This patient with a history of bariatric surgery has a nonhealing bruise with hemarthrosis (arthrocentesis with xanthochromia) 2 weeks following knee trauma, along with petechiae, mild anemia, and normal coagulation studies.  This presentation is concerning for vitamin C deficiency (scurvy).  Vitamin C is a water-soluble vitamin found in citrus fruits and vegetables.  Deficiency typically occurs in patients with significant malnutrition, alcohol use disorder, or intravenous drug use.  However, cases can occasionally arise in populations that voluntarily restrict the intake of certain foods (eg, following bariatric surgery) or in situations where access to fruits and vegetables is severely limited (eg, refugee camps).

Vitamin C deficiency generally manifests ~3 months after insufficient intake with follicular hyperkeratosis, perifollicular hemorrhage, coiled hairs, arthralgia, ecchymosis, petechiae, and/or gingivitis.  Because vitamin C facilitates collagen synthesis, deficiency can lead to impaired wound healing and exacerbate bleeding.  Laboratory studies often reveal mild anemia (possibly due to blood vessel fragility and bleeding), but platelet count, prothrombin time (PT), and activated partial thromboplastin time (PTT) will be normal; signs of impaired macronutrient intake (eg, low albumin) can also sometimes occur.  The diagnosis is generally made clinically, and treatment with vitamin C supplementation (ascorbic acid) is curative.

Patients who undergo Roux-en-Y surgery are at greatest risk for fat-soluble vitamin and vitamin B₁₂ deficiency (due to reduced exposure of food to gastric acid and pancreatic enzymes), but vitamin C deficiency can sometimes occur due to poor adherence to postoperative dietary recommendations.

(Choice A)  Factor VIII inhibitors are autoantibodies against factor VIII that usually develop in the setting of pregnancy, malignancy, rheumatoid arthritis, or systemic lupus erythematosus.  Patients generally have easy bleeding, hematomas, and prolonged PTT.  This patient's normal PTT makes a factor VIII inhibitor unlikely.

(Choice B)  Acquired platelet dysfunction is usually seen in the setting of aspirin use, uremia, advanced liver disease, or cardiopulmonary bypass.  Although this can cause ecchymosis and easy bleeding, Roux-en-Y bypass is not associated with acquired platelet dysfunction; vitamin deficiency is far more likely.

(Choice C)  Small vessel vasculitis (eg, microscopic polyangiitis, granulomatosis with polyangiitis) usually causes palpable purpura and nonblanching petechiae; large ecchymoses and hemarthroses are less common.

Educational objective:
Patients who undergo Roux-en-Y gastric bypass are at risk for multiple vitamin deficiencies.  Fat-soluble vitamins and vitamin B₁₂ deficiency are most common, but vitamin C deficiency can occur in the setting of poor postoperative diet.  Vitamin C deficiency is associated with ecchymosis, petechiae, poor wound healing, perifollicular hemorrhage, coiled hairs, and gingivitis; platelet count, prothrombin time, and partial thromboplastin time will be normal.