Positive Coombs Test In Newborns: Causes And Tips To Follow

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Coomb’s test or antiglobulin test (AGT) is a blood test that helps detect the presence of antibodies against red blood cells (erythrocytes) in the body, which cause hemolysis. A positive coomb’s test in newborns indicates two health problems – anemia and jaundice.

However, it doesn’t necessarily mean that the baby has anemia or jaundice but rather that they should be checked for these conditions. Blood samples are taken from the neonate’s umbilical cord during delivery or the veins after birth to conduct this test.

Read on to learn more about different types of coomb tests, their interpretations, and the outcomes for babies with a positive coomb’s test

Types Of Coombs Tests

There are two types of Coombs tests to detect various pathologies (1).

1. Direct Coombs test

Direct Coombs test detects antibodies attached to the red blood cells. After collecting the blood sample, the red blood cells are washed in the laboratory to remove the plasma and unbound antibodies. The washed red blood cells are incubated with Coombs reagent (anti-human globulin) in the next step.

The test is considered positive if the red blood cells agglutinate, that is, appear clumpy or sticky. This indicates that the antibodies or complement proteins are attached to the red blood cells causing their destruction. A baby with a positive direct Coombs test may have autoimmune hemolytic anemia.

2. Indirect Coombs test

Indirect Coombs test detects free antibodies in the blood.

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Indirect Coombs test detects free antibodies in the blood. These antibodies are not attached to the red blood cells and work against foreign red blood cells. In the laboratory, the blood serum is extracted and incubated with foreign red blood cells and anti-human globulin or Coombs reagent. Indirect Coombs test is considered positive if agglutination is observed.

Indirect Coombs tests help diagnose reactions to blood transfusion. It is also used in prenatal testing to check for Rh compatibility issues in pregnant women. Mothers with Rh-negative blood groups should take an Rh immunoglobulin shot during pregnancy to avoid Rh incompatibility-related complications in their subsequent pregnancies (2).

What Problems Are Seen In Coombs Positive Babies?

Babies with Coombs positive test could have jaundice.

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The health problems in positive direct and indirect Coombs tests may vary. These may include (3):

1. Autoimmune hemolytic anemia

In this condition, the immune system destroys the red blood cells, resulting in anemia. The lifespan of red blood cells is 120 days, but they are destroyed earlier in this condition. It could lead to anemia since there are inadequate mature cells to compensate for the loss.

Swelling under the skin is one of the common symptoms of hemolytic anemia in babies. Destruction of red blood cells could also cause jaundice.

2. Jaundice

Yellow discoloration of skin and whites of the eyes (sclera) is called jaundice. It is caused by excess bilirubin, a byproduct of red blood cell destruction. Babies with indirect or direct Coombs positive test could have jaundice since both attached and free antibodies damage the red blood cells.

Note: Coombs negative babies may also develop jaundice due to immature liver function, breast milk, or erythrocyte disorders.

How To Take Care Of A Coombs Positive Baby?

Adequate feeding is recommended.

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There is no need for specific treatment in some babies with mild elevation of bilirubin levels. However, babies are closely monitored for changes in bilirubin levels and symptoms. Treatment options may include the following.

  • Adequate feeding is recommended since poor feeding may worsen jaundice due to other reasons
  • Intravenous fluids are given if required
  • Medications to keep blood pressure normal
  • IVIG-intra venus immunoglobulin may be required in some cases to neutrilize preformed antibodies
  • Phototherapy is given for jaundice
  • Severe cases may require a blood transfusion

You may discuss the appropriate treatment plan with a pediatrician.

When Can A Coombs Positive Newborn Go Home?

Breathing difficulties or fast breathing

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Coombs positive babies can go home in usual time after birth unless there are complications of high bilirubin levels and anemia. However, you may need to visit a pediatrician within a few days for blood tests to assess the progress.

Sometimes, jaundice and anemia may worsen after going home. You may call the healthcare provider if you notice any of these signs and symptoms (4).

  • Increased yellowing of the skin and eye
  • Poor feeding
  • Breathing difficulties or fast breathing
  • Pallor
  • Sleepiness

Long-term Complications In Coombs Positive Infants

Most Coombs positive babies do not develop any long-term problems since the maternal antibodies clear within a few weeks after birth. The immune reaction slowly resolves, and the formation of new blood cells helps the infant recover completely in a few weeks (4).

If left untreated, very high bilirubin levels may cause brain damage known as kernicterus and other issues, such as cerebral palsy or deafness. However, in most cases, jaundice is diagnosed and treated before the bilirubin reaches a level high enough to cause complications.

What Happens If The Coombs Test Is Negative?

A negative result (no agglutination present) on direct and indirect Coombs tests means no antibodies or complement proteins are against the red blood cells. It is possible to develop jaundice and hemolytic anemia in babies with negative Coombs tests due to other medical conditions that do not involve antibodies against the red blood cells. Newborns may also develop physiological jaundice and breast milk jaundice during the initial days of life (5).

Frequently Asked Questions

1. How long do positive Coombs test results last?

If a baby’s Coombs test results show positive due to maternal antibodies, they may return to normal within two months. Moreover, most babies do not have any long-term effects due to this phenomenon. However, checking for any atypical signs following a positive Coombs test in your baby is essential. Speak to a doctor if you have any concerns (4).

2. Why do newborns undergo the Coombs test?

A pediatrician may suggest a Coombs test if they suspect jaundice in your newborn. The test is also helpful in detecting foreign antibodies, which may lead to blood disorders such as hemolysis (5).

Coombs test helps detect antibodies against red blood cells and determine any related underlying issues. If you are an Rh-negative mother, you may consider testing and taking Rh immunoglobulin injections to avoid complications. Severe cases can also be treated with intrauterine blood transfusions. If the baby has a positive Coombs test, they may require close monitoring, and their health condition will eventually improve over time.

Infographic Title: What Causes A False Positive Coombs Test In Newborns?

There can be various clinical situations where the Coombs test can be positive without the presence of red blood cell destruction or hemolysis in the newborn. Go through the below infographic to know some of the common reasons for a false positive Coombs test in newborns.

positive coombs newborn [infographic]
Illustration: MomJunction Design Team

Key Pointers

  • Coombs test detects the antibodies present against red blood cells in a newborn.
  • A positive Coombs test may indicate autoimmune hemolytic anemia or jaundice in babies.
  • Consult a doctor if babies show signs, such as breathing difficulties, poor feeding, or excessive yellowing of skin and eyes.
  • In most babies, the condition resolves after a few weeks from birth.


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
1. Coombs Test; Johns Hopkins Lupus Center
2. The Rh Factor: How It Can Affect Your Pregnancy; American College of Obstetricians and Gynecologists
3. Coombs Antibody Test (Indirect and Direct); Michigan Medicine; University of Michigan
4. Direct Coombs Test (DCT);; National Health Service
5. The Coombs Test; Stanford Medicine
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Dr Bisny T. Joseph

Dr. Bisny T. Joseph is a Georgian Board-certified physician. She has completed her professional graduate degree as a medical doctor from Tbilisi State Medical University, Georgia. She has 3+ years of experience in various sectors of medical affairs as a physician, medical reviewer, medical writer, health coach, and Q&A expert. Her interest in digital medical education and patient education made...
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Dr. Aarti R. Motiani

Dr. Aarti Motiani is a child specialist with a decade of experience in patient care.  She has special interest in nutrition, immunization, and development of kids. Dr. Motiani treats kids with minimal medicine and believes in parents counselling for every behavior of the child.