Cutaneous surgeons cannot predict blood-thinner status by intraoperative visual inspection.

Cutaneous surgeons cannot predict blood-thinner status by intraoperative visual inspection. Many surgeons believe they can discern whether a patient is taking an anticoagulant or a platelet inhibitor (blood thinner) by visual inspection of intraoperative oozing. However, there is little objective evidence to support this strongly held belief. The authors' objective was to determine whether visual inspection of intraoperative oozing during cutaneous surgery is accurate in identifying use of blood thinners. Blinded physician evaluators observed intraoperative oozing in 110 patients having cutaneous excisional surgery, rated the amount of oozing, and judged the likelihood that the patient was taking a blood-thinning agent. On the basis of the impressions of the most senior evaluator, 43 patients having used aspirin in the past 14 days or warfarin or vitamin E in the past 2 days, seven were judged as definitely or probably taking blood-thinning agents (sensitivity, 16.3 percent; 95 percent confidence interval, 6.8 to 30.7 percent). Of 67 patients who did not report recent use of a blood-thinning agent, just 11 were judged as definitely or probably taking blood-thinning agents (false-positive rate, 16.4 percent; 95 percent confidence interval, 8.5 to 27.5 percent). The level of training of the physicians doing the judging did not affect diagnostic sensitivity. Only 10 of the 110 patients (9.1 percent) were assessed as exhibiting excessive oozing, and of those, only four (40 percent) were actually taking a blood thinner. Results were similar when only patients who were taking aspirin or warfarin were analyzed. Thus, contrary to a commonly and strongly held belief, visual inspection of intraoperative oozing during cutaneous excisional surgery correlates poorly with blood-thinner use by patients. The data add further evidence that use of blood thinners does not have an objectively measurable adverse effect during cutaneous surgery.