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Indirect Coombs Test

Topic Overview

An indirect Coombs test can be used to determine whether there are antibodies to the Rh factor in the mother's blood. In this case:

  • 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.

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 sensitized.

Credits

Current as ofSeptember 5, 2018

Author: Healthwise Staff
Medical Review: Sarah A. Marshall, MD - Family Medicine
Femi Olatunbosun, MB, FRCSC, FACOG - Obstetrics and Gynecology, Reproductive Endocrinology
E. Gregory Thompson, MD - Internal Medicine
Adam Husney, MD - Family Medicine
Kathleen Romito, MD - Family Medicine
Elizabeth T. Russo, MD - Internal Medicine
William M. Gilbert, MD - Maternal and Fetal Medicine
Kirtly Jones, MD - Obstetrics and Gynecology, Reproductive Endocrinology

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