Risk of postoperative bleeding after dental procedures in patients on warfarin: a retrospective study Catherine Hong, BDS, MS, a Joel J. Napenas, DDS, b Michael Brennan, DDS, MHS, c Scott Furney, MD, d and Peter Lockhart, DDS e Objectives. The purpose of this retrospective study was to investigate the frequency of bleeding complications after invasive dental procedures in warfarinized patients and the possible risk factors. Study Design. The CoaguChek System was used to obtain an in-office international normalized ratio (INR) value for 122 patients (240 appointments), of which the mean age was 57.0  15.9 years and 50% were males. Demographic and clinical information were obtained retrospectively from dental and medical records. Results. Five episodes (mean INR: 2.0  0.8) of persistent bleeding were identified; 4 were after extractions and 1 was after implant placement. The frequency of bleeding was 4.8%, if only considering surgical procedures. Postoperative bleeding was significantly higher (P  .05) in patients who were taking anti-thrombotic medications in addition to warfarin. Conclusions. There is a low incidence of persistent bleeding after invasive dental procedures in warfarinized patients but the risk appears to increase with the use of concomitant anti-thrombotic medications. (Oral Surg Oral Med Oral Pathol Oral Radiol 2012;114:464-468) Warfarin is an anticoagulant often prescribed to prevent thromboembolic events. The need to modify or discon- tinue the patient’s anticoagulant medication before an invasive dental procedure is controversial, as noted from the various proposed protocols in the literature. 1,2 A physician’s decision to discontinue anticoagulation therapy, is often based on his or her experiences with general surgery procedures and the assumption that the risk of bleeding is analogous to that of a dental proce- dure. The literature is clear that clinically significant bleeding in properly anticoagulated patients following invasive dental procedures is a rare occurrence, 3-5 with fewer than 2% of bleeding events being uncontrolled by local hemostatic measures alone. 6 The international normalized ratio (INR) was devel- oped by the World Health Organization as a means of standardizing prothrombin time results among different laboratories. It is now widely used to monitor oral anticoagulant therapy and dosage planning for patients receiving warfarin. The INR for a healthy patient not on warfarin is 1 and the therapeutic INR for those on warfarin therapy typically ranges from 2 to 4, depend- ing on the reason for anticoagulation. In the past de- cade, it has become clear that routine discontinuation of oral anticoagulant therapy for dental procedures is not supported by the scientific literature, as it may put patients at unnecessary medical risk for thromboem- bolic events either from the cessation of anticoagulant therapy or because of “rebound phenomenon.” 7-10 Ako- pov et al. 9 found 14 cases of cardioembolic cerebral infarction that occurred owing to the discontinuation of warfarin for a medical procedure; all were found to be potentially preventable as the planned procedure either did not require discontinuation of warfarin, or in in- stances when withdrawal was warranted, no bridging therapy was instituted. Currently, most guidelines indicate that patients with an INR less than 3.5 can undergo minor oral surgery (e.g., simple single extraction) without any adjustment in anticoagulation (Level of Evidence: A). 1 Some INR guidelines allow for an upper safety limit of 4.0 8 ; however, the proposed upper safety limit has not been vigorously investigated and the risk of bleeding at these limits is particularly unclear for the more invasive oral surgical procedures. 1 Most studies on this subject focus on bleeding com- plications following dental extractions; however, given the larger surface area involved with dental office hy- giene procedures (e.g., gross debridement, scaling, and root planning) by comparison with a single tooth socket, hygiene procedures may carry similar or higher risk of bleeding than extractions. Furthermore, achiev- The abstract for this article was presented at the International Asso- ciation of Dental Research—South East Asia Division in 2011. a Assistant Professor, Division of Orthodontics and Pediatric Den- tistry, Faculty of Dentistry, National University of Singapore, Singa- pore. b Director, General Practice Residency, Department of Oral Medicine, Carolinas Medical Center. c Oral Medicine Residency and Associate Chair, Department of Oral Medicine, Carolinas Medical Center. d Chair, Department of Internal Medicine, Carolinas Medical Center. e Chair, Department of Oral Medicine, Carolinas Medical Center, Charlotte, NC. Received for publication Feb 8, 2012; returned for revision Apr 25, 2012; accepted for publication Apr 30, 2012. © 2012 Elsevier Inc. All rights reserved. 2212-4403/$ - see front matter http://dx.doi.org/10.1016/j.oooo.2012.04.017 Vol. 114 No. 4 October 2012 464