This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
Most common cause of acute mesenteric ischemia is 
Select and explain. 
A. Aerial thrombosis, B. Venous thrombosis, C. Embolism, D. Non occlusive disease
C: Embolism
Answer: C: Embolism 
Explanation: .Superior mesenteric aery is commonly involved than inferior mesenteric aery. Often superior mesenteric vein can also get involved. Causes * Embolism (50%)--Sources - From left auricle, as seen in atrial fibrillation. - A mural infarct. - Atheroma from aoa or aneurysm. - Endocarditis vegetations. - Left atrial myxoma. * Thrombosis--may block the origin of the superior mesenteric aery and can cause ischaemia of full length of small bowel. It is life threatening. ref:SRB&;s manual of surgery,ed 3,pg no 806