Blood transfusion reactions and transplant rejection Quiz: Ace Your Exams

A 57-year-old individual is brought to the emergency department by their spouse due to an episode of vomiting blood several hours ago. The patient has a history of chronic alcohol use and was diagnosed with liver cirrhosis two years ago. The patient vomits blood twice in the emergency department. Temperature is 37.2°C (98.9°F), pulse is 108/minute, and blood pressure is 92/62 mmHg. The patient appears to be disoriented. Two intravenous lines are secured, and the patient is started on a blood transfusion. Thirty minutes later, the patient begins experiencing chills and flank pain. In addition, the patient’s urine appears red. The patient’s temperature is now 38.6°C (101.5°F), pulse is 130/minute, and blood pressure is 80/50 mmHg. Transfusion is immediately stopped, and aggressive hydration is started. Which of the following is the most likely cause of this patient’s condition?