erythroblastosis fetalis


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Erythroblastosis Fetalis

 

Definition

Erythroblastosis fetalis refers to two potentially disabling or fatal blood disorders in infants: Rh incompatibility disease and ABO incompatibility disease. Either disease may be apparent before birth and can cause fetal death in some cases. The disorder is caused by incompatibility between a mother's blood and her unborn baby's blood. Because of the incompatibility, the mother's immune system may launch an immune response against the baby's red blood cells. As a result, the baby's blood cells are destroyed, and the baby may suffer severe anemia (deficiency in red blood cells), brain damage, or death.

Description

Red blood cells carry several types of proteins, called antigens, on their surfaces. The A, B, and O antigens are used to classify a person's blood as type A, B, AB, or O. Each parent passes one A, B, or O antigen gene to their child. How the genes are paired determines the person's blood type.
A person who inherits an A antigen gene from each parent has type A blood; receiving two B antigen genes corresponds with type B blood; and inheriting A and B antigen genes means a person has type AB blood. If the O antigen gene is inherited from both parents, the child has type O blood; however, the pairing of A and O antigen genes corresponds with type A blood; and if the B antigen gene is matched with the O antigen gene, the person has type B blood.
Another red blood cell antigen, called the Rh factor, also plays a role in describing a person's blood type. A person with at least one copy of the gene for the Rh factor has Rh-positive blood; if no copies are inherited, the person's blood type is Rh-negative. In blood typing, the presence of A, B, and O antigens, plus the presence or absence of the Rh-factor, determine a person's specific blood type, such as A-positive, B-negative, and so on.
A person's blood type has no effect on health. However, an individual's immune system considers only that person's specific blood type, or a close match, acceptable. If a radically different blood type is introduced into the bloodstream, the immune system produces antibodies, proteins that specifically attack and destroy any cell carrying the foreign antigen.
Determining a person's blood type is very important if she becomes pregnant. Blood cells from the unborn baby (fetal red blood cells) can cross over into the mother's bloodstream, especially at delivery. If the mother and her baby have compatible blood types, the crossover does not present any danger. However, if the blood types are incompatible, the mother's immune system manufactures antibodies against the baby's blood.
Usually, this incompatibility is not a factor in a first pregnancy, because few fetal blood cells reach the mother's bloodstream until delivery. The antibodies that form after delivery cannot affect the first child. In later pregnancies, fetuses and babies may be in grave danger. The danger arises from the possibility that the mother's antibodies will attack the fetal red blood cells. If this happens, the fetus or baby can suffer severe health effects and may die.
There are two types of incompatibility diseases: Rh incompatibility disease and ABO incompatibility disease. Both diseases have similar symptoms, but Rh disease is much more severe, because anti-Rh antibodies cross over the placenta more readily than anti-A or anti-B antibodies. (The immune system does not form antibodies against the O antigen.) Therefore, a greater percentage of the baby's blood cells are destroyed by Rh disease.
Both incompatibility diseases are uncommon in the United States due to medical advances over the last 50 years. For example, prior to 1946 (when newborn blood transfusions were introduced) 20,000 babies were affected by Rh disease yearly. Further advances, such as suppressing the mother's antibody response, have reduced the incidence of Rh disease to approximately 4,000 cases per year.
Rh disease only occurs if a mother is Rh-negative and her baby is Rh-positive. For this situation to occur, the baby must inherit the Rh factor gene from the father. Most people are Rh-positive. Only 15% of the Caucasian population is Rh-negative, compared to 5-7% of the African-American population and virtually none of Asian populations.
ABO incompatibility disease is almost always limited to babies with A or B antigens whose mothers have type O blood. Approximately one third of these babies show evidence of the mother's antibodies in their bloodstream, but only a small percentage develop symptoms of ABO incompatibility disease.

