Urgent extraction in a patient on warfarin and aspirin with a supratherapeutic INR

Answer: a single, simple extraction can reasonably go ahead today, but only after specific safeguards - and it is equally defensible to defer if any safeguard cannot be met.

Reasoning:

• She is on warfarin plus an antiplatelet, so she is in a higher bleeding-risk group than a warfarin-only patient.
• Current guidance for primary care is that warfarin should not be stopped for simple extractions; instead the INR is checked within 24-72 hours and a single simple extraction is acceptable at an INR of 4.0 or below, provided local haemostatic measures are used. Her INR of 3.4 falls within that range but above her own therapeutic target of 2.0-3.0.
• The INR was taken yesterday and she took her dose last night, so the value is current enough to act on.
• Bleeding risk must be balanced against the risk of leaving a necrotic, infected tooth in a patient who will be abroad in a week - a dental emergency in another country, on anticoagulants, is a worse scenario.

Safeguards before starting:

1. Confirm the INR result with the anticoagulation clinic or the laboratory rather than accepting a verbal report, and tell them what you plan to do.
2. Confirm there is no history of abnormal bleeding, no liver disease and no other interacting drug; check her most recent renal function.
3. Control the blood pressure - 150/95 is acceptable for a simple extraction in primary care, but re-measure calmly; defer if it is ≥180/110.
4. Plan a single-tooth, atraumatic procedure with a clear haemostatic protocol and a follow-up contact.

If the INR had been above 4.0, or if the extraction were surgical/multiple, the correct decision would be to defer and refer to a hospital or specialist setting - not to alter the warfarin herself.

Intra-operative:

• Single tooth only; minimise trauma - periotome, careful luxation, avoid raising a flap if possible, avoid excessive bone removal.
• Aspirate gently and use a local anaesthetic with vasoconstrictor; infiltrate rather than block where feasible to reduce the risk of a deep haematoma.
• Secure haemostasis with a pressure pack (gauze, bitten firmly for 15-20 minutes) before letting the patient leave the chair.
• If oozing persists: place a haemostatic agent (oxidised cellulose or collagen sponge) in the socket, suture the socket (figure-of-eight or interrupted), and re-apply pressure.
• Consider tranexamic acid 4.8% mouthwash, 10 mL rinsed for 2 minutes four times daily for 2 days, not swallowed - good evidence for reducing post-extraction bleeding in anticoagulated patients.

Post-operative instructions (written):

• Do not rinse, spit, smoke, drink hot fluids or exercise for 24 hours; do not disturb the socket with the tongue or fingers.
• Soft cold diet; continue normal oral hygiene elsewhere in the mouth.
• Continue warfarin and aspirin exactly as prescribed - this must be stated explicitly, as patients often assume they should stop.
• If bleeding starts: firm pressure with clean gauze for 20 minutes; if it does not stop, contact the practice or attend the emergency department.
• Provide a direct telephone number and arrange review in 5-7 days, before she travels. Warn her that dental care abroad should mention her anticoagulant status.

Analgesia - stop the ibuprofen. NSAIDs are the wrong choice here for three reasons: they inhibit platelet cyclo-oxygenase and impair platelet aggregation (adding to the antiplatelet effect of aspirin and the anticoagulant effect of warfarin); they increase the risk of gastrointestinal bleeding in a patient on dual antithrombotic therapy; and they can raise blood pressure and cause renal impairment.

Replace with paracetamol 1 g up to four times daily (maximum 4 g/day), which does not affect platelets or INR. Note that sustained use of high-dose paracetamol can modestly raise the INR, so she should stay within the standard dose.

Antibiotics - not indicated. A chronic periapical radiolucency with no swelling, no pus, no fever and no systemic involvement is managed by removing the source, which is the extraction itself. Prophylactic or 'cover' antibiotics would not reduce post-extraction infection in a healthy patient and would add interactions.

If an antibiotic were genuinely needed (e.g. spreading infection with systemic signs), the interaction rules are:

• Avoid metronidazole - it inhibits CYP2C9 and markedly potentiates warfarin, raising INR and bleeding risk. If it is unavoidable, the warfarin dose must be reduced and the INR monitored closely with the anticoagulation team.
• Also avoid macrolides (erythromycin, clarithromycin), fluconazole and ciprofloxacin for the same reason.
• Amoxicillin (or amoxicillin-clavulanate) has no significant interaction with warfarin and is a reasonable choice if treatment is required; it does not interact with her aspirin either.

Document the medication review and the reasons for declining her requests - she asked for 'strong painkillers and antibiotics', and the discussion itself is part of safe prescribing.