American Society for Clinical Pathology (ASCP) Histotechnician Certification Practice Exam

When performing a bleeding time test, what role does the sphygmomanometer play?

1. To increase blood flow

2. To maintain a constant pressure

3. To measure clotting time

4. To assess blood volume

The correct answer is: To maintain a constant pressure

In a bleeding time test, the sphygmomanometer is used to maintain a constant pressure. This is essential for generating a standardized environment in which the test can be conducted. By inflating the sphygmomanometer around the arm, the pressure can be controlled precisely to occlude venous return while allowing arterial blood flow, which helps to create a consistent and reproducible testing condition. Maintaining a consistent pressure ensures that variations in individual blood pressure do not affect the bleeding time measurement. It allows for the evaluation of the time it takes for bleeding to stop after a standardized incision or puncture is made. The measurement focuses specifically on the ability of the platelets to form a plug at the site of the injury, thereby assessing the hemostatic function of the blood vessels and platelets under controlled conditions. This usage is crucial for ensuring accurate and comparable results, allowing clinicians to assess potential bleeding disorders effectively while eliminating confounding variables that could arise from changes in blood flow or pressure during the test.