Women: Splenic Artery Aneurysms
Lawrence H. "Larry" Knott, Jr., MD, FACS

With the rapid proliferation of cross-sectional imaging (i.e., CT scan, ultrasound, MRI), visceral arterial aneurysms are being diagnosed more frequently. Splenic artery aneurysms account for more than 60% of these aneurysms. The true incidence of splenic artery aneurysms remains unknown but has been reported to be between 0.02% and 10.4% in the general population.

Though men usually predominate in aneurysmal formation by a factor of 8:1, nearly 80% of splenic artery aneurysms occur in women. They are especially common in multiparous females, and many theories have been postulated to explain this relationship. Hormonal shifts of gestation involving estrogen, progesterone, and relaxin have been implicated. The increased blood volume associated with pregnancy as well as arteriovenous shunting in the splenic system may explain the predisposition of the splenic artery to form aneurysms. The incidence of splenic artery aneurysms is increased in women with fibromuscular dysplasia disease involving the renal vessels. Likewise, the incidence of splenic artery aneurysm is increased in patients with portal hypertension and splenomegaly.

Most splenic artery aneurysms are diagnosed from studies done to evaluate other unrelated conditions. The classic finding is the signet ring calcification seen in the left upper quadrant (photo). While usually asymptomatic, vague left upper quadrant, epigastric, or back pain may be present. Symptoms associated with rupture are much more dramatic, including left upper quadrant pain and shock. Occasionally the rupture is contained in the lesser sac only to be followed later by decompression into the free peritoneal cavity with decompensation. The "double rupture" phenomenon may provide an opportunity to diagnose and treat this condition.

The exact risk of rupture remains uncertain. There appears to be a bimodal age distribution with the majority of aneurysms seen in young adults or in the elderly. Splenic artery aneurysms in the pregnant patient have a poor prognosis with high maternal and fetal mortality with rupture common. However, the risk of rupture in the elderly patient appears much less. Indications for treatment of asymptomatic splenic artery aneurysms remain controversial. Size of the aneurysm, age of the patient, and presence of symptoms are all considered. Calcification of the aneurysm wall has not been shown to protect from rupture.

Most would agree that splenic artery aneurysms in the pregnant patient or in patients of childbearing age should be considered for repair. In the elderly patient, one would treat aneurysms greater than two to three centimeters in size if the patient is a good operative risk with a life expectancy of two years or more.

Appropriate therapy depends on the location of the aneurysm. Formal arteriography is recommended prior to intervention. Proximal and distal ligation of the aneurysm with splenic preservation may be possible for more proximally-located aneurysms, but many involve the hilum of the spleen and necessitate splenectomy. Transcatheter embolization is likewise an effective method to treat selected splenic artery aneurysms. Laparoscopic ligation of splenic aneurysms has been successfully performed in very select cases.