Bleeding Time

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	Bleeding Time

Procedure	Physician's Notes	Patient Instructions
Document History	Equipment	Procedural Notes
Principle	Calibration	Clinical Significance
Specimen	Quality Control	References

Principle:
An incision 5 mm long x 1 mm deep is made on the lateral aspect of the volar surface of the forearm and the time to cessation of bleeding is measured. Constant pressure (supplied by a sphygmomanometer) of 40 mm Hg. is applied and a disposable incision device is used to standardize the procedure. Provided that fibrinogen levels and platelet count is normal, this procedure will detect defective platelet function and is used as a screening test for inherited and acquired platelet defects.

Specimen:
A complete explanation of the procedure to the patient is appropriate before proceeding. Small children may have to be restrained as excessive movement may render performance difficult and may invalidate the test. The patient should be advised as to the possibility of some scaring. An accurate drug history is often useful to the interpretation of the test. The test may be performed routinely if the platelet count is in excess of 100,000/mm3 and a free (i.e. free of IVs etc.) arm is available. The test is performed on forearms only.

Equipment and supplies:

1. stopwatch
2. sphygmomanometer (blood pressure cuff)
3. filter paper
4. Surgicutt ^tmAutomated Incision Making Instrument (International Technidyne Corp.)
5. alcohol prep
6. butterfly bandages

Calibration: None

Quality Control:
No external QC is available. Care must be taken to standardize the procedure.
The protocol must followed exactly!

Procedure:

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1. Select a site on the patient's arm on the lateral aspect volar surface that is free of veins, bruises, edematous areas, and scars and is approximately 5 cm below the antecubital crease.
2. Clean the site with the alcohol prep.
3. Place the sphygmomanometer around the patient's arm approximately two inches above the elbow and maintain 40 mm Hg.
4. Remove the "trigger" safety and place the incision device on the site with minimal pressure so that both ends of the device touch the skin. Do not press hard.
5. Depress the "trigger" to make the incision then remove the device.
Discard the device in a "sharps" container.
6. Start the timing device and blot the edge of the incision at 30-second intervals with the filter paper. Do not touch the incision with the filter paper.
7. Note the time that bleeding stops and report to the nearest 30 seconds.

Note: If the bleeding time exceeds 15 minutes:
stop the procedure
apply pressure to stop the bleeding
report as greater than 15 min.

8. To minimize scaring, bandage with a bandage is applied perpendicular to the incision.

Expected results:
Normal Values: 2- 9 minutes.

Procedure Notes:
Sources of Error:

Errors producing false positive results

Blood pressure cuff maintained too high (>40mm Hg.)

Incision too deep, caused by excessive pressure on the incision device.

Disturbing the clot with the filter paper.

Low fibrinogen (<100 mg/dl) or platelet count (100,00 /mm3).

Drug ingestion affecting platelet function (e.g. asprin)

Errors producing false negative results

Blood pressure cuff maintained too low (<40 mm Hg).

Incision too shallow.

Clinical Significance: See physicians instructions for more detail

The bleeding time test is primarily a test of platelet function. It is usually significantly prolonged in the case of congenital or acquired platelet defects. Disease states in which abnormal bleeding times may be found include:

a. Thrombastenia
b. Von Willebrand's Disease
c. Storage Pool Disease
d. Bernard Soulier Syndrome
e. Sensitivity to Asprin

References:

Wintrobe,M.M. Clinical Hematology , Lea and Febinger, Philadelphia, 1974, p1049.

Miekle, C.H., Kaneshiro,M.N.,Weiner J.M. and Rapaport,S.I., The Standardized Normal Ivy Bleeding Time and its Prolongation by Asprin. Blood, 34:204, 1969.

Laboratory Manual of Hemostasis, WB Saunders Co., Philadelphia, 1971.

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