Blutausstrichen

Blutausstrich (blood smear) is a thin layer of blood spread on a glass slide for microscopic examination of blood cells. It is prepared from peripheral blood and enables detailed assessment of cell morphology at high magnification.

Preparation and staining: A drop of capillary or venous blood is placed near one end of a slide. A spreader slide is drawn across at a slight angle to create a monolayer smear, which air-dries. Smears are fixed with methanol if required and stained with Romanowsky-type stains such as Giemsa or Wright-Giemsa to reveal erythrocytes, leukocytes, and platelets.

Diagnostic value: The smear provides information on red blood cell size and shape, color, and inclusions; it enables a white blood cell differential and detection of abnormal cells; it allows estimation of platelet number and morphology. It can also reveal blood parasites (e.g., malaria, Babesia) and supports diagnosing hematologic disorders such as leukemias and myelodysplastic syndromes.

Indications and limitations: Blutausstriche are used to investigate anemia, infections, and hematologic diseases, and to monitor certain treatments. They are rapid and inexpensive but highly operator-dependent; smear quality, staining quality, and artifacts influence interpretation. They are best used in conjunction with automated counts and other laboratory tests.

Safety and handling: Preparation and analysis follow standard biosafety practices for handling human blood and require trained laboratory personnel.