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Aborhbldcfm

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

A blood test that determines your ABO blood group (A, B, AB, or O) and Rh factor (positive or negative).

Quick summary

{"Identifies your blood type (A, B, AB, or O) and Rh status","Essential for safe blood transfusions and pregnancy care","A simple blood test with no special preparation needed","Results help doctors match blood for transfusions","Your blood type is inherited from your parents"}

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

Key facts at a glance

LOINC
77397-8
Short code
ABO/Rh Type
Synonyms
ABO + Rh Bld Cfm
Category
chemistry
Sample
whole-blood
Container
EDTA purple-top (lavender) whole blood tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
confirm
CPT
86900
SNOMED
299571000136102
Specimen volume
3-5 mL whole blood
Stability
Room temperature (20-25°C): 72 hours; Refrigerated (2-8°C): 7 days; Do not freeze
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
1–4 hours
Order
routine

What is this test?

The ABO and Rh blood type test is a routine blood test that determines two important things about your blood: your ABO blood group (whether you have type A, B, AB, or O blood) and your Rh factor (whether your blood is positive or negative). This test is performed using a confirmatory method, which means it uses specialized techniques to ensure accurate results.

Why is this test important?

Knowing your blood type is crucial for several medical situations. If you ever need a blood transfusion, doctors must give you the correct blood type to prevent a dangerous reaction. During pregnancy, knowing the mother's Rh status is essential to prevent complications between the mother and baby. This test is also commonly performed before surgery, when donating blood, or as part of routine health screening.

How is the test done?

A healthcare professional will draw a small sample of blood from a vein in your arm. The blood sample is then sent to a laboratory where it is tested to determine your ABO group and Rh factor. You do not need to fast or make any special preparations before this test. The draw typically takes only a few minutes.

What do the results mean?

Your ABO blood type will be one of four groups: A, B, AB, or O. Your Rh factor will be either positive (+) or negative (-). Together, these determine your full blood type, such as A positive or O negative. If you are Rh-negative, this is particularly important for women of childbearing age, as special care may be needed during pregnancy.

Reference range

ABO Group: A, B, AB, or O; Rh Type: Positive or Negative. Results should show concordance between forward and reverse grouping.N/A

Specimen: whole-blood

No fasting required. Inform laboratory of recent blood transfusions, intravenous fluids, or hematopoietic stem cell transplantation as these may affect results. Patient identification is critical.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

The ABO and Rh blood type test is critical for safe blood transfusion practices. Receiving the wrong blood type can cause a severe and potentially life-threatening immune reaction. For pregnancy, Rh-negative mothers may need special medication (Rh immunoglobulin) to prevent complications in future pregnancies. This test also helps in organ transplantation compatibility, paternity testing, and forensic investigations.

Frequently asked questions

Does it hurt?
You may feel a brief sting or pinch when the needle is inserted to draw blood. The discomfort is usually minimal and goes away quickly. Some people may experience slight bruising at the puncture site afterward.
How long does it take to get results?
Results are typically available within a few hours to one day, depending on the laboratory. Your healthcare provider will inform you when and how you can access your results.
Do I need to fast before this test?
No, you do not need to fast or make any special preparations before this test. You can eat and drink normally.
Can my blood type change over time?
No, your ABO and Rh blood type does not change throughout your lifetime. It is determined by your genetic makeup and remains constant from birth.
What if I'm Rh-negative?
Being Rh-negative means you lack the Rh factor protein on your red blood cells. This is important during pregnancy if the mother is Rh-negative and the baby is Rh-positive. Your doctor may recommend Rh immunoglobulin injections to prevent complications.
  1. 1
    Mayo Clinic - Blood typesSource
  2. 2
    American Red Cross - Blood TypesSource
  3. 3
    Lab Tests Online - Blood TypingSource

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