University:
Mt. San Antonio College
Course:
MEDI 90 | Medical Terminology
Academic year:

2024
Views:

325

Pages:

1
Author:

Larbi M.

Practical realization about blood It is, in the vast majority of cases, carried out on venous blood (elbow vein) quickly after application of a loose tourniquet; in infants, it is most often carried out after a small cut in the skin either at the level of the pad of a finger or at the level of the heel; in this case, the blood collected is essentially capillary whose composition (cell/plasma ratio) is very slightly different from that of venous blood. This type of sampling requires rigorous technique. In practice, this examination is taken on dry anticoagulant (calcium EDTA). During collection, the tube must be shaken successively to avoid the formation of micro-clots. In addition, to have a correct cytological analysis and an accurate platelet count, the examination must be carried out quickly (<2 hours) after collection. The blood can be stored for up to 24 hours at +4°C without any notable change in the count but the cytology of the cells may change. Blood counts and formulas are now carried out on machines with sufficient reliability. However, these devices do not always detect cells whose presence in the blood is abnormal (malignant cells for example). Consequently, in the event of a quantitative or qualitative anomaly detected by the machine, a morphological study of the blood smear is essential. It is carried out by spreading a drop of blood on a glass slide and staining with May-Grünwald-Giemsa. Microscopic analysis allows the biologist: • to study the morphology of red blood cells, leukocytes and platelets. Microscopic examination of the blood smear allows the biologist to provide information on the morphology of the cells which can quickly make or suspect the diagnosis. These comments are traditionally made after the expression of the leukocyte formula. They may, depending on the case, relate to: -red blood cells, for example: poikilocytosis, sickle cells, schistocytes, etc. - leukocytes, for example: absence of granulations in PNN... - platelets, for example: giant platelets.. • to establish a leukocyte formula with detection of possible abnormal cells not identified by the machine (blasts, myelemia, lymphoma cells, etc.), to assess the presence of possible platelet aggregates allowing the detection of false thrombocutonenia