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Aborhbldfetus

Published: August 9, 2026Updated: August 16, 2026

This test determines the blood type (ABO group) and Rh factor of a fetus by analyzing a blood sample collected during pregnancy.

Quick summary

{"The test identifies the fetus's ABO blood type (A, B, AB, or O) and Rh status (positive or negative)","Results help predict potential blood type incompatibility between mother and baby","Rh-negative mothers may need special care if carrying an Rh-positive baby","Early detection allows doctors to prevent complications like hemolytic disease","The test requires a blood sample collected from the fetus or mother"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
54417-1
Short code
ABO + Rh Bld Fetus
Synonyms
ABO + Rh Bld Fetus
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What is this test?

The ABO and Rh blood group test for fetal blood is a laboratory analysis that determines the blood type of an unborn baby. It identifies two important blood characteristics: the ABO blood group (A, B, AB, or O) and the Rh factor (Rh-positive or Rh-negative). This information is crucial for managing pregnancy and preventing potential health complications for both the mother and the baby.

How is the test performed?

The fetal blood sample can be obtained through different methods depending on the gestational age and clinical situation. These methods may include amniocentesis (collecting amniotic fluid), chorionic villus sampling (CVS), or cordocentesis (sampling blood from the umbilical cord). In some cases, the mother's blood can be used to analyze fetal DNA non-invasively. The sample is then tested in a laboratory to determine the blood type antigens present on the fetal red blood cells.

Why is this test important?

Knowing the fetal blood type is essential for several reasons. Most importantly, it helps identify the risk of Rh incompatibility, a condition that occurs when a Rh-negative mother carries a Rh-positive baby. During pregnancy, small amounts of the baby's blood can enter the mother's bloodstream, causing her immune system to produce antibodies against Rh-positive blood cells. These antibodies can cross the placenta in subsequent pregnancies and attack the baby's red blood cells, potentially causing severe complications or even fetal death.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

Is this test safe for my baby?
The procedures used to obtain fetal blood samples (like amniocentesis or CVS) carry a small risk of complications, including infection, bleeding, or in rare cases, miscarriage. However, when performed by experienced specialists, these risks are minimal. Non-invasive testing using maternal blood to analyze fetal DNA is also available and carries no risk to the pregnancy.
When is this test typically performed?
Fetal blood type testing may be recommended in specific situations, such as when the mother is Rh-negative and the father is Rh-positive (suggesting the baby could be Rh-positive), or when there's a history of blood type incompatibility in previous pregnancies. The timing depends on the clinical situation and the method used for testing.
What happens if my baby has a different blood type than mine?
If blood type incompatibility is detected, your healthcare provider will develop a monitoring and treatment plan. For Rh incompatibility, you may receive Rh immunoglobulin injections at around 28 weeks of pregnancy and within 72 hours after delivery if the baby is Rh-positive. Your doctor may also recommend additional monitoring, such as ultrasound exams to check for signs of fetal anemia.
Does ABO blood type matter as much as Rh type?
While both ABO and Rh incompatibility can occur, Rh incompatibility is generally more clinically significant and can cause more severe complications. ABO incompatibility is more common but usually results in milder symptoms, such as mild jaundice in the newborn that often resolves without treatment.
  1. 1
    American College of Obstetricians and Gynecologists - Rh DiseaseSource
  2. 2
    Mayo Clinic - Rh diseaseSource
  3. 3
    UpToDate - Rh alloimmunization: OverviewSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy