A 2-year-old boy with sickle cell disease presents to the emergency department for lethargy. He is hypotensive, tachycardic, and has pale conjunctivae and dry mucous membranes. Laboratory studies are notable for hemoglobin 4 g/dL with a baseline of 7.5 g/dL and a high reticulocyte count. Which of the following is the most important step for preventing a recurrence of this condition after acute management?

A 45-year-old G3P3 woman is transfused one unit of packed red blood cell for symptomatic anemia. One hour after the completion of the transfusion she develops a fever of 100.7°F, but denies myalgias, shortness of breath, headache, or urticaria. On examination she has clear breath sounds bilaterally and no rash or ecchymosis. Which of the following interventions could have helped to prevent this reaction?

A 3-year-old girl is brought in after her mother noticed a rash and bruising over her trunk and extremities. She also has intermittent epistaxis over the past few days. She had an upper respiratory illness two weeks ago but otherwise is well. Examination reveals a well-appearing child with scattered petechiae and mild mucosal bleeding. Her hemoglobin is 12 g/dL, WBC 8,000, INR 1.0, and platelets 8,000. Which of the following is the most appropriate initial treatment?

A 27-year-old man with known history of hemophilia B presents to the emergency department after being hit in the head with a baseball bat. The patient denies loss of consciousness and is currently asymptomatic. Vital signs are within normal limits. Physical examination, including neurological exam, is normal. CT of the head without contrast is negative for acute hemorrhage. What is the most appropriate next step in management?

A 7-year-old boy presents to the emergency department with left upper quadrant abdominal pain and left lower chest pain. He has a history of sickle cell disease and has had frequent vaso-occlusive pain crises. His baseline hemoglobin is 9.3 g/dL. What combination of results would suggest a vaso-occlusive crisis without other complications related to sickle cell disease?

You diagnose a 43-year-old man with alcohol withdrawal. Lab results reveal a hemoglobin of 12 g/dL and an MCV of 115 fL. Which of the following is the most likely cause of these findings?

A 27-year-old man with a past medical history of sickle cell disease presents to the emergency department with shortness of breath and chest discomfort with exertion. The patient is requesting hydromorphone. His temperature is 100°F (37.8°C), blood pressure is 102/68 mm Hg, pulse is 120/min, respiratory rate is 18/min, and oxygen saturation is 99% on room air. Physical exam is notable for an uncomfortable-appearing, pale young man who vomits during his exam. His lungs are clear to auscultation. Laboratory values are notable for a hemoglobin of 5.5 mg/dL and a reticulocyte count of 0.5%. An initial ECG is notable for sinus tachycardia and his chest X-ray is shown above. Which of the following is the best next step in management?

A 5-year-old boy presents to the emergency department with malaise and bone pain that has gradually been worsening over the last few weeks. His T is 99.5°F (37.5°C), BP is 97/68 mm Hg, HR is 100 bpm, RR is 18/min, and oxygen saturation is 98% on room air. Physical exam reveals diffuse lymphadenopathy. Basic laboratory studies are notable for neutropenia, thrombocytopenia, and anemia. Which of the following is the most likely diagnosis?

A 49-year-old woman presents for evaluation of epistaxis. She reports 4 days of mild intermittent bleeding. Review of systems is significant for several weeks of fatigue and dyspnea on exertion. Her temperature is 98°F, heart rate is 115 beats/min, respirations are 20/min, blood pressure is 100/50 mm Hg, and SaO₂ is 98% on room air. Her exam is significant for petechiae and scattered bruising. She is not actively bleeding. Blood work reveals white blood cell count of 32,500/µL, hemoglobin of 6 g/dL, platelet count of 34,000/µL, prolonged prothrombin time, fibrinogen of 20 mg/dL, and D-dimer 14,500 ng/mL. Which of the following is the most effective management?

A 38-year-old woman presents to the ED following 1 week of progressive confusion and a rash. She is otherwise healthy except for a recent history of joint pains and facial erythema. Her vital signs are BP 110/70 mm Hg T 101.1°F, HR 105 beats per minute, RR 18, and oxygen saturation 98% on room air. Her exam is remarkable for conjunctival pallor and petechiae of the extremities and the oral mucosa. Which of the following is the most appropriate next step in management?