High Yield Overview

PERIOPERATIVE ANTICOAGULATION MANAGEMENT

Balance Thrombosis Risk | Balance Bleeding Risk | Evidence-Based Protocols

5 daysWarfarin cessation before surgery

24-48hDOAC cessation time

4-6hNeuraxial anesthesia after LMWH

INR less than 1.5Safe for most surgery

BLEEDING RISK STRATIFICATION

Low Risk

PatternMinor procedures, catheter removal

TreatmentContinue anticoagulation or minimal interruption

Moderate Risk

PatternMost orthopaedic surgery

TreatmentStop anticoagulants, restart postop when safe

High Risk

PatternSpine, neuraxial, revision THA/TKA

TreatmentExtended cessation, careful restart timing

Critical Must-Knows

Warfarin: stop 5 days preop, bridge if high thrombosis risk (mechanical valve, recent VTE)
DOACs: stop 24h if CrCl greater than 50, 48h if CrCl less than 50
Neuraxial anesthesia: 12h after LMWH prophylactic, 24h after therapeutic
Restart anticoagulation 24-72h postop depending on bleeding risk
Australian eTG guidelines provide evidence-based protocols

Examiner's Pearls

"
Bridging with LMWH/UFH only for HIGH thrombosis risk patients (mechanical valve, recent VTE less than 3mo)
"
Most patients do NOT need bridging - BRIDGE trial showed bridging increases bleeding without preventing thrombosis
"
DOACs easier than warfarin - predictable offset, no bridging needed
"
Neuraxial timing critical - spinal hematoma is catastrophic complication

Critical Exam Concepts

Bridging is NOT Routine

Only bridge HIGH thrombosis risk: mechanical mitral valve, recent VTE (less than 3 months), AF with CHA2DS2-VASc greater than or equal to 5. Bridging increases bleeding risk.

DOAC Timing is Drug-Specific

Apixaban, Rivaroxaban: 24-48h. Dabigatran: 24-96h (renal dependent). Check CrCl and use eTG tables.

Neuraxial Anesthesia Timing

Spinal hematoma is catastrophic. Wait 12h after prophylactic LMWH, 24h after therapeutic LMWH before neuraxial.

Restart Based on Bleeding Risk

Low risk: 6-12h. Moderate: 24-48h. High risk (spine, revision): 48-72h. Balance VTE vs bleeding.

Quick Decision Guide

Anticoagulant	Stop Before Surgery	Restart After Surgery	Bridge?
Warfarin (low thrombo risk)	5 days preop	24-72h postop	NO - do not bridge
Warfarin (high thrombo risk)	5 days preop + LMWH bridge	LMWH 24h postop, warfarin overlap	YES - mechanical valve, recent VTE
DOACs (CrCl greater than 50)	24-48h preop	24-72h postop	NO - never bridge DOACs
DOACs (CrCl less than 50)	48-96h preop (longer)	24-72h postop	NO - never bridge DOACs
LMWH prophylactic	12h before neuraxial	Restart 6-12h postop	N/A - this IS prophylaxis

Mnemonic

BRAVEHigh Thrombosis Risk Requiring Bridging

BiMechanical valve

Mechanical MITRAL valve (highest risk)

Recent VTE

VTE less than 3 months ago

AF severe

CHA2DS2-VASc greater than or equal to 5

Valve in mitral position

Mitral worse than aortic

Event history

Prior stroke or VTE on therapeutic AC

Memory Hook:Be BRAVE and bridge only the highest thrombosis risk patients - most do NOT need bridging!

Mnemonic

RENALDOAC Cessation Timing Factors

Renal function

CrCl less than 50 = longer cessation (48-96h)

Elimination half-life

Dabigatran longest (12-14h), apixaban/rivaroxaban shorter

Normal CrCl

If CrCl greater than 50, stop 24-48h preop

Age matters

Elderly have lower CrCl - calculate eGFR

Low bleeding risk surgery

May stop 24h only; high risk stop 48-96h

Memory Hook:Check RENAL function before deciding DOAC cessation timing - it is the key variable!

Mnemonic

CLOTNeuraxial Timing Safety

Catheter removal

Wait 12h after prophylactic LMWH, 24h after therapeutic

LMWH timing

12h before spinal for prophylactic, 24h for therapeutic

Observe for hematoma

Monitor for back pain, weakness, urinary retention

Timing restart

Wait 4h after catheter removal before LMWH dose

Memory Hook:Prevent CLOT complications with proper neuraxial timing - spinal hematoma is catastrophic!

