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Basic Approach to Anticoagulation and regional/ Blocks

Quick 4-Step Safety Screen

1. Patient: bleeding diathesis, renal/hepatic failure, age > 65 yr, concurrent antiplatelet.
2. Drug: half-life, low vs high-dose*, renal clearance, specific antidote.
3. Procedure:
   • Low risk = superficial, compressible (e.g. fascia iliaca, TAP).
   • Intermediate = deep non-compressible (e.g. paravertebral, ESP, shoulder catheter).
   • High risk = neuraxial, psoas compartment, deep cervical/axillary, interlaminar injections.
4. Rescue–24 h staffed ward neuro-checks, MRI ± decompression reachable ≤ 8 h.

• ASRA 2025 replaces “prophylactic/therapeutic” with low-dose (VTE prophylaxis) and high-dose (treatment or twice-daily schedule).

The Catheter Removal Window

• The minimum safe interval that must elapse between the patient’s last dose of a specific antithrombotic-/antiplatelet agent and the physical removal of an indwelling neuraxial or deep-plexus catheter (e.g. epidural, continuous paravertebral, femoral, or brachial plexus catheter).
• Why it matters
  • Removing the catheter during peak (or even residual) anticoagulant effect markedly increases the risk of spinal or deep-tissue haematoma.
  • Observing the recommended window allows enough drug clearance (often ≥2–3 half-lives, or a verified normal coagulation test) so that clotting function has returned to a level that makes bleeding complications highly unlikely.
• Practical use
  1. Note last dose time of the anticoagulant/antiplatelet.
  2. Count forward the guideline-specified interval (e.g. 24 h for LMWH therapeutic dose, 24 h for most DOACs).
  3. Remove catheter only after that point, provided the patient shows no additional bleeding risk factors and (if indicated) coagulation tests are within normal limits.
  4. After removal, delay the next anticoagulant dose by the further interval shown in the table (e.g. ≥6 h) to let the puncture track seal.

Guideline Tables

• To minimise spinal / epidural haematoma you must treat two separate clocks for every antithrombotic agent:

1. “Hold-to-block / catheter-removal” clock–how long you stop the drug before neuraxial puncture and before you pull an indwelling catheter.
2. “Restart-after-removal” clock–the minimum delay after the catheter (or needle) leaves the epidural / intrathecal space before the next dose is given.

• The first clock protects against bleeding into the neuraxis during instrumentation; the second allows the dural or epidural track to seal once all hardware is out.
• Latest consensus statements (ASRA 2018, ESAIC–ESRA 2022, ASA practice advisories and NYSORA) agree that the restart interval is usually ≥ 6 h for antiplatelet drugs and ≥ 4–6 h (UFH/LMWH prophylaxis) to ≥ 6 h (DOACs/warfarin) for anticoagulants.
• Restarting sooner, or maintaining full-dose anticoagulation while a catheter remains in situ, is the commonest root cause of neuraxial haematoma in case series.

Antiplatelet & NSAID Timetable

Agent	Stop before high-risk block	Catheter-removal window	Restart ≥ this many h after catheter removal	First postoperative dose if no catheter
Aspirin ≤ 325 mg day⁻¹	Continue (stop 3 d if ≥2 bleeding RF)	N/A	0 h – can continue	6 h
Non-selective NSAIDs	Continue	N/A	0 h	6 h
Clopidogrel	5 d	≥ 24 h after last dose	6 h	6 h
Prasugrel	7 d	≥ 24 h	6 h	6 h
Ticagrelor	5 d	≥ 24 h	6 h	6 h
Ticlopidine	10 d	≥ 24 h	6 h	6 h
Cangrelor	3 h	3 h	8 h	8 h
GP IIb/IIIa (abciximab)	24h-48h	Contra-indicated	≥ 24 h	≥ 24 h
GP IIb/IIIa (eptifibatide/tirofiban)	8-12 h	Contra-indicated	≥ 24 h	≥ 24 h
Dipyridamole ER	24 h	Remove first	6 h	6 h
Cilostazol	48 h	Remove first	6 h	6 h
Garlic / Ginkgo / Ginseng	No stop (document)	N/A	0 h	–

Sources: ASRA 2018, ESAIC-ESRA 2022, Stanford 2019 table, NYSORA tips

• Continuing low-dose aspirin is appropriate for most neuraxial and surgical cases except in surgeries in closed spaces (intracranial neurosurgery, intramedullary spine, posterior eye) often warrant holding aspirin 7–10 days prior due to catastrophic bleeding risk
• Consider stopping longer-half-life NSAIDs (piroxicam, etc.) in high-risk patients or if combined with other agents.

