Haemostasis in menstrual endometrium in the presence of an intrauterine device.

The histology and ultrastructure of the haemostatic response in the endometrium have been studied in 12 uteri containing an inert or copper wound intrauterine contraceptive device (IUCD). The uteri were removed during the premenstrual phase or during the first 96 hours of menstruation. The results have been compared to earlier observations in non-IUCD influenced endometrium. In all uteri the tissue shedding proceeded more slowly in the presence of an IUCD and considerably fewer haemostatic plugs were found. The platelets in these plugs were more loosely packed and less degranulated, and the plugs contained less fibrin than in the absence of an IUCD. Haemostatic plugs were still observed at times when no such plugs were seen in uteri without an IUCD. Unoccluded vessel lesions were regularly seen and vessels open to the shedding surface were occasionally encountered. These observations suggest that IUCD-induced menorrhagia is caused by the combination of delayed shedding and a decreased haemostatic reaction in the endometrium.