CPT (Certified Phlebotomy Technician) Practice Exam

The presence of a red mark after applying a tourniquet is most likely indicative of petechiae. Petechiae are small, pinpoint flat red or purple spots that appear on the skin due to bleeding under the skin's surface. They can occur when blood vessels are under increased pressure, such as when a tourniquet is applied. This pressure can cause minor capillary bleeding, leading to the formation of these small marks.

In contrast, a hematoma refers to a larger area of localized bleeding that occurs when blood collects outside of blood vessels, often due to a more significant injury or a needle puncture gone wrong. A thrombus is a blood clot that can form within a blood vessel, and a bruise typically appears as a larger area of discoloration that changes color over time due to internal bleeding. These conditions do not align with the specific characteristic of the small, pinpoint marks observed with petechiae, making it the most appropriate choice given the scenario.