Anticoagulants–neuraxial & Deep-plexus Timing

Agent	Stop before block	Catheter-removal window	Restart ≥ this many h after catheter removal	First postoperative dose if no catheter
UFH 5 000 U SC q12/q8	4–6 h	4–6 h (check aPTT)	1 h	1 h
UFH IV infusion	Stop 4–6 h; ∆aPTT	4–6 h	1 h	1 h
LMWH prophylactic (40 mg qd OR 30 mg q12h)	12 h	12 h	4 h	6–12 h†
LMWH therapeutic (1 mg kg⁻¹ q12 OR 1.5 mg kg⁻¹ qd)	24 h	24 h	4 h	≥24 h (low bleed) / 48 h (high bleed)
Warfarin	Stop 5 d, ensure INR < 1.5 (≥40% factor activity)	Remove when INR < 1.5	6 h	6-12h. Evening of surgery (if haemostasis OK)
Dabigatran (CrCl > 80 / 50–80 / 30–50 mL min⁻¹)	2 / 3 / 4–5 d	72 h	6 h	24 h (VTE ppx) or ≥ 48 h (therapeutic)
Rivaroxaban / Apixaban / Edoxaban / Betrixaban	For full-dose DOAC (e.g. AF therapy) hold ~72 h. For low-dose prophylactic DOAC (e.g. rivaroxaban 10 mg daily), a 24–36 h hold may suffice in normal renal function	24 h	6 h	24 h (VTE ppx) or ≥ 48 h (therapeutic)
Fondaparinux	36–42 h	Avoid neuraxial catheter; if present, remove ≥ 36 h since last dose	12 h	6 h (single shot only)
IV direct thrombin in. (bivalirudin/argatroban)	Contra-indicated	Contra-indicated	–	–
Thrombolytics / fibrinolytics	Contra-indicated ≤ 72 h	—	72 h & normal fibrinogen

• Use calibrated anti-Xa or dTT/Etc assays to shorten interval when urgently required. (DOAC’s)
• † ESAIC-ESRA allow 6–8 h for once-daily prophylaxis; ASRA remains 12 h–adopt the stricter interval unless a local protocol allows shorter.
• Intervals from ASRA 5th ed 2025, ESRA–ESAIC 2021, and SASA 2019; choose the longer interval if imaging/neurosurgery access is delayed.
• Sources: ASRA 2018, GuidelineCentral summary 2024, ESAIC-ESRA 2022, Stanford 2019, OpenAnesthesia,

How to Interpret the Two Postoperative Clocks

Scenario	What starts the clock	Why it matters	Typical interval*
1. Restart after surgery (no catheter left)	Skin closure or single-shot puncture (which ever comes last)	Ensures surgical haemostasis before systemic anticoagulation rises	See “First post-op dose” column
2. Restart after indwelling catheter removal	Actual moment the epidural/spinal catheter leaves the space	Allows the needle/catheter track to seal and epidural veins to compress	See “Restart ≥ h after catheter removal” column

*Always longer if high-bleeding surgery, renal impairment, or traumatic tap.

Post-Block Surveillance

• Q4-hour motor, sensory & back-pain checks × 24 h (neuraxial/deep catheters).
• Red flags (new weakness, saddle numbness, sphincter change) ⇒ urgent escalation.

Using Anticoagulants while a Neuraxial Catheter Remains in Situ

Drug class	Permitted with catheter?	Essential safeguards
UFH SC ≤ 5 000 U q8–q12	Yes	Dose ≤ 10 000 U day⁻¹; neuro-checks q4 h; remove catheter 4–6 h post-dose and restart ≥ 1 h later
UFH IV infusion	Discouraged	If unavoidable: keep aPTT < 2× control, stop infusion 4–6 h pre-removal, restart ≥ 1 h after
LMWH prophylaxis (40mg daily)	Yes	First postoperative dose ≥ 12 h after insertion; remove catheter ≥ 12 h after last dose; restart ≥ 4 h later; no additional antiplatelets
LMWH therapeutic (≥ 1 mg kg⁻¹ q12 h), Fondaparinux, DOACs, GP IIb/IIIa, thrombolytics	No	Convert to safer agent or delay until catheter out and restart window met
Warfarin (INR < 1.5)	Acceptable	Daily INR; pull catheter when INR < 1.5; restart ≥ 6 h post-removal

