A 54-year-old woman with known arterial hypertension admitted to the emergency department with epigastric pain and nausea for the previous 4 hours. During her stay in the emergency room, she became unstable, with hypotension and tachycardia. Hemogram showed a decrease of 2,5g/dL of haemoglobin in 5 hours.
Computed Tomography (CT) demonstrated a rounded lesion in the left upper quadrant of the abdomen, in proximity to the pancreatic tail and located superiorly and medially to the left kidney. It had a hyperdense component on CT before intravenous (IV) contrast administration, suggesting clotted blood (figure 1). After IV contrast, it filled almost completely with contrast, with opacification similar to that of the splenic artery, which was seen to be its origin (figure 2). This communication between the lesion and the splenic artery was best depicted on sagittal and coronal reconstructions (figures 3 and 4)
Peripheral hypodense lesions were found in the spleen, suggesting splenic infarcts (figure 5).
Additionally, there was peri-hepatic and peri-splenic free fluid (figure 5) and haemoperitoneum in the pelvis (figure 6), consistent with rupture of the splenic artery aneurism.
Splenic artery aneurysms are the third most common site of intraabdominal aneurysms and are more frequent in women. 
They can be true aneurysms (which have all three arterial wall layers) or pseudoaneurysms (which contain only intima and media).
True aneurysms of the splenic artery are usually found associated with high flow conditions, such as pregnancy, portal hypertension, systemic arterial hypertension; they can also be associated with cirrhosis, liver transplantation, arterial fibrodysplasia, arteritis, collagen vascular disease and alfa1-antitrypsin deficiency. Splenic artery pseudoaneurysms are typically found in the setting of splenic trauma, pancreatitis or, more rarely, mycotic infection of the arterial wall or peptic ulcer disease. [1,2]
The risk of rupture is about 2-10% for true aneurysms; but can be as high as 37% for pseudoaneurysms, with very high rates of mortality if untreated. 
Clinical setting can help differentiate a true aneurysm from a pseudoaneurysm, as the first is usually asymptomatic and the latter almost always present with symptoms. [1,3] The most common symptom is abdominal pain and it can be associated with upper or lower gastrointestinal bleeding or with haemorrhage into the pancreatic duct.
Presentation with rupture and haemorrhagic shock requires life-saving surgery.
CT is the imaging method of choice. Arterial phase images are very important to make the diagnosis, usually obtained 20-30 seconds after the onset of peripheral intravenous contrast injection, which will show a vascular lesion arising from the splenic artery. 3D reconstructions may ease the diagnosis.
True aneurysms and pseudoaneurysms have similar imaging appearances. Some CT findings may be clues to the diagnosis: in general, splenic artery aneurysms appear well defined and homogeneous while the margin of the pseudoaneurysm is typically more irregular ; peripheral calcifications can be seen in many cases of true aneurysms of the splenic artery  but are rare in pseudoaneurysms, and pseudoaneurysms are typically surrounded by a hematoma. [1, 2]
Additionally, associated CT findings can help differentiate true aneurysms from pseudoaneurysms: signs of cirrhosis, portal hypertension or arthritis are associated with true aneurysms, while pancreatitis and peptic ulcer disease can be seen in some cases of pseudoaneurysms.
In the setting of haemorrhagic shock due to rupture of a splenic artery aneurysm, life-saving surgery usually requires splenectomy (figure 7). Elective repair with endovascular intervention or open surgery is indicated in all pseudoaneurysms and in true aneurysms with 2 cm or more in diameter or with rapid growth. 
 Agrawal GA, Johnson PT, Fishman EK, Splenic Artery Aneurysms and Pseudoaneurysms: Clinical Distinctions and CT Appearances, AJR 2007;188:992-999
 Varshney P, Songra B, Mathur S et al., Splenic Artery Pseudoaneurysm Presenting as Massive Hematemesis: a Diagnostic Dilemma, Case Reports in Surgery 2014, ID 501937
 Jesinger RA, Thoreson AA and Lamba R, Abdominal and Pelvic Aneurysms and Pseudoaneurysms: Imaging Review with Clinical, Radiological and Treatment Correlation, RadioGraphics 2013;33:E71-E96