Tareq Abadl: Bleeding Time (BT) and Clotting Time (CT) Comparison
Tareq Abadl, Medical Laboratory Specialist and Director of the Blood Bank at Dr. Abdelkader Al-Mutawakkil Hospital, shared a post on LinkedIn:
“Bleeding Time (BT) and Clotting Time (CT)

Bleeding Time (BT)
Purpose:
Used to assess platelet function and capillary integrity.
- Ivy Method (Standard Method)
Principle:
Measures the time required for bleeding to stop after a standardized skin incision under controlled pressure.
Procedure:
- Apply a blood pressure cuff to the upper arm and inflate to 40 mmHg.
- Clean the volar surface of the forearm with antiseptic and allow to dry.
- Make a standardized incision (approximately 5 mm long and 1 mm deep).
- Start the stopwatch immediately.
- Blot the blood gently every 30 seconds using filter paper without touching the wound.
- Stop timing when bleeding has completely stopped.
Normal Range:
2–7 minutes
- Duke Method (Older Method)
Principle:
Measures bleeding time after a simple skin puncture.
Procedure:
- Prick the earlobe or fingertip with a sterile lancet.
- Start timing immediately.
- Blot the blood every 30 seconds.
- Stop timing once bleeding stops.
Normal Range:
1–3 minutes
This method is less accurate due to poor standardization.
Clotting Time (CT)
Purpose:
Evaluates the intrinsic coagulation pathway and clotting factors.
- Capillary Tube Method
Principle:
Determines the time taken for blood to clot inside a capillary tube.
Procedure:
- Prick the fingertip using a sterile lancet.
- Fill a clean, dry capillary tube with blood.
- Start the stopwatch immediately.
- Break a small piece of the tube every 30 seconds.
- Stop timing when a fibrin thread is observed between the broken ends.
Normal Range:
3–8 minutes
- Lee–White Method (Venous Blood)
Principle:
Measures clotting time using venous blood in glass tubes.
Procedure:
- Collect venous blood into clean, dry glass tubes.
- Start timing immediately after collection.
- Gently tilt the tubes every 30–60 seconds.
- Stop timing when the blood no longer flows upon tilting.
Normal Range:
5–15 minutes
Important Notes
Bleeding Time assesses platelet function, not coagulation factors.
Clotting Time assesses coagulation factors, not platelet function.
Both tests are screening tests and have limited clinical use today.”
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