VTE Prophylaxis
Every inpatient needs VTE risk assessment. Padua score for medical patients. Caprini score for surgical. Pharmacologic (LMWH preferred) unless contraindicated. Mechanical (SCDs) if bleeding risk. "Did you order the DVT ppx?" -yes, always.
🔍 Overview
Risk Assessment
| Tool | Population | Threshold |
|---|---|---|
| Padua Score | Medical inpatients | ≥ 4 = high risk → pharmacologic prophylaxis |
| Caprini Score | Surgical patients | Score-based: 0 = early ambulation, 1–2 = SCDs, 3–4 = pharmacologic, ≥ 5 = extended prophylaxis |
| IMPROVE Bleed Score | Medical inpatients | Assesses bleeding risk -high score → mechanical prophylaxis instead |
Padua Score Components
- Active cancer (+3)
- Previous VTE (+3)
- Reduced mobility (+3)
- Known thrombophilia (+3)
- Recent trauma/surgery (+2)
- Age ≥ 70 (+1)
- Heart or respiratory failure (+1)
- AMI or stroke (+1)
- Acute infection or rheumatic disorder (+1)
- Obesity BMI ≥ 30 (+1)
- Hormonal therapy (+1)
VTE prophylaxis is one of the most impactful things you order every day. Hospital-acquired VTE is preventable. Not ordering prophylaxis is a patient safety event.
Key Evidence: Enoxaparin 40 mg daily reduced VTE by 63% in acutely ill medical patients MEDENOX, 1999. Dalteparin reduced VTE in medical patients PREVENT, 2004. Fondaparinux reduced VTE in medical patients ARTEMIS, 2006. Extended post-discharge prophylaxis with rivaroxaban did not significantly reduce symptomatic VTE MARINER, 2018.
Special Populations
| Population | Recommendation | Notes |
|---|---|---|
| Pregnancy | Enoxaparin preferred; avoid warfarin | Increased VTE risk in pregnancy + postpartum. Warfarin is teratogenic (crosses placenta). |
| Cancer patients | LMWH superior to UFH | Consider extended prophylaxis post-discharge (COMPASS-CAT score for risk stratification). CASSINI/AVERT, 2019 |
| Orthopedic surgery (hip/knee) | Extended prophylaxis × 35 days post-op | LMWH, rivaroxaban, or apixaban all acceptable ADVANCE-3, 2010. Standard 10-14 days is insufficient. |
| Morbid obesity (BMI >40) | Standard enoxaparin 40 mg may be subtherapeutic | Consider enoxaparin 40 mg q12h or UFH 7,500 units q8h for adequate prophylaxis. |
| CKD (CrCl <30) | Use UFH instead of LMWH | LMWH is renally cleared and accumulates → increased bleeding risk. |
| HIT history | Mechanical only or fondaparinux | NO heparin products (UFH or LMWH). Fondaparinux does not cross-react with HIT antibodies. |
| ICU patients | Pharmacologic + mechanical | Highest risk population, combination prophylaxis recommended. |
Mnemonic for VTE Risk Factors, "THROMBOSIS":
Travel / Thrombophilia · Hypercoagulable / HRT · Recent surgery · Obesity / Oral contraceptives · Malignancy · Bed rest / immobility · Obstetric (pregnancy) · Smoking · Injury / Inflammation · Sickle cell / SLE
Travel / Thrombophilia · Hypercoagulable / HRT · Recent surgery · Obesity / Oral contraceptives · Malignancy · Bed rest / immobility · Obstetric (pregnancy) · Smoking · Injury / Inflammation · Sickle cell / SLE
Clinical Examples
📋 Case 1, Medical Patient VTE Prophylaxis
Patient: 72M admitted for pneumonia, BMI 25, no active bleeding.
Risk assessment (Padua Score):
- Acute infection (+1)
- Age ≥ 70 (+1)
- Reduced mobility (+3)
- Total = 5 → High risk
IMPROVE Bleed Score: Low → pharmacologic prophylaxis appropriate.
Order: Enoxaparin 40 mg SC daily + SCDs.
Key lesson: Most medical inpatients with acute illness + reduced mobility will score ≥ 4 on Padua. Always calculate, always prophylax.
📋 Case 2, Extended Prophylaxis Post-Hip Replacement
Patient: 55F post-hip replacement, no active bleeding risk.
Risk assessment: Caprini ≥ 5 (major orthopedic surgery).
Order:
- Inpatient: Enoxaparin 40 mg SC daily starting 12h post-op.
- Extended prophylaxis: Continue × 35 days post-op (not just until discharge).
- At discharge: May switch to rivaroxaban 10 mg PO daily for convenience.
Key lesson: Hip and knee replacement require extended prophylaxis × 35 days. VTE risk persists well beyond hospitalization. Standard 10–14 days is insufficient.
