Complete Blood Count (CBC) Test: What Patients Should Know
This test checks a newborn's cord tissue for acetyl norfentanyl, a substance that appears when the mother has used fentanyl during pregnancy.
{"Acetyl norfentanyl is a marker showing fentanyl exposure during pregnancy","The test uses umbilical cord tissue to detect drug exposure before birth","Results help doctors provide appropriate care for mother and baby","A positive result does not mean the baby is currently impaired","This is a confirmatory test, meaning it provides definitive results"}
Key facts at a glance
- LOINC
- 103594-8
- Short code
- Acetyl norfentanyl TissCo Cfm-mCnc
- Synonyms
- Acetyl norfentanyl TissCo Cfm-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- confirm
- CPT
- 86430
- 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
What is a complete blood count (CBC) test, and what does it measure in my blood?
The acetyl norfentanyl test looks for traces of acetyl norfentanyl in the umbilical cord tissue. When a pregnant person takes fentanyl (a strong pain medication), the body breaks it down into various substances, including norfentanyl and acetyl norfentanyl. These substances can cross the placenta and enter the baby's blood supply. The cord tissue absorbs and preserves these substances, allowing doctors to detect drug exposure that occurred during pregnancy.
Why might my doctor order a complete blood count (CBC) test for me?
This test is performed on newborns to find out if they were exposed to fentanyl before birth. Knowing about prenatal drug exposure helps healthcare providers give the right care to both mother and baby. It may also be important for legal or social work reasons, such as when child protective services are involved. The test is often done when there is a reason to suspect drug use during pregnancy, but it may also be part of routine screening in some hospitals.
How is the blood sample for a complete blood count (CBC) test collected?
After the baby is born, a small piece of the umbilical cord is collected. This is usually done right after the cord is cut and clamped. The tissue is then sent to a laboratory for testing. The collection process is painless for both mother and baby and does not interfere with the birth process. The cord tissue is preferred over other samples because it can detect drug use over a longer period during pregnancy compared to urine or blood tests.
What do the results of my complete blood count (CBC) test mean?
A negative result means no acetyl norfentanyl was found in the cord tissue, suggesting the baby was not exposed to fentanyl during pregnancy. A positive result indicates that fentanyl or related substances were present in the mother's system and crossed the placenta. It is important to remember that a positive result does not mean the baby is currently affected or addicted. Rather, it shows that exposure occurred. Healthcare providers will use this information along with other clinical findings to determine what care is needed.
How reliable and accurate is a complete blood count (CBC) test?
Yes, this is a confirmatory test, which means it is very accurate and specific. It uses advanced laboratory methods to identify acetyl norfentanyl with high certainty. Unlike screening tests that can sometimes give false positives, confirmatory tests are considered definitive. However, like all tests, there is a small chance of error, which is why results are always interpreted alongside the patient's clinical situation.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Detecting prenatal fentanyl exposure is important for newborn care. Babies exposed to opioids before birth may need special monitoring for withdrawal symptoms, also called neonatal abstinence syndrome (NAS). Early identification allows doctors to provide appropriate treatment and support. Additionally, knowing about maternal drug use helps connect families with resources for addiction treatment and ongoing support. In some cases, this information may be required by child welfare agencies for safety planning.
From a public health perspective, cord tissue testing helps healthcare providers understand the scope of prenatal drug exposure in their communities. This information can guide prevention efforts and resource allocation. It also helps identify trends in substance use among pregnant populations, which is critical for addressing the ongoing opioid crisis.
Frequently asked questions
Will this test hurt my baby?
What is fentanyl?
Does a positive result mean my baby is addicted?
Who can see my test results?
What happens if the test is positive?
Sources
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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.
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