Overview and Clinical Significance

The Bridging Paradigm Shift

The BRIDGE trial (2015) changed practice. It showed that bridging with LMWH for AF patients increased bleeding (3.2% vs 1.3%) WITHOUT reducing thrombosis. Most patients do NOT need bridging. Only bridge if HIGH thrombosis risk (mechanical mitral valve, recent VTE less than 3mo).

Common Indications for Anticoagulation

Atrial fibrillation (most common in ortho)
Mechanical heart valves
VTE treatment or prophylaxis
Coronary stents (antiplatelet)
Stroke prevention

Why Perioperative Management Matters

Bleeding risk with ongoing anticoagulation
Thrombosis risk if stopped too long
Neuraxial anesthesia contraindicated if coagulopathic
Major surgery requires INR normalization
Balance is patient-specific

Pathophysiology and Risk Stratification

Risk Stratification Determines Bridging

Assess THROMBOSIS risk first. Only HIGH-risk patients need bridging. Most orthopaedic patients are LOW-MODERATE thrombosis risk and do NOT need bridging.

Risk Category	Clinical Features	Annual Risk	Periop Management
HIGH	Mechanical MITRAL valve, VTE less than 3mo, stroke less than 3mo	Greater than 10%	BRIDGE with LMWH or UFH
MODERATE	Mechanical AORTIC valve, VTE 3-12mo ago, AF CHA2DS2-VASc 3-4	5-10%	Consider bridging, individualize
LOW	AF CHA2DS2-VASc 0-2, VTE greater than 12mo, bioprosthetic valve	Less than 5%	NO bridging - stop AC, restart postop

AF Thrombosis Risk (CHA2DS2-VASc Score)

CHA2DS2-VASc Scoring:

CHF (1 point)
Hypertension (1)
Age greater than or equal to 75 (2)
Diabetes (1)
Stroke/TIA/thromboembolism (2)
Vascular disease (1)
Age 65-74 (1)
Sex female (1)

Score	Risk	Bridging Decision
0-2	Low	NO bridging
3-4	Moderate	Consider bridging if additional risks
5 or more	High	Bridge with LMWH

Why Mitral Valves are Higher Risk

Mechanical mitral valves have 2-4x higher thrombosis risk than aortic valves due to larger surface area, lower flow velocities, and left atrial stasis. Always bridge mechanical mitral valves.

Classification

Classification of Anticoagulant Agents

Class	Examples	Mechanism	Half-life
Vitamin K antagonists	Warfarin	Inhibits factors II, VII, IX, X	36-42 hours
Direct thrombin inhibitors	Dabigatran	Direct factor IIa inhibition	12-17 hours
Factor Xa inhibitors	Rivaroxaban, Apixaban	Direct factor Xa inhibition	8-15 hours
Heparins	Enoxaparin, UFH	AT-III mediated	4-7 hours (LMWH)
Antiplatelet agents	Aspirin, Clopidogrel	Platelet inhibition	Variable

DOAC Considerations:

Renal clearance varies (dabigatran 80%, apixaban 25%)
No reliable reversal agents for all DOACs
Shorter half-life allows faster cessation

Clinical Assessment and Bleeding Risk

Risk Category	Orthopaedic Procedures	Management
LOW	Arthroscopy, carpal tunnel, trigger finger, K-wire removal	Minimal interruption, restart 6-12h
MODERATE	THA, TKA, ORIF, shoulder arthroplasty, fracture fixation	Stop AC preop, restart 24-48h postop
HIGH	Spine surgery, revision THA/TKA, pelvic ORIF, tumor resection	Extended cessation, restart 48-72h postop

Neuraxial Anesthesia = High Bleeding Risk

Spinal or epidural anesthesia is considered HIGH bleeding risk due to catastrophic consequences of spinal hematoma (paralysis). This determines timing of anticoagulation cessation and restart.

Investigations and Monitoring

Laboratory Monitoring Preoperatively

INR testing if on warfarin - check day before and day of surgery
Creatinine/eGFR for DOAC patients - determines cessation timing
Platelet count if on heparin - HIT screening if indicated
Coagulation studies (PT, APTT) if bleeding concern
Blood group and crossmatch for major procedures

eTG Anticoagulation Guidelines (Australian)

Evidence-based cessation/restart protocols
DOAC timing tables based on renal function
Bridging decision algorithms
Neuraxial anesthesia safety guidelines
Updated regularly with new evidence

Australian-Specific Considerations

Use eTG (Therapeutic Guidelines) as authoritative source for Australian practice. PBS coverage influences DOAC choice. Rural/remote patients may have delayed access to reversal agents.

Management Algorithm

Warfarin Perioperative Management

Warfarin Perioperative Protocol

5 Days PreopStop Warfarin

Stop warfarin 5 days before surgery. INR will normalize to less than 1.5 by day of surgery in most patients. Check INR on day before surgery to confirm.