Cause and symptoms

Rh disease and ABO incompatibility disease are caused when a mother's immune system produces antibodies against the red blood cells of her unborn child. The antibodies cause the baby's red blood cells to be destroyed and the baby develops anemia. The baby's body tries to compensate for the anemia by releasing immature red blood cells, called erythroblasts, from the bone marrow.
The overproduction of erythroblasts can cause the liver and spleen to become enlarged, potentially causing liver damage or a ruptured spleen. The emphasis on erythroblast production is at the cost of producing other types of blood cells, such as platelets and other factors important for blood clotting. Since the blood lacks clotting factors, excessive bleeding can be a complication.
The destroyed red blood cells release the blood's red pigment (hemoglobin) which degrades into a yellow substance called bilirubin. Bilirubin is normally produced as red blood cells die, but the body is only equipped to handle a certain low level of bilirubin in the bloodstream at one time. Erythroblastosis fetalis overwhelms the removal system, and high levels of bilirubin accumulate, causing hyperbilirubinemia, a condition in which the baby becomes jaundiced. The jaundice is apparent from the yellowish tone of the baby's eyes and skin. If hyperbilirubinemia cannot be controlled, the baby develops kernicterus. The term kernicterus means that bilirubin is being deposited in the brain, possibly causing permanent damage.
Other symptoms that may be present include high levels of insulin and low blood sugar, as well as a condition called hydrops fetalis. Hydrops fetalis is characterized by an accumulation of fluids within the baby's body, giving it a swollen appearance. This fluid accumulation inhibits normal breathing, because the lungs cannot expand fully and may contain fluid. If this condition continues for an extended period, it can interfere with lung growth. Hydrops fetalis and anemia can also contribute to heart problems.

Diagnosis

Erythroblastosis fetalis can be predicted before birth by determining the mother's blood type. If she is Rh-negative, the father's blood is tested to determine whether he is Rh-positive. If the father is Rh-positive, the mother's blood will be checked for antibodies against the Rh factor. A test that demonstrates no antibodies is repeated at week 26 or 27 of the pregnancy. If antibodies are present, treatment is begun.
In cases in which incompatibility is not identified before birth, the baby suffers recognizable characteristic symptoms such as anemia, hyperbilirubinemia, and hydrops fetalis. The blood incompatibility is uncovered through blood tests such as the Coombs test, which measures the level of maternal antibodies attached to the baby's red blood cells. Other blood tests reveal anemia, abnormal blood counts, and high levels of bilirubin.

Treatment

When a mother has antibodies against her unborn infant's blood, the pregnancy is watched very carefully. The antibodies are monitored and if levels increase, amniocentesis, fetal umbilical cord blood sampling, and ultrasound are used to assess any effects on the baby. Trouble is indicated by high levels of bilirubin in the amniotic fluid or baby's blood, or if the ultrasound reveals hydrops fetalis. If the baby is in danger, and the pregnancy is at least 32-34 weeks along, labor is induced. Under 32 weeks, the baby is given blood transfusions while still in the mother's uterus.
There are two techniques that are used to deliver a blood transfusion to a baby before birth. In the first, a needle is inserted through the mother's abdomen and uterus, and into the baby's abdomen. Red blood cells injected into the baby's abdominal cavity are absorbed into its bloodstream. In early pregnancy or if the baby's bilirubin levels are gravely high, cordocentesis is performed. This procedure involves sliding a very fine needle through the mother's abdomen and, guided by ultrasound, into a vein in the umbilical cord to inject red blood cells directly into the baby's bloodstream.
After birth, the severity of the baby's symptoms are assessed. One or more transfusions may be necessary to treat anemia, hyperbilirubinemia, and bleeding. Hyperbilirubinemia is also treated with phototherapy, a treatment in which the baby is placed under a special light. This light causes changes in how the bilirubin molecule is shaped, which makes it easier to excrete. The baby may also receive oxygen and intravenous fluids containing electrolytes or drugs to treat other symptoms.

Prognosis

In many cases of blood type incompatibility, the symptoms of erythroblastosis fetalis are prevented with careful monitoring and blood type screening. Treatment of minor symptoms is typically successful and the baby will not suffer long-term problems.
Nevertheless, erythroblastosis is a very serious condition for approximately 4,000 babies annually. In about 15% of cases, the baby is severely affected and dies before birth. Babies who survive pregnancy may develop kernicterus, which can lead to deafness, speech problems, cerebral palsy, or mental retardation. Extended hydrops fetalis can inhibit lung growth and contribute to heart failure. These serious complications are life threatening, but with good medical treatment, the fatality rate is very low. According to the U.S. Centers for Disease Control and Prevention, there were 21 infant deaths in the United States during 1996 that were attributable to hemolytic disease (erythroblastosis fetalis) and jaundice.

