# VTE Prophylaxis Resident Quick Guide

**Scope:** Adult trauma/orthopedic admissions (>=15 years).
**Operational aim:** start mechanical + chemoprophylaxis early once hemostasis is secure.

## Immediate Admission Actions

- Apply mechanical prophylaxis (SCDs) unless contraindicated.
- Use standard administration windows:
  - Enoxaparin at 09:00 and 21:00.
  - UFH at 06:00, 14:00, and 22:00.
- Start chemoprophylaxis once hemostasis is secure (goal <=24-48h in most patients).
- Reassess holds daily; avoid unexamined prolonged holds.

## First-Line Strategy

- **LMWH (enoxaparin) weight-based** is default.
- **UFH** if severe renal dysfunction or specific contraindication to LMWH.

## Weight-Based Dosing (Current Protocol)

| Weight (kg) | Standard Dose | High-Risk TBI/SCI First 72h* | Renal (CrCl <30) |
|---|---|---|---|
| <50 | Enoxaparin 30 mg q12h | Enoxaparin 30 mg daily | UFH 5,000 U q8h |
| 50-75 | Enoxaparin 30 mg q12h | Enoxaparin 30 mg q12h | UFH 5,000 U q8h |
| 76-100 | Enoxaparin 40 mg q12h | Enoxaparin 30 mg q12h | LMWH 30 mg daily + anti-Xa |
| 101-130 | Enoxaparin 50 mg q12h | Enoxaparin 40 mg q12h | LMWH 30 mg daily + anti-Xa |
| 131-160 | Enoxaparin 60 mg q12h | Enoxaparin 50 mg q12h | Pharmacy consult |
| >=161 | Enoxaparin 0.5 mg/kg q12h (max 80 mg) | 0.5 mg/kg q12h (max 60 mg) | Pharmacy consult |

*High-risk reduction applies to BIG 3 TBI, post-craniotomy, or complete SCI (AIS A) during first 72 hours.

### Exceptions

- Age >65 or weight <50 kg: start 30 mg q12h.
- CrCl 15-29: LMWH 30 mg daily with anti-Xa preferred over UFH.

## Timing by Injury (Use Most Conservative If Multiple Injuries)

- Pelvic/long-bone fracture post-op: <=24h post-op.
- Hip fracture operative: 6-12h post-op.
- Spine surgery instrumented: 24-48h post-op.
- Spine fracture non-op stable: 24-48h.
- SCI (with or without surgery): <=48h.
- TBI BIG 1-2 (stable): <=24h.
- TBI BIG 3/post-craniotomy: 24-72h after stable CT.
- Solid organ NOM grade I-III: <=24h.
- Solid organ NOM grade IV-V: <=48h once hemostasis confirmed.
- Post-SAE/AE: approximately 48h.

**Polytrauma rule:** use latest needed timing among injury patterns, but do not extend beyond 48h without explicit bleeding-risk rationale and attending-level documentation.

## Anti-Xa Monitoring

Not routine for all patients. Check peak anti-Xa (4h after 3rd dose) for:

- BMI >=40 or weight >100 kg (mandatory if >130 kg).
- ICU patients with multiple VTE risk factors.
- CrCl 15-29 on LMWH.
- TBI/SCI reduced-dose pathway.

Target: 0.2-0.4 IU/mL.
If <0.2, increase LMWH by 10 mg and recheck.

## Peri-Neuraxial / CSF Drain Practical Rules

- Hold LMWH >=12h before neuraxial placement.
- Avoid LMWH while neuraxial catheter is indwelling.
- Restart LMWH >=4h after catheter removal.
- Bridge with UFH + SCDs while catheter remains in place.
- If EVD/ICP drain present, UFH-first strategy is preferred.

## Discharge Planning

| Risk Category | Typical Duration | Preferred Agent | Alternative |
|---|---|---|---|
| High-risk trauma | Up to 4 weeks | LMWH | -- |
| Major ortho/hip fracture | 28-35 days | LMWH | DOAC or aspirin if isolated injury |
| SCI/immobility | 8-12 weeks | LMWH | -- |
| Isolated extremity/pelvis NWB | 3-6 weeks | LMWH | Aspirin 81 mg BID |

Confirm plan in discharge summary and medication reconciliation.

## IVC Filter Rule

- Avoid prophylactic IVC filters.
- Temporary filter only for acute VTE + temporary absolute contraindication to anticoagulation.

## Hard Stops

- Do not hold prophylaxis >48h without clear bleeding-risk documentation.
- Do not miss scheduled doses without documented reason.
- Do not ignore VTE prophylaxis at transition points (OR, ICU transfer, discharge).
- Do not use aspirin/DOAC pathways for polytrauma, SCI, or TBI by default.

## PIPS Trigger Events

- Any inpatient DVT/PE event.
- Chemoprophylaxis hold >48h without documented bleeding risk.
- Weight >100 kg receiving less than 40 mg BID without anti-Xa strategy.
- High-risk patient discharged without extended prophylaxis plan.

## Daily Rounds Check

- Mechanical prophylaxis in place?
- Chemoprophylaxis active or hold reason documented?
- Last dose given on time?
- Is the current dose aligned with weight/renal protocol?
- New contraindication today?
- Discharge prophylaxis plan needed?

## Source Basis

Condensed from current institutional VTE prophylaxis guideline (revision dated February 9, 2026).