3 Days Preop (if bridging)Start LMWH or UFH

If HIGH thrombosis risk, start LMWH (enoxaparin 1mg/kg BD) or UFH infusion when INR less than 2. Give last LMWH dose 24h before surgery.

Day of SurgeryCheck INR

Confirm INR less than 1.5 (ideally less than 1.2 for neuraxial). If INR greater than 1.5, delay or give vitamin K 1-2mg PO.

24-72h PostopRestart Warfarin

Restart warfarin when hemostasis secure (24h for low bleeding risk, 48-72h for high). If bridging, give LMWH until INR greater than 2 for 2 consecutive days.

This protocol follows eTG recommendations and BRIDGE trial evidence.

Perioperative anticoagulation management algorithm showing decision tree for bridging and cessation timing — Perioperative anticoagulation management algorithm - Decision tree for warfarin bridging based on thrombosis risk, DOAC cessation based on renal function, and neuraxial anesthesia timingCredit: OrthoVellum

Direct Oral Anticoagulant (DOAC) Management

DOACs are Simpler Than Warfarin

Advantages of DOACs: Predictable pharmacokinetics, no INR monitoring needed, no bridging required, rapid offset. Key variable: RENAL FUNCTION determines cessation timing.

DOAC Cessation Timing (eTG Guidelines)

DOAC	CrCl greater than 50	CrCl 30-50	CrCl less than 30
Apixaban	24-48h preop	48h preop	48-72h preop
Rivaroxaban	24-48h preop	48h preop	48-72h preop
Dabigatran	24-48h preop	72h preop	96h preop (4 days)
Edoxaban	24-48h preop	48h preop	48-72h preop

Preoperative DOAC Management

Calculate CrCl (Cockcroft-Gault)
Stop 24h if CrCl greater than 50 and LOW bleeding risk surgery
Stop 48h if CrCl greater than 50 and HIGH bleeding risk surgery
Stop 48-96h if CrCl less than 50 (dabigatran longest)
NO bridging - DOACs have rapid offset

Postoperative DOAC Restart

Low bleeding risk: Restart 6-12h postop (full dose)
Moderate risk: Restart 24-48h postop
High risk: Restart 48-72h postop
Start at full therapeutic dose (no loading)
Ensure hemostasis before restarting

Dabigatran is Renally Cleared

Dabigatran is 80% renally excreted. If CrCl less than 50, stop 72-96h preop (3-4 days). Check renal function in all patients on dabigatran. Apixaban and rivaroxaban are less renal-dependent.

Neuraxial Anesthesia and Anticoagulation

Spinal Hematoma is Catastrophic

Spinal epidural hematoma causes irreversible paralysis if not decompressed within 8 hours. Prevention requires strict adherence to anticoagulation timing guidelines.

Anticoagulant	BEFORE Neuraxial (Wait Time)	AFTER Neuraxial (Wait Time)
LMWH prophylactic	12 hours	4 hours (wait 4h to give LMWH)
LMWH therapeutic	24 hours	4 hours (wait 4h to give LMWH)
Unfractionated heparin SC	12 hours	1 hour
Warfarin	INR less than 1.5	Safe when catheter out
Apixaban/Rivaroxaban	48 hours	6 hours
Dabigatran	72-96 hours	6 hours

Catheter Removal Timing

If epidural catheter in situ, anticoagulation must be held until AFTER catheter removal. Wait 12h after LMWH prophylactic dose, 24h after therapeutic dose, before removing catheter. Then wait 4h after removal before next LMWH dose.

Surgical Technique

Pre-operative Assessment

Confirm Anticoagulation Status:

Document last dose date/time
Check INR (warfarin) or drug levels if available (DOACs)
Review renal function for DOAC clearance
Confirm bridging plan if applicable

Pre-operative Checklist:

Anticoagulation held per protocol
Bridging LMWH stopped appropriately (24h for prophylactic, 24-48h therapeutic)
Platelet function normal if on aspirin/clopidogrel
Group and screen current
Discuss plan with anaesthesia for neuraxial

Day of Surgery:

Confirm patient fasted and anticoagulation held
Recheck INR for warfarin patients (target less than 1.5)
Document consent includes bleeding risks

Complications and Special Situations

Emergency Surgery on Anticoagulation

Patient needs urgent surgery but is anticoagulated:

Emergency Reversal Protocol

INR greater than 1.5Warfarin

Give Vitamin K 5-10mg IV (onset 6-12h) PLUS Prothrombin Complex Concentrate (PCC) 25-50 units/kg (immediate reversal). Check INR 30 min after PCC.

