📅 Last Updated: April 2026 | 🩺 Medically Reviewed by: Edward Salko, D.O., Medical Director | 🧪 Lab Partner: Labcorp
Why Knowing Your Blood Type Matters
Most people don’t know their blood type — and for most of daily life that’s fine. But there are several situations where not knowing can become a medical emergency.
Emergency transfusions — in a severe accident or emergency surgery, transfusion may be needed before your medical records can be located. O-negative blood is given to unknown patients because it is compatible with all blood types. Knowing your own blood type allows medical teams to use your exact match faster and preserve the limited supply of O-negative blood for those who truly need it.
Pregnancy and Rh incompatibility — Rh-negative women carrying Rh-positive babies (when the father is Rh-positive) face a risk called Rh incompatibility. If Rh-negative blood is exposed to Rh-positive blood — typically at delivery — the mother’s immune system develops anti-Rh antibodies. In a subsequent Rh-positive pregnancy these antibodies can attack the baby’s red blood cells, causing hemolytic disease of the newborn. Rh immunoglobulin (RhoGAM) injections prevent this — but only if the Rh-negative status is known.
Blood donation — knowing your blood type helps blood banks match you to recipients who need your specific type most urgently. O-negative donors are in particularly high demand.
Personal health awareness — some research suggests correlations between blood type and certain disease risks, medication
responses, and nutritional needs — though the clinical significance is still studied.
No fasting required. No special preparation. Just one blood draw at any Labcorp location.
Reviewed by Edward Salko, D.O., Medical Director, Personalabs
Blood Type Results — What They Mean
| Blood Type | Antigens on RBCs | Antibodies in Plasma | Can Donate To | Can Receive From |
|—|—|—|—|—|
| A positive | A + Rh | Anti-B | A+, AB+ | A+, A-, O+, O- |
| A negative | A only | Anti-B, Anti-Rh | A+, A-, AB+, AB- | A-, O- |
| B positive | B + Rh | Anti-A | B+, AB+ | B+, B-, O+, O- |
| B negative | B only | Anti-A, Anti-Rh | B+, B-, AB+, AB- | B-, O- |
| AB positive | A + B + Rh | None | AB+ only | All blood types |
| AB negative | A + B | Anti-Rh | AB+, AB- | AB-, A-, B-, O- |
| O positive | Rh only | Anti-A, Anti-B | O+, A+, B+, AB+ | O+, O- |
| O negative | None | Anti-A, Anti-B, Anti-Rh | All types (universal donor) | O- only |
Also Known As
ABO Group and Rh Type, Blood Group, Rh Factor
The Purpose of Blood Type Testing
Blood type testing provides essential information that’s used in many medical situations. Blood types are divided into three groups–A, B, and O–based on the antigens, or proteins, in red blood cells. Additionally, blood is categorized by whether it has a Rhesus, or Rh, factor, which refers to a substance on the surface of red blood cells. Blood is either Rh positive or Rh negative. So someone who is A negative has type A blood without an Rh factor.
A test for blood type is common and can be used for:
- Blood transfusions
- Detecting Rh immune globulin candidacy for prenatal and postpartum individuals as well as potential ABO hemolytic disease in newborns
- Special blood type-based diets
What Does the ABO Rh Test Measure?
The blood group test will determine your blood type by detecting antigens in your blood. You will have either A or B antigens, both antigens (blood type AB), or no antigens (type O). The test will also look for the presence of Rh factor.
Who Should Take an ABO Rh Blood Test?
This test is recommended for anyone who:
- Wants to learn their blood type for general health knowledge
- Needs to undergo prenatal testing
- Will have surgery or a blood transfusion
- Follows a blood type diet plan for weight loss
ABO/Rh Test Preparation
No special preparation is required for a blood typing test.
Blood Typing Test Results
You will learn your blood type, which would typically be A, B, AB, or O. You will also learn whether you are positive or negative for Rh factor.
Where Can I Get a Blood Type Test Near Me?
Personalabs makes it easy to get the information you need to take control of your health. Our partnerships with Labcorp and Quest Diagnostics give you access to more than 4,000 lab locations across the country for your convenience.
It’s easy to get a blood type test with Personalabs:
Step 1: Purchase a test online and download the lab order. (You won’t need approval from your doctor, depending on which state you live in.)
Step 2: Use our lab locator to find the facility near you and make an appointment.
Step 3: Bring the ABO Rh test order to your appointment and have your blood drawn.
Step 4: Test results typically arrive in your private and secure Personalabs account within 2 to 10 business days. (Contact us for a specific turnaround time, which can vary by location, and we will contact the lab for you.)
Shop our selection of men’s and women’s health tests today.
Frequently Asked Questions: Blood Type Test
What does the ABO RH blood type test measure?
The ABO RH blood type test determines your ABO blood group (A, B, AB, or O) by detecting the antigens on your red blood cells. It also determines your Rh factor — whether you are positive or negative. Your complete blood type is the combination of both — for example A positive or O negative. This information is essential for blood transfusions, organ transplants, and pregnancy.
Why is knowing your Rh factor important during pregnancy?
Rh-negative women carrying Rh-positive babies face a risk called Rh incompatibility. During delivery Rh-negative blood can be exposed to the baby’s Rh-positive blood, triggering the mother’s immune system to develop antibodies. In a subsequent pregnancy these antibodies can attack an Rh-positive baby’s red blood cells. RhoGAM injections prevent this — but only when Rh-negative status is known. All pregnant women should know their Rh factor.
What is the universal donor blood type?
O-negative (O-) is the universal donor blood type — O-negative blood can be safely given to patients of any blood type in an emergency when there is no time to determine the recipient’s type. O-negative donors are in high demand. Conversely AB-positive (AB+) is the universal recipient — people with AB+ blood can receive any blood type.
Do I need to fast for a blood type test?
No fasting required. No special preparation needed. Available through Personalabs without a doctor’s visit — order online, visit any Labcorp location, results in 24 to 48 hours. HSA and FSA eligible.