📋 Case 3, CKD Patient (LMWH Contraindicated)
Patient: 68M with CKD stage 4 (CrCl 22 mL/min), admitted for CHF exacerbation.
Why LMWH is contraindicated: Enoxaparin is renally cleared. CrCl < 30 → drug accumulates → bleeding risk.
Order:
- Heparin 5,000 units SC q8h (hepatic metabolism, not renally cleared)
- SCDs (combination prophylaxis for added protection)
Key lesson: Always check CrCl before ordering enoxaparin. CrCl < 30 = use UFH. This is one of the most common prophylaxis errors on wards.
🚨 Management
Prophylaxis Options
| Method | Option | Dose |
|---|---|---|
| Pharmacologic (preferred) | Enoxaparin (Lovenox) | 40 mg SC daily (or 30 mg SC q12h if BMI > 40 or CrCl < 30 → use UFH) |
| Heparin (unfractionated) | 5,000 units SC q8h (preferred if CrCl < 30 or high bleed risk -shorter half-life) | |
| Mechanical | SCDs (sequential compression devices) | Both legs, worn whenever in bed |
| Extended prophylaxis | Rivaroxaban (Xarelto) or Enoxaparin (Lovenox) | Post-discharge for high-risk medical (MARINER) or post-surgical (hip/knee) |
🔄 Updated Practice: Old teaching: sequential compression devices (SCDs) are equivalent to pharmacologic VTE prophylaxis. Current practice: pharmacologic prophylaxis (enoxaparin 40 mg SQ daily or heparin 5000 units SQ q8-12h) is superior to mechanical prophylaxis alone. SCDs should be used only when pharmacologic prophylaxis is contraindicated (active bleeding, severe thrombocytopenia). The combination of both is used in highest-risk patients (trauma, major orthopedic surgery).
Extended Prophylaxis Evidence: Hip/knee replacement: Extended prophylaxis x 35 days reduces VTE by ~60% RECORD, 2008. Cancer surgery: Extended LMWH x 4 weeks post-op reduces VTE ENOXACAN II, 2002. Medical patients: Extended prophylaxis NOT routinely recommended APEX, 2016 EXCLAIM, 2010.
Contraindications to Pharmacologic Prophylaxis
- Active bleeding
- Severe thrombocytopenia (platelets < 50K)
- Recent intracranial hemorrhage
- Epidural/spinal anesthesia (hold LMWH around procedure)
- HIT (heparin-induced thrombocytopenia) -use mechanical only or argatroban if treatment-dose needed
🧪 Workup
- Padua Score (medical) or Caprini Score (surgical) -on admission
- IMPROVE Bleed Score -if considering pharmacologic
- Platelet count -< 50K → mechanical only
- Creatinine/CrCl -CrCl < 30 → use UFH instead of LMWH
- Review medications -anticoagulants already on board?
💊 Medications
| Drug | Dose | Key Notes |
|---|---|---|
| Enoxaparin (Lovenox) | 40 mg SC daily | Preferred LMWH. Predictable pharmacokinetics. No monitoring needed. |
| Heparin (UFH) | 5,000 units SC q8h | Use if CrCl < 30, high bleed risk (shorter half-life), or obese patients. |
| Fondaparinux (Arixtra) | 2.5 mg SC daily | Alternative if HIT. Factor Xa inhibitor. Renally cleared. |
📋 On Rounds
Pimp Questions
Why is q8h UFH preferred over q12h for VTE prophylaxis?
Multiple meta-analyses show that 5,000 units SC q8h (TID) is superior to q12h (BID) for preventing VTE in medical patients. The difference is particularly significant for DVT prevention. Q8h maintains more consistent anti-Xa levels. The trade-off is slightly higher minor bleeding risk, but the VTE prevention benefit outweighs this.
When should you use UFH instead of LMWH for prophylaxis?
(1) CrCl < 30 mL/min -LMWH is renally cleared and accumulates → bleeding risk. UFH is metabolized by the reticuloendothelial system. (2) High bleeding risk -UFH has a shorter half-life (1–2h vs 4–5h for LMWH), so effects wear off faster if bleeding occurs. (3) Planned procedures -easier to manage perioperatively. (4) Morbid obesity -some guidelines recommend UFH q8h or adjusted LMWH dosing (enoxaparin 40 mg q12h for BMI > 40).
Why is LMWH preferred over UFH for VTE prophylaxis?
LMWH has more predictable pharmacokinetics, longer half-life allowing once daily dosing (vs q8h for UFH), lower risk of HIT, and no need for aPTT monitoring. RCTs have shown LMWH is at least as effective as UFH for VTE prevention. UFH is preferred only when LMWH is contraindicated: CrCl < 30 (LMWH accumulates), high bleed risk (shorter half-life advantage), or perioperative setting (easier to hold and reverse).
Should you hold DVT prophylaxis for a procedure?
