Splenic artery aneurysm

Last revised by Yahya Baba on 24 Mar 2023

Splenic artery aneurysms are the most common visceral arterial aneurysm formation as well as the third most common abdominal aneurysm (after the aorta and iliac vessels). Aneurysms are usually saccular in configuration and they can either be in the form of a true aneurysm (much more common) or as a pseudoaneurysm.

This article focuses on the true splenic artery aneurysm, please refer to splenic artery pseudoaneurysms for a specific discussion on this entity. 

The true prevalence of splenic artery aneurysms is unknown. Estimates vary widely from 0.2% to 10.4%, but generally, it is the third most common site of intra-abdominal aneurysms after abdominal aorta and iliac arteries 1,6. Incidentally discovered splenic artery aneurysms are being diagnosed more frequently with wider use of cross-sectional imaging modalities 7.

Splenic artery aneurysms are about 4x more common in females, yet the risk of its rupture is about 3x more common in males 13.

Most splenic artery aneurysms are silent and are discovered in asymptomatic patients 2. More than 95% of patients with non-ruptured splenic artery aneurysms were asymptomatic 13. The risk of rupture increases with liver transplantation, portal hypertension, and pregnancy. A ruptured splenic artery aneurysm usually presents with sudden onset left upper quadrant abdominal pain followed by hemodynamic instability, and gastrointestinal bleeding 14.

The so-called “double rupture” phenomenon occurs when initial spontaneous stabilization followed by subsequent sudden circulatory collapse is experienced. This is caused by initial bleeding, collecting into the lesser sac then followed by flooding into the peritoneal cavity 15

The size of splenic artery aneurysms can range from 2 to 9 cm, but usually, it is smaller than 3 cm. Those may be single or multiple and are most commonly involving the distal portion of the artery. Peripheral calcification is common, and mural thrombus may be present 12

Several imaging modalities can be used to diagnose splenic artery aneurysms.

Ultrasound with Doppler is a non-ionizing modality and relatively cheap and available yet it is operator dependent, has limited spatial resolution and may be difficult in cases of obesity, bowel shadowing and atherosclerosis.

CT angiography is a quick and efficient examination, has a higher resolution than MR and its MPR capabilities greatly help in diagnosis, yet it has its contraindications (renal failure, allergy to contrast).

MR angiography is of higher spatial resolution than ultrasound but it is relatively expensive and contraindicated in some patients (claustrophobia, aneurysm clips, cardiac pacemakers).

Direct catheter angiography is the gold standard imaging test, has the highest resolution and concomitant management can be applied, yet it still carries the complications of arterial puncture 8-11.

The overall risk of rupture is thought to be ~6%. However, in an event of rupture, there is a relatively high mortality rate of ~36% 4.

Follow-up of incidentally-detected splenic artery aneurysms 5:

  • <2 cm

    • spontaneous rupture is rare

      • 1 year follow up if no risk factors

      • follow up interval may be extended if other comorbidities are present, or if there is a decreased life expectancy

  • ≥2 cm

    • endovascular therapy should be considered

      • coil embolization is increasingly used to treat larger aneurysms

Rapidly increasing size, presence in a premenopausal woman, cirrhosis, and symptomatic aneurysm may warrant intervention, regardless of size.

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