• If you have a bloody or traumatic tap, extend every restart interval by ≥ 24 h and intensify neuro-checks (hourly × 24 h).
• When a patient genuinely needs therapeutic-dose anticoagulation (e.g., heparin infusion, therapeutic LMWH, warfarin with INR 2–3, or a DOAC at full strength) but also “needs an epidural,” modern guidelines make one point crystal-clear: continuous neuraxial catheterisation is normally incompatible with full anticoagulation.
• The clinician must either (1) de-escalate or interrupt the anticoagulant long enough to insert and later remove the catheter under guideline time-windows, or (2) abandon the epidural in favour of alternative analgesia or peripheral blocks.
  • Low–moderate thrombotic risk (e.g., VTE > 3 months ago, AF without prosthetic valve):
    • Hold therapeutic anticoagulation, convert temporarily to prophylactic LMWH (40 mg daily) or mini-dose UFH, and follow the standard neuraxial timing rules.
  • High thrombotic risk (e.g., mechanical mitral valve, VTE < 30 days, LV assist device, acute coronary syndrome):
    • Epidural catheter is usually abandoned. Use single-shot spinal or catheter-free peripheral/plane blocks plus multimodal systemic analgesia.

Obstetric Anticoagulation & Neuraxial Guidance

Antenatal VTE-risk Assessment (apply at Booking, at 28 Weeks, on Admission & postpartum)

Risk tier (RCOG 37a 2022)	Typical factors	LMWH prophylaxis
Very high	Previous VTE + thrombophilia or > 1 previous VTE	Begin immediately antenatally (from confirmation of pregnancy) and continue for 6 weeks postpartum
High	Single previous VTE, high-risk thrombophilia, current ovarian hyper-stimulation syndrome, morbid obesity (BMI ≥ 40) with ≥ 1 additional factor	Start from first trimester or as soon as diagnosis is made; continue for 6 weeks postpartum
Intermediate	≥ 3 risk factors* (age ≥ 35, BMI ≥ 30, multiparity ≥ 3, IVF, smoker, medical comorbidity)	Start from 28 weeks and continue 10 days postpartum
Low	≤ 2 risk factors	No routine LMWH; encourage mobilisation + hydration

• Add transient factors (e.g. hospital admission, infection, long-haul flight) as they arise and escalate tier if cumulative score ≥ 3.

LMWH Dosing in Pregnancy (RCOG / CHEST 2022)

Booking weight	Prophylactic dose (enoxaparin)	Intermediate dose‡	Therapeutic dose
50–< 90 kg	40 mg SC OD	40 mg SC BD	1 mg kg⁻¹ SC BD
90–< 120 kg	40 mg SC BD	60 mg SC BD	1 mg kg⁻¹ SC BD
120–< 150 kg	60 mg SC BD	80 mg SC BD	1 mg kg⁻¹ SC BD
≥ 150 kg	80 mg SC BD (monitor anti-Xa 0.2–0.4 IU mL⁻¹)	100 mg SC BD	1 mg kg⁻¹ SC TDS ± monitoring

• ‡Used after caesarean in BMI ≥ 40 kg m⁻² or multiple major risk factors.
• Fondaparinux and DOACs are contra-indicated antenatally; warfarin is teratogenic (avoid weeks 6–12) but acceptable during breastfeeding.

Timing of Neuraxial Block & Catheter Removal (pregnancy-specific)

Anticoagulant	Last prophylactic dose → epidural / spinal	Therapeutic dose → epidural / spinal	Catheter removal	Restart after removal
LMWH	≥ 12 h	≥ 24 h	≥ 12 h after last prophylactic • ≥ 24 h after last therapeutic	≥ 4 h (prophylactic) • ≥ 6 h (therapeutic)
UFH s.c. 5 000 IU BD/TID	≥ 4 h	n/a (avoid high-dose antenatally)	≥ 4 h	≥ 1 h
Warfarin (postpartum only)	Contra-indicated before delivery	Convert to LMWH ≥ 5 d before	When INR < 1.5	Restart when haemostasis secure
Aspirin ≤ 150 mg	No restriction	—	No restriction	Continue
GP IIb/IIIa, DOACs, fondaparinux	Do NOT perform neuraxial–switch to LMWH	—	—	—

• Lab tests: consider anti-Xa if BMI > 40 kg m⁻², renal impairment, or timing uncertain; safe threshold < 0.1 IU mL⁻¹.

Post-partum Prophylaxis

• All caesarean births with ≥ 1 additional risk factor: LMWH 10 days.
• VTE during pregnancy, very-/high-risk groups: LMWH or warfarin (target INR 2–3) for 6 weeks; DOACs suitable if not breastfeeding.
• Delay first LMWH dose: 4–6 h after vaginal delivery, 6–12 h after caesarean once bleeding controlled.
• Combine with IPC sleeves until fully mobile

Regional-to-General Conversion during Labour

• If spontaneous labour begins while on prophylactic LMWH: omit next dose and reassess epidural eligibility after 12 h.
• On therapeutic LMWH: advise elective induction 24 h after last dose or consider regional anaesthesia alternatives (CSE after 24 h + normal anti-Xa).
• Suspected PPH or need for urgent CS before interval elapsed–proceed under GA; reverse LMWH with protamine 1 mg per 1 mg enoxaparin (max 50 mg).

