Hemolytic Disease of the Newborn
What is hemolytic disease of the newborn (HDN)?
Hemolytic Disease of the Newborn is also called erythroblastosis fetalis.
This condition occurs when there is an incompatibility between the blood
types of the mother and baby.
- "hemolytic" means breaking down of red blood cells
- "erythroblastosis" refers to making of immature red blood cells
- "fetalis" refers to fetus
What causes hemolytic disease of the newborn (HDN)?
HDN most frequently occurs when an Rh negative mother has a baby with an
Rh positive father. When the baby's Rh factor is positive, like the
father's, problems can develop if the baby's red blood cells cross to the
Rh negative mother. This usually happens at delivery when the placenta
detaches. However, it may also happen anytime blood cells of the two
circulations mix, such as during a miscarriage or abortion, with a fall,
or during an invasive prenatal testing procedure (i.e., an amniocentesis
or chorionic villus sampling).
The mother's immune system sees the baby's Rh positive red blood cells
as "foreign." Just as when bacteria invade the body, the immune system
responds by developing antibodies to fight and destroy these foreign
cells. The mother's immune system then keeps the antibodies in case the
foreign cells appear again, even in a future pregnancy. The mother is now
"Rh sensitized."
Although it is not as common, a similar problem of incompatibility may
happen between the blood types (A, B, O, AB) of the mother and baby in the
following situations:
In a first pregnancy, Rh sensitization is not likely. Usually it only
becomes a problem in a future pregnancy with another Rh positive baby.
During that pregnancy, the mother's antibodies cross the placenta to fight
the Rh positive cells in the baby's body. As the antibodies destroy the
red blood cells, the baby can become sick. This is called erythroblastosis
fetalis during pregnancy. In the newborn, the condition is called
hemolytic disease of the newborn.
Who is affected by hemolytic disease of the newborn?
Babies affected by HDN are usually in a mother's second or higher
pregnancy, after she has become sensitized with a first baby. HDN due to
Rh incompatibility is about three times more likely in Caucasian babies
than African-American babies.
Why is hemolytic disease of the newborn a concern?
When the mother's antibodies attack the red blood cells, they are broken
down and destroyed (hemolysis). This makes the baby anemic. Anemia is
dangerous because it limits the ability of the blood to carry oxygen to
the baby's organs and tissues. As a result:
- The baby's body responds to the hemolysis by trying to make more red
blood cells very quickly in the bone marrow and the liver and spleen.
This causes these organs to get bigger. The new red blood cells, called
erythroblasts, are often immature and are not able to do the work of
mature red blood cells.
- As the red blood cells break down, a substance called bilirubin is
formed. Babies are not easily able to get rid of the bilirubin and it
can build up in the blood and other tissues and fluids of the baby's
body. This is called hyperbilirubinemia. Because bilirubin has a pigment
or coloring, it causes a yellowing of the baby's skin and tissues. This
is called jaundice.
Complications of hemolytic disease of the newborn can range from mild
to severe. The following are some of the problems that can result:
During pregnancy:
- mild anemia, hyperbilirubinemia, and jaundice
The placenta helps rid some of the bilirubin, but not all.
- severe anemia with enlargement of the liver and spleen
When these organs and the bone marrow cannot compensate for the fast
destruction of red blood cells, severe anemia results and other organs
are affected.
- hydrops fetalis
This occurs as the baby's organs are unable to handle the anemia. The
heart begins to fail and large amounts of fluid build up in the baby's
tissues and organs. A fetus with hydrops is at great risk of being
stillborn.
After birth:
- severe hyperbilirubinemia and jaundice
The baby's liver is unable to handle the large amount of bilirubin that
results from red blood cell breakdown. The baby's liver is enlarged and
anemia continues.
- kernicterus
Kernicterus is the most severe form of hyperbilirubinemia and results
from the buildup of bilirubin in the brain. This can cause seizures,
brain damage, deafness, and death.
What are the symptoms of hemolytic disease of the
newborn?
