Understanding Your Laboratory Test: What It Is, Why It Is Ordered, and What to Expect
A specialized bone marrow test that uses flow cytometry to detect and analyze early B-cell development, helping diagnose blood cancers and immune disorders.
{"Measures B-cell precursors (early B cells) in bone marrow","Helps diagnose B-cell leukemias and lymphomas","Performed on a bone marrow sample using flow cytometry","Results help doctors stage cancer and monitor treatment","Sample is collected via bone marrow aspiration procedure"}
Key facts at a glance
- LOINC
- 101131-1
- Short code
- BCPFC
- Synonyms
- B-cell precursors NFr Mar FC
- Category
- chemistry
- Sample
- serum
- Container
- Heparinized bone marrow aspirate collected in sodium heparin or EDTA anticoagulant tube (green-top or lavender-top); sterile collection required
- Units
- N/A
- Ref low
- 5
- Ref high
- 15
- Critical range
- 1 N/A – 50 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–99 years
- Method
- flow-cytometry
- CPT
- 88184 (Flow cytometry, cell surface, cytoplasmic, or nuclear marker, technical component only - first marker); 88185 (each additional marker); 88187-88189 (interpretation)
- SNOMED
- 395124008 |Measurement of lymphocyte subset by flow cytometry (procedure)|; 42857008 |Bone marrow aspirate (procedure)|; 71493000 |B-cell lineage (cell)|
- Specimen volume
- 1-3 mL of bone marrow aspirate (first pull preferred to avoid peripheral blood dilution); minimum 0.5 mL acceptable for flow cytometry
- Stability
- Specimen must be processed within 24-48 hours of collection at room temperature (18-25°C); do not refrigerate or freeze. Viability decreases significantly after 48 hours. If delayed, store at room temperature and process ASAP.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
This test is a laboratory analysis performed on a sample of your blood, urine, or other body fluid to help your doctor evaluate how well your body is working and to look for signs of possible health conditions.
This test detects and counts B-cell precursors (immature B cells) in your bone marrow using a technique called flow cytometry. B-cell precursors are early-stage B cells that develop in the bone marrow before maturing into fully functional B cells. Flow cytometry can identify specific proteins (markers) on the surface of cells, allowing doctors to see exactly what types of cells are present and in what proportions.
Your doctor may order this test to help diagnose a medical condition, monitor an ongoing illness, check how well a treatment is working, or screen for potential problems before any symptoms have appeared.
Your doctor may order this test if they suspect a B-cell blood cancer such as acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), or B-cell lymphoma. It is also used to evaluate unexplained cytopenias (low blood counts), monitor disease progression, assess how well treatment is working, or investigate potential immune system disorders affecting B-cell development.
A trained healthcare professional will collect the sample, usually by drawing a small amount of blood from a vein in your arm using a sterile needle, though some tests instead require a urine, saliva, or swab sample.
A small sample of bone marrow is collected via bone marrow aspiration, usually from the hip bone (iliac crest). The area is cleaned and numbed with local anesthesia. A thin needle is inserted to draw out liquid bone marrow. You may feel brief pain or pressure during the procedure. The sample is then sent to a laboratory where flow cytometry analyzes the cells.
The risks are generally very small. You may feel a brief sting or pinch during the collection, and mild bruising, soreness, or slight bleeding at the puncture site can occur, but serious complications are extremely rare.
Bone marrow aspiration is generally safe. Minor risks include bruising, bleeding, or infection at the puncture site. Some people experience brief dizziness or soreness. Serious complications are rare. Your healthcare team will take steps to minimize discomfort and ensure safety.
Reference range
B-cell precursors in normal bone marrow typically represent 5-15% of nucleated cells. Pro-B cells (CD19+/CD10+/CD34+/TdT+) are rare (<1%), pre-B cells (CD19+/CD10+/cytoplasmic μ+) account for 5-10%, and immature/transitional B cells constitute <5%. Reference ranges vary by age; pediatric values are higher. Results expressed as percentage of total nucleated cells and absolute count per microliter.N/A
No special patient preparation required. Bone marrow aspiration is performed by a qualified physician under local anesthesia (and optional sedation). Inform the physician of any bleeding disorders, anticoagulant use, or allergies to anesthetics. Recent chemotherapy, immunotherapy, or corticosteroid use should be reported as these can affect precursor populations.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test plays a critical role in diagnosing and classifying B-cell malignancies. Abnormal increases in B-cell precursors may indicate acute lymphoblastic leukemia (ALL) of the B-cell type or other B-cell proliferative disorders. The test can identify specific cell markers (like CD19, CD20, CD10) that help determine the exact type and subtype of blood cancer, which guides treatment decisions. It is also valuable for detecting minimal residual disease (MRD)—tiny amounts of cancer that remain after treatment—which predicts relapse risk. Additionally, reduced B-cell precursors may suggest bone marrow failure syndromes or immunodeficiencies affecting B-cell development.
Frequently asked questions
How long does it take to get results?
Do I need to fast before this test?
Can this test tell if cancer has spread?
What do abnormal results mean?
Sources
- 1
- 2
- 3
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