A comparative study of variables affecting the bleeding time using two disposable devices.

A number of variables affect the result of the bleeding time, the most frequently used test assessing primary hemostasis. Although the test is now usually performed with one of several commercially available disposable devices, most previous studies of the bleeding time have evaluated only the original template device described nearly 20 years ago. Therefore, we compared two commonly used bleeding time devices (Surgicutt and Simplate) with regard to multiple variables affecting the test in 40 hematologically normal young adults. Bleeding time was performed by the modified Ivy method according to the manufacturers' instructions in both horizontal (transverse) and vertical directions, before and two hours after a test dose of 650 mg of aspirin was administered. With both horizontal and vertical incisions, Simplate bleeding time values were greater than with the Surgicutt device (P = 0.0025). Bleeding time in the horizontal direction was greater than vertical with both devices (P = 0.0001). Values in males and females were not significantly different. Aspirin sensitivity, the difference between preaspirin and postaspirin values, was greatest with the use of the Surgicutt device in the horizontal position (mean postaspirin value 8.0 minutes). Both devices produced a reproducible uniform incision, caused minimal discomfort, and resulted in little or no scarring. The authors conclude that the results with Surgicutt and Simplate devices were comparable in many respects but that a horizontal Surgicutt bleeding time might be most sensitive in detecting disorders of primary hemostasis. Comparative studies of different bleeding time devices in normal subjects are necessary in order to accurately assess their clinical utility.