Within 2-4h of last doseDOACs

Consider Idarucizumab (dabigatran reversal) or Andexanet alfa (Xa inhibitor reversal). Expensive and limited availability. May delay surgery 12-24h if possible.

Ongoing effectLMWH/UFH

Protamine sulfate reverses heparin (1mg per 100 units UFH). Partial reversal of LMWH. Wait 4-6h if possible.

Balance: Bleeding risk of surgery vs thrombosis risk of reversal. Discuss with hematology.

Postoperative Care

Anticoagulation Restart Timing

Procedure Risk	DOAC Restart	Warfarin Restart
Low bleeding risk	24-48 hours	Day 1 (takes days to effect)
Moderate risk	48-72 hours	Day 1-2
High risk	72-96 hours	Day 2-3, check hemostasis
Very high risk (spine, intracranial)	5-7 days	Delayed, individualized

Decision Factors:

Hemostasis adequacy (drain output, wound)
Thrombotic risk vs bleeding risk
Neuraxial anaesthesia removal timing
Hematology input for complex cases

Bridging Phase-out:

For high-risk patients who were bridged, continue LMWH until INR therapeutic (warfarin) or 24-48 hours (DOACs)

Outcomes

Bleeding Outcomes

Scenario	Major Bleeding Risk
Bridging (therapeutic LMWH)	3-5%
No bridging	1-2%
DOACs held appropriately	1-2%
Continued anticoagulation	5-10%

Major Bleeding Definitions:

Hb drop ≥20 g/L
Transfusion ≥2 units
Bleeding at critical site
Reoperation for bleeding
Fatal bleeding

Risk Factors for Bleeding:

Inadequate drug cessation
Renal impairment (DOAC accumulation)
Concurrent antiplatelet therapy
Complex/revision surgery

Evidence Base and Key Trials

BRIDGE Trial - Bridging Anticoagulation

Douketis et al. • NEJM (2015)

Key Findings:

RCT of 1884 AF patients on warfarin undergoing procedures
Bridging with LMWH vs no bridging
Bridging increased bleeding (3.2% vs 1.3%, p less than 0.001)
No reduction in thromboembolism (0.3% vs 0.4%, NS)

Clinical Implication: Bridging is NOT needed for most AF patients. Only bridge HIGH-risk patients.

Limitation: Excluded mechanical valves and recent VTE - these still need bridging.

PAUSE Trial - DOAC Management

Spyropoulos et al. • NEJM (2018)

Key Findings:

Prospective cohort of 3007 patients on DOACs
Standardized perioperative management (no bridging)
Bleeding rate 2% (high-risk surgery), 0.9% (low-risk)
Thrombosis rate 0.2% (low-risk), 0.6% (high-risk)

Clinical Implication: Standardized DOAC cessation without bridging is safe and effective.

Limitation: Observational cohort; not randomized.

ARISTOTLE Trial - Apixaban vs Warfarin

Granger et al. • NEJM (2011)

Key Findings:

RCT of 18,201 AF patients comparing apixaban to warfarin
Superior efficacy (stroke/embolism 1.27% vs 1.60% annual)
Lower major bleeding (2.13% vs 3.09% annual)
Lower all-cause mortality (3.52% vs 3.94%)

Clinical Implication: Apixaban is safer and more effective than warfarin for AF - supports DOAC use perioperatively.

Limitation: Did not specifically study perioperative management.

RE-LY Trial - Dabigatran in AF

Connolly et al. • NEJM (2009)

Key Findings:

RCT of 18,113 AF patients comparing dabigatran 110mg and 150mg to warfarin
Dabigatran 150mg reduced stroke (1.11% vs 1.69% annual)
Dabigatran 110mg had lower bleeding than warfarin
GI bleeding higher with dabigatran 150mg

Clinical Implication: Dabigatran is an effective alternative to warfarin - note 80% renal excretion affects perioperative cessation timing.

Limitation: Higher GI bleeding with 150mg dose; renal function critical for clearance.

PERIOP-2 Trial - Bridging with LMWH

Douketis et al. • Circulation (2019)

Key Findings:

Follow-up analysis from BRIDGE trial patient subgroups
Even moderate-risk AF patients (CHA2DS2-VASc 3-4) did not benefit from bridging
Bleeding risk increased across all risk strata when bridged
Only very high-risk patients may benefit (mechanical mitral valve)

Clinical Implication: Confirms that bridging should be reserved for highest-risk patients only - do not bridge moderate-risk AF.