South-African Context

• SASA 2022 endorses RCOG thresholds but stresses limited access to anti-Xa assays; default to conservative 24 h interval for therapeutic LMWH before neuraxial when testing unavailable.

Key Take-aways

1. Assess VTE risk at every maternity contact–pregnancy itself multiplies baseline risk ×4.
2. Weight-adjust LMWH; monitor anti-Xa only if extremes of weight/renal dysfunction.
3. Strict 12 h (prophylactic) / 24 h (therapeutic) rule around neuraxial; document timing in note
4. Continue prophylaxis for 10 days after vaginal/CS in intermediate-risk, 6 weeks in high-risk.
5. Warfarin safe in breastfeeding; DOACs only if formula-feeding.

Laboratory & Clinical Monitoring

• (Consolidated from ASRA 2025, ASRA–ESRA 2022, ESAIC/ESRA 2021 and SASA 2019)

When to Order Tests

Situation	Recommended test(s)	Rationale
Warfarin–before puncture or catheter removal	INR (target < 1.4)	Confirms adequate reversal/clearance.
IV unfractionated heparin (UFH)	aPTT or ACT within normal range	Short half-life but high inter-patient variability.
SC UFH ≥ 4 days, any dose	Platelet count	Detect heparin-induced thrombocytopenia (HIT).
Therapeutic or prolonged LMWH (> 4 days)	Platelet count ± anti-Xa (selected cases*)	Screen for HIT; anti-Xa if obesity, pregnancy, renal failure, or high-bleed surgery.
Fondaparinux / DOAC (rivaroxaban, apixaban, edoxaban)—unexpected dosing with indwelling catheter	Drug-specific anti-Xa assay	Assesses residual activity when timing uncertain.
Dabigatran—renal impairment or timing uncertainty	Dilute thrombin time (dTT) or ecarin clotting time (Etc)	Sensitive to dabigatran concentration.
Thrombolytics / fibrinolytics	Fibrinogen level (> 1.5 g L⁻¹) & global coagulation screen	Ensure return of clotting factors before neuraxial access.
Suspected coagulopathy (liver failure, massive transfusion)	Full blood count, PT/INR, aPTT, fibrinogen, viscoelastic test (ROTEM/TEG)	Comprehensive assessment of acquired disorders.

• *Anti-Xa target 0.1–0.3 IU mL⁻¹ (prophylactic), 0.5–1.0 IU mL⁻¹ (therapeutic).
• DOAC and Fondaparinux: Anti-Xa assay must be calibrated to the specific factor-Xa inhibitor.

Situations Where Routine Testing Is Not Required

• Aspirin, NSAIDs, clopidogrel and other antiplatelets (platelet-function assays add no clinical value).
• Prophylactic low-dose SC UFH (≤ 5 000 IU BID/TID) unless therapy > 4 days.
• Standard prophylactic LMWH in patients with normal renal function and body habitus.
• Direct oral anticoagulants if timing since last dose is clearly > 5 half-lives and renal function is normal.

Renal & Hepatic Function Considerations

• Estimate creatinine clearance before scheduling dabigatran or DOAC interruption; extend holding period if CrCl < 50 mL min⁻¹.
• Liver function tests for patients on warfarin, rivaroxaban or apixaban with suspected hepatic impairment.

Using Labs to Guide Blocks

Drug / situation	“Fit-to-block” laboratory target*	When to order	Evidence & caveats
Warfarin	INR ≤ 1.4 (ideally ≤ 1.1)	– Timing unclear (unknown last dose) – INR still > 1.5 on planned day	Threshold derived from pooled case reports and expert consensus; bleeding risk rises steeply once INR > 1.5, especially with neuraxial techniques.
IV unfractionated heparin	Normal aPTT or ACT < 120 s	– High-dose infusion stopped ≤ 4 h ago	Short half-life but large inter-patient variability justifies a single check before puncture/catheter removal.
LMWH (therapeutic or prolonged use)	Anti-Xa < 0.1 IU mL⁻¹ (prophylactic range)	– BMI > 35 kg m⁻², eGFR < 30 mL min⁻¹, pregnancy, or urgent/unsure timing	Anti-Xa sampling 4 h post-dose; below cut-off correlates with minimal residual anticoagulation, but routine testing not cost-effective for standard patients.
Factor-Xa inhibitors (rivaroxaban, apixaban, edoxaban, betrixaban, fondaparinux)	Drug-calibrated anti-Xa < 30 ng mL⁻¹†	– Last dose < guideline interval – Accidental in-hospital dose with catheter in situ	Anti-Xa assays must be agent-specific; correlate reasonably with plasma concentration but no randomised outcome data—use only when timing is uncertain.
Dabigatran	dTT < 34 s or Etc < 40 s	– Impaired renal function – Last dose < suggested hold-time	dTT/Etc highly sensitive for residual drug; safe thresholds extrapolated from cohort studies.
Post-fibrinolytic therapy	Fibrinogen > 1.5 g L⁻¹ and PT/aPTT normal	– < 72 h since alteplase/streptokinase	Low fibrinogen predicts ongoing lysis and high bleeding risk; wait ≥ 48 h and document normalisation.
Heparin (IV or SC) ≥ 4 d	Platelets > 100 × 10⁹ L⁻¹	– Screen for HIT	Drop > 50 % from baseline or < 100 × 10⁹ L⁻¹ warrants HIT work-up and deferral of block.
Viscoelastic tests (TEG/ROTEM)	Not validated for anticoagulant quantification	—	CT/ACT values poorly correlate with DOAC or LMWH levels; cannot be relied on to override guideline timing.
Platelet-function assays (e.g. PFA-100, VerifyNow)	Not recommended	—	Do not predict spinal haematoma risk; add cost without improving safety.