The following are the most common symptoms of hemolytic disease of the
newborn. However, each baby may experience symptoms differently. During
pregnancy symptoms may include:
- With amniocentesis, the amniotic fluid may have a yellow coloring
and contain bilirubin.
- Ultrasound of the fetus shows enlarged liver, spleen, or heart and
fluid buildup in the fetus' abdomen.
After birth, symptoms may include:
- A pale coloring may be evident, due to anemia.
- Jaundice, or yellow coloring of amniotic fluid, umbilical cord,
skin, and eyes may be present. The baby may not look yellow immediately
after birth, but jaundice can develop quickly, usually within 24 to 36
hours.
- The newborn may have an enlarged liver and spleen.
- Babies with hydrops fetalis have severe edema (swelling) of the
entire body and are extremely pale. They often have difficulty
breathing.
How is hemolytic disease of the newborn diagnosed?
Because anemia, hyperbilirubinemia, and hydrops fetalis can occur with
other diseases and conditions, the accurate diagnosis of HDN depends on
determining if there is a blood group or blood type incompatibility.
Sometimes, the diagnosis can be made during pregnancy based on information
from the following tests:
- testing the presence of Rh positive antibodies in the mother's blood
- ultrasound - to detect organ enlargement or fluid buildup in the
fetus. Ultrasound is a diagnostic imaging technique which uses
high-frequency sound waves and a computer to create images of blood
vessels, tissues, and organs. Ultrasound is used to view internal organs
as they function, and to assess blood flow through various vessels.
- amniocentesis - to measure the amount of bilirubin in the amniotic
fluid. Amniocentesis is a test performed to determine chromosomal and
genetic disorders and certain birth defects. The test involves inserting
a needle through the abdominal and uterine wall into the amniotic sac to
retrieve a sample of amniotic fluid.
- sampling of some of the blood from the fetal umbilical cord during
pregnancy to check for antibodies, bilirubin, and anemia in the fetus.
Once a baby is born, diagnostic tests for HDN may include the
following:
- testing of the baby's umbilical cord blood for blood group, Rh
factor, red blood cell count, and antibodies
- testing of the baby's blood for bilirubin levels
Treatment for hemolytic disease of the newborn:Once HDN is diagnosed, treatment may be needed. Specific treatment for
hemolytic disease of the newborn will be determined by your baby's
physician based on:
- your baby's gestational age, overall health, and medical history
- extent of the disease
- your baby's tolerance for specific medications, procedures, or
therapies
- expectations for the course of the disease
- your opinion or preference
During pregnancy, treatment for HDN may include:
- intrauterine blood transfusion of red blood cells into the baby's
circulation
This is done by placing a needle through the mother's uterus and into
the abdominal cavity of the fetus or directly into the vein in the
umbilical cord. It may be necessary to give a sedative medication to
keep the baby from moving. Intrauterine transfusions may need to be
repeated.
- early delivery if the fetus develops complications
If the fetus has mature lungs, labor and delivery may be induced to
prevent worsening of HDN.
After birth, treatment may include:
- blood transfusions (for severe anemia)
- intravenous fluids (for low blood pressure)
- help for respiratory distress using oxygen or a mechanical breathing
machine
- exchange transfusion to replace the baby's damaged blood with fresh
blood
The exchange transfusion helps increase the red blood cell count and
lower the levels of bilirubin. An exchange transfusion is done by
alternating giving and withdrawing blood in small amounts through a vein
or artery. Exchange transfusions may need to be repeated if the
bilirubin levels remain high.
Prevention of hemolytic disease of the newborn:
Fortunately, HDN is a very preventable disease. Because of the advances in
prenatal care, nearly all women with Rh negative blood are identified in
early pregnancy by blood testing. If a mother is Rh negative and has not
been sensitized, she is usually given a drug called Rh immunoglobulin
(RhIg), also known as RhoGAM. This is a specially developed blood product
that can prevent an Rh negative mother's antibodies from being able to
react to Rh positive cells. Many women are given RhoGAM around the 28th
week of pregnancy. After the baby is born, a woman should receive a second
dose of the drug within 72 hours.
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