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24: Platelet reactivity and pregnancy loss

      Objective

      To determine the role of Platelet Reactivity in recurrent pregnancy loss.

      Study Design

      A prospective study was performed comparing 30 patients with a history of unexplained recurrent first trimester pregnancy loss with 30 control subjects matched for age and serum progesterone level.Platelet function was determined using a novel assay of platelet reactivity. A fasting blood sample was taken and platelet aggregation to multiple concentrations of Arachidonic Acid (AA), Collagen, Epinephrine, Thrombin Receptor Activating Peptide (TRAP) and Adenosine Diphosphate were measured simultaneously over successive time-points using a modification of light transmission aggregometry. Dose –response curves were created and half-maximal effective concentration (EC50) values calculated using graphpad prism software. Chi-squared tests were performed to determine the difference between groups with respect to levels of platelet aggregation to each agonist at successive time points.

      Results

      At test completion the EC50 values for AA in the recurrent pregnancy loss patients were significantly less than the control subjects, 0.0074 vs 0.0278 (p <0.01). This indicates a greater aggregation response at submaximal doses of Arachidonic Acid. A significant difference was also found between the groups for the doses of AA at which 20% of maximum aggregation was achieved. For dose 23.4μg/ml AA 63% of patients vs 30% control subjects had reached 20% aggregation response (p< 0.02). The dose-response curves were tightly matched for the other agonists.

      Conclusion

      Patients with a history of unexplained recurrent first trimester pregnancy loss demonstrate significantly increased platelet reactivity in the presence of Arachidonic Acid .This agonist causes aggregation through the same thromboxane pathway that is inhibited by aspirin therapy thus supporting the use of aspirin in management of this clinical condition.