<prompt> Most common cause of acute superior mesenteric aerial obstruction is: March 2012EmbolismThrombosisNon occlusive ischemiaAtherosclerosis  <response>: Ans: A i.e. Embolism Superior mesenteric aerial obstruction An embolus from the hea or aoa to the superior mesenteric aery is responsible for 40-50 of cases of acute small bowel ischemia Thrombosis of underlying atheromatous disease for approximately 25 and non-occlusive ischemia due to hypotension complicating myocardial infarction, hea failure, arrhythmias or sudden blood loss for approximately 25 of cases of acute small bowel ischemia Chronic mesenteric ischemia results from atherosclerotic stenosis affecting at least two of the celiac axis, superior mesenteric and inferior mesenteric aeries 