Increased erythrocyte aggregation in ovarian hyperstimulation syndrome: a possible contributing factor in the pathophysiology of this disease.

BACKGROUND Many theories regarding the pathophysiology leading to ovarian hyperstimulation syndrome (OHSS) have been proposed and tested. Increased erythrocyte aggregation is associated with capillary slow flow and tissue hypoxaemia. We performed this study in order to assess the degree of erythrocyte aggregation in the peripheral blood of individuals with OHSS and undergoing controlled ovarian stimulation (COH). METHODS Twenty women with severe OHSS, 20 women undergoing COH under IVF protocol, and 20 healthy matched controls were recruited for this prospective study. Blood samples were drawn for determination of erythrocyte aggregation as well as haematological indices. The percentage of slide covered by the cells ('erythrocyte percentage': EP) was determined using a simple slide test and image analysis. Lower EP values correspond to higher degrees of aggregation. RESULTS The respective measures of EP were 59.2 +/- 3.0, 42.0 +/- 3.0 and 35.0 +/- 2.4% micro m for the controls, women with COH and OHSS (P < 0.01 between controls and the two stimulation groups). CONCLUSIONS The degree of erythrocyte aggregation is enhanced in the peripheral venous blood of patients with both COH and OHSS. This finding, known to cause capillary leak, may contribute to the pathophysiology of the OHSS.