Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

What is the probable reason for a blood smear that is too thick?

1. Blood drop too small

2. Spreader angle too low

3. Blood drop too large

4. Spreader angle too high

The correct answer is: Spreader angle too high

A blood smear that is too thick is typically caused by an improper spreader angle during the sliding process. When the angle is too high, the spreader may not adequately thin the blood drop out, resulting in a thicker smear. The blood may not be evenly distributed, leading to areas of excess cellularity, which can obscure the observation of individual cells, making it challenging for microscopic examination. In contrast, if the angle were too low, the blood would be distributed too thinly, likely resulting in a smear that is too thin rather than too thick. A small blood drop could lead to a thin smear as well, giving rise to the opposite issue. Finally, using a drop that is too large can still create thicker areas, but the primary concern in this scenario relates to the angle of the spreader and how it affects the overall distribution and thickness of the smear. Understanding the mechanics of creating an effective blood smear is essential in laboratory practice, as it directly impacts the quality of diagnostic results.