BLEEDING TIME

Principle

A blood pressure cuff is placed on the patient's arm above the elbow and inflated to 40 mmHg to create venostasis. A standardized incision is made on the volar surface of the forearm utilizing a disposable bleeding time device. A stopwatch is started and at 30-second intervals the blood is blotted away using filter paper. The bleeding time is the length of time required for bleeding to cease.1,2

Quality Control

Quality control is accomplished through the standardization of the procedure. The wound should be a standard length and depth and a constant pressure of 40 mmHg should be maintained throughout the procedure.

Reagents and Equipment

  1. Blood pressure cuff

  2. Sterile disposable bleeding time device

  3. Stopwatch

  4. Whatman No. 1 filter paper

  5. Alcohol swabs

  6. Butterfly bandage

Procedure

  1. Select the site for the puncture. This site should be located on the volar surface of the forearm approximately 5 cm below the antecubital crease.

  2. Prepare the site by cleansing with an alcohol swab. Allow alcohol to dry completely.

  3. Place a blood pressure cuff around the upper arm and inflate to 40 mm Hg.

  4. With a disposable bleeding time device, make a standard incision and start a stopwatch.

  5. At 30-second intervals, blot the blood from the puncture site using filter paper. Care must be taken to avoid touching the wound at any time.

  6. When blood is no longer drawn to the filter paper, stop the timer. Record the length of time required for bleeding to stop.

  7. Release the blood pressure cuff and apply a butterfly bandage over the puncture site.

Reference Interval

Each laboratory should establish its own reference interval. The general reference interval is 1-9 minutes.

Comments

  1. A platelet count should be performed prior to the bleeding time. A platelet count less than 100.0 x 109/L will result in a prolonged bleeding time.

  2. The direction of the incision should be consistent. A horizontal incision gives a longer bleeding time than a vertical incision.

  3. The sensitivity of the procedure is determined by venostasis and the direction of the incision. The most sensitive technique is a horizontal incision with venostasis.

  4. If the bleeding has not ceased at 15 minutes, stop the timer and apply pressure to the incision site. The bleeding time should be reported as greater than 15 minutes.

  5. Disposable bleeding time devices are also available for newborns. These devices make a standard incision that is shorter and not as deep as the adult devices. In performing a bleeding time on a newborn, the pressure applied by the blood pressure cuff must be adjusted to the weight of the newborn.

  6. Since the ingestion of aspirin and many aspirin-like drugs results in a prolonged bleeding time, a true bleeding time is obtained by requiring the patient to remain aspirin-free for seven days.

  7. The bleeding time is prolonged in thrombocytopenia, hereditary and acquired platelet dysfunctions, von Willebrand's disease, afibrinogenemia, severe hypofibrinogenemia, and some vascular bleeding disorders.

Reference

  1. Mielke CH. International committee communications: Measurement of the bleeding time. Thromb Hemostas. 1984; 52:210.

  2. National Committee for Clinical Laboratory Standards. Performance of the bleeding time test, H45-A. 1998; Villanova, Pa.: NCCLS.


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