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Case Report | Discussion

Case report:

A 53 year-old-man was referred with vague symptoms of pain of a gnawing type in the epigastric region. He was a chronic alcoholic, but had no history of being admitted to a hospital for any acute abdominal episode .

A screening ultrasound revealed a mildly coarse hepatic echotexture. The pancreas appeared normal in size as well as echotexture.

The other abdominal organs appeared normal.

However in the region of the spleno-portal confluence a cystic swelling was seen just to the left and posterior to the superior mesenteric vein, in the location of the superior mesenteric artery (Fig 1)

Fig 1

On sagittal sonogram, it was revealed that the swelling elongated into a tubular anechoic channel communicating directly with the aorta just underneath the origin of the celiac axis. This was the superior mesenteric artery.(SMA)

A color Doppler evaluation showed blood flow into the swelling directly from the aorta .The ectasia was 1.5 cm distal to the origin of the SMA, it showed aliasing of blood flow into the saccular structure (Fig 2) with normal flow in the distal part of the vessel.

Fig 2

The Doppler wave form pattern also showed an arterial pattern (Fig 3)

Fig 3

Thus a diagnosis of a superior mesenteric artery aneurysm was made.

An angiogram of the abdominal aorta and the superior mesenteric artery has been advised for the patient; however the patient is reticent for the investigation or any further definitive treatment..

Discussion

Superior mesenteric artery (SMA) aneurysms represent approximately 5% of all splanchnic aneurysms. The most common etiology is infection, and streptococcal species are the most commonly isolated organisms. The SMA has the highest frequency of infectious aneurysms of all muscular arteries. Steptococcal infections are usually associated with left-sided endocarditis; staphyloccocal infections are associated with non-cardiac septicemia.

SMA aneurysms are most frequently isolated to the first 5 cm of the SMA but may be located in any segment adjacent to a bifurcation. Symptoms are often vague but may become severe as a result of aneurysm expansion or mesenteric ischemia. Repair is considered mandatory because of the potential for rupture or occlusion with intestinal infarction. However, the exact risks of these complications remain unknown.

Because of the risk of infection, open repair with exclusion and evacuation of the aneurysm contents is considered to be optimal treatment. Ligation of feeding vessels is most easily accomplished from within the aneurysm sac. Bowel viability must be ascertained intra-operatively using clinical inspection and noninvasive tests. Following exclusion, proximal SMA aneurysms often require bypass, but more distal aneurysms usually have adequate collaterals to support intestinal flow without bypass. Treatment of SMA aneurysms using catheter-based techniques is limited by the aneurysm location, the risk of infection, and the need to assess bowel viability.