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Blood Type

Published: July 27, 2026Updated: August 25, 2026

Blood type measures the specific antigens present on the surface of red blood cells, determining compatibility for blood transfusions and organ transplants.

Quick summary

Blood type identifies the antigens on red blood cells to ensure safe transfusions and transplants.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
type
Clinical utility
diagnostic
Result kind
qualitative
FDA-cleared
Ortho BioVue, Grifols Galileo, Immucor Echo
interpretation: {"text":"The person has A antigens and the Rh factor, making their blood type A positive.","label":"A+"}; {"text":"The person has neither A nor B antigens and lacks the Rh factor, making their blood type O negative.","label":"O-"}

Blood typing is a critical test in hematology that determines the presence or absence of specific antigens (A, B, and Rh) on the surface of red blood cells. These antigens are essential for categorizing blood into different types, such as A, B, AB, and O, with further classification based on the presence or absence of the Rh factor.

The primary utility of blood typing is to ensure compatibility in blood transfusions and organ transplants. A mismatch in blood type can lead to severe immune reactions, making accurate typing essential for patient safety.

Beyond transfusion and transplantation, blood typing is also used in prenatal care to assess the risk of Rh incompatibility between mother and fetus, which can lead to hemolytic disease of the newborn if not managed properly.

Frequently asked questions

Why is blood type important for transfusions?
Blood type is crucial for transfusions because a mismatch can cause a severe immune response, leading to rejection of the donated blood and potentially life-threatening complications.
Can blood type change over time?
No, a person's blood type is determined by their genetics and remains constant throughout their life.
  1. 1
    American Red Cross - Blood TypesSource
  2. 2
    Mayo Clinic - 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 25, 2026. · Read our editorial policy