Bleeding time

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Bleeding time is a medical test used to see how well your platelets (the blood’s tiny cells that help it clot) work and how your small blood vessels respond. It’s done by making a small controlled cut on the skin and timing how long bleeding lasts until it stops.

How the test is done
- IVY method: A standardized cut (about 10 mm long, 1 mm deep) is made on the forearm. A blood pressure cuff around the arm is inflated to 40 mmHg. Blood is blotted with paper every 30 seconds until bleeding stops. Normal results are usually about 3 to 10 minutes. This method can be more invasive and can be impacted by how the wound is made.
- Duke’s method: A small puncture (3–4 mm deep) is made on the earlobe or fingertip after swabbing with alcohol. Blood is wiped away every 30 seconds until bleeding stops. Typical results are around 2 to 5 minutes. This method isn’t standardized and can cause a hematoma, so it’s not commonly used.

What the result means
- A longer bleeding time suggests problems with platelets or blood vessel function, not with the coagulation factors themselves (like in hemophilia).
- Conditions that can prolong bleeding time include low platelet number (thrombocytopenia), certain bleeding disorders, Bernard-Soulier disease, and Glanzmann’s thrombasthenia.
- Certain medicines can also extend bleeding time, notably aspirin and other drugs that affect platelets. Warfarin and heparin mostly affect coagulation factors, but bleeding time can be prolonged in some cases.
- Von Willebrand disease (a common bleeding disorder) often increases bleeding time, but bleeding time is not a reliable test to diagnose it.

Why is it used
- Historically, bleeding time was a common way to assess bleeding risk when other, more reliable tests weren’t available. Today, it’s used less often because it can be unreliable and is being replaced by newer platelet function tests.

Modern alternatives
- Platelet function tests, such as the platelet function screen on the PFA-100 analyzer, are now preferred for assessing platelet function.

Bottom line
Bleeding time checks how long it takes for bleeding to stop after a small skin cut. It mainly reflects platelet function and vessel health, can be influenced by certain drugs, and is less commonly used today in favor of newer tests.