis testing, an experimental maternal blood test appears to be highly accurate in determining whether the fetus is Rh-positive or negative. While this blood test is not yet widely available in the United States, it may soon become more standard and help to reduce the need for amniocentesis. Additionally, some major medical centers have begun offering an examination with a special form of ultrasound, called Doppler ultrasound, to determine if the fetus is developing anemia. The Doppler ultrasound measures the speed of blood flowing through an artery in the fetus’s head. This test poses no risk to the fetus and is more accurate than amniocentesis in detecting anemia. At present, the test is not available everywhere and should only be performed at medical centers where the health professionals have adequate training and experience with the technique.
If testing reveals that the fetus may be developing severe anemia, the doctor may recommend another test called cordocentesis wherein the doctor inserts a thin needle through the mother’s abdomen, guided by ultrasound, into a tiny blood vessel in the umbilical cord to take a blood sample from the fetus. As with amniocentesis, this test also poses a small risk of miscarriage.
 Treatment for Fetuses and Newborns
If the fetus is close to term and tests show that it is developing anemia, the health care provider may recommend inducing labor early, before the mother’s antibodies destroy too many fetal blood cells. After delivery, if the newborn has jaundice, he may be treated with phototherapy. In certain cases, the baby may require a blood transfusion but some cases of Rh disease are so mild that the baby does not need any treatment at all. About 10 percent of fetuses with Rh disease develop severe anemia. Today anemia need not be fatal as these fetuses can be treated in the uterus as early as 18 weeks gestation with blood transfusions, which are given using cordocentesis. About 90 percent of treated fetuses now survive.