CD-ROM Today 1996 January/CD-ROM Today 1996 January.iso/dp/0418/04187.txt

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$Unique_ID{BRK04187}
$Pretitle{}
$Title{Rh Disease}
$Subject{Rh Disease Erythroblastosis Fetalis Erythroblastosis Neonatorum
Hemolytic Disease of Newborn Hemolytic Anemia of Newborn Congenital Anemia of
Newborn Icterus Gravis Neonatorum Hydrops Fetalis Rhesus Incompatibility Rh
Incompatibility Rh Factor Incompatibility }
$Volume{}
$Log{}

Copyright (C) 1986, 1989, 1992 National Organization for Rare Disorders, Inc.

251:
Rh Disease

** IMPORTANT **
It is possible the main title of the article (Rh Disease) is not the name
you expected.  Please check the SYNONYMS listing to find the alternate names
and disorder subdivisions covered by this article.

Synonyms

     Erythroblastosis Fetalis
     Erythroblastosis Neonatorum
     Hemolytic Disease of Newborn
     Hemolytic Anemia of Newborn
     Congenital Anemia of Newborn
     Icterus Gravis Neonatorum
     Hydrops Fetalis
     Rhesus Incompatibility
     Rh Incompatibility
     Rh Factor Incompatibility

General Discussion

** REMINDER **
The information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section of this report.


Rh disease is an Rh incompatibility between the blood of a mother and
fetus.  It causes anemia and other more serious conditions.  Red blood cells
are broken down (hemolysis) because of the incompatibility.

Symptoms

During the first pregnancy of an Rh-negative woman carrying an Rh-positive
fetus, there are rarely any symptoms.  However, the risks of sensitization
increase with each subsequent pregnancy when the fetus is Rh-positive.

In Rh disease, red blood cells from the fetus cross the placenta and
enter into the mother's circulation during pregnancy.  This stimulates
maternal antibody formation against the Rh factor.  These antibodies reach
the fetus via the placenta and cause destruction of the fetal red blood cells
(hemolysis).  This consequently causes anemia in the fetus.  To overcome this
anemia, the fetal bone marrow releases immature red blood cells
(erythroblasts) into the fetal circulation.  The hemoglobin from the
destroyed red blood cells is broken down to bilirubin, which is cleared from
the fetal circulation by crossing the placenta into the mother's blood.
After birth, however, bilirubin builds up in the newborn's circulation and
high levels of bilirubin may sometimes be deposited in the basal ganglia of
the brain causing Kernicterus.  (For more information, please choose
"kernicterus" as your search term in the Rare Disease Database.)

In women who have developed Rh-sensitization, succeeding pregnancies with Rh
incompatibility produce progressively more seriously affected infants, unless
treatment with an anti-Rh-gammaglobulin (RhoGAM) is given to the mother within
72 hours after each childbirth or termination of pregnancy. The more severely
affected fetuses develop profound anemia in the womb and are delivered with
gross edema (swelling) of the entire body (hydrops fetalis).  This may be
suspected before delivery if excessive fluid around the fetus in the amnion
sac (polyhydramnios) is present (detected through x-rays).  Sometimes a
picture of the fetus in the uterus (amniogram) reveals severe scalp edema.

Newborn infants with Rh disease are extremely pale and may have severe
generalized edema, including the presence of liquid in the pleural cavity
around the lungs (pleural effusion) and an accumulation of serous fluid in
the abdominal cavity (ascites).  The liver and spleen are enlarged because of
production of red blood cells outside the bone marrow.  Congestive heart
failure may sometimes occur.  Because of anemia and prematurity, lack of
oxygen in the lungs (asphyxia) is likely during labor and delivery.  The
prematurity and asphyxia along with an abnormal decrease of the amount of
protein in the blood (hypoproteinemia) may predispose the infant to
respiratory distress syndrome (RDS), the signs of which may be difficult to
distinguish from those of congestive heart failure.

Less severely affected newborn infants may be anemic, but do not have
edema or other signs of hydrops.  Others may have little or no anemia at
birth.  Affected infants usually develop severe hyperbilirubinemia shortly
after delivery because of the continuing hemolytic effect of Rh-antibodies
that have crossed the placenta.

Succeeding pregnancies tend to produce more seriously affected fetuses.
Erythroblastosis can be prevented by injecting the mother with a high-titer
anti-Rh-gammaglobulin preparation within 72 hours after delivery to prevent
her from developing antibodies.  (For more information, see Therapies:
Standard.)

Causes

Rh incompatibility occurs when a woman with Rh-negative blood conceives a
child with Rh-positive blood.  Red blood cells from the fetus cross the
placenta and enter into the mother's circulation stimulating maternal
antibody formation against the Rh factor.  These antibodies reach the fetus
via the placenta and cause destruction of the fetal red blood cells,
consequently causing anemia and bilirubin in the fetal blood (jaundice) which
makes the infant appear yellow.  Rh-negative and -positive blood types are
determined by genetic factors.

Affected Population

Rh Disease occurs only in infants who have Rh-positive blood and whose
mothers have Rh-negative blood.  In the U.S. only about 13% of marriages
result in pairing of an Rh-positive man and an Rh-negative woman.  Only 1:27
children born to these couples will suffer from Rh disease.

