01Purpose and principlesWhat the treatment does and how it fits into care.
Proximal DVT includes popliteal, femoral and iliac thrombus and carries important embolic and recurrence risk. NICE requires at least three months of treatment. A resolved major transient factor often supports stopping at review, while unprovoked disease, recurrence, persistent risk or active cancer may justify extension after balancing bleeding and preference.
Distal DVT is confined to calf deep veins. ESVS advises an individual decision based on symptoms, progression risks and bleeding. When selected for treatment, symptomatic calf DVT generally receives three months. When treatment is withheld, surveillance includes reassessment and whole-leg ultrasound after one week. Active cancer increases recurrence and may support therapy beyond three months.
Drug choice changes with renal failure, cancer, pregnancy, breastfeeding, extreme weight and antiphospholipid syndrome. Active cancer requires tumour-site, interaction and bleeding review. Pregnancy uses LMWH rather than DOACs. RCOG regards heparins and warfarin as compatible with breastfeeding, whereas rivaroxaban is contraindicated and the apixaban SmPC requires choosing between breastfeeding and treatment.
Key points
- Confirmed proximal DVT requires therapeutic anticoagulation for at least 3 months; reassess recurrence risk, bleeding and preference at 3 months before stopping, changing or extending treatment.
- Take FBC, renal and hepatic function, PT and APTT before treatment; active significant bleeding contraindicates anticoagulation, but do not await results before indicated interim therapy. In pregnancy, use therapeutic LMWH based on booking or early-pregnancy weight through pregnancy and at least 6 weeks postpartum, for at least 3 months total.
- Isolated distal DVT has no universal anticoagulation rule: assess symptoms, extension risk, cancer and bleeding; if untreated, repeat clinical assessment and whole-leg ultrasound after 1 week. At weight below 50 kg or above 120 kg, monitor therapeutic anticoagulant levels regularly with specialist or agreed-protocol input; established triple-positive APS requires LMWH with a VKA for at least 5 days and until INR is at least 2.0 twice, then VKA alone.
- NICE offers apixaban or rivaroxaban for most eligible non-pregnant adults with proximal DVT, using the exact product loading and maintenance sequence.
- Apixaban is 10 mg orally twice daily for 7 days then 5 mg twice daily; 2.5 mg twice daily is only for indicated recurrence prevention after completing 6 months.
- Rivaroxaban is 15 mg orally twice daily with food for 21 days then 20 mg once daily with food; extended prevention after at least 6 months may use 10 mg once daily.
- Apixaban and rivaroxaban require caution at CrCl 15–29 mL/min and are not recommended below 15 mL/min; renal rules remain product specific.
- Pregnancy uses weight-based LMWH through pregnancy and at least 6 weeks postpartum, for at least 3 months total; heparins and warfarin are compatible with breastfeeding.
02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.
Popliteal, femoral or iliac thrombosis normally requires prompt treatment for at least three months.
Calf-confined axial or muscular thrombosis needs a documented treatment-versus-surveillance decision.
Recent major surgery, trauma or immobilisation may permit stopping after the minimum course when fully resolved.
Unprovoked disease, active cancer, severe thrombophilia or recurrence strengthens the case for extended treatment.
New objective clot despite reported adherence requires dose, interaction, absorption and compliance checks.
Shock, intracranial signs, overt gastrointestinal blood loss or falling haemoglobin requires emergency haemorrhage control.
03Assessment before treatmentTests and checks that guide safe selection.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Compression or whole-leg ultrasoundFirst step - Why
- Confirm DVT and define proximal or distal extent.
- Interpretation and limitations
- Iliac, femoral or popliteal disease is proximal; calf-confined disease is distal and may be surveilled.
- 02
Full blood count - Why
- Identify anaemia and platelet abnormalities before treatment.
- Interpretation and limitations
- Falling haemoglobin suggests bleeding; platelet decline after heparin requires HIT assessment.
- 03
Creatinine clearance - Why
- Apply the chosen anticoagulant renal rules.
- Interpretation and limitations
- Use product-specific CrCl limits; do not copy an atrial-fibrillation dose rule into acute DVT.
- 04
Liver function and coagulation - Why
- Identify hepatic coagulopathy and establish baseline values.
- Interpretation and limitations
- Hepatic coagulopathy with relevant bleeding risk contraindicates apixaban and rivaroxaban; PT and APTT do not quantify DOAC effect.
- 05
Medication interaction review - Why
- Detect duplicate anticoagulants and exposure-changing drugs.
- Interpretation and limitations
- Check antiplatelets, NSAIDs, strong CYP3A4/P-gp modifiers and cancer treatment before prescribing.
- 06
Pregnancy test when relevant - Why
- Prevent unsafe DOAC exposure and select LMWH.
- Interpretation and limitations
- Rivaroxaban is contraindicated and apixaban should be avoided during pregnancy.
04Treatment approachPreparation, options, escalation and aftercare.
01Worked case: provoked proximal DVTTreat and reviewFirst stepA stable adult has femoral DVT after surgery, acceptable bleeding risk and CrCl 72 mL/min.+
- 1Confirm extent, screen for PE or limb threat and take baseline blood tests.
- 2Discuss apixaban or rivaroxaban and prescribe the entire licensed acute sequence.
- 3Review early for bleeding, renal change and progression, then continue to at least three months.
- 4At three months confirm provocation has resolved and discuss stopping with recurrence safety-netting.
02Distal DVT decisionTreat or surveilWhole-leg ultrasound confirms calf-confined thrombosis without PE or proximal extension.+
- 1Assess symptoms, clot extent, inpatient status, cancer, unprovoked status and other progression factors.
- 2Balance these against bleeding and preference and record the reason for the chosen branch.
