An in vitro bleeding time test

A new conical plastic device and method, the Platelet-Stat test, has been developed to measure in vitro bleeding time. Ten milliliters of citrated blood, collected by venipuncture, was used. The in vitro bleeding time test was validated by several criteria. Eight volunteers tested had a mean bleeding time of less than 1 minute. Different anticoagulants were evaluated, and the test performed optimally with citrate. Within-run precision had a mean time of 39 +/- 6.7 seconds with a coefficient of variation of 17%. An aspirin study was done on eight volunteers. Preaspirin in vitro bleeding time was less than 1 minute, whereas postaspirin times were more than 7 minutes at 18-24 hours. This test is a reproducible method of performing the bleeding time with greater precision than the in vivo test.