Depends on the procedure and bleeding risk. LMWH: hold 12h before and resume 12h after low-bleed-risk procedures. For high-bleed-risk procedures: hold 24h before. UFH: hold 4–6h (shorter half-life is an advantage here). Neuraxial procedures (epidural/spinal): hold LMWH ≥12h before placement and ≥4h after catheter removal, risk of epidural hematoma is devastating.
What is the IMPROVE VTE score?
A validated risk assessment tool specifically for acutely ill medical patients that predicts 3-month VTE risk. Components: Previous VTE (+3), known thrombophilia (+2), lower limb paralysis (+2), active cancer (+2), ICU/CCU stay (+1), complete immobilization ≥1 day (+1), age ≥60 (+1). Score ≥ 4 = high risk → pharmacologic prophylaxis indicated.
What did the MEDENOX trial show?
MEDENOX, 1999: Enoxaparin 40 mg daily reduced VTE in acutely ill medical patients by 63% vs placebo. Established the standard prophylactic dose of enoxaparin 40 mg SC daily. The 20 mg dose was NOT effective - only 40 mg showed benefit. Landmark trial that changed practice for medical inpatient prophylaxis.
What is the evidence for extended VTE prophylaxis after hospital discharge?
MARINER, 2018: Rivaroxaban 10 mg x 45 days post-discharge did NOT significantly reduce symptomatic VTE in acutely ill medical patients. APEX, 2016: Betrixaban showed modest benefit. Extended prophylaxis is supported for orthopedic surgery (hip/knee x 35 days) but NOT routinely for medical patients.
What is the Caprini score and how does it differ from Padua?
Caprini is for SURGICAL patients. Assigns weighted points for risk factors (prior VTE, cancer, age, surgery type, immobility). Score determines prophylaxis intensity: 0 = ambulation only, 1-2 = SCDs, 3-4 = pharmacologic, ≥ 5 = pharmacologic + extended. Padua is for MEDICAL patients with threshold ≥ 4 for pharmacologic prophylaxis.
Why is fondaparinux safe in HIT?
Fondaparinux (Arixtra) is a synthetic pentasaccharide that inhibits factor Xa. Unlike UFH and LMWH, it does NOT bind to platelet factor 4 (PF4), so it does not trigger the HIT antibody response. Can be used for prophylaxis (2.5 mg SC daily) or treatment-dose anticoagulation in confirmed HIT as an alternative to argatroban or bivalirudin.
⚡ Summary
Assess Every Inpatient, Every Admission
Hospital-acquired VTE is preventable, and failing to order prophylaxis is a patient safety event, not an oversight. Risk assessment goes on the admission order set and gets revisited when the clinical picture changes.
Use the Right Score for the Right Patient
Padua for medical inpatients: 4 or more is high risk and earns pharmacologic prophylaxis. Caprini for surgical patients: 0 early ambulation, 1 to 2 mechanical, 3 to 4 pharmacologic, 5 or more pharmacologic plus mechanical. IMPROVE Bleed scores the other side of the ledger and pushes a high scorer to mechanical prophylaxis instead.
Default Regimen
Enoxaparin 40 mg SC daily is preferred: predictable kinetics, no monitoring, once-daily dosing. Unfractionated heparin 5,000 units SC q8h is the alternative when renal function is poor or bleeding risk is high, because its short half-life is easier to reverse and stop.
Mechanical Is a Fallback, Not an Equal
Old teaching treated SCDs as equivalent; they are not. Pharmacologic prophylaxis is superior in medical inpatients. Use SCDs alone only when anticoagulation is contraindicated, and switch to pharmacologic prophylaxis as soon as the bleeding risk resolves.
Adjust the Dose for the Patient
CrCl below 30: use UFH, since LMWH is renally cleared and accumulates. BMI above 40: standard 40 mg daily is likely subtherapeutic, so use enoxaparin 40 mg q12h or UFH 7,500 units q8h. Pregnancy: enoxaparin, never warfarin (teratogenic). Cancer: LMWH beats UFH.
The One Absolute Rule About Heparin
A history of HIT means no heparin product at all, neither unfractionated nor low molecular weight. Use mechanical prophylaxis or fondaparinux, which does not cross-react with HIT antibodies.
Know When Prophylaxis Continues After Discharge
Hip or knee replacement: 35 days, which cuts VTE by roughly 60% (RECORD). Major cancer surgery: 4 weeks of LMWH (ENOXACAN II). Selected high-risk medical patients may continue post-discharge (MARINER). The risk does not end at the hospital door, and most post-operative VTE presents after discharge.
Check Contraindications Before You Click Order
Active bleeding, platelets below 50,000, recent intracranial hemorrhage or neurosurgery, and an epidural catheter in place all block pharmacologic prophylaxis. These are almost always temporary, so document the reason and set a date to reassess rather than leaving the patient unprotected for the whole admission.
Related Topics
Discharge Planning ChecklistFalls & Delirium PreventionPerioperative Medicine