Limitation: Post-hoc analysis; not powered for subgroup comparisons.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Scenario 1: Elective THA on Warfarin (~2-3 min)

EXAMINER

"A 72-year-old woman is scheduled for elective total hip arthroplasty in 10 days. She takes warfarin for atrial fibrillation (CHA2DS2-VASc score 3). Her INR today is 2.5. How would you manage her anticoagulation perioperatively?"

EXCEPTIONAL ANSWER

This patient is on warfarin for AF with moderate thrombosis risk. My approach: First, I would assess her thrombosis risk using CHA2DS2-VASc score - she scores 3 which is MODERATE risk, so bridging is NOT routinely indicated. Second, I would ask about bleeding history, renal function, and prior thrombotic events. Third, I would implement a standardized protocol: Stop warfarin 5 days before surgery. Check INR the day before surgery to confirm it is less than 1.5. No bridging with LMWH unless she has additional high-risk features. On day of surgery, recheck INR to confirm less than 1.5 before proceeding. Postoperatively, restart warfarin on evening of surgery or day 1 if hemostasis is secure. Give prophylactic LMWH (enoxaparin 40mg daily) starting 12-24h postop until INR is therapeutic (greater than 2) for 2 consecutive days. Total hip arthroplasty is moderate bleeding risk, so I would restart warfarin at 24-48h.

KEY POINTS TO SCORE

CHA2DS2-VASc 3 = MODERATE risk = NO bridging (based on BRIDGE trial)

Stop warfarin 5 days preop, check INR day before and day of surgery

No LMWH bridging needed for AF with CHA2DS2-VASc less than 5

Restart warfarin 24-48h postop once hemostasis secure

Standard VTE prophylaxis until INR therapeutic

COMMON TRAPS

✗Automatically bridging all warfarin patients - most do NOT need it

✗Not checking INR before surgery - may still be elevated

✗Restarting warfarin too early (increases bleeding) or too late (increases VTE)

✗Forgetting standard VTE prophylaxis while warfarin subtherapeutic

LIKELY FOLLOW-UPS

"What if she had a mechanical mitral valve instead?"

"What if her INR is 2.0 on the day before surgery?"

"When would you restart warfarin if this was a revision THA?"

VIVA SCENARIOChallenging

Scenario 2: TKA on Apixaban with Spinal (~3-4 min)

EXAMINER

"A 68-year-old man on apixaban 5mg BD for AF is scheduled for TKA with spinal anesthesia. His CrCl is 55 ml/min. When would you stop the apixaban, when is it safe to perform the spinal, and when would you restart?"

EXCEPTIONAL ANSWER

This patient is on a DOAC (apixaban) with planned neuraxial anesthesia, which requires careful timing to avoid spinal hematoma. My approach: First, I would assess renal function - CrCl 55 is borderline, so I'll use the standard 48-hour cessation protocol for moderate-high bleeding risk surgery. Second, I would stop apixaban 48 hours before surgery. Last dose would be 2 days preop at evening. Third, neuraxial timing is critical: Spinal anesthesia is safe at least 48 hours after the last apixaban dose. I would perform the spinal on the morning of surgery (48h after last dose). Fourth, postoperative management: Apixaban has rapid onset, so I need to balance VTE prophylaxis vs bleeding risk. For TKA (moderate bleeding risk), I would restart apixaban at 24-48 hours postoperatively, once hemostasis is secure and no epidural catheter in situ. If using epidural catheter, I must wait 6 hours after catheter removal before first apixaban dose. I would give standard mechanical VTE prophylaxis (compression devices) in the interim. Fifth, I would restart apixaban at full therapeutic dose (5mg BD) - no bridging needed with DOACs.

KEY POINTS TO SCORE

Apixaban cessation: 48h before surgery (CrCl greater than 50 + high-risk surgery)

Neuraxial MUST wait 48h after last DOAC dose (spinal hematoma risk)

Restart 24-48h postop for moderate bleeding risk (TKA)

If epidural: wait 6h after catheter removal before DOAC

NO bridging with DOACs - predictable offset/onset

COMMON TRAPS

✗Performing spinal too early (less than 48h after DOAC) - risks spinal hematoma

✗Bridging a DOAC patient with LMWH - never needed

✗Restarting DOAC before catheter removed - spinal hematoma risk

✗Not checking renal function - determines DOAC cessation timing

LIKELY FOLLOW-UPS

"What if his CrCl was 35 ml/min?"

"What would you do if he developed signs of spinal hematoma postop?"

"How does apixaban differ from dabigatran in this scenario?"

MCQ Practice Points

Warfarin Cessation Timing

Q: How many days before elective surgery should warfarin be stopped? A: 5 days. Warfarin half-life is 36-42 hours. Stopping 5 days preop allows INR to normalize to less than 1.5 in most patients.

