Mycotic aneurysm of the superior and inferior mesenteric artery

Visceral artery aneurysms as a result of arterial degenerative disease are rare (0.1%-2%), and the superior mesenteric artery (SMA) accounts for 3.2% of all reported series. The current incidence of inferior mesenteric artery (IMA) aneurysm is unknown. However, infective causes (mycotic) of SMA and IMA aneurysm as a result of primary, secondary, and cryptogenic etiology remain a separate entity and attain fewer cases in the literature. Currently, there is no consensus on their presentation, diagnosis, and overall management.

A systematic review and meta-aggregation of literature from 1944 to March 2015 in the English language and of adult subjects in MEDLINE, Ovid, CINAHL, and the Cochrane database was conducted.

The median age of patients with SMA aneurysm was 36 (range, 14-92) years, with a significant male predominance (73% vs 27%). In order of prevalence, abdominal pain (n = 25; 65%), low-grade fever (n = 23; 60%), malaise (n = 10; 26%), weight loss (n = 9; 23%), and nausea and vomiting (n = 8; 20%) were the most common presenting signs and symptoms. The most common microorganism was Streptococcus (n = 18; 47%), followed by Staphylococcus (n = 11; 28%). The investigative modality of choice was computed tomography (n = 22; 57.8%), followed by ultrasonography of the abdomen (n = 9; 23%). Primary etiology was noted in 5.4%, secondary in 71%, and cryptogenic in 13% of all cases. Aneurysmectomy alone was associated with bowel resection in four cases (10.5%), whereas aneurysmectomy with interposition vein grafting required no further intervention. The inpatient mortality after surgery was 7.8%, and the overall mortality was 15%. The median follow-up was 12 months (range, 2-120 months). The median age of patients with IMA aneurysm was 48 (range, 22-64) years, with a male predominance of 2:1 and abdominal pain in all cases (n = 3; 100%). The most common microorganism was Streptococcus (n = 2; 66.6%), and the operation of choice was aneurysmectomy (n = 2; 66.6%) after computed tomography scan (n = 3; 100%) as an investigative modality of choice.

The pentad of abdominal pain, pyrexia of unknown origin, malaise, weight loss, and nausea remains the most convincing presentation of mycotic aneurysms of the SMA and IMA. Computed tomography is the investigative modality of choice, and such patients are best served with aneurysmectomy alone in IMA aneurysms and interposition vein grafting in SMA aneurysms after initiation of antimicrobial therapy on suspicion of the diagnosis.