Hello,Rh incompatibility, also known as Rh disease, is a condition that occurs when a woman with Rh-negative blood type is exposed to Rh-positive blood cells, leading to the development of Rh antibodies.
Rh incompatibility can occur by 2 main mechanisms. The most common type occurs when an Rh-negative pregnant mother is exposed to Rh-positive fetal red blood cells secondary to fetomaternal hemorrhage during the course of pregnancy from spontaneous or induced abortion, trauma, invasive obstetric procedures, or normal delivery. Rh incompatibility can also occur when an Rh-negative female receives an Rh-positive blood transfusion. In part, this is the reason that blood banks prefer using blood type "O negative" or "type O, Rh negative," as the universal donor type in emergency situations when there is no time to type and crossmatch blood.
The most common cause of Rh incompatibility is exposure from an Rh-negative mother by Rh-positive fetal blood during pregnancy or delivery. As a consequence, blood from the fetal circulation may leak into the maternal circulation, and, after a significant exposure, sensitization occurs leading to maternal antibody production against the foreign Rh antigen.
An indirect Coombs' test determines whether there are antibodies to the Rh factor in the mother’s blood.
A normal (negative) result means that the mother has not developed antibodies against the fetus's blood. A negative Coombs' test indicates that the fetus is not presently in danger from problems relating to Rh incompatibility.
An abnormal (positive) result means that the mother has developed antibodies to the fetal red blood cells and is sensitized. However, a positive Coombs' test only indicates that an Rh-positive fetus has a possibility of being harmed. A positive test cannot indicate the amount of fetal harm that has occurred or is likely to occur. Consult your obstetrician for further information.