|Birth||Postnatal||Childhood Illness||Glossary A-Z|
In more than 98% of cases, red blood cell incompatibility between a mother
and the baby she is carrying involves the Rhesus
or Rh D antigen so the disease is known as
Rhesus disease , Rh disease
or Rh Incompatibility .
During the birthing process , blood
cells from the unborn child can escape into the mother's bloodstream.
These cells are recognised as foreign if they are Rh-incompatible (Rh
positive compared to mother's Rh-negative) and a natural rejection process
will ensue with the formation of antibodies. The process is known as red
cell alloimmunisation and typically occurs after the delivery
of a baby at the end of pregnancy, but other pregnancy-related events
such as ectopic pregnancy , chorionic
villus sampling , amniocentesis ,
elective abortion or spontaneous
miscarriage can result in antibody formation. Although the pregnancy
in which the alloimmunisation first occurs results in an unaffected child,
future children are at substantial risk, as in subsequent pregnancies,
newly formed antibodies in the pregnant woman can cross to her unborn
child and attach to its red blood cells producing anaemia and in the worst
case scenario, foetal death.
Prevention & Treatment
Medication is available to prevent Rhesus disease. Rh0(D) immune globulin should be administered to the Rh-negative woman with a Rh-positive partner any time there is a chance foetal cells may enter the pregnant woman's circulation. Rhesus immune globulin should be administered routinely at 28 weeks of pregnancy and after the delivery of an Rh-positive infant. If given correctly, this medication is more than 99% effective in the prevention of Rhesus disease. Rhesus immune globulin is only effective in preventing Rhesus disease; it is not effective in preventing worsening disease once alloimmunisation has occurred.
In 12% of first affected pregnancies, the infant may require intrauterine transfusions. In this procedure, a needle is directed under ultrasound guidance into the umbilical cord and blood is infused directly into the foetus to correct its anaemia. The procedure is usually repeated at 2 to 3 week intervals for the remainder of the pregnancy until approximately 35 weeks of the pregnancy. The survival rate after intrauterine transfusion is approximately 85%.
The information in this page is presented in summarised form and has been taken
from the following source(s):
|http://www.hon.ch/Dossier/MotherChild/complications/complicate_rh.html||Last modified: Jun 25 2002|