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A woman of 76 with a history of hypertension, pulmonary embolus and rectal adenocarcinoma was found to have a splenic artery aneurysm (SAA) of 3-4 cm on routine surveillance ultrasound scan of the liver. She had never been pregnant. At no point did she have any symptoms or signs of the aneurysm, such as abdominal pain or an abdominal mass. Initial contrast runs of the coeliac axis showed a 4 cm aneurysm at the splenic hilum and also a 1.5 cm aneurysm of the left hepatic artery (Figure 1). The splenic artery aneurysm was not suitable for embolization because its position close to the splenic hilum allowed for little collateral blood supply and post-embolization infarction of the spleen was likely. The hepatic artery aneurysm was successfully embolized with thrombogenic steel coils. The following day, after immunization against Streptococcus pneumoniae and Haemophilus influenzae type b, she underwent splenectomy and removal of the SAA. Sixteen months postoperatively she was in good health.
The incidence of SAA is quoted as being 0.7% of the population but necropsy studies have given rates as high as 10%2. The incidence of SAA in females is four times the rate in males. This difference, thought to be due to the hormonal and haemodynamic changes associated with pregnancy, is not seen with other visceral artery aneurysms3. SAA is the second commonest intra-abdominal aneurysm after aortoiliac aneurysms; usually there are no symptoms and only 27% present with abdominal pain2,4.
Incidental diagnosis of SAA is becoming increasingly frequent with the growing use of angiograms, CT scans and ultrasonograms for investigation of other lesions2. The peak age of detection is the sixth decade1. The cause of these aneurysms is uncertain, but increased blood flow through the splenic artery may be a factor. Portal hypertension with large portasystemic shunts causes a rise in portal blood inflow volume which is thought to increase the aneurysmal propensity of the splenic artery'1,2,5. Arteriosclerosis is the commonest pathological finding and is probably a post-aneurysmal phenomenon rather than a primary cause of the aneurysm. Half the ruptures occur in pregnant women and the mortality after rupture is 70-90%6.
For patients aged over 60 years with no symptoms and with aneurysms less than 20 mm in diameter, conservative management with CT scans every six to twelve months is advocated4. Treatment is indicated for aneurysms that cause symptoms, those more than 30 mm in diameter, and those detected in women who are pregnant or of childbearing age: these are groups with an increased risk of rupture2,3. There is no clear advice on how to manage aneurysms between 20 and 30 mm.
The favoured method of treatment at present is embolization. However, there is little follow-up information for this method and recurrence is a possible long-term hazard3. When embolization is difficult or contraindicated by the proximity of the aneurysm to the spleen (with risk of splenic infarction) the options are open or laparoscopic surgery with ligation of the splenic artery, excision of the aneurysm with reanastomosis of the artery or splenectomy with removal of the aneurysm3.