Question 1 of 170
A 19-year-old man presents with 18 hours of abdominal pain that began around the umbilicus and has now migrated to the right lower quadrant. He reports anorexia, nausea, and one episode of vomiting. Temperature is 38.1°C (100.6°F). On examination he has maximal tenderness at a point two-thirds of the way from the umbilicus to the right anterior superior iliac spine, with involuntary guarding. Palpation of the left lower quadrant elicits pain in the right lower quadrant. WBC is 14,200/µL with a left shift. Which of the following is the most likely diagnosis?