Definition: For a blood smear, a sample of blood is taken and examined under a microscope. To obtain the blood sample, a lab technician inserts a needle into a vein, usually in your arm in the inside of your elbow. Sometimes, especially in babies, the blood sample may be taken from a vein somewhere else on the body, like the back of the hand. The technician puts the blood sample in a vial and it is sent to the laboratory for analysis.
Blood is made of three types of cells: red cells, white cells, and platelets. The blood smear measures:
- the number of white blood cells
- the kinds of white blood cells
- if any abnormally shaped blood cells are present
- estimated of number of platelets
The information from the blood smear can help diagnose and manage diseases. Different diseases can cause changes in the numbers and kinds of white blood cells, the shape or size of white or red blood cells, or the number of platelets.
