Management of patients with abnormal coagulation screens, on anticoagulants or antiplatelet medications

Abnormal coagulation screen

Prolonged prothrombin time or activated partial thromboplastin time

If possible, postpone surgery until the cause of the abnormality is identified.

Known or suspected congenital bleeding disorder

The patient must be managed in conjunction with a haemophilia centre: www.haemophilia.org

Low platelet count

Bone marrow aspiration and biopsy

May be performed in patients with severe thrombocytopenia without platelet support, with adequate local pressure.

Lumbar puncture, epidural anaesthesia, endoscopy and biopsy, surgery in non-critical sites

Count should be raised to at least 50 x 10⁹/l.

(BCSH Guildeline for ITP (2003) recommends 80 x 10⁹/l for epidural and spinal anaesthesia in pregnancy.)

Operations in critical sites such as the brain or eyes

Count should be raised to 100 x 10⁹/l.

Platelets should be given immediately before the procedure and the count checked before proceeding.

Medication

Illustrative management plans

Warfarin

Options:

• Continue warfarin through surgery, e.g. most dental procedures
• Reduce/stop until INR acceptable
• Stop warfarin until INR normal
• Stop and give ‘bridging’ heparin

In each case, balance the reason for warfarin treatment against the risk of discontinuing warfarin.

There are often locally agreed protocols for management of surgery in patients on anticoagulants, and these should be followed. Refer to BCSH Guidelines on oral anticoagulation (www.bcshguidelines.com) and Transfusion Toolkit (www.transfusionguidelines.org). The following are illustrative examples only.

Moderate/high risk of haemorrhage, low risk of thrombosis

e.g. lone atrial fibrillation; thrombosis or embolism > 6 months ago

Stop warfarin day 4 pre-op. Check INR day 1. If < 1.3, proceed. If still too high, give oral or IV vitamin K 1−2 mg (depending on INR and size of patient). Repeat INR on day of surgery. Restart warfarin on evening of operation or first post-operative day. Double maintenance dose first day only.

Moderate/high risk of haemorrhage, high risk of thrombosis

e.g. mechanical heart valve; thrombosis or embolism < 2 months ago

Stop warfarin day 4 pre-op. Check INR daily and start therapeutic dose of low molecular weight heparin (LMWH) when INR falls below therapeutic range. Give last dose 12−24 hours before surgery. Restart LMWH 12−24 hours post-op when haemostasis secure. Restart warfarin (usual dose) when oral intake possible post-op. Stop LMWH when INR in therapeutic range.

Low risk of haemorrhage, moderate risk of thrombosis

e.g. dental procedures, skin biopsy, cataract surgery

Halve normal maintenance dose of warfarin on days 4 to 2 pre-op. Normal dose from day 1 onwards. On day 0 check INR is in surgeon’s acceptable range. INR should be in therapeutic range again by day 2 post-op.

Surgery needed in > 6 hours

If no acute bleeding, give vitamin K 1−2 mg iv. Check INR at 6 hours.

Life-threatening bleeding, emergency surgery

Give prothrombin complex (PC) 30−50 units/kg plus vitamin K 1−5 mg iv (dose depending on requirement for continuing anticoagulation and INR). If PC not available, give FFP 15−20 ml/kg (e.g. 4 units in 70 kg adult). Further FFP doses given perioperatively as required.

Unfractionated heparins (UFH)

Stop iv infusion 6 hours before surgery for full reversal.

Low molecular weight heparins

(NB prolonged half life in renal failure)

Prophylactic dose: stop 8−12 hours pre-operatively.

Therapeutic doses: stop 18−24 hours pre-operatively.

Aspirin*

Even if last dose 5 days ago, consider as a cause of bleeding tendency

Preop: General guidance − stop the drug at least 7 days before planned surgery,

but note that there may be specific reasons for continuing the drug.

Intraop, post-op: Consider platelet transfusion early in a bleeding patient.

Clopidogrel*

Even if last dose 5 days ago, consider as a cause of bleeding tendency

Preop: General guidance − stop the drug at least 7 days before planned surgery,

but note that there may be specific reasons for continuing the drug.

Intraop, post-op: Consider platelet transfusion early in a bleeding patient.

Combination of aspirin and clopidogrel*

Even if last dose 5 days ago, consider as a cause of bleeding tendency

Preop: General guidance − stop the drug at least 7 days before planned surgery,

but note that there may be specific reasons for continuing the drug.

Intraop, post-op: Consider platelet transfusion early in a bleeding patient.

Non-steroidal anti-inflammatory agents

Impair platelet function but the effect is reversed when the drug is stopped

Preop: Stop the drugs a few days before surgery if there is no specific indication to continue.

Note:

*  A single dose of aspirin (75mg) or clopidogrel causes permanent blockade of platelet receptors and so impairs platelet function for about 5 days.