Future research needs for venous thrombo-embolic disease in obstetrics and gynaecology.

The clinical management of thrombo-embolic disease in obstetrics and gynaecology is hampered by the paucity of firm evidence on which to base clinical decisions. This is particularly so in obstetrics where there have been no randomized controlled trials of thromboprophylaxis in pregnancy or the puerperium of sufficient size to detect differences in the incidence of clinical thrombo-embolic events. The incidence of osteoporosis and bleeding complications associated with heparin have not been precisely defined in pregnancy and we are already using low-molecular-weight heparin in place of unfractionated heparin when we do not know whether either heparin is preferable to nothing. In gynaecology, the various thromboprophylactic modalities for use in relation to surgery need to be compared. The small randomized comparisons that have been performed suggest that relatively non-invasive procedures may be just as effective as heparin in preventing thrombo-embolism without the associated complications. Recent controversies concerning the effect of the OCP and HRT on the risk of thrombo-embolic disease indicate that the present methods we use to evaluate these interventions needs to be urgently addressed so that safety rather than efficacy becomes the principle outcome.