Blood Smear Test
A blood smear is a test that looks at your blood cells under a microscope to check their size, shape, and number. It helps diagnose and monitor blood disorders, infections, and certain cancers.
What this test measures
A blood smear examines red blood cells, white blood cells, and platelets to see if they look normal. It can also detect parasites.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
A higher-than-normal number of platelets (thrombocytosis) may be caused by another condition like anemia or infection. Thrombocythemia is a high platelet count from a bone marrow problem.
Lower-than-normal results
A lower-than-normal number of platelets (thrombocytopenia) may increase bleeding risk.
Frequently asked questions
What is a blood smear?
A blood smear is a test where a sample of blood is spread on a slide, stained, and examined under a microscope to check the appearance and number of blood cells.
What conditions can a blood smear help diagnose?
It can help diagnose blood disorders, bone marrow disorders, certain cancers, infections, and parasites.
Can a blood smear alone diagnose a disease?
No, a blood smear alone usually can't diagnose a condition. Your provider will combine it with your medical history, symptoms, and other tests.
What do abnormal red blood cell results mean?
Abnormal red blood cells may be a sign of anemia, sickle cell disease, hemolytic anemia, thalassemia, or bone marrow disorders.
What do abnormal white blood cell results mean?
Abnormal white blood cells may indicate infection, leukemia, or bone marrow disorders.
Related lab tests
Sources
- MedlinePlus: Blood Smear — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.