Splenic artery aneurysm (SAA) is focal dilatation of the splenic artery and is the most common type of visceral artery aneurysm (60-70%). Prevalence in autopsy series is 0.01-0.2%. Four times more common in women. Multiparity, portal hypertension, and pancreatitis are risk factors. Rupture risk is significantly increased during pregnancy (95% maternal mortality, 75% fetal mortality), therefore SAA detection in pregnant women or those planning pregnancy requires urgent surgical/interventional evaluation. Characteristic calcified ring appearance on CT is diagnostic.
Age Range
40-80
Peak Age
60
Gender
Female predominant
Prevalence
Uncommon
Splenic artery aneurysm develops from degeneration of elastic fibers in the arterial wall and medial fibrodysplasia. Higher prevalence in women is explained by estrogen effect — estrogen increases elastic fiber remodeling and weakens the arterial wall. In multiparity, increased splenic artery flow and hormonal changes increase wall stress. In portal hypertension, splenic artery flow is increased — increased hemodynamic stress triggers aneurysm formation. In pancreatitis-associated SAA, pancreatic enzymes erode peripancreatic adventitia causing pseudoaneurysm. On imaging, the calcified ring reflects dystrophic calcification of the aneurysm wall — calcium deposits in areas of chronic wall damage and fibrosis. The aneurysm lumen fills with contrast on CT angiography and appears as a dilated structure separate from the splenic artery.
Round calcified ring structure in the splenic artery course in the left upper quadrant on non-contrast CT or plain radiographs. Reflects circumferential distribution of dystrophic calcification in the aneurysm wall. This finding is the most characteristic and recognizable sign of incidentally detected SAA — radiologically pathognomonic.
Focal dilatation filling with contrast in the splenic artery course in arterial phase. Aneurysm lumen enhances simultaneously with splenic artery. Generally round/fusiform, well-defined. Aneurysm diameter >1 cm is considered diagnostic. If wall thrombus is present, partially non-filling area may be seen.
Report Sentence
Focal dilatation of ... mm diameter filling with contrast in the splenic artery course, consistent with splenic artery aneurysm.
Calcified ring structure in the splenic artery course in the left upper quadrant on non-contrast CT. Wall calcification is peripheral, ring-shaped — dystrophic calcification of aneurysm wall. Can be detected even on incidental plain radiographs. Calcification thickness varies; may be thin linear or coarse.
Report Sentence
Calcified ring structure in the splenic artery course in the left upper quadrant, consistent with splenic artery aneurysm.
Anechoic or hypoechoic round/oval structure along the splenic artery course on B-mode US. Anechoic if no thrombus (fluid-filled lumen); contains hypoechoic solid component if partial thrombus present. Calcified wall may cause posterior acoustic shadowing. Located in peripancreatic or splenic hilum location.
Report Sentence
Anechoic/hypoechoic round structure of ... mm diameter along the splenic artery course, consistent with splenic artery aneurysm.
Yin-yang sign (to-and-fro flow pattern) in aneurysm lumen on color Doppler US. Flow entering in systole and exiting in diastole creates red-blue swirl pattern. This pattern is more prominent in pseudoaneurysms (pancreatitis-associated). Spectral Doppler shows bidirectional flow wave.
Report Sentence
Vascular structure showing yin-yang flow pattern on color Doppler examination, consistent with splenic artery aneurysm.
On MRI, aneurysm lumen shows different signal depending on flow status. Fast flow shows flow void (signal loss) on T2. Slow flow or thrombus shows variable signal on T2 — fresh thrombus may be hyperintense, organized thrombus hypointense. Time-of-flight (TOF) or phase-contrast MR angiography confirms diagnosis.
Report Sentence
Focal dilatation with flow void/variable signal in the splenic artery course, consistent with splenic artery aneurysm.
Aneurysm lumen still contrast-filled in portal venous phase (persistent enhancement). If mural thrombus present, seen as hypodense peripheral layer — lumen contrast-filled, surrounding thrombus hypodense. In delayed phase, thrombus wall may show minimal enhancement (vasa vasorum).
Report Sentence
Splenic artery aneurysm showing persistent enhancement in portal venous phase, with/without accompanying mural thrombus.
Criteria
Involves all three layers of arterial wall (intima, media, adventitia). Most common type. Associated with medial fibrodysplasia, multiparity, and portal hypertension. Generally fusiform or saccular. Wall calcification is common. Rupture risk is lower than pseudoaneurysms (2-10%).
Distinct Features
All wall layers intact, calcified wall common, fusiform/saccular, lower rupture risk (2-10%)
Criteria
Arterial wall integrity disrupted — contained by adventitia or surrounding tissue. Develops after pancreatitis (60-80%), trauma, or surgery. Rupture risk very high (37-47%). Requires emergent treatment. Calcification is rare.
Distinct Features
Wall defect, pancreatitis/trauma-related, calcification rare, very high rupture risk, requires emergent treatment
Criteria
SAA with diameter >5 cm. Very rare. Rupture risk increases proportionally with diameter. May compress surrounding organs (stomach, pancreas) with mass effect. Surgical/endovascular treatment is mandatory.
Distinct Features
Diameter >5 cm, very rare, mass effect, high rupture risk, treatment mandatory
Distinguishing Feature
Simple cyst is anechoic, avascular — shows no flow on Doppler. SAA shows yin-yang flow pattern on Doppler. Cyst is located in splenic parenchyma, aneurysm is along the splenic artery course. Calcified wall can be seen in both but cyst wall is thin and smooth, aneurysm wall may be thick.
Distinguishing Feature
Hemangioma shows peripheral nodular enhancement and centripetal fill-in — aneurysm shows uniform contrast filling of lumen. Hemangioma is located in splenic parenchyma, aneurysm along arterial course. Hemangioma is T2 hyperintense, aneurysm shows T2 flow void.
Distinguishing Feature
Abscess shows rim enhancement, internal fluid density, and gas; clinically fever and leukocytosis are prominent. SAA shows arterial enhancement and no inflammatory findings. On Doppler, abscess is avascular, SAA shows flow.
Distinguishing Feature
Lymphoma is solid, minimally enhancing mass — SAA is vascular structure enhancing by lumen filling. Lymphoma shows internal vascularity (irregular) on Doppler, SAA shows yin-yang pattern. CTA reformat confirms SAA — lymphoma has no vascular connection.
Urgency
urgentManagement
interventionalBiopsy
Not NeededFollow-up
6-monthSAA management is determined by size, type (true/pseudo), symptoms, and patient profile. For asymptomatic true SAA <2 cm, 6-12 month US/CT follow-up may be sufficient. Treatment indications: size >2 cm, growing aneurysm, symptomatic, pseudoaneurysm (urgent treatment for all pseudoaneurysms), pregnant or planning pregnancy (rupture mortality 95%). Treatment options: endovascular embolization (coil/plug — first choice), stent-graft placement, or surgery (splenectomy ± distal pancreatectomy). Emergent surgery required for rupture.
Splenic artery aneurysm requires treatment when >2 cm or symptomatic due to rupture risk. Rupture risk is high during pregnancy (95% maternal mortality). Treatment options include embolization or surgery.