RecommendationAdvise patients to consider stopping oestrogen-containing oral contraceptives or hormone replacement therapy 4 weeks before elective surgery. If stopped, provide advice on alternative contraceptive methods.
Relative values of different outcomesThe main outcomes considered were venous thromboembolic events (asymptomatic and symptomatic DVT, symptomatic pulmonary embolism and fatal pulmonary embolism), bleeding events (major bleeding, fatal bleeding and stroke) and other long term events occurring as a result of VTE (chronic thromboembolic pulmonary hypertension and post thrombotic syndrome).
Trade off between clinical benefit and harmsThe increased risk of VTE through use of oestrogen containing oral contraceptives and hormone replacement therapy was considered.
Economic considerationsNo cost effectiveness model was completed to identify the cost effectiveness of stopping these treatments before surgery. The guideline development group felt that the benefits in terms of reducing the risk of VTE after surgery may, in some patients, outweigh the benefits of maintaining therapy, and so felt that it should be considered for all relevant patients.
Quality of evidenceThe systematic reviews of risk factors for VTE identified oestrogen containing oral contraceptives and hormone replacement therapy as factors which significantly increased the risk of VTE (section 5.7.7 and 5.7.8). These treatments although improve the quality of the patient’s life are unlikely to be life threatening if stopped. Therefore consideration should be given to their continued use.
Other considerationsThis recommendation is based on the recommendation from the previous surgical guideline. The Guideline Development Group used both the evidence from systematic reviews and advice provided in the BNF313, which included the advice of when to stop these hormone treatments before elective surgery (4–6 weeks).
Additional guidance can be found in the RCOG guidelines on guidance on venous thromboembolism and hormonal contraceptives564 and hormonal replacement therapy and venous thromboembolism 562, and the BNF313.

From: 5, Risk, risk reduction and harm

Cover of Venous Thromboembolism
Venous Thromboembolism: Reducing the Risk of Venous Thromboembolism (Deep Vein Thrombosis and Pulmonary Embolism) in Patients Admitted to Hospital.
NICE Clinical Guidelines, No. 92.
National Clinical Guideline Centre – Acute and Chronic Conditions (UK).
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