Skip to content

Information and Resources

Font Size
A
A
A

Antibody Tests (Coombs Test)

Why It Is Done

Direct Coombs test

The direct Coombs test finds antibodies attached to your red blood cells. The antibodies may be those your body made because of disease or those you get in a blood transfusion.

The direct Coombs test also may be done on a newborn baby with Rh-positive blood whose mother has Rh-negative blood. The test shows whether the mother has made antibodies and if the antibodies have moved through the placenta to her baby.

Indirect Coombs test

The indirect Coombs test finds certain antibodies that are in the liquid part of your blood (serum). These antibodies can attack red blood cells but are not attached to your red blood cells. The indirect Coombs test is commonly done to find antibodies in a recipient's or donor's blood before a transfusion.

A test to determine whether a woman has Rh-positive or Rh-negative blood (Rh antibody titer) is done early in pregnancy. If she is Rh-negative, steps can be taken to protect the baby.

How To Prepare

You do not need to do anything before you have this test.

How It Is Done

The health professional drawing blood will:

  • Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
  • Clean the needle site with alcohol.
  • Put the needle into the vein. If the needle is not placed correctly or if the vein collapses, more than one needle stick may be needed.
  • Hook a tube to the needle to fill it with blood.
  • Remove the band from your arm when enough blood is collected.
  • Put a gauze pad or cotton ball over the needle site as the needle is removed.
  • Put pressure to the site and then a bandage.

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

WebMD Medical Reference from Healthwise

Last Updated: March 12, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

Hot Topics

WebMD Video: Now Playing

Click here to wach video: Dirty Truth About Hand Washing

Which sex is the worst about washing up? Why is it so important? We’ve got the dirty truth on how and when to wash your hands.

Click here to watch video: Dirty Truth About Hand Washing

Popular Slideshows & Tools on WebMD

MS Overview
Recognizing symptoms.
feet
Solutions for 19 types.
pregnancy test and calendar
Helping you get pregnant.
build a better butt
How to build a better butt.
lone star tick
How to identify that bite.
woman standing behind curtains
How it affects you.
brain scan with soda
Tips to avoid complications.
row of colored highlighter pens
Tips for living better.
psoriasis
How to keep flares at bay.
woman dreaming
What Do Your Dreams Say About You?
spinal compression fracture
Treatment options.

Pollen counts, treatment tips, and more.

It's nothing to sneeze at.

Loading ...

Sending your email...

This feature is temporarily unavailable. Please try again later.

Thanks!

Now check your email account on your mobile phone to download your new app.

Women's Health Newsletter

Find out what women really need.