A 23-year-old man is admitted to the hospital through the emergency depament with probable appendicitis. He has been having right lower quadrant abdominal pain for several days, which has been becoming increasingly worse. His temperature 39.2 C (102.6 F), blood pressure is 80/40 mm Hg, Pulse is 120/min, and Respiratory rate is 35/min. The abdomen is rigid with guarding. Multiple petechiae and purpura are present, and the patient is oozing blood from his oral mucosa. According to the patient's wife, he has not had bleeding problems in the past. The fact the abdomen is rigid with guarding suggests which of the following?