A thick drop is a method of microscopy of human and mammalian blood, which allows you to view a significant amount of blood in a short time (several dozen times more than in the study of smear).
To prepare a thick drop, 2-3 drops of test blood are applied to a glass slide, which is distributed in an even layer to the size of a fifteen-pound coin. In another modification, a blood smear is first made on a glass slide, then a drop of blood is applied to it, which, spreading evenly, forms the correct circle. In the Rukhadze modification, a glass with a drop of fresh blood is placed somewhat obliquely, as a result of which the blood in the form of a half moon collects along its lower edge.
The preparation is dried in the air (to protect from dust) and, without fixing, is stained according to the Romanovsky - Giemsa method. In a non-fixed thick drop in the process of staining, hemolysis of erythrocytes occurs, staining of leukocytes, platelets , blood parasites.
A thick drop is used in the diagnosis of malaria, spirochetosis , trypanosomiasis , filariasis (microfilariae are found). Parasites in the thick drop are deformed, but with a low level of parasitemia, the possibility of their detection increases. The number of parasites is converted to the number of leukocytes (in the counting chamber) or 1 mm 3 of blood. See also Blood (study).