A functional study of platelets in menstrual fluid

Platelets were isolated from menstrual and peripheral venous blood samples taken from nine women during the first 2 days of menstruation. The washed platelets were tested for their ability to aggregate in response to arachidonic acid, ADP, and collagen, and to metabolize arachidonic acid. Menstrual platelets differed from venous platelets in (1) failing to aggregate when challenged with aggregatory stimuli and (2) producing no appreciable cyclo‐oxygenase products from arachidonic acid as reflected in thromboxane B₂ release. However, incubation of peripheral venous platelets with menstrual serum obtained from the same patients induced aggregation. The responses of menstrual and peripheral venous platelets were the same irrespective of the patients’ total menstrual blood loss. Uterine venous platelets collected during menstruation from two patients at hysterectomy aggregated normally and produced thromboxane B₂.