Prevention

With any pregnancy, whether it results in a live birth, miscarriage, stillbirth, or abortion, blood typing is a universal precaution against blood compatibility disease. Blood types cannot be changed, but adequate forewarning allows precautions and treatments that limit the danger to unborn babies.
If an Rh-negative woman gives birth to an Rh-positive baby, she is given an injection of immunoglobulin G, a type of antibody protein, within 72 hours of the birth. The immunoglobulin destroys any fetal blood cells in her bloodstream before her immune system can react to them. In cases where this precaution is not taken, antibodies are created and future pregnancies may be complicated.

Resources

Periodicals

Bowman, John. "The Management of Hemolytic Disease in the Fetus and Newborn." Seminars in Perinatology 21, no. 1 (February 1997): 39.

Key terms

Amniocentesis — A procedure in which a needle is inserted through a pregnant woman's abdomen and into her uterus to withdraw a small sample of amniotic fluid. The amniotic fluid can be examined for sign of disease or other problems afflicting the fetus.
Amniotic fluid — The fluid that surrounds a fetus in the uterus.
Anemia — A condition in which there is an abnormally low number of red blood cells in the bloodstream. Major symptoms are paleness, shortness of breath, unusually fast or strong heart beats, and tiredness.
Antibody — A protein molecule produced by the immune system in response to a protein that is not recognized as belonging in the body.
Antigen — A protein that can elicit an immune response in the form of antibody formation. With regard to red blood cells, the major antigens are A, B, O, and the Rh factor.
Bilirubin — A yellow-colored end-product of hemoglobin degradation. It is normally present at very low levels in the bloodstream; at high levels, it produces jaundice.
Cordocentesis — A procedure for delivering a blood transfusion to a fetus. It involves a fine needle being threaded through a pregnant woman's abdomen and into the umbilical cord with the aid of ultrasound imaging.
Hemoglobin — A molecule in red blood cells that transports oxygen and gives the cells their characteristic color.
Hydrops fetalis — A condition in which a fetus or newborn baby accumulates fluids, causing swollen arms and legs and impaired breathing.
Hyperbilirubinemia — A condition in which bilirubin accumulates to abnormally high levels in the bloodstream
Placenta — A protective membrane that surrounds and protects the fetus during pregnancy.
Platelet — A blood factor that is important in forming blood clots.
Rh factor — An antigen that is found on the red blood cells of most people. If it is present, the blood type is referred to as Rh-positive; if absent, the blood type is Rh-negative.

erythroblastosis

 [ĕ-rith″ro-blas-to´sis]
the presence of erythroblasts in the circulating blood; called also erythroblastemia. adj., adj erythroblastot´ic.
erythroblastosis feta´lis (erythroblastosis neonato´rum) a blood dyscrasia of the newborn characterized by agglutination and hemolysis of erythrocytes and usually due to incompatibility between the infant's blood and that of the mother. In most cases the fetus or infant has Rh-positive blood and its mother has Rh-negative blood (see rh factor). Another form is seen when the fetus or infant has blood of type A or B and the mother has blood of type O; it is much milder than the Rh type because anti-A and anti-B antibodies only occasionally cross the placenta. Called also hemolytic disease of the newborn.

In Rh incompatibility the mother builds up antibodies against the red blood cells of the fetus; these pass through the placenta, enter the fetal circulation., and proceed to rapidly destroy the fetal red blood cells. In order to compensate for this, there is an ever-increasing effort on the part of the fetus to avoid anemia. This results in the release of very immature red blood cells (erythroblasts). Thus an extremely high percentage of fetal erythrocytes are erythroblasts, giving the condition its name of erythroblastosis.
Symptoms. If it survives under these circumstances, at birth the baby is jaundiced and usually anemic. The immune bodies from the mother's blood usually circulate in the baby's blood for 1 to 2 months after birth, continuing the destruction of red blood cells unless an exchange transfusion is done. Other symptoms depend on the number of red cells destroyed and the amount of damage done to other tissues of the body, such as the brain and central nervous system.
Treatment. The usual treatment for erythroblastosis fetalis is exchange transfusion in which the infant's blood is replaced with Rh-negative blood. This measure stops the destruction of the infant's red blood cells, and gradually the Rh-negative blood is replaced with the baby's own blood. In about 6 weeks the immune bodies left over from the mother's blood have been destroyed and are no longer a menace to the baby. Exposure to ultraviolet light (phototherapy) breaks down the bilirubin causing the jaundice and reduces the number of transfusions that are required.ƒ

