Does occlusion of the inferior mesenteric artery cause small bowel ischemia?
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Dear Dr. Grief: I had a total colectomy 13 years ago. Just got the report from a CT angiography of abdomen/pelvis which notes that "the inferior mesenteric artery is chronically occluded". Since this artery is normally supplying blood to the colon, finding it to be occluded is what one would expect when the colon has been surgically removed. Is that right or do I have a problem? I'll see my GI Dr tomorrow, but I'd appreciate if you could enlight me on that in the mean time. Is having an occlusion of the inferior mesenteric artery likely to cause small bowel ischemia? Thank for your answer and for your time. Yours sincerely, XXXX
Posted Wed, 5 Feb 2014 in Digestion and Bowels
Answered by Dr. Ivan R. Rommstein 49 minutes later
Brief Answer: Hi and welcome to XXXXXXX Detailed Answer: Thanks for the query. Small bowels blood supply come from jejunal and ileal branches of superior mesenteric artery. Inferior mesenteric artery supplies part of descending colon and upper part of rectum. In colectomy, subtotal colectomy, left hemicolectomy or rectal resections, inferior mesenteric artery is ligated( it means it is occluded with sutures). Usually it is done close to the origin at 1cm apart from aorta. So ct scan probably verified this surgical ligation(maybe radiologist didnt read your medical history),but also it may mean that this 1cm of residual IMA is occluded with thrombus. In every case,this is normal and since you dont have colon,you dont need IMA. So this is not cause of your symptoms. By the way, small bowel ischaemia usually results from occlusion of superior mesenteric artery and if this artery is normal,you dont have to be concerned about bowel ischaemia. Bacterial overgrowth is possible but it would develop much earlier. however you should do D-xylose test to rule this out. Bowel obstruction due to adhesion is very common after abdominal procedures,especially colectomies. It would manifest with abdominal distension and opstipation and the best way to diagnose it is to do barium exam,not CT scan. IBS isnt common after total colectomies. I dont know is there "pouch" in your case or stoma,but certain degree of abdominal pain and discomfort is expected and it should be terated mainly by changing dietary habits. Of course, if pain persist ,you should do those tests I ve mentioned to rule out some specific cause. Wish you good health. Feel free to ask. Regards
Follow-up: Does occlusion of the inferior mesenteric artery cause small bowel ischemia? 17 hours later
Dear Dr Romic, Thank you for your detailed answer to my concerns. Just to further inquire about the possibility of small bowel ischemia, I'd like to ask you a few more questions. You state that "Small bowels blood supply come from jejunal and ileal branches of superior mesenteric artery" and that if the superior mesenteric artery is normal I don't have to be concerned about bowel ischemia. The radiologist report indicates that the SMA is indeed OK, at least at the level of its main branch. There is no mention of the jejunal or ileal branches however. Perhaps reading of the scan was not thorough enough to look at this level or there was really nothing wrong here. So it's still possible that the ileal branch for instance or its ramifications (intestinal arteries?) might be somehow affected by say atherosclerosis, which would reduce blood flow and cause ischemic pain in a segment of ileum after eating. To be sure, should we consider an arteriogram with catheterization? or have the scan data be examined by a peer reviewer? Thank you in advance for your thoughts on that FJD
Answered by Dr. Ivan R. Rommstein 21 hours later
Brief Answer: Hi. Detailed Answer: Jejunal and ileal arteries are small but also visible on CT angiography,of course when catheterisation is used test is more specific. I am sure that radiologist would describe occlusion of these arteries if there was one. Rarely there is isolated occlusion of these small arteries,unless you have atrial fibrilation. usually,only SMA is problematic and SMA trombosis will cause serious consequances. Jejunal and ileal arteries form lot of collaterals so it should cause serious bowel infarction unless there is very severe occlusion. However,some chronic thrombosis or atherosclerosis of bowel arteries can be cause of unexplained abdominal pain, especially postprandial. If there are no proven adhesions or other causes of pain,then you can presume it is ischameic colitis and try with empiric therapy with antiagregatory medicines, blood lipids and sugar regulation and BP regulation. It should improve blood flow,but effect on symptoms are always unpredictable
Follow-up: Does occlusion of the inferior mesenteric artery cause small bowel ischemia? 24 hours later
Dear Dr Romic, Thank you for the info. Just a quick final follow up question. In case of ischemic ileitis, besides it causing pain after eating, could it also cause long-lasting, quasi-permanent lower left-sided abdominal (lower left quadrant below navel) pain irrespective of food intake? Thank you XXXX
Answered by Dr. Ivan R. Rommstein 8 hours later
Brief Answer: Hi Detailed Answer: Yes, it may cause pain which is not related to eating. this is similar to angina pectoris; in most cases it activates during exercise but sometimes it may be felt in rest. So intestinal blood flow is affected by digestion but also many other factors such as certain drugs,food that you take, stress, environment temperature etc. I dont think this is something related to surgery. the only possible such late complication could be adhesions formation. if there is no abdominal distension and you have frequent stool,then i doubt this can be bowel obstruction due to adhesions. Some patient use antispasmodics and it may help. but if pain persist,you should do barium follow-through. Till that,try to be patient and find food that which aggravate symptoms, eat smaller meals and lot of fluids. i am sure this is not something serious.