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
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.
If test results show that antibody amounts are increasing during
pregnancy, the fetus may be at greater risk of harm.
A fetus who is Rh-negative will not be harmed, even if the mother is
ByHealthwise Staff Primary Medical ReviewerSarah Marshall, MD - Family Medicine E. Gregory Thompson, MD - Internal Medicine Adam Husney, MD - Family Medicine Specialist Medical ReviewerWilliam Gilbert, MD - Maternal and Fetal Medicine