What are the characteristics of a splenic artery aneurysm?

Splenic Artery Aneurysm Characteristics

Splenic artery aneurysms can present with the double-rupture phenomenon, are more common in women (not males), can be multiple, and will likely continue to enlarge if left untreated. 1

Double-Rupture Phenomenon

• Approximately 25% of patients with ruptured splenic artery aneurysms (SAAs) present with the "double rupture phenomenon" 1
• This involves:
  • An initial small herald bleed that is self-contained
  • Followed by a major rupture with rapid intra-abdominal bleeding and hemorrhagic shock
• This phenomenon is particularly dangerous during pregnancy, where maternal mortality can reach 70-95% and fetal mortality exceeds 90% 1, 2

Gender Distribution

• SAAs are more common in women, not men 1, 3
• According to ACC/AHA guidelines, splenic artery aneurysms have historically been the most common visceral artery aneurysms 1
• Studies show a clear female predominance:
  • In one series, 87 out of 100 patients with SAAs were women 1
  • Another study reported 20 out of 31 patients were women 1
• The risk is particularly elevated in multiparous women 4

Multiplicity

• SAAs can frequently be multiple, contrary to option (c) 5
• In a 14-year study of 23 patients with SAAs, 12 patients (52%) had multiple aneurysms 5
• Multiple aneurysms are often found in the distal third of the splenic artery 5

Natural History and Growth

• SAAs will typically continue to enlarge if left untreated 3, 5
• This growth pattern is the basis for recommendations to treat:
  • Symptomatic aneurysms
  • Enlarging aneurysms
  • Aneurysms larger than 2 cm
  • Aneurysms in women of childbearing age or during pregnancy
  • Aneurysms following liver transplantation 3
• The risk of rupture increases with size, but importantly, up to 50% of SAAs that rupture during pregnancy are smaller than 2 cm 6

Risk Factors and Complications

• Portal hypertension is a significant risk factor (16 of 23 patients in one study) 5
• Splenomegaly is often present in patients with portal hypertension and SAAs 5
• Rupture carries high mortality:
  • 10-25% in non-pregnant patients
  • Up to 75% maternal and 95% fetal mortality during pregnancy 1, 7, 2
• Rupture can present as free intraperitoneal hemorrhage or erosion into adjacent organs 4

Management Implications

• Active treatment is recommended for:
  • Symptomatic SAAs
  • Enlarging SAAs
  • SAAs >2 cm in diameter
  • SAAs in pregnant women or women of childbearing age
  • SAAs in liver transplant recipients 3, 5
• Treatment options include:
  • Endovascular therapy (embolization or stent grafting) as primary approach 3
  • Surgical options: aneurysm excision, ligation, or splenectomy 5, 4
• Asymptomatic aneurysms <2 cm may be managed conservatively with regular imaging surveillance 3, 5

In summary, splenic artery aneurysms present a significant clinical risk, particularly in women and during pregnancy, and understanding their characteristics is crucial for appropriate management and prevention of potentially fatal outcomes.