OSMT (Ontario Society of Medical Technologists) Practice Exam

A good blood film demonstrates all of the following except:

1. Feathered edges

2. Consistent thickness throughout

3. ½ - ¾ the length of the slide

4. Space at the lateral edges

The correct answer is: Consistent thickness throughout

In the context of preparing a blood film, a good blood film does indeed demonstrate certain qualities that facilitate effective microscopic examination. Among these qualities, consistent thickness throughout is not desirable. A properly prepared blood film is characterized by a gradient of thickness, with a thin area at the feathered edge for the examination of individual cells and thicker areas to provide a representative sample of the blood. Feathered edges are crucial as they allow for a smooth transition from thick to thin areas of the film, enhancing the visualization of different cell types. The optimal length of ½ - ¾ the length of the slide ensures that there's enough area for analysis without overcrowding. Additionally, space at the lateral edges is important as it allows for manipulation of the slide and ensures that cells are not too close to the edge, which could distort the view. Therefore, while consistent thickness would not contribute to an effective blood film, the other qualities mentioned are essential for a good preparation.