Bridging Indication

Q: Which patients require bridging anticoagulation with LMWH when stopping warfarin? A: HIGH thrombosis risk only: Mechanical MITRAL valve, recent VTE (less than 3 months), or AF with CHA2DS2-VASc greater than or equal to 5. BRIDGE trial showed bridging increases bleeding without preventing thrombosis in most patients.

DOAC Advantage

Q: What is the main advantage of DOACs over warfarin for perioperative management? A: Predictable offset and NO bridging needed. DOACs can be stopped 24-48h preop and restarted postop without bridging, unlike warfarin which may need LMWH bridging in high-risk patients.

Neuraxial Timing

Q: How long after prophylactic LMWH is it safe to perform spinal anesthesia? A: 12 hours. Therapeutic LMWH requires 24 hours. This prevents spinal epidural hematoma, which causes irreversible paralysis.

Dabigatran Cessation

Q: Why does dabigatran require longer preoperative cessation than other DOACs? A: 80% renal excretion. If CrCl less than 50, dabigatran must be stopped 72-96h preop (3-4 days) vs 48h for apixaban/rivaroxaban.

Australian Context

Australian Guidelines

ANZCA Guidelines (Neuraxial Anaesthesia):

Warfarin: INR less than 1.4 before neuraxial
LMWH prophylactic: 12 hours before insertion
LMWH therapeutic: 24 hours before insertion
DOACs: variable based on renal function and drug

Therapeutic Guidelines (eTG):

Bridging rarely needed for AF (BRIDGE trial evidence)
High-risk patients (mechanical valves, recent VTE) may require bridging
Multidisciplinary consultation for complex cases

NHMRC VTE Prevention Guidelines:

Mechanical prophylaxis for all major orthopaedic surgery
Pharmacological prophylaxis: LMWH or DOACs
Extended prophylaxis for THA (28-35 days)

AOA Position Statement:

Risk stratification before surgery
Standardized cessation protocols
Early mobilization as primary prevention

PERIOPERATIVE ANTICOAGULATION MANAGEMENT

High-Yield Exam Summary

Warfarin Protocol

•Stop 5 days preop, check INR day before surgery (target less than 1.5)
•Bridge only if HIGH risk: mechanical mitral, VTE less than 3mo, AF CHA2DS2-VASc greater than or equal to 5
•Last LMWH bridge dose 24h before surgery
•Restart 24-72h postop (bleeding risk dependent)

DOAC Protocol

•Calculate CrCl first - determines cessation timing
•Stop 24-48h if CrCl greater than 50, 48-96h if CrCl less than 50
•Dabigatran longest (96h if CrCl less than 50)
•NO bridging ever - DOACs have rapid offset

Neuraxial Timing (Spinal Hematoma Prevention)

•LMWH prophylactic: Wait 12h before neuraxial, 4h after
•LMWH therapeutic: Wait 24h before neuraxial, 4h after
•DOACs: Wait 48h (apixaban/rivaroxaban) or 72-96h (dabigatran)
•Catheter removal: 12h after LMWH, then wait 4h to restart

Bridging Indications (HIGH Risk Only)

•Mechanical MITRAL valve (always bridge)
•Recent VTE less than 3 months
•AF with CHA2DS2-VASc greater than or equal to 5
•Prior stroke/VTE while on therapeutic anticoagulation

Bleeding Risk Stratification

•LOW: Minor procedures - restart 6-12h postop
•MODERATE: THA/TKA/fracture ORIF - restart 24-48h
•HIGH: Spine, revision THA/TKA - restart 48-72h
•Neuraxial anesthesia = HIGH bleeding risk

Anticoagulant

Stop Before Surgery

Restart After Surgery

Bridge?

Warfarin (low thrombo risk)

5 days preop

24-72h postop

NO - do not bridge

Warfarin (high thrombo risk)

5 days preop + LMWH bridge

LMWH 24h postop, warfarin overlap

YES - mechanical valve, recent VTE

DOACs (CrCl greater than 50)

24-48h preop

24-72h postop

NO - never bridge DOACs

DOACs (CrCl less than 50)

48-96h preop (longer)

