White Blood Cell Differential with Specimen Preparation Instructions (Wet Mount)

What This Test Measures

A small amount of your blood is placed on a microscope slide and covered with a thin layer of liquid (wet mount). A trained technician then examines the cells under a microscope to count and identify different types of white blood cells, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils. This method provides a qualitative view of cell morphology rather than precise counts.

Why It’s Done

Your healthcare provider may order this test to investigate symptoms like frequent infections, unexplained fatigue, swollen lymph nodes, or unusual bruising. It can also help diagnose conditions such as leukemia, lymphoma, or immune deficiencies.

Sample Preparation

Before your blood is drawn, the technician will prepare the sample by mixing it with a liquid buffer to prevent clotting. A drop of this mixture is placed on a slide and covered with a cover slip. This ensures the cells remain spread evenly for accurate microscopic examination.

What to Expect

You’ll receive standard blood draw instructions, including fasting if required. The wet mount preparation is quick and non-invasive but requires a trained technician to perform it correctly. Results are qualitative and interpreted by a pathologist.