Women taking the combined contraceptive pill or hormone replacement therapy (HRT) should continue such medication prior to surgery, says a review in Drug and Therapeutics Bulletin (1999;37:10).
Hormonal contraceptives, HRT and surgery all carry an increased risk of venous thromboembolism. Published advice about the advisability of stopping these drugs prior to surgery, found in the British National Formulary and summaries of product characteristics, conflicts with its experts' opinion, according to the bulletin.
The bulletin says the risk of unwanted effects outweigh the benefits of stopping combined oral contraceptives or HRT and that there is little evidence to support stopping treatment. The main risk of stopping oral contraceptives is unwanted pregnancy. Other problems include the effects of surgery and anaesthesia on the foetus and the risks associated with termination. The risk of stopping HRT is a recurrence of menopausal symptoms. Therefore, the bulletin advises that treatment is continued but that women undergoing major operations or leg surgery are given thromboprophylaxis and graduated compression stockings peri-operatively.
It adds that there is no risk associated with progestogen only contraceptives and these could be substituted for combined oral contraceptives prior to surgery.