24-72h postop

NO - never bridge DOACs

LMWH prophylactic

12h before neuraxial

Restart 6-12h postop

N/A - this IS prophylaxis

Risk Category

Clinical Features

Annual Risk

Periop Management

HIGH

Mechanical MITRAL valve, VTE less than 3mo, stroke less than 3mo

Greater than 10%

BRIDGE with LMWH or UFH

MODERATE

Mechanical AORTIC valve, VTE 3-12mo ago, AF CHA2DS2-VASc 3-4

5-10%

Consider bridging, individualize

LOW

AF CHA2DS2-VASc 0-2, VTE greater than 12mo, bioprosthetic valve

Less than 5%

NO bridging - stop AC, restart postop

Score

Risk

Bridging Decision

0-2

Low

NO bridging

3-4

Moderate

Consider bridging if additional risks

5 or more

High

Bridge with LMWH

Class

Examples

Mechanism

Half-life

Vitamin K antagonists

Warfarin

Inhibits factors II, VII, IX, X

36-42 hours

Direct thrombin inhibitors

Dabigatran

Direct factor IIa inhibition

12-17 hours

Factor Xa inhibitors

Rivaroxaban, Apixaban

Direct factor Xa inhibition

8-15 hours

Heparins

Enoxaparin, UFH

AT-III mediated

4-7 hours (LMWH)

Antiplatelet agents

Aspirin, Clopidogrel

Platelet inhibition

Variable

Risk Category

Orthopaedic Procedures

Management

LOW

Arthroscopy, carpal tunnel, trigger finger, K-wire removal

Minimal interruption, restart 6-12h

MODERATE

THA, TKA, ORIF, shoulder arthroplasty, fracture fixation

Stop AC preop, restart 24-48h postop

HIGH

Spine surgery, revision THA/TKA, pelvic ORIF, tumor resection

Extended cessation, restart 48-72h postop

DOAC

CrCl greater than 50

CrCl 30-50

CrCl less than 30

Apixaban

24-48h preop

48h preop

48-72h preop

Rivaroxaban

24-48h preop

48h preop

48-72h preop

Dabigatran

24-48h preop

72h preop

96h preop (4 days)

Edoxaban

24-48h preop

48h preop

48-72h preop

Anticoagulant

BEFORE Neuraxial (Wait Time)

AFTER Neuraxial (Wait Time)

LMWH prophylactic

12 hours

4 hours (wait 4h to give LMWH)

LMWH therapeutic

24 hours

4 hours (wait 4h to give LMWH)

Unfractionated heparin SC

12 hours

1 hour

Warfarin

INR less than 1.5

Safe when catheter out

Apixaban/Rivaroxaban

48 hours

6 hours

Dabigatran

72-96 hours

6 hours

Procedure Risk

DOAC Restart

Warfarin Restart

Low bleeding risk

24-48 hours

Day 1 (takes days to effect)

Moderate risk

48-72 hours

Day 1-2

High risk

72-96 hours

Day 2-3, check hemostasis

Very high risk (spine, intracranial)

5-7 days

Delayed, individualized

Scenario

Major Bleeding Risk

Bridging (therapeutic LMWH)

3-5%

No bridging

1-2%

DOACs held appropriately

1-2%

Continued anticoagulation

5-10%

Australian Guidelines

ANZCA Guidelines (Neuraxial Anaesthesia):

Warfarin: INR less than 1.4 before neuraxial
LMWH prophylactic: 12 hours before insertion
LMWH therapeutic: 24 hours before insertion
DOACs: variable based on renal function and drug

Therapeutic Guidelines (eTG):

Bridging rarely needed for AF (BRIDGE trial evidence)
High-risk patients (mechanical valves, recent VTE) may require bridging
Multidisciplinary consultation for complex cases

NHMRC VTE Prevention Guidelines:

Mechanical prophylaxis for all major orthopaedic surgery
Pharmacological prophylaxis: LMWH or DOACs
Extended prophylaxis for THA (28-35 days)

AOA Position Statement:

Risk stratification before surgery
Standardized cessation protocols
Early mobilization as primary prevention

Timing of VTE	Risk	Bridging Decision
VTE less than 3 months ago	HIGH (10-15%)	BRIDGE with LMWH
VTE 3-12 months ago	MODERATE (5-10%)	Consider bridging
VTE greater than 12 months ago	LOW (less than 5%)	NO bridging
Unprovoked VTE or recurrent	HIGHER	Lower threshold to bridge

Risk Level	Examples	Anticoagulation Strategy
Minimal	Carpal tunnel, trigger finger	Continue or hold 24 hours
Low	Knee arthroscopy, hardware removal	Hold DOACs 24-48 hours
Moderate	Hip/knee TJA, spinal without fusion	Hold 48-72 hours, consider bridging
High	Spinal fusion, pelvic surgery, revision TJA	Hold 5+ days, bridging if high risk

Strategy	Indication	Notes
Tourniquet	Extremity surgery	Deflate before closure to check
Electrocautery	Soft tissue bleeding	Bipolar for precise control
Bone wax	Cancellous bone	Use sparingly, foreign body
Topical hemostatics	Oozing surfaces	Gelfoam, Surgicel, Floseal
Tranexamic acid	Major surgery	1g IV ± topical 1-2g
Drain placement	High-risk procedures	Monitor output closely

