The principle of bleeding time (BT) is that when a standard cut is made on the volar surface of the forearm. All clotting mechanisms are activated to stop the bleeding. Time spend during blood flow from cut till it stops without any kind of assistance is bleeding time.
Example. You make a standard incision on the baby’s finger at 9:10 am. You notice that bleeding stops at 9:15 am. So the gap between 9:10 to 9:15 is 5 minutes. The bleeding time is 5 minutes for that baby.
What are the Bleeding time test requirements?
- Filter paper
2 types of bleeding time methods
There are 2 methods for measuring the bleeding time (BT).
- Duke’s Method: Sometimes this method is used to check the infant BT.
- Ivey’s Method: It is the standard method for estimating the bleeding time.
Duke method bleeding time
In this method, an incision is made on the ear lobe, the pupil of a finger, or the heel because these sites are rich in capillaries. Following is the procedure.
- 1st clean the site of the incision with a spirit swab.
- Allow drying.
- Puncture deeply, so that blood flows out freely. Start the stopwatch. Blot the cut area with filter paper.
- Keep on going until blood stop flowing there. At this time stop the stopwatch and note the time. This is bleeding time.
Lvey’s Method bleeding time
This method is standard for bleeding time estimation. Following are the steps.
- 1st apply a sphygmomanometer cuff to the arm of the patient.
- Inflate the cuff to 40 mm Hg. This pressure should be maintained throughout the test.
- Clean the forearm with a spirit swab.
- Make 6-8 mm long and 1 mm deep incision with a lancet.
- keep on blotting the blood with filter paper, until the blood stops.
- Stop the stopwatch and note the time.
If the bleeding time is more than 15 minutes, and blood is still oozing. stope the test and apply pressure until the blood stops. Write the result, Bleeding time more than 15 minutes..
What is the BT(Bleeding time) test normal range(Reference Range)
- Dukes method: 3 to 7 mint
- Ivey’s method (lancet): 2 to 7 mints
- Ivey’s method (Template): 3 to 9 mints
Factors affecting bleeding time
Following are the factors which affect the bleeding time
- Number of platelets
- Function of platelets
- Willebrand disease. In this disease, platelets lack Von Willebrand Factor.
List of 5 diseases, which increase the bleeding time.
- Von Willebrand disease
- Platelet function defect
- Aspirin Ingestion
Clinical significance of bleeding time
A bleeding time test (BT test) is important before any kind of surgery. When the patient’s BT test results are within normal range, the doctor performs an operation without any kind of hesitation. But if the BT test range is more than 15 minutes then special precautions are taken before surgery, so that blood can stop in the cut area.
what are the 3 main Sources of error in bleeding time calculation
- The superficial cut results in a bleeding time error.
- Blood pressure and variations in incision size result in bleeding time errors. Therefore standard incisions should be made.
- The incision area should be clear of visible veins.
What causes decreased bleeding time?
Bleeding time (BT) directly links to platelets because these platelets are used to make clots on the cut site. Therefore Bleeding time directly links to the platelet amount in the blood.