Splenic artery aneurysms are the most frequent visceral arterial aneurysms, accounting for as many as 60% of all splanchnic artery aneurysms.[1] The reported incidences in autopsy series ranges from 0.098 to -10.4%.[2] The most common etiologies include medial degeneration with superimposed atherosclerosis, congenital, mycotic, portal hypertension, fibromuscular dysplasia, and pseudoaneurysms from trauma and pancreatitis.[3]

Pseudoaneurysms of the splenic artery can occur in up to 10% of patients with pancreatitis as a result of enzymatic injury to the vessel wall.[4] Hemorrhage from the pseudoaneurysms has been reported in up to 37% of patients.[5] Pseudoaneurysms can occur in any vessel around the pancreas but the most common is the splenic artery.

In some patients, prospective diagnosis of a pseudoaneurysm may not be made and patients may present with acute hemorrhage. On imaging studies such as CT scan or ultrasound, pseudoaneurysms may be mistaken for a pseudocyst or other peripancreatic fluid collections. On CT scan, high density within a peripancreatic fluid collection should raise suspicion for clot within a pseudoaneurysm though hemorrhage into a pseudocyst may have a similar appearance. With dynamic bolus contrast enhancement, CT should allow improved sensitivity in detecting pseudoaneurysms (Fig. 2A & 2B). Ultrasound is often utilized as an imaging modality to evaluate the pancreas in the setting of acute pancreatitis. Doppler evaluation of peripancreatic fluid collections and in particular, color Doppler evaluation can aid in diagnosing pseudoaneurysms.

Operative repair of the pseudoaneurysms may be undertaken with relatively low risk in many patients and may involve splenectomy for distal aneurysms or aneurysmectomy with proximal and distal arterial ligation for more proximal lesions. In debilitated patients carrying a higher surgical risk, percutaneous transcatheter embolization may be performed safely [6,7]. The procedure is performed via selective arterial catheterization with initial deployment of metallic embolization coils distal to the aneurysm neck with continued coil placement across the neck extending proximally (Fig. 2E). Working in this fashion minimizes the risk of continued aneurysmal filling from collateral vessels which would supply the aneurysm distally (Fig. 2F). Risks of transcatheter embolization include splenic infarction and abscess formation.

References:
1. Graham LM, Rubin JR. Visceral arterial aneurysms. In: Strandness DE, Van Breda
A, eds. Vascular Diseases - surgical and interventional therapy. New York:
Churchill Livingstone, 1994:811-813.

2. Stanley JC, Wakefield TW, Graham LM et al. Clinical importance and management
of splanchnic artery aneurysms. J Vasc Surg 1986;3:836-840.

3. White AF, Baum S, Buranasiri S. Aneurysms secondary to pancreatitis. AJR 1976;
127:393-396.

4. Tylen U, Arnesjo B. Angiographic diagnosis of inflammatory disease of the pancreas.
ACTA Radiol 1973:14;215-217.

5. Pantongrag-Brown L, Suwanwela N, Arjhansiri K, et al. Demonstration on computed
tomography of two pseudoaneurysms complicating chronic pancreatitis. Br J Radiol
1991;64:754-757.

6. Carr SC, Pearce WH, Vogelzang RL, et al. Current management of visceral arterial
aneurysms. Surgery 1996;120:627-633.

7. McDermott VG, Schlansky-Goldberg R, Cope C. Endovascular management of
splenic artery aneurysms and pseudoaneurysms. Cardiovasc-Int-Radiology
1994;17:179-184.

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