Patient Risk	Perioperative VTE/Stroke
Low risk (CHA₂DS₂-VASc 0-2)	less than 1%
Moderate risk (CHA₂DS₂-VASc 3-4)	1-2%
High risk (mechanical valve, recent VTE)	2-5%

Drug	PBS Status	Indications
Warfarin	PBS general	AF, VTE, mechanical valve
Dabigatran	PBS restricted	Non-valvular AF
Rivaroxaban	PBS restricted	AF, VTE treatment/prophylaxis
Apixaban	PBS restricted	AF, VTE
Enoxaparin	PBS restricted	VTE prophylaxis/treatment

Valve Type	Position	Risk	Bridging
Mechanical	MITRAL	HIGH (4-8% annual)	ALWAYS bridge
Mechanical	AORTIC + risk factors	MODERATE	Consider bridging
Mechanical	AORTIC alone	LOW-MODERATE	Usually do not bridge
Bioprosthetic	Any position	LOW	NO bridging

Drug	Renal Elimination	Adjustment Needed
Dabigatran	80%	Contraindicated if CrCl less than 30, stop 96h if CrCl 30-50
Rivaroxaban	33%	Stop 48h if CrCl less than 50
Apixaban	27%	Stop 48h if CrCl less than 50
Warfarin	Minimal	No dose adjustment, but monitor INR closely
LMWH	Renal clearance	Avoid if CrCl less than 30 or use UFH

Perioperative Anticoagulation Management

Perioperative Anticoagulation Management

PERIOPERATIVE ANTICOAGULATION MANAGEMENT

BLEEDING RISK STRATIFICATION

Critical Must-Knows

Examiner's Pearls

Critical Exam Concepts

Bridging is NOT Routine

DOAC Timing is Drug-Specific

Neuraxial Anesthesia Timing

Restart Based on Bleeding Risk

Quick Decision Guide

BRAVEHigh Thrombosis Risk Requiring Bridging

RENALDOAC Cessation Timing Factors

CLOTNeuraxial Timing Safety

Overview and Clinical Significance

Common Indications for Anticoagulation

Why Perioperative Management Matters

Pathophysiology and Risk Stratification

Risk Stratification Determines Bridging

AF Thrombosis Risk (CHA2DS2-VASc Score)

Mechanical Heart Valve Risk

VTE Thrombosis Risk

Classification

Classification of Anticoagulant Agents

Thromboembolic Risk Stratification

Procedure Bleeding Risk Classification

Clinical Assessment and Bleeding Risk

Investigations and Monitoring

Laboratory Monitoring Preoperatively

eTG Anticoagulation Guidelines (Australian)

Management Algorithm

Warfarin Perioperative Management

Warfarin Perioperative Protocol

LMWH Bridging Protocol

LMWH Bridging Timing Critical

Direct Oral Anticoagulant (DOAC) Management

DOAC Cessation Timing (eTG Guidelines)

Preoperative DOAC Management

Postoperative DOAC Restart

Dabigatran is Renally Cleared

Neuraxial Anesthesia and Anticoagulation

Spinal Hematoma is Catastrophic

Surgical Technique

Pre-operative Assessment

Intraoperative Considerations

Hemostasis Strategies

Complications and Special Situations

Emergency Surgery on Anticoagulation

Emergency Reversal Protocol

Suspected Spinal Epidural Hematoma

Anticoagulation in Renal Impairment

Postoperative Care

Anticoagulation Restart Timing

VTE Prophylaxis Protocol

Postoperative Monitoring

Outcomes

Bleeding Outcomes

Thrombotic Outcomes

Optimal Management Outcomes

Evidence Base and Key Trials

BRIDGE Trial - Bridging Anticoagulation

PAUSE Trial - DOAC Management

ARISTOTLE Trial - Apixaban vs Warfarin

RE-LY Trial - Dabigatran in AF

PERIOP-2 Trial - Bridging with LMWH

Exam Viva Scenarios

Scenario 1: Elective THA on Warfarin (~2-3 min)

Scenario 2: TKA on Apixaban with Spinal (~3-4 min)

MCQ Practice Points

Australian Context

Australian Guidelines

PBS Considerations

Australian Practice Patterns

PERIOPERATIVE ANTICOAGULATION MANAGEMENT

Warfarin Protocol

DOAC Protocol

Neuraxial Timing (Spinal Hematoma Prevention)

Bridging Indications (HIGH Risk Only)

Bleeding Risk Stratification