LAB TEST
Blood smear
A blood smear is a blood test that gives information about the number and shape of blood cells. It is often done as part of or along with a complete blood count (CBC).
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 provides this information: The number and kinds of white blood cells ( differential , or percentage of each type of cell) The number…
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 health care provider may recommend this test if you have signs of: Any known or suspected blood disorder Cancer Leukemia A blood smear may also be done to monitor the side effects of chemotherapy or to help diagnose an…
Normal Results
Red blood cells (RBCs) normally are of similar size and color and are a lighter color in the center. The blood smear is considered normal if there is: Normal appearance of cells Normal white blood cell differential Normal value ranges may vary slightly among different laboratories. Some labs use different measurements…
What Abnormal Results Mean
Abnormal results mean the size, shape, color, or coating of the RBCs is not normal. Some abnormalities may be graded on a 4-point scale: 1+ means one quarter of cells are affected 2+ means one half of cells are affected 3+ means three quarters of cells are affected 4+ means all of the cells are affected Presence of…
Risks
There is little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others. Other risks associated with having blood drawn are slight, but may…
References
Bain BJ. The peripheral blood smear. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine . 27th ed. Philadelphia, PA: Elsevier; 2024:chap 143. Lim HI, Lee A. Peripheral blood smear. In: Leppert BC, Kelly CR, eds. Netter's integrated review of medicine: pathogens to treatment . Philadelphia, PA: Elsevier; 2021:chap…
This is a summary. Read the full article at www.ucsfbenioffchildrens.org (reviewed 11/03/2024).
This page is general information and is not medical advice. It does not replace a registered doctor, and it is not a prescription or a recommendation to use any medicine or test. Prices are listed prices and may change. Always follow the advice of your doctor or pharmacist.