• *Values reflect the consensus position of ASRA 2025, ASRA-ESRA 2022 and ESAIC/ESRA 2021; laboratories should confirm local reference ranges.
• †Many centres use 30 ng mL⁻¹ as a pragmatic threshold; no outcome‐validated cut-off exists.
• Safe neuraxial threshold: drug-calibrated anti-Xa < 25–30 ng mL⁻¹ (rivaroxaban/apixaban/edoxaban). Validate with the local laboratory and document result before proceeding.

Practical Take-aways

1. Timing first, labs second. When the interval since the last dose is clear and kidney function normal, guideline hold-times remain the safest trigger to proceed; tests add little.
2. Use a test when timing is uncertain or compressed. A single INR, aPTT/ACT, anti-Xa or dTT/Etc can confirm drug clearance and avoid unnecessary delay—or flag residual activity that mandates postponement.
3. Assay must match the drug. A generic anti-Xa assay will under-estimate apixaban or rivaroxaban; insist on a drug-calibrated test or do not rely on the result.
4. Normal result ≠ zero risk. Even with reassuring labs, maintain 4-hourly neuro-checks for 24 h after neuraxial or deep blocks.
5. Do not use platelet-function or viscoelastic tests to “shortcut” recommended intervals. Current evidence does not support their predictive value for spinal haematoma.

Post-Block Clinical Monitoring

• Neurological checks (motor power, sensory level, back pain) q4 h for 24 h after neuraxial or deep-plexus block in any anticoagulated patient.
• Continue until 12 h after last high-dose anticoagulant or after catheter removal plus next safe anticoagulant dose, whichever is longer.
• Immediate MRI and neurosurgical referral if red-flag symptoms arise.
• If HIT is confirmed (platelet drop ≥ 50 % or < 100 ×10⁹ L⁻¹ and positive PF4 assay), stop all heparins, start argatroban or fondaparinux, and defer neuraxial or deep plexus block until platelet recovery and stable alternative anticoagulation are achieved.

Bridging & Reversal (evidence-based algorithm)

