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Red Blood Cell Agglutination Antibody Screening Test (Serum)

Published: August 9, 2026Updated: August 17, 2026

This test checks for antibodies that may cause red blood cells to clump together in your blood. It helps identify potential blood compatibility issues, which can be important before certain medical procedures.

Quick summary

["This test helps ensure safe blood transfusions or prevent reactions in sensitive patients."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
50670-9
Short code
RBC agglut Bld Ql
Synonyms
RBC agglut Bld Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
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 This Test Measures

The test detects the presence of antibodies that can cause red blood cells to stick together (agglutinate). This happens through an immunoassay method that identifies specific immune responses in your serum.

Why It Might Be Ordered

Your healthcare provider may recommend this test if you have a history of blood transfusion reactions, autoimmune conditions, or if you’re preparing for a procedure requiring blood compatibility screening.

Sample Collection and Preparation

A blood sample is drawn from your arm, and the serum (liquid part after clotting) is separated for testing. This process is quick and typically done in a lab setting.

What to Expect Before the Test

No special preparation is needed, but inform your doctor about any medications, recent illnesses, or allergies that could affect results.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Agglutination Antibody Screen

Frequently asked questions

When might I need this test?
Your doctor may order this test if you’re preparing for a blood transfusion, have symptoms of autoimmune conditions, or if you’ve had previous transfusion reactions.
What does a positive result mean?
A positive result indicates the presence of antibodies that could cause red blood cells to clump, which may affect blood compatibility. Further testing (like confirmation) might be needed to determine the specific antibody involved.
How long does it take to get results?
Results are usually available within 1 to 3 business days, depending on lab processing times. Follow up with your healthcare provider for interpretation.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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 17, 2026. · Read our editorial policy