A 77-year-old man presents to the emergency department (ED) in the early morning with a 4-hour history of severe, generalized abdominal pain. He describes some “cramp-like” abdominal pain and bilious vomiting yesterday, but states he simply “got on with things”. His condition had worsened considerably by late evening. He describes the sudden onset of generalized, constant, intense abdominal pain necessitating an ambulance call. On presentation to the ED, he has no current vomiting. He complains of episodic “indigestion” that has occurred off and on for the past few months. On further questioning, the patient reports experiencing infrequent but quite painful episodes of upper abdominal pain after meals which sometimes feel as if it is ”going to his right upper back” and is associated with intermittent vomiting. This lasts for minutes to hours after the intake of meals. He states that antacid preparations do little good in controlling these symptoms, but he takes them anyway. His past medical history includes hypertension, ischemic heart disease, chronic obstructive pulmonary disease (COPD), and gout. He has no significant past surgical history and his currently prescribed medications include aspirin, atenolol, furosemide, a glyceryl trinitrate spray, and 2 inhalers for his COPD (the names of which the patient does not know).

On examination, the patient is lying quite still. He does not appear cachectic, but does seem clinically dehydrated. His heart rate is 80 bpm, his blood pressure is 102/65 mm Hg, his capillary refill time is prolonged, and cool extremities are noted. He is afebrile. His lungs are clear to auscultation and his heart sounds are normal, with no added sounds. His abdomen is mildly distended, without visible scars, and there is no discoloration of the skin. When asked to cough, the patient winces in pain. No hernias are appreciated on examination. Palpation of the abdomen reveals generalized, diffuse tenderness and board-like rigidity. The abdomen is tender to percussion throughout all 4 quadrants, with a tympanitic note that is associated with loss of liver dullness. A rectal examination reveals a small amount of normal stool. Both femoral pulses are palpable and equal. The neurologic examination reveals no abnormalities. The peripheral examination is normal except for cool extremities. A fluid challenge of 500 mL 0.9% saline is given along with analgesia, and his vital signs improve. Laboratory investigations yield the following information: a white blood cell (WBC) count of 15.8 × 10³/µL (15.8 × 10⁹/L), C-reactive protein is 247 mg/L, sodium is 148 mEq/L (148 mmol/L), potassium is 3.1 mEq/L (3.1 mmol/L), urea is 28.6 mg/dL (10.2 mmol/L), creatinine is 1.5 mg/dL (131µmol L). Blood gas analysis reveals a pH of 7.31, HCO₃ of 20 mEq/L (20 mmol/L), _PCO₂ 4.1 kPa, and lactate of 23.4 mg/dL (2.6 mmol/L). Erect chest and supine abdominal radiographs are obtained (see Figures 1 and 2). A nasogastric tube is inserted and instructions are given for the patient to remain ‘nil by mouth’. He is catheterized and the urinary output is monitored along with the vitals. A further 1000 mL of 0.9% is initiated. Cefuroxime and metronidazole are started intravenously, and after urgent surgical consultation the patient is taken to the operating room for an emergency laparotomy.