Related Disorders

Kernicterus is a condition characterized by an excess of bilirubin in the
blood which is deposited in the basal ganglia of the brain and in the
brainstem nuclei.  (For more information, choose "Kernicterus" as your search
term in the Rare Disease database.)

Therapies:  Standard

An infant with hydrops fetalis or severe erythroblastosis fetalis (without
hydrops) due to Rh disease is usually critically ill and should be treated in
a perinatal intensive care facility whenever possible.  Fetal heart rate
should be monitored during labor.  If signs of lack of oxygen (asphyxia)
occur, or if the infant is severely affected, cesarean section delivery
should be performed.  The mainstay of treatment is "exchange transfusion."
This is a blood transfusion using twice the infant's calculated blood volume
which removes 85% of the infant's blood, including circulating antibodies,
sensitized red blood cells, accumulated bilirubin, and replenishes red blood
cells.

In hydrops fetalis, profound anemia should be corrected immediately by
giving a partial (1-volume or less) exchange transfusion using packed red
blood cells.  After the infant's condition stabilizes, a 2-volume exchange
transfusion should be performed.  In addition, digoxin and diuretics for
heart failure, alkali therapy for metabolic acidity of the body tissues
(acidosis), and supportive treatment for RDS may be required.

When an Rh-negative sensitized woman delivers a less severely ill infant,
umbilical cord blood should be examined immediately to determine the infant's
blood type, and the direct Coombs' test for the presence of antibodies should
be performed.  If the infant is Rh-positive and the Coombs' test is positive,
the infant's percentage of red blood cell volume in the blood (and
reticulocyte count) should be determined.  A blood smear should be obtained
to check for reticulocytes and red blood cells with nuclei.  The bilirubin
level in umbilical cord blood should also be determined.

Laboratory and clinical evaluations of some infants suggest such a severe
rate of hemolysis that exchange transfusion will almost certainly be required
in the future.  If the infant's condition is stable, an early exchange
transfusion removes sensitized red blood cells and antibodies before
hemolysis produces large amounts of bilirubin and may avert the need for
multiple transfusions at a later time.

If an exchange transfusion is not needed immediately, the infant can be
monitored, determining both the bilirubin and red blood cell count in the
blood (hematocrit).  Should bilirubin levels become dangerously elevated or
should significant anemia develop, an exchange transfusion is normally
indicated.  Some sensitized Rh-positive infants do not require an exchange
transfusion in the newborn period.  However, the hematocrit must be followed
serially for several weeks or months as severe anemia may develop because of
slow, ongoing hemolysis.  Such infants may require a simple transfusion with
packed red blood cells at a later time.

Erythroblastosis can be prevented by injecting a high-titer
anti-Rh-gammaglobulin preparation into the mother within 72 hours after each
birth or termination of pregnancy.  This preparation prevents the formation of
maternal antibodies.  During pregnancy of an Rh-negative mother (when the
father is Rh-positive), maternal Rh antibody levels should be measured at
monthly intervals.  If the titers are higher than 1:32 a surgical entry into
the abdomen to obtain amniotic fluid (amniocentesis) for measurement of
bilirubin concentration in amniotic fluid, should be conducted usually at 2-
week intervals.  If bilirubin levels are elevated, the fetus can be given
blood transfusions inside the uterus at 10-day to 2-week intervals, generally
until the 32nd to 34th week of pregnancy at which time delivery may be
performed.

Therapies:  Investigational

Clinical trials are underway to study Human Parvovirus Infection and it's
sequelae in Iowa and Northwestern Illinois.  Interested persons may wish to
contact:

     Stanley J. Naides, M.D.
     Division of Rheumatology, GH E400
     Dept. of Internal Medicine
     University of Iowa
     Iowa City, IA  52242
     [phone]

to see if further patients are needed for this research.

This disease entry is based upon medical information available through
January 1992.  Since NORD's resources are limited, it is not possible to keep
every entry in the Rare Disease Database completely current and accurate.
Please check with the agencies listed in the Resources section for the most
current information about this disorder.

Resources

For more information on Rh Disease, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     [phone]

     NIH/National Institute of Child Health and Human Development (NICHHD)
     9000 Rockville Pike
     Bethesda, MD 20892
     [phone]

     NIH/National Heart, Lung and Blood Institute (NHLBI)
     9000 Rockville Pike
     Bethesda, MD  20892
     [phone]

For information on genetics and genetic counseling referrals, please
contact:

     March of Dimes Birth Defects Foundation
     1275 Mamaroneck Avenue
     White Plains, NY 10605
     [phone]

     Alliance of Genetic Support Groups
     35 Wisconsin Circle, Suite 440
     Chevy Chase, MD  20815
     (800) 336-GENE
     [phone]

References

CECIL TEXTBOOK OF MEDICINE, 18th ed.:  James B. Wyngaarden, and Lloyd H.
Smith, Jr., Eds.:  W.B. Saunders Co., 1988.  P. 948.

THE MERCK MANUAL 15th ed:  R. Berkow, et al:  eds; Merck, Sharp & Dohme
Research Laboratories, 1987.  Pp. 1766, 1875.