Synopsis
Diagnose and treat thrombosis safely when pregnancy, postpartum physiology or active cancer changes presentation, anticoagulant choice, duration, procedures and bleeding risk.
- Pregnancy and cancer raise VTE probability but symptoms still require objective imaging; do not use D-dimer or a non-validated score alone to dismiss a clinically suspected event.
- Therapeutic LMWH is first-line treatment for most pregnancy-associated DVT or PE because it does not cross the placenta and has extensive obstetric experience.
- Continue pregnancy-associated VTE treatment for the remainder of pregnancy and at least 6 weeks postpartum, with at least 3 months total therapy.
Key red flags
Sudden dyspnoea, syncope, hypotension, chest pain or hypoxaemia in pregnancy, postpartum or cancer is possible PE and requires urgent objective assessment rather than attribution to physiology or malignancy.
Investigation priorities
Confirm proximal lower-limb thrombosis without ionising radiation.
Management branches
Pregnant or postpartum patient has clinical features of DVT or PE.
- Assess stability, bleeding and delivery context and begin therapeutic LMWH while arranging imaging if delay is expected and no contraindication exists.
- Use compression ultrasound for leg symptoms and a chest X-ray-guided V/Q or CTPA pathway for suspected PE.
Key medicines
Enoxaparin in pregnancy-associated VTEA common therapeutic regimen is 1 mg/kg subcutaneously every 12 hours, using the weight rule in the obstetric protocol; continue for the remainder of pregnancy and at least 6 weeks postpartum, with at least 3 months total.
Apixaban for cancer-associated VTEGive 10 mg orally twice daily for 7 days then 5 mg twice daily; after 6 months, any move to 2.5 mg twice daily must follow an individual extended-treatment decision rather than automatic reduction in active cancer.