Most common cause of acute superior mesenteric aerial obstruction is: March 2012
**Core Concept**
Acute superior mesenteric arterial obstruction is a life-threatening condition that requires prompt diagnosis and treatment. This condition is often caused by external compression or thrombosis of the superior mesenteric artery (SMA), leading to ischemia and necrosis of the midgut.
**Why the Correct Answer is Right**
The most common cause of acute superior mesenteric arterial obstruction is **thrombosis** of the SMA. This occurs due to the formation of a blood clot within the artery, which can be triggered by various factors such as atherosclerosis, embolism, or hypercoagulability. The SMA is a long and narrow artery that supplies blood to the midgut, and its occlusion can lead to severe abdominal pain, vomiting, and potentially life-threatening complications.
**Why Each Wrong Option is Incorrect**
**Option A:** External compression of the SMA is a possible cause, but it is less common than thrombosis. External compression can be caused by various conditions such as a tumor or an abdominal mass.
**Option B:** Embolism is a possible cause of acute superior mesenteric arterial obstruction, but it is not the most common cause. Embolism occurs when a blood clot or foreign material travels from another location and lodges in the SMA.
**Option C:** Atherosclerosis is a risk factor for thrombosis, but it is not a direct cause of acute superior mesenteric arterial obstruction. Atherosclerosis is a condition characterized by the buildup of plaque in the arteries, which can increase the risk of thrombosis.
**Clinical Pearl / High-Yield Fact**
The "triad" of symptoms associated with acute superior mesenteric arterial obstruction includes abdominal pain, vomiting, and hemodynamic instability. Prompt recognition and treatment of this condition are crucial to prevent long-term complications and mortality.
**Correct Answer: C. Atherosclerosis**