Painful bruising: Gynecology, hematology, or just pill bias? A case report

A 23-year-old woman, G0, presented to the emergency department with painful bruising of the legs shortly after starting an oral contraceptive pill. The presumed diagnosis was pill-induced ecchymosis, and she was instructed to discontinue the medication. Her bruising resolved. However, the working diagnosis was later questioned as the patient had used other oral contraceptive pills in the past without any adverse reaction. In addition, there is robust literature associating these medications with thrombosis, not bruising. The patient later disclosed that she had concomitantly started an oral hair supplement along with her oral contraceptive pill. Analysis of the supplement contents revealed that it contained extract of Aesculus hippocastanum, a herbal anticoagulant, making this a much more plausible explanation for the ecchymosis. She then resumed the original oral contraceptive pill alone without any reaction. The case highlights how cognitive bias resulted in a misdiagnosis. Specifically, this case introduces the concept of pill bias, as the patient's unexplained bruising was presumed to be a result of her use of an oral contraceptive despite the lack of evidence to support this claim. This bias has the potential to impact clinical decision-making and lead to clinical errors.