Perioperative international normalized ratio level is a poor predictor of postoperative bleeding complications in dermatological surgery patients taking warfarin

Background When planning dermatological surgery with patients on warfarin, clinicians must balance the risk of bleeding complications against that of a thrombotic event if anticoagulation is interrupted. Objectives To evaluate the frequency of bleeding complications in warfarinized subjects undergoing cutaneous surgery, and to correlate the risk of bleeding with the international normalized ratio (INR) at the time of surgery. Methods In this prospective controlled observational study, 65 patients on warfarin underwent excision of 70 cutaneous tumours. Mean perioperative INR was 2.1 (range 1.0-4.2). A group of 92 nonwarfarinized controls underwent excision of 100 tumours by the same surgeons. The INR of those on warfarin was checked at the time of surgery. Intraoperative and postoperative bleeding was recorded by the operating surgeon. Results No increase in bleeding tendency during surgery was seen in those on warfarin when compared with controls. Five patients on warfarin (8%) reported moderate or severe postoperative bleeding. No significant postoperative bleeding was reported by controls (P = 0.01). All patients on warfarin with bleeding complications had an INR of < 2.6 at the time of surgery. Conclusions Bleeding risk could not be correlated with INR and this study demonstrates that even when INR is in the therapeutic range the risk of postoperative bleeding is increased for warfarinized patients. The need for meticulous haemostasis in all patients on warfarin should not be forgotten and patients should be made aware preoperatively of the small but significant risk of postoperative bleeding complications.