Step	Action	Evidence highlights
1–Risk-stratify thrombo-embolism (TE)	Very-high: • VTE < 6 wk • Stroke/TIA < 3 mo • Mechanical mitral or caged-ball/tilting-disc valve • APS with arterial event. High: • VTE 6 wk–3 mo • CHADS-VASc ≥ 7 (or 5-6 + recent stroke) • Bileaflet aortic mechanical valve + risk factors. Moderate: • VTE 3–12 mo • CHADS-VASc 5-6. Low: • VTE > 12 mo • CHADS-VASc 0-4 (no stroke) • Bileaflet aortic valve with no risk factors.	ACC/AHA 2024 Table 14; ASRA-ESRA 2022.
2–Assess surgical/neuraxial bleeding risk	High bleeding risk = neuraxial/deep plexus block, cancer surgery, major spine/brain/joint, vascular; Low = cataract, dental, ports.	ASRA 2025; PAUSE & BRIDGE trials.
3–Decide on bridging	• Warfarin:  –No bridge for low/moderate TE risk (BRIDGE RCT ↑major bleed 3.2 % vs 1.3 %, no ↓TE).  –Therapeutic LMWH bridge only in very-high / high TE risk and high-bleed procedures avoided; consider prophylactic LMWH instead.  –Stop warfarin 5 d pre-block, start LMWH (1 mg kg⁻¹ BID or 1.5 mg kg⁻¹ OD) once INR < 2; give last LMWH dose ≥ 24 h pre-puncture (≥ 36 h if renal CrCl < 30 mL min⁻¹).	BRIDGE RCT NEJM 2015; ACC/AHA 2024 Class III-Harm for routine bridging, Class 2a for high-risk only.
	• DOACs (dabigatran, apixaban, rivaroxaban, edoxaban, betrixaban): Do not bridge–predictable short half-life; bridging adds bleeding without TE benefit (PAUSE trial major bleed 1.6 %, no LMWH).	PAUSE study; ACC 2024 “no role for heparin bridging for DOACs”.
	• Mechanical heart valves:  –Mitral/older aortic valve → bridge with therapeutic LMWH.  –Bileaflet aortic valve + no stroke/TIA and CHA₂DS₂-VASc < 5 → no bridge (low risk).	ESC 2023 valvular guidance; ACC/AHA 2024.
	• Active cancer or APS: consider risk-adjusted LMWH bridge; observational QI study showed ↓bleeding with patient-tailored protocols vs blanket bridging.	BMC Anaesthesiol 2023 risk-adjusted bridging.
4–Post-operative LMWH “re-bridge”	Start once haemostasis secure:  –Low-bleed procedure: 24 h (prophylactic) → escalate to therapeutic after 48 h.  –High-bleed / neuraxial: wait ≥ 48 h; remove catheter first (see timing table).	ASRA 2025; ACC/AHA 2024
5–Reversal for urgent block / bleed	• Warfarin: 4-factor PCC 25–50 IU kg⁻¹ + 5 mg IV vit K. • FXa inhibitors: Andexanet alfa (bolus + infusion) or PCC 50 IU kg⁻¹ if unavailable. • Dabigatran: Idarucizumab 5 g IV. • Heparins: Protamine (1 mg per 100 IU heparin in last 2 h; max 50 mg). Antiplatelet reversal: if life-saving neuraxial block or uncontrolled bleeding is required within the P2Y₁₂ wash-out period, transfuse 1 apheresis platelet concentrate (≈ 1 pool); repeat once if platelet inhibition persists. Evidence is limited; use only when no pharmacological alternative exists.	ASRA-ESRA 2022; ESAIC 2021 pharmacology table.
6–Suspected neuraxial haematoma	STAT neuro exam → stop anticoagulant → urgent MRI/CT → surgical decompression ≤ 8 h from symptom onset.	ASRA 2025 safety statement.

• Ciraparantag (aripazine)–broad-spectrum reversal of heparins and DOACs; in phase-III trials (not yet licensed). Monitor guideline updates for future availability.*
• PAUSE management strategy (skip 0–2–2 days depending on bleed risk, no bridging) in 3 007 atrial-fibrillation patients produced major-bleed 1.6 %, arterial TE ≤ 0.5 %.
• ACC 2024 review states:
  • “Uninterrupted DOAC is preferred for some low-bleeding-risk procedures.”
  • “Hold factor-Xa inhibitors 2 days and dabigatran 2-4 days for higher-risk surgery.”
  • “There is no role for LMWH bridging for DOACs because the drug-free window is already short.”
• For high-bleeding-risk operations you simply pause the DOAC for the recommended 2to 4-day window and restart 2–3 days later, without heparin bridging.
• For truly low-risk procedures most patients can stay on their DOAC (or at most skip a single dose).

Patients on Dual Antiplatelet Therapy

Scenario	Current recommendation (ACC / AHA peri-operative guideline 2024)	Key peri-operative antiplatelet points
Balloon angioplasty without stent	Postpone elective non-cardiac surgery (NCS) ≥ 14 days after procedure if ≥ 1 antiplatelet drug would need to be stopped.	Continue aspirin 75–100 mg day⁻¹ where possible.
Bare-metal stent (BMS)	> 30 days after PCI before interrupting any component of dual antiplatelet therapy (DAPT). Surgery within 30 days is potentially harmful.	If surgery cannot be delayed to ≥ 30 days, keep full DAPT (aspirin + P2Y₁₂ inhibitor) unless life-threatening bleeding risk. Bridging with i.v. cangrelor may be considered when DAPT interruption is unavoidable.
Drug-eluting stent (DES)–placed for acute coronary syndrome (ACS)	Defer elective NCS ≥ 12 months if interruption of ≥ 1 antiplatelet agent is required.	Within 12 months keep DAPT if surgery must proceed; weigh bleeding vs stent-thrombosis risk in a multidisciplinary forum.
DES–placed for chronic coronary disease (stable CAD)	Defer elective NCS ≥ 6 months. If the risk of delaying surgery exceeds cardiac risk, NCS may be considered ≥ 3 months after PCI when a short (≤ 5 day) interruption of the P2Y₁₂ inhibitor is essential.	Aspirin should be continued; stop clopidogrel/ticagrelor 5 days (prasugrel 7 days) before surgery if absolutely required, and restart as soon as haemostasis permits (within 24 h is preferred).
Any PCI ≤ 30 days (BMS or DES) requiring antiplatelet interruption	Elective NCS is strongly discouraged because of very high stent-thrombosis risk.	Proceed only if life-saving surgery; maintain DAPT throughout or arrange i.v. bridging (e.g. cangrelor).
High cardiac-risk patients without stent (e.g. recent MI, high CHADS-VASc)	Continue aspirin peri-operatively; withhold clopidogrel/prasugrel/ticagrelor for 5–7 days if surgical bleeding risk is high, then restart within 24 h once haemostasis secured.	Applies to open vascular, major spine or intracranial procedures where bleeding consequences are extreme.
Low cardiac-risk patients without stent	Discontinue P2Y₁₂ inhibitor 5–7 days before surgery; consider stopping aspirin if bleeding risk outweighs ischaemic benefit, then restart antiplatelet(s) within 24 h post-op.	Routine “cover” with aspirin in patients who were never on it is not beneficial.

