338 Anatomy & Physiology Essentials Copyright Goodheart-Willcox Co., Inc. has been exposed to the Rh+ blood, she will develop anti-Rh+ antibodies. If the woman becomes pregnant with another child who is Rh+, the woman’s anti-Rh+ antibodies will attack the red blood cells of the fetus, causing agglutination and hemolysis. This condition causes anemia and an elevated plasma bilirubin level leading to jaundice. The action by the antibodies also depletes the number of mature RBCs in the fetus. As a result, erythroblasts (immature RBCs) leave the bone marrow of the fetus before they are mature. If this condition is left untreated, the baby will develop erythroblastosis fetalis, or hemolytic disease of the newborn (HDN). Erythroblastosis fetalis can be fatal. Fortunately, erythroblastosis fetalis is rare in developed countries due to good pre- and post- natal care as well as the development of the immune serum RhoGAM. RhoGAM prevents the mother’s immune system from developing antibodies against Rh+ blood, which could affect a future Rh+ fetus. RhoGAM is administered to the Rh– woman shortly after she has given birth to an Rh+ baby. Transfusion Reactions Plasma does not naturally contain an antibody for the Rh factor. However, antibodies to the Rh factor will develop if a person with Rh– blood is transfused with Rh+ blood. After exposure to the Rh+ blood, antibodies begin to form against the positive Rh antigen. If the person is exposed to Rh+ blood again, the antibodies will cause agglutination and hemolysis. Pregnancy Complications Any woman considering pregnancy should know her blood type and seek early prenatal healthcare. It is essential for the health of the woman and her baby because women can become sensitized to the Rh factor during pregnancy. If a woman who is Rh– has a baby who is Rh+, her first pregnancy will not cause a problem because her blood has not yet developed antibodies, or sensitivity to the Rh+ blood. However, during childbirth, some of the baby’s Rh+ blood may come in contact with the woman’s Rh– blood through the placenta, the organ that transports nutrients from the woman to her child. Once the woman’s blood SECTION 11.2 REVIEW Mini-Glossary agglutination the process by which red blood cells clump together, usually in response to an antibody antibodies immune proteins that react with the antigen that caused its synthesis antigen a protein on the surface of RBCs that is used to identify blood type by identifying cells as “self” or “nonself” (foreign) cells erythroblastosis fetalis a severe hemolytic disease found in fetuses or newborns that is caused by the production of maternal antibodies against the antigens on fetal red blood cells usually involves Rh incompatibility between the mother and fetus also known as hemolytic disease of the newborn (HDN) Rh factor the antigen of the Rh blood group that is found on the surface of red blood cells people with the Rh factor are Rh+ and those lacking it are Rh– RhoGAM an immune serum that prevents a Rh– pregnant woman’s blood from becoming sensitized to her Rh+ fetus universal donor a person with type O blood, which has neither A nor B antigens can donate blood for transfusion to people of all blood types universal recipient a person with type AB blood, which has neither A nor B antibodies can safely receive a transfusion of any blood type Review Questions 1. What is an antigen? 2. Explain the process of agglutination. 3. Besides the antigens that determine blood type, what other antigen is sometimes found on the surface of red blood cells? 4. Define RhoGAM and explain its use. 5. If a person’s parents both have type B blood, what blood types might that person have? 6. If you have type B blood, what kind of antibodies do you have? 7. True or False? If you are Rh-positive, you have a higher than normal amount of Rh factor. 8. What is the difference between an antigen and an antibody? 9. Explain why a person with type AB blood is a universal recipient. 10. Explain why a person with type O blood is a universal donor.