Developments in the management of erythroblastosis include amniocentesis and intrauterine fetal transfusion. The former is puncture of the amniotic sac through the maternal abdomen and is done for the purpose of obtaining a sample of amniotic fluid for analysis. This allows for determination of concentration of bilirubin pigments and protein in the amniotic fluid; a high concentration indicates excessive destruction of fetal erythrocytes. If there is a mild hemolysis the mother is watched closely and allowed to deliver at term. In more severe cases, induced labor and premature delivery are usually advised so that further destruction of erythrocytes will not take place and an exchange transfusion can be performed as soon as possible. For cases of very severe hemolysis it has been recommended that an intrauterine transfusion be administered to the fetus. This is a delicate procedure that involves certain risks, and is advised only if the mother's past history and the present evidence indicate that the infant would not survive or would suffer damage from erythroblastosis.

e·ryth·ro·blas·to·sis fe·ta·lis

a grave hemolytic anemia that, in most instances, results from development in an Rh-negative mother of anti-Rh antibody in response to the Rh factor in the (Rh-positive) fetal blood; it is characterized by many erythroblasts in the circulation, and often generalized edema (hydrops fetalis) and enlargement of the liver and spleen; the disease is sometimes caused by antibodies for antigens other than Rh.

erythroblastosis fetalis

(fē-tā′lĭs)
n.
A severe hemolytic disease of a fetus or newborn infant caused by the production of maternal antibodies against the fetal red blood cells, usually involving Rh incompatibility between the mother and fetus. Also called RH disease.

erythroblastosis fetalis

[-blastō′sis]
Etymology: Gk, erythros + blastos, germ, osis, condition; L, fetus, bringing forth
a type of hemolytic anemia in newborns that results from maternal-fetal blood group incompatibility, specifically involving the Rh factor and the ABO blood groups. The condition is caused by an antigen-antibody reaction in the bloodstream of the infant resulting from placental transmission of maternally formed antibodies against the incompatible antigens of the fetal blood. In Rh factor incompatibility, the hemolytic reaction occurs only when the mother is Rh negative and the infant is Rh positive. The isoimmunization process rarely occurs in the first pregnancy, but there is increased risk with each succeeding pregnancy. See also hydrops fetalis, hyperbilirubinemia of the newborn, Rh factor, hemolytic disease of the fetus and newborn (HDFN)

erythroblastosis fetalis

 Hemolytic disease of the newborn, see there.

e·ryth·ro·blas·to·sis fe·ta·lis

(ĕ-rith'rō-blas-tō'sis fē-tā'lis)
A grave hemolytic anemia that, in most instances, results from development in the mother of anti-Rh antibody in response to the Rh factor in the (Rh-positive) fetal blood; characterized by many erythroblasts in the circulation, and often generalized edema (hydrops fetalis) and enlargement of the liver and spleen; sometimes caused by antibodies for antigens other than Rh.
Synonym(s): congenital anemia, hemolytic disease of newborn, neonatal anemia, Rh antigen incompatibility.

erythroblastosis fetalis

The type of severe anaemia with JAUNDICE caused in babies by RHESUS FACTOR incompatibility when the mother is rhesus negative and the baby rhesus positive. The risk to the baby increases with successive pregnancies because of the ever rising levels of antibodies in the mother's blood.

e·ryth·ro·blas·to·sis fe·ta·lis

(ĕ-rith'rō-blas-tō'sis fē-tā'lis)
Grave hemolytic anemia that, in most instances, results from development in an Rh-negative mother of anti-Rh antibody in response to the Rh factor in the (Rh-positive) fetal blood.

erythroblastosis fetalis (ərith´rō-blastō´sis fētal´is),

n an excessive destruction of red blood cells begun before or shortly after birth in the fetus or newborn. It may be caused by an Rh factor reaction. After birth the skin is yellow, and the teeth may be markedly discolored.
References in periodicals archive ?
Erythroblastosis fetalis, before the treatment of Rh-negative mothers with anti-Rh immune globulin, provided us with experience with hyperbilirubinemia and its effect on the brain.