- 3If treating, use an eligible regimen for three months in most non-pregnant adults.
- 4If not treating, arrange one-week clinical review and repeat whole-leg imaging.
03Special population selectionModify the drug planRenal failure, active cancer, extreme body weight, pregnancy, breastfeeding or triple-positive antiphospholipid syndrome is present.+
- 1For CrCl 15–50 use NICE options with the selected SmPC; below 15 consider heparin or heparin-to-VKA routes.
- 2For active cancer assess tumour site, anticancer and other drug interactions, and bleeding risk before selecting a DOAC or LMWH; treat for three to six months and review.
- 3At body weight below 50 kg or above 120 kg, use regular monitoring of therapeutic anticoagulant levels, apply the selected SmPC cautions and follow an agreed specialist or multidisciplinary protocol.
- 4For established triple-positive antiphospholipid syndrome, give LMWH concurrently with a VKA for at least five days and until INR is at least 2.0 on two consecutive readings, then continue VKA alone.
- 5For pregnancy use therapeutic LMWH based on booking or early-pregnancy weight under a defined obstetric dosing protocol throughout pregnancy and for at least six weeks postpartum, ensuring at least three months total; during breastfeeding use compatible heparin or warfarin rather than transferring a DOAC regimen.
04Secondary prevention reviewDecide on extensionThree months ends after unprovoked proximal DVT or persistent recurrence risk remains.+
- 1Reassess provocation, recurrence, bleeding, renal function, adherence and preference.
- 2Use a licensed extended dose only after completing the product-specific initial period.
- 3Review long-term therapy at least annually and after any material clinical change.
05Regimens, contraindications and interactionsTreatment details and the circumstances that modify them.
Apixaban
Give 10 mg orally twice daily for 7 days, then 5 mg twice daily; if extended prevention is chosen after 6 months, give 2.5 mg twice daily.Contraindicated in active significant bleeding or hepatic coagulopathy with bleeding risk. Use cautiously at CrCl 15–29 and not below 15 mL/min or in dialysis. Avoid pregnancy; breastfeeding requires stopping either breastfeeding or apixaban. In active cancer, assess tumour site, anticancer and other drug interactions, and bleeding risk before selection. Review at three months and annually if continued.
Rivaroxaban
Give 15 mg orally twice daily with food for days 1–21, then 20 mg once daily with food. Only when CrCl is 15–49 mL/min, after day 21 when 20 mg once daily would otherwise apply, consider 15 mg once daily if assessed bleeding risk outweighs recurrent DVT or PE risk. After at least 6 months, extended prevention is 10 mg once daily, or 20 mg when recurrence risk remains high.Contraindicated with active bleeding, hepatic coagulopathy, pregnancy and breastfeeding. Use cautiously at CrCl 15–29 and not below 15 mL/min. The optional 15 mg maintenance reduction for CrCl 15–49 mL/min is based on pharmacokinetic modelling and has not been studied in this clinical setting. In active cancer, assess tumour site, anticancer and other drug interactions, and bleeding risk before selection; review at three months.
Enoxaparin sodium
For acute DVT or PE, give 1.5 mg/kg subcutaneously once daily in uncomplicated low-recurrence-risk disease or 1 mg/kg subcutaneously every 12 hours for obesity, cancer, recurrent VTE, symptomatic PE or iliac thrombosis; average initial treatment is 10 days before a suitable oral agent when oral transition is appropriate. For extended treatment in active cancer, give 1 mg/kg subcutaneously every 12 hours for 5–10 days, then 1.5 mg/kg once daily for up to 6 months and reassess benefit after 6 months. In pregnancy, use a therapeutic subcutaneous LMWH regimen from a defined obstetric protocol based on booking or early-pregnancy weight, continuing through pregnancy and at least 6 weeks postpartum for at least 3 months total.Contraindicated with active significant bleeding or recent immune-mediated HIT. At CrCl 15–30 use 1 mg/kg subcutaneously once daily; it is not recommended below 15 mL/min outside dialysis-circuit use. The average 10-day oral-transition statement applies to suitable non-pregnant pathways and must not imply oral transition during pregnancy. Pregnancy dosing follows booking or early-pregnancy weight and a defined obstetric protocol; neuraxial timing requires planning.
06Complications, monitoring and follow-upAdverse effects, response and longer-term review.
- Record drug, dose, route, phase-transition date, duration and review endpoint.
- Act on baseline blood results within 24 hours when interim treatment began first.
- Check adherence, bleeding, interactions and renal function after initiation and clinical change.
- Review at three months, cancer at 3–6 months, and pregnancy through the postpartum endpoint.
- Review long-term therapy at least annually.
- Verify one-week surveillance imaging when distal DVT is untreated.
07Special situationsVariants, exceptions and circumstances that change the usual approach.
Loading phases differ
Apixaban uses seven high-dose days while rivaroxaban uses twenty-one, so schedules are not interchangeable.
Renal rules differ
CrCl limits belong to each drug and indication; atrial-fibrillation reductions cannot be copied.
Cancer is heterogeneous
Tumour bleeding, interactions, thrombocytopenia and procedures can make LMWH preferable to a DOAC.
Distal means decision
Calf DVT can be treated or surveilled, but surveillance demands timely repeat whole-leg imaging.
Intervention preserves duration
Thrombus removal or stenting does not shorten the anticoagulation course required by the original DVT.
08Common pitfallsFrequent interpretation and management errors.
- 01
Stopping proximal treatment before three months.
- 02
Giving every distal DVT the same plan.
- 03
Using apixaban 2.5 mg during acute treatment.
- 04
Copying atrial-fibrillation renal dosing into DVT.
- 05
Giving a DOAC during pregnancy.
- 06
Omitting a named duration review endpoint.