Clinical Pearls

• Aspirin 75–100 mg day⁻¹ should be continued in almost all patients with previous PCI unless surgical bleeding risk is extreme.
• If a P2Y₁₂ inhibitor must be paused in a patient with a stent < 6 months old (DES) or < 30 days old (BMS), consider short-acting i.v. cangrelor bridging.
• Decisions should be multidisciplinary, balancing haemorrhage risk, stent-thrombosis risk and the consequences of delaying surgery.

Peri-operative Venous Thrombo-embolism (VTE) Prophylaxis

Risk Assessment Framework

Caprini Venous Thrombo-embolism (VTE) Risk Assessment Model (2021 update)

Points	Risk factor
1 point	Age 41–60 yr • Minor surgery (<45 min) • BMI ≥ 25 kg m⁻² • Swollen ankles (current) • Varicose veins • Sepsis (<1 mo) • Pregnancy or ≤ 1 mo post-partum • Oral contraceptives or HRT • History of unexplained/recurrent miscarriages • Abnormal pulmonary function (COPD, asthma) • Acute myocardial infarction (<1 mo) • Congestive heart failure (<1 mo) • Bed rest > 72 h • Immobility (limb cast, paralysis)
2 points	Age 61–74 yr • Arthroscopic or laparoscopic surgery ≥ 45 min • Major open surgery < 45 min • Malignancy (active or within 1 yr) • Confined to bed (>72 h) with plaster immobilisation • Central venous access • Inflammatory bowel disease • Chemotherapy or radiotherapy within 6 mo
3 points	Age ≥ 75 yr • Major surgery ≥ 45 min • Emergency abdominal or thoracic surgery • History of VTE (DVT/PE) • Known thrombophilia • Stroke (<1 mo) • Acute spinal-cord injury (<1 mo) • Chronic kidney disease (eGFR < 30 mL min⁻¹) • Severe lung disease requiring oxygen
5 points	Hip, pelvis or lower-limb fracture • Hip or knee arthroplasty • Major trauma (> 12 h) • Spinal surgery with instrumentation • Multiple major injuries • Elective neurosurgery • Acute leukaemia • Bone-marrow transplant

Interpreting the Total Score (caprini Et Al. 2021)

Total score	VTE risk category	Estimated post-operative VTE incidence without prophylaxis	Prophylaxis recommendation (CHEST 2022 / NICE NG89)
0	Very low	< 0.5 %	Early mobilisation only
1–2	Low	~ 1 %	Mechanical prophylaxis (IPC or GCS); pharmacological cover usually not required
3–4	Moderate	1–2 %	IPC ± GCS plus LMWH or low-dose UFH (unless contra-indicated)
≥ 5	High	2–6 % (≥ 8 % if ≥ 8 points)	IPC ± GCS and LMWH/UFH or DOAC*; extend to 28–35 days after major cancer surgery or hip/knee arthroplasty

• Applying the score:
  • 0–2 (low): early mobilisation only.
  • 3–4 (moderate): IPC ± GCS plus LMWH/UFH if bleeding risk is low.
  • ≥ 5 (high): IPC + GCS and LMWH/UFH or DOAC; extend prophylaxis 28–35 days in hip/knee arthroplasty or major cancer surgery.
  • ≥ 8 (very high): consider dual prophylaxis (mechanical + pharmacological) and extended 4-week course irrespective of procedure type.
• Add points cumulatively for all present risk factors at the time of surgery or hospital admission.
• The model predicts symptomatic DVT/PE and informs duration/intensity of prophylaxis.
• For day-case or minimally invasive procedures, use the score but consider shorter prophylaxis courses.
• The Caprini tool is validated across surgical specialties and endorsed by the American Society of Hematology (2023) and NICE (UK) for individualised risk assessment.
• Continue IPC/GCS until the patient ambulates independently ≥ 3 times/day or until hospital discharge, even when pharmacological prophylaxis has started.

