Skip to content

Eosinophil count in fetal blood (manual cell differential)

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

This test measures the number of eosinophils—a type of white blood cell—in fetal blood, using a manual cell differential method. It helps assess immune or inflammatory conditions in the fetus.

Quick summary

["Eosinophil counts in fetal blood can indicate potential immune or allergic responses during pregnancy."]

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

Key facts at a glance

LOINC
66141-3
Short code
Eosinophil # Bld Fetus Manual
Synonyms
Eosinophil # Bld Fetus Manual
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
manual-count
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

Why is this test done?

Your healthcare provider may order this test if there are concerns about fetal immune function, congenital infections, or certain genetic conditions that affect white blood cell counts. It may also be part of prenatal monitoring for high-risk pregnancies.

What does the result mean?

Eosinophil counts in fetal blood are not typically provided as a single reference range since they vary widely. High levels may suggest immune activation, while very low levels could indicate immune deficiency or other underlying issues. Your results will be interpreted by a healthcare professional in the context of your overall health and pregnancy.

How is the test performed?

This test involves drawing blood from the fetus (often via umbilical cord sampling or fetal blood sampling during a procedure). The blood is then examined under a microscope by a trained technician to count eosinophils and other white blood cells manually.

What should you expect before the test?

No special preparation is needed, but you may be asked to lie down for a few minutes before the procedure to reduce discomfort. Discuss any concerns or medications with your healthcare provider beforehand.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance

Short name

Fetal eosinophil count

Frequently asked questions

What does an abnormal result mean?
Elevated eosinophil counts in fetal blood may signal potential immune responses, such as allergic reactions, infections, or certain genetic disorders. Very low counts could suggest immune deficiencies or other congenital conditions. Always consult your healthcare provider for personalized interpretation.
Is this test painful?
The procedure involves drawing blood, which may cause mild discomfort, but it is generally well-tolerated. Local anesthesia may be used to minimize pain. Recovery is quick, and most women can resume normal activities immediately.
How often is this test done?
This test is rarely routine and is typically performed only when there is a specific clinical indication, such as suspected fetal infection, genetic testing, or monitoring of high-risk pregnancies. Your provider will determine the need based on your situation.
  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