Lethal cause of abdominal pain: a diagnosis not to be missed

Abstract

A 77-year-old woman was brought to the accident and emergency department with a 11-day history of abdominal pain. She was in shock and required resuscitation. She had attended the accident and emergency a few days before and had been discharged home with a diagnosis of non-specific abdominal pain. The previous abdominal X-ray is shown in Figure 1. Her past medical history included bilateral below knee amputation for peripheral vascular disease, pacemaker for heart block and hypertension. On examination, post-resuscitation, she was confused and apyrexial with a heart rate of 100 beats/minute and a blood pressure of 110/70 mmHg. Her abdomen was diffusely distended with minimal tenderness in the epigastrium and supra-umbilical region. There was no rigidity or guarding. Bowel sounds were normal. Digital rectal examination showed soft faeces. Blood test showed a haemoglobin of 6.6 g/dl (down from 11 g/dl during her previous accident and emergency visit). There was slight impairment of renal function with a urea of 11 mg/dl and creatinine of 160 mg/dl. The rest of the blood tests were within normal limits. Arterial blood gases showed metabolic acidosis with a pH of 7.2 and lactate of 3 mmol/litre. A computed tomography scan of the abdomen was performed. 1. What is the differential diagnosis? 2. What can you find in the abdominal X-ray? 3. What can you find in the computed tomography scan? 4. What is the treatment? 5. What is the prognosis of this patient? The differential diagnoses in this case are peritonitis from hollow viscus perforation, ischaemic bowel and leaking abdominal aortic aneurysm. The abdominal X-ray (Figure 1) shows minimal dilatation of the right and transverse colon and a tortuous calcified aorta. However the upper aortic calcification is not obvious. Computed tomography scan shows an abdominal aortic aneurysm which commences immediately distal to the origin of the right renal artery with not involving the bifurcation. There is leakage from this aneurysm (Figure 2b arrow) which has a maximum diameter of 5 cm. There is a periaortic haematoma which extends anteriorly to displace the loops of bowel anteriorly (Figure 2b). There is free fluid in the peritoneal cavity (Figure 2a). The right kidney is well perfused but the left kidney shows no evidence of perfusion (Figure 2c). There are some calculi in the left pelvis. In this patient, palliation was felt to be the most appropriate treatment option (her case was discussed with the on-call vascular surgeons). The patient died a few hours after her hospital admission. In a relatively fitter patient, open surgery is the treatment of choice.