Non-pharmacological Measures (all risk Tiers unless contraindicated)

Modality	Start	Stop	Comments
Intermittent pneumatic compression (IPC)	Before induction	On full mobile ambulation	First-line where pharmacological prophylaxis is delayed/contra-indicated.
Graduated compression stockings (GCS, 18 mm Hg)	Pre-op	Until discharge or patient mobile ≥ 3×/day	Ensure correct sizing; omit in severe PAD.
Early, aggressive mobilisation	Day 0	Lifelong	Document in post-op orders; most cost-effective intervention.
Inferior vena-cava (IVC) filter	Only if anticoagulation absolutely impossible and acute proximal DVT/PE present	Remove when anticoagulation feasible	No role as primary prevention.

Pharmacological Prophylaxis–Timing & Duration

Drug (prophylactic dose)	First dose pre-/post-op	Daily schedule	Stop (standard)	Extended-duration indications
Enoxaparin 40 mg SC	Usual surgery: 2 h pre-incision or 6–12 h post-op if high bleeding risk / neuraxial catheter in situ	OD	Day 7–10	Hip/knee arthroplasty, major cancer abdo/pelvis, lower-limb fracture: continue 28–35 d
Dalteparin 5 000 IU SC	2 h pre or 6–12 h post	OD	Day 7–10	Same as above
Fondaparinux 2.5 mg SC	≥ 6 h post-skin closure	OD	Day 7–10	Hip fracture surgery or cancer: extend to 28 d
Rivaroxaban 10 mg PO	6–10 h post-op, once haemostasis secure	OD	Day 10–14	Total hip replacement (THR): 35 d
Apixaban 2.5 mg PO	12–24 h post-op	BD	Day 10–14	THR: 35 d
UFH 5 000 IU SC	2 h pre-incision	8-hourly	Until mobile or switch to LMWH	Preferred in severe renal failure (CrCl < 15 mL min⁻¹)
Low-dose aspirin 75–100 mg PO	6 h post-op	OD	Day 28–35 (orthopaedics)	AAOS-endorsed option for isolated THR/TKR where bleeding risk high

• Key timing principles
  • With neuraxial or deep plexus catheters: defer first LMWH/fondaparinux until ≥ 12 h after puncture; remove catheter ≥ 12 h after last prophylactic LMWH dose and ≥ 36 h after fondaparinux, then postpone next dose ≥ 4–6 h.
  • Resume prophylaxis immediately if unexpected delay > 24 h and patient remains immobile.
  • Re-assess daily: hold drug if active bleeding, platelets < 50 × 10⁹ L⁻¹ or spinal haematoma suspected.

Special Populations

Group	Adjustment
Renal impairment (CrCl < 30 mL min⁻¹)	LMWH: halve dose or use UFH 5 000 IU 8-hourly; avoid fondaparinux.
Obesity (BMI > 40 kg m⁻²)	Enoxaparin 40 mg BD or weight-based 0.5 mg kg⁻¹ OD. If BMI: > 50 or weight > 150 kg.Check anti-Xa (goal 0.2–0.4 IU mL⁻¹) after 3rd dose
Pregnancy / puerperium	LMWH preferred; start 6 h post-C-section or 12 h post-vaginal delivery; continue 6 weeks if high risk.
Paediatric ≥ 12 y	Dalteparin 50 IU kg⁻¹ SC OD (max 5 000 IU).
South-African resource-limited settings	Prioritise mechanical prophylaxis + UFH where LMWH unaffordable; document daily mobility review (SASA Day-Case & Arthroplasty Guideli

When to Omit or Stop Pharmacological VTE Prophylaxis

• Active intracranial or GI bleeding, platelet count < 50 × 10⁹ L⁻¹.
• Spinal/epidural haematoma suspicion–hold immediately and investigate.
• Neuraxial catheter in situ and insertion < 6 h ago (see timing table above).
• Epidural haematoma decompression surgery–restart only after neurosurgical clearance (usually ≥ 24–48 h).

Links

• Ortho regionals
• Obstetrics Anticoagulation|Obstetrics Anticoagulation
• Upper limb blocks
• Lower limb blocks
• Truncal blocks
• Neuraxial and Epidural

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References:

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18. Baron TH, Kamath PS, McBane RD. Management of antithrombotic therapy in patients undergoing invasive procedures. N Engl J Med. 2013;368(22):2113-2124. (Updated 2020 ACCP guidance).
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Summaries:

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