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Urgent contrast enhanced computed tomography in the diagnosis of acute bowel infarction
  1. L R Gellett,
  2. S R Harries,
  3. C A Roobottom
  1. Department of Clinical Imaging, Derriford Hospital, Plymouth, Devon, UK
  1. Correspondence to:
 Dr L R Gellett, Department of Radiology, Abdominal Division, Vancouver General Hospital, 899 West 12th Avenue, Vancouver, Canada V5Z 1M9;
 lauragellett{at}hotmail.com

Abstract

Bowel infarction commonly presents as an acute abdomen that rapidly progresses to severe shock. The diagnosis is often not clinically suspected. Three cases are described where the diagnosis was made during dynamic contrast enhanced computed tomography (CT), when gas was demonstrated in the portal venous system and liver. Two patients died during surgery, the third survived because of the prompt diagnosis made on CT, and subsequent surgical treatment. The radiological findings are reviewed.

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CASE 1

A 72 year old man presented with a three week history of anorexia and worsening epigastric pain. Over the next five days the severity of his abdominal pain increased and was associated with rebound tenderness and active bowel sounds. Plain abdominal radiography, amylase and white cell count (WCC) were normal. Computed tomography (CT) was eventually performed and this showed extensive gas within the portal venous system (fig 1). At operation the distal small bowel was found to be ischaemic. The patient died shortly after surgery.

Figure 1

Contrast enhanced CT through the upper abdomen shows peripheral branching gas densities in the distribution of the left portal vein (black arrow).

CASE 2

A 52 year old female patient was admitted with sudden onset generalised abdominal pain and diarrhoea. On examination she was hypotensive and tachycardic, with abdominal peritonism. Laboratory investigation revealed a raised WCC, and abdominal radiography demonstrated multiple gas filled loops of bowel. CT 24 hours after admission demonstrated gas within the portal venous system, superior mesenteric vein (SMV) and throughout the walls of the large bowel and terminal ileum (fig 2). The patient died during surgery and a postmortem examination revealed luminal thrombus within the superior mesenteric artery (SMA) and associated small bowel and right colonic infarction.

Figure 2

CT demonstrating extensive gas throughout the walls of the large bowel and terminal ileum (black arrows).

CASE 3

A 62 year old man was admitted to hospital for control of his warfarinisation, with an INR >10. He developed sudden onset lower abdominal pain and bright red blood per rectum five days after admission, with tenderness in his right iliac fossa and absent bowel sounds. Investigation revealed a raised WCC. Abdominal radiography demonstrated small bowel dilatation with separation of the loops. CT was performed immediately for a suspected retroperitoneal bleed. This demonstrated air in the small bowel wall and SMV (figs 3A and 3B). At operation infarction of the upper jejunum was found. The patient made a full recovery.

Figure 3

(A) Post contrast CT demonstrating air fluid level within the SMV (black arrow) but no filling defect in the SMA (white arrow). (B) CT showing air within the mesenteric veins (white arrow).

DISCUSSION

Bowel infarction is a common disorder that continues to be associated with a high mortality rate because of difficulties in making the diagnosis both clinically and radiologically. Plain abdominal film findings are usually normal or non-specific.1 The demonstration of portal vein gas or intramural gas on plain film are highly specific but late findings seen in a small minority of patients. The demonstration of portal vein gas on plain film is associated with an overall mortality rate of 75% because of its association with bowel infarction.2 Plain films in patients with suspected mesenteric infarction are therefore performed to exclude other causes for abdominal pain.

Contrast enhanced CT is increasingly being used in the examination of patients with severe abdominal pain of unknown aetiology, and bowel infarction is only one of a number of potential diagnoses. Non-specific CT findings in acute mesenteric ischaemia include bowel distension, bowel wall thickening, mesenteric oedema, and ascites. These findings are unfortunately also seen in a wide variety of other inflammatory, infective, and neoplastic conditions. Findings with a specificity of >95% on contrast enhanced CT include SMA or SMV thrombus, intramural bowel gas, portal vein gas, focal lack of bowel wall enhancement and ischaemia of other organs.3 The detection of at least one of these signs on contrast enhanced CT results in a sensitivity of 64% for the diagnosis of acute mesenteric ischaemia.3

Contrast enhanced CT is of value in clinical practice as bowel infarction is only one of a number of potential diagnoses. Careful evaluation of patient history and clinical examination in the emergency room should lead to a suspicion of mesenteric ischaemia. If the patient is to have any chance of survival, as was shown by the third case in our series, early referral for contrast enhanced CT is mandatory.

Contributors

Simon Harries and Carl Roobottom initiated the original idea for the paper and provided the index cases. Laura Gellett carried out the literature search and wrote the paper. Carl Roobottom made amendments to the original draft of the paper. All authors proof read the paper before submitting the manuscript for publication. Laura Gellett is the guarantor of the paper.

REFERENCES

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