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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

ByHealthwise Staff
Primary Medical Reviewer Sarah A. Marshall, MD - Family Medicine
E. Gregory Thompson, MD - Internal Medicine
Adam Husney, MD - Family Medicine
Kathleen Romito, MD - Family Medicine
Elizabeth T. Russo, MD - Internal Medicine
Specialist Medical Reviewer Kirtly Jones, MD - Obstetrics and Gynecology, Reproductive Endocrinology

Current as ofNovember 21, 2017

Current as of: November 21, 2017

Author: Healthwise Staff

Medical Review: Sarah A. Marshall, MD - Family Medicine & E. Gregory Thompson, MD - Internal Medicine & Adam Husney, MD - Family Medicine & Kathleen Romito, MD - Family Medicine & Elizabeth T. Russo, MD - Internal Medicine & Kirtly Jones, MD - Obstetrics and Gynecology, Reproductive Endocrinology