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Lymphocytes, Peripheral Blood — Qualitative Smear

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

A qualitative peripheral blood smear examines the appearance of lymphocytes for reactive, atypical, or immature-appearing forms.

Quick summary

["This test looks for unusual lymphocyte forms that may prompt further evaluation for infection or a blood disorder."]

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

Key facts at a glance

LOINC
74357-5
Short code
Ib Lymphs Bld Ql Smear
Synonyms
Ib Lymphs Bld Ql Smear
Category
liver
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
microscopy-light
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 is this test?

This test examines a stained blood smear under a microscope to evaluate the appearance of lymphocytes. It may identify reactive or atypical lymphocytes, immature cells, or cells that look different from normal mature lymphocytes.

Why might I need this test?

A clinician may order it as part of an unexplained fever, infection, enlarged lymph nodes, or an abnormal blood count. It can also help investigate suspected blood disorders or monitor the effects of treatment.

How is the test performed?

A small blood sample is spread thinly on a glass slide, stained, and viewed under a microscope. A laboratory professional records whether the lymphocytes have a normal or unusual appearance.

How do I prepare for the test?

No special preparation is usually needed, and fasting is generally not required. Follow any instructions from the laboratory, particularly if the test is being collected with other blood tests.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Reactive or atypical lymphocytes may occur with viral or other infections. Immature-appearing cells or other abnormal forms may suggest a blood-forming disorder, but a smear alone cannot establish the diagnosis. Follow-up testing, such as flow cytometry or additional laboratory studies, may be needed.

Short name

Peripheral blood lymphocyte smear

Frequently asked questions

Does a qualitative result provide a lymphocyte count?
No. This test primarily evaluates the appearance of lymphocytes rather than providing a precise count. A complete blood count or differential count may be used to measure the cells.
Can this test diagnose leukemia or lymphoma?
Not by itself. The smear may identify findings that require further evaluation, but diagnosis usually requires additional blood tests, specialized cell testing, and sometimes a bone marrow sample.
What might cause atypical lymphocytes?
Reactive lymphocytes are most often associated with infections, especially viral illnesses. Other causes can include medications, immune conditions, or certain blood disorders.
  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