Elective Reversal of Warfarin Therapy
The following are guidelines for elective reversal of warfarin therapy.
Modifications for individual clinical circumstances may be necessary.
If rapid reversal is required, please refer to warfarin antidote section
of the general warfarin guidelines.
Low Dose Warfarin
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If INR < 1.5, no reversal is necessary for most surgeries: exceptions
include high risk surgeries, for example eye surgery, neurosurgery: use
complete warfarin reversal (i.e., normalize INR).
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Hold warfarin 72 hours prior to procedure.
Full Dose Warfarin
Patients on full dose warfarin are at risk of significant hemorrhage at
the time of surgery, therefore reversal is required.
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In certain cases (e.g., mechanical valves), if no anticoagulant therapy
is used even for a short period, there is high risk for thrombosis.
The following suggestions should be discussed with surgery.
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Discontinue warfarin 72 hours prior to surgery.
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Admit 24 hours prior to surgery and initiate heparin therapy without a
bolus at appropriate dose for age. See heparin
protocol for further monitoring guidelines.
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If the INR is greater than 1.5 twelve hours before surgery, administer
low dose vitamin K (0.5 mg) subcutaneously and recheck the INR approximately
6 hours later.
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Discontinue IV heparin 6 hours prior to surgery. Send a stat PT, and
aPTT 3 hours prior to surgery. Pre-op PT, aPTT should be within normal
limits.
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In consultation with surgery, resume IV heparin 8 hours post-op at previous
rate. Aim for an aPTT between 60-85 seconds.
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If the patient develops any signs of bleeding, discontinue heparin IV immediately.
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Oral warfarin can be resumed postoperatively in the evening of day 1 as
tolerated.
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Discontinue IV heparin when warfarin reaches the therapeutic range of an
INR between 2.0 to 3.0 (or, for mechanical valves, 2.5 to 3.5).
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Where the risk of thrombosis is low, if no anticoagulant is present
(e.g., no thrombotic event several weeks past)
-
Discontinue warfarin 72 hours prior to surgery.
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Admit the day or evening before (as would be usual practice). Measure
PT (INR) with results available prior to surgery.
-
Depending upon surgery, initiate maintenance dose of warfarin at the end
of the day of surgery.
This protocol is adapted from Guidelines distributed by the
Children's Thrombophilia Network, 1996.
Please direct all comments to: 
Last modification: April 15, 2001