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Direct Chromogenic Anti-D Prothrombin Antibody Test (Serum)

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

This test measures antibodies against the D protein of prothrombin, a blood protein involved in clotting. It helps assess risks of blood clots or bleeding disorders in pregnant individuals or those with certain blood conditions.

Quick summary

["Checks for antibodies linked to hemolytic disease of the fetus/newborn (HDFN) or other clotting disorders."]

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

Key facts at a glance

LOINC
111938-7
Short code
Dx chrctr Esoph Endscpy
Synonyms
Dx chrctr Esoph Endscpy
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
endoscopy
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Matters for Pregnancy

If you’re pregnant or planning pregnancy, this test may be used to detect antibodies that could cause complications like HDFN, where your baby’s red blood cells are destroyed by your immune system. Early identification helps guide care to prevent risks to your baby’s health.

How the Test Works

A small blood sample is drawn and tested for specific antibodies against the D protein of prothrombin. The test uses a chromogenic method to detect these antibodies, which may appear if your immune system has been exposed to the D protein (e.g., from blood transfusions or pregnancy).

Sample Collection and Preparation

Your blood is collected in a sterile tube and sent to the lab. Serum (the liquid part after clotting) is separated and analyzed. This test does not require fasting or special preparation.

What to Expect Before or After the Test

You may experience mild discomfort at the needle site, but most people tolerate blood draws well. Afterward, apply gentle pressure to stop bleeding and ice if needed. Avoid heavy lifting or strenuous activity for a few hours.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Anti-D (Prothrombin) Antibody

Frequently asked questions

When might I need this test?
This test is typically ordered during pregnancy (often at 28 weeks or later) if you’re Rh-negative (lacking the D protein) and at risk of developing anti-D antibodies, such as after a previous pregnancy loss, miscarriage, or blood transfusion.
What does a positive result mean?
A positive result means your blood contains antibodies against the D protein. This could increase the risk of HDFN in future pregnancies, so your doctor may recommend additional monitoring, such as regular blood tests for your baby or immune globulin treatment.
How often will I need this test?
If your initial test is positive, your doctor may repeat it during later pregnancies or monitor antibody levels through other tests (like indirect Coombs’ test) to assess risk. Follow-up depends on your specific situation and healthcare provider’s recommendations.
  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 16, 2026. · Read our editorial policy