An 84 year old woman presented with acute, diffuse, colicky abdominal pain associated with intermittent vomiting, and had a six week background of general malaise and weight loss. Her medical history included atrial fibrillation, peripheral vascular disease, transitional cell carcinoma of the bladder, pulmonary embolism, and chronic obstructive pulmonary disease.

At initial assessment, the patient’s temperature was 36.7 °C, pulse 112 beats/min irregular, and blood pressure 91/71 mm Hg. Her respiratory rate was 20 breaths/min and her blood oxygen saturation was 98% on 15 litres oxygen.

On examination, the patient was dehydrated but alert and oriented. Her abdomen was rigid with absent bowel sounds. Digital rectal examination was tender for the patient and there were firm stools in the rectum. Both feet were pale, cold, and cyanosed with a capillary refill time of more than 5 seconds.

The patient’s arterial blood gas results on 10 litres oxygen were as follows: pH 7.33; pCO₂ 5.1 mm Hg; pO₂ 24.7 mm Hg; lactic acid 2.7 mmol/l; base excess 5.9 mmol/l; and HCO₃ 20.8 mmol/l. Her blood results were: haemoglobin 13.1 g/dl; white cell count 57.9 × 10⁹/l; neutrophils 54.6 × 10⁹/l; Na⁺ 138 mmol/l; K⁺ 4.2 mmol/l; urea 25.8 mmol/l; creatinine 363 μmol/l; and C reactive protein 307 mg/l. Her liver function tests were normal.

Electrocardiography confirmed atrial fibrillation. Urgent computed tomography of the abdomen and pelvis was performed the same day.⇓ ⇓