Suspected VTE During Hormonal Contraception

Combined hormonal methods increase the risk of deep vein thrombosis and pulmonary embolism, with the highest risk in the first year of use, in women over 35 years, in smokers, in obesity, after recent surgery or immobilisation and in the postpartum period. Progestin-only pills, implants and levonorgestrel intrauterine devices carry little or no added risk. Depot medroxyprogesterone acetate is associated with a possible small increase. Suspected venous thromboembolism in a method user is an emergency.

Symptoms. Unilateral leg pain, swelling or warmth; sudden dyspnoea, pleuritic chest pain, cough or haemoptysis, syncope, tachycardia. The danger signs are abdominal pain, chest pain or shortness of breath, severe headache, eye problems and severe calf pain.

Risk factors. Combined method use, age over 35, smoking, obesity, previous venous thromboembolism, family history, inherited thrombophilia, recent major surgery or immobilisation, cancer, pregnancy and the postpartum period, antiphospholipid antibodies, nephrotic syndrome, and long travel.

Examination. Vital signs including oxygen saturation, leg circumference, tenderness along the deep veins, signs of right heart strain, and a pregnancy test.

Differential diagnosis. Deep vein thrombosis, ruptured Baker cyst, cellulitis, muscle tear, lymphoedema, pulmonary embolism, pneumonia, pneumothorax, pericarditis, myocardial infarction, anxiety and musculoskeletal pain.

Pretest probability. Use a validated clinical probability score for deep vein thrombosis or pulmonary embolism.

Investigations.

• Compression ultrasound of the leg veins for suspected deep vein thrombosis.
• D-dimer when probability is low or moderate and imaging is delayed. A raised D-dimer does not confirm thrombosis.
• CT pulmonary angiography or ventilation perfusion scan for suspected pulmonary embolism.
• Electrocardiogram, chest film, full blood count, creatinine, liver enzymes and coagulation screen before starting anticoagulation.
• Thrombophilia testing is not needed to start treatment and is not routine.

Do not delay treatment. When probability is high and imaging is delayed, start anticoagulation after a baseline blood sample is taken.

Immediate actions. Stop the combined method now. Give oxygen for hypoxia. Start anticoagulation without waiting for imaging when probability is high. Admit or refer urgently.

Anticoagulation regimens.

Duration. At least 3 months. Stop the combined method permanently. Duration beyond this depends on whether the event was provoked.

Massive pulmonary embolism with instability. Resuscitate and refer for thrombolysis or embolectomy.

Pregnancy. A positive test changes treatment: use enoxaparin and avoid oral anticoagulants other than where specialist advice is given.

Interacting medicines. Review all current medicines for interaction with the chosen anticoagulant.

Follow up. Review at 1 week, at 4 to 6 weeks and at 3 months. Monitor international normalised ratio for patients on warfarin.

Method decisions. After a thromboembolic event, combined methods are category 4. A copper intrauterine device is suitable, and progestin-only methods may be used with specialist input, especially with anticoagulation. Continue effective contraception during treatment, particularly with warfarin or rivaroxaban, which are harmful in pregnancy.

Referral and escalation. Refer all suspected cases the same day. Refer patients with recurrent events, positive antiphospholipid antibodies, pregnancy and unusual sites of thrombosis.