Enhanced sensitivity of the extrinsic coagulation system during ovarian stimulation for in-vitro fertilization

The tissue factor activity in blood monocytes was investigated during ovarian stimulation for in-vitro fertilization (IVF) in 13 women. Blood samples were taken prior to hormonal stimulation (days 2-3 of the menstrual cycle, median serum oestradiol concentration 70 pmol/l) and the day after ovulation induction with human chorionic gonadotrophin (days 11-13, median serum oestradiol concentration 6270 pmol/l). The tissue factor activity in unstimulated monocytes and factor VII concentration were unchanged during the treatment. However, the tissue factor activity in lipopolysaccharide-stimulated monocytes was on average more than twice as high after stimulation (P < 0.02). A positive correlation was found between the tissue factor activity and the serum concentration of oestradiol (r = 0.514, P < 0.02). The tumour necrosis factor (TNF)-alpha increased during ovarian stimulation (P = 0.05), and there was a positive correlation between the change in TNF-alpha and the change in tissue factor activity (r = 0.663, P < 0.05). Our results indicate an enhanced sensitivity of the extrinsic coagulation system during IVF treatment since more tissue factor is available upon stimulation. It is suggested that this may be important in thrombotic situations. Further studies are necessary to elucidate the mechanism behind this response.