Arterial occlusive mesenteric ischemia

Case contributed by Dr Mohamed Saber

Presentation

Acute onset of severe abdominal pain mainly epigastric and right-sided, toxic look, high fever, and profuse sweating. The blood picture shows leukocytosis.

Patient Data

Age: 45 years
Gender: Male

Initial routine CT study

CT

Contrast-enhanced CT study (portal venous phase) showed the following:

  • moderate dilatation of the stomach seen distended with an internal air-fluid level. The transitional point is seen in the second part of the duodenum.
  • mildly distended small bowel loops were more prominent at the central abdomen with visualized intraluminal gas. Fluid distension of the right colon is also noted.
  • minimal intramural gas is seen involving a segment of an ileal loop.
  • poorly enhanced terminal superior mesenteric artery

Initially, the gastric dilatation distracted attention for a possible complicated duodenal ulcer disease. However, questionable minimal pneumatosis intestinalis and poor enhancement of the terminal SMA requiring further evaluation. Multiphasic CT was recommended.

CT study (arterial)

CT

There is complete occlusion of the distal main trunk of the superior mesenteric artery and its branches sparing left proximal jejunal branches and right middle colic artery. Distal jejunal branches, ileal branches, ileocolic and right colic arteries were occluded.

Urgent laparotomy was done and revealed extensive small bowel ischemia sparing a short segment of proximal jejunum. The distal jejunum, whole ileum, and cecum were gangrenous and resected. Jejuno-ascending anastomosis was performed.

Intra-operative

Photo

Intra-operative photos show clear demarcation between the pink color of viable proximal jejunum and dark gangrenous bowel loops.

Annotated CT images

Annotated image

Annotated images clarifying the main study findings

Normal SMA anatomy for comparison

Annotated image

Annotated images clarifying normal superior mesenteric artery and its branches in another normal case for comparison

Case Discussion

This is a very tricky case with unexpected outcomes either clinically or radiologically. The patient is middle-aged, his pain was mainly epigastric and right-sided, no atherosclerosis, no cardiac disease, no relevant past history. Why anyone could expect mesenteric ischemia on such occasions. One important clinical sign was present and could be helpful: the pain is not relieved by analgesics.

In this case, we note how subtle and easily missed bowel changes in arterial ischemia, the bowel wall is not thickened even thinned out and the pneumatosis was very subtle. Also, note how very clear mesenteric fat. This is completely different from venous ischemia in which there is marked wall thickening, intramural hemorrhage, and blurred edematous mesenteric fat.

In routine single-phase portal venous CT study, the mission will be more and more difficult as the degree of arterial enhancement will not be conclusive.

In this case, the proximal jejunum remains viable due to patent proximal jejunal branches and the right colon also remains viable despite right colic artery occlusion due to supply by the marginal artery of Drummond.

Surprisingly the patient survived postoperatively, and was discharged in a good condition however he will need special care due to his new problem "short-gut syndrome" 

Mesenteric ischemia is a nightmare for radiologists. Here are some important points to remember:

  • evaluation of the visceral arteries and veins should be a routine part of the assessment of CT abdominal study even the clinical scenario is so away from ischemia.
  • follow the artery and vein along their courses with the assessment of their small branches
  • consider multiphasic contrast-enhanced CT in cases of acute abdomen.
  • gangrenous bowel secondary to arterial mesenteric ischemia has no thickened wall but even thin wall and pneumatosis may be minimal if any. This is so different from venous mesenteric ischemia

Intraoperative photos contribution by Dr/ Adel Abdelwahed

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