Ruptured splenic artery aneurysm detected by emergency ultrasound—a case report

Splenic artery aneurysm (SAA) is defined as an abnormal dilatation of the splenic artery more than 1 cm in diameter. It was first described on cadavers in 1770 by Beaussier [7]. It accounts for approximately 60 % of all visceral arterial aneurysms [2]. It is the third most common intra-abdominal aneurysm, following aortic and iliac artery aneurysms [3]. SAA is rarely seen with a prevalence of 1 % [1]. It is four times more common in females compared to males [8‐10]. Risk factors correlating to the development of SAA include fibromuscular dysplasia, collagen vascular diseases, female gender, history of multiple pregnancies, and portal hypertension, although the pathogenesis is not fully understood [11].

Splenic artery pseudoaneurysms are less prevalent than true SAA. They differ from true SAA in that the dilatation occurs following the disruption of one or more layers of the vessel wall. Splenic artery accounts for the majority of splanchnic pseudoaneurysms. Unlike true SAA, they have a slight male predominance. The underlying causes in most of the cases are trauma, infection, or weakening of the splenic artery wall from exposure to pancreatic enzymes. The latter is usually associated with pancreatic anastomotic leaks, severe pancreatitis, and pancreatic pseudocysts [3]. However, in our patient, no risk factors could be identified. He did not have previous history suggestive of pancreatitis but presented as acute rupture of splenic artery pseudoaneurysm. A pancreatic pseudocyst was found intraoperatively. It can be postulated that he might have subclinical pancreatitis in the past resulting in pseudocyst formation. The pseudocyst caused erosion into the splenic artery, leading to formation of a pseudoaneurysm.

Patients with SAA are usually asymptomatic, only 20 % of then have symptoms such as abdominal pain, chest pain, and most are diagnosed incidentally. SAA can be complicated by rupture resulting in hypovolemic shock as illustrated in your case. It can be fatal if not treated properly and timely. It can rupture freely in the peritoneal cavity, in the gastrointestinal (GI) tract causing GI hemorrhage or eroding into surrounding structures, such as the splenic vein, resulting in a splenic arteriovenous fistula [12]. Double rupture phenomenon may occur, in which the aneurysm first ruptures into the lesser sac with mild clinical symptoms then the blood overflows into the peritoneal cavity through the Winslow foramen with hemorrhagic shock [5, 13].

The significance of diagnosing and treating SAA lies in the potential risk for rupture and life-threatening hemorrhage, which occur in 10 % of cases with a mortality rate of 10–25 % in nonpregnant patients and up to 70 % during pregnancy [14]. The risk of rupture however is much higher for aneurysms larger than 2 cm in diameter [15].

The emergency physician’s role in the care of