A blood smear is a blood test that gives information about the number and shape of blood cells.
How the Test is Performed
A blood sample is needed.
The blood sample is sent to a lab. There, the lab technician looks at it under a microscope. Or, the blood may be examined by an automated machine. The smear shows the number and kinds of white blood cells (differential), abnormally-shaped blood cells, and gives a rough estimate of white blood cell and platelet counts.
How to Prepare for the Test
No special preparation is necessary.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
This test may be done as part of a general health exam to help diagnose many illnesses. Or, your doctor may order this test if you have signs of any of the following disorders: Any known or suspected blood disorder
Vajpayee N, Graham SS, Bern S. Basic examination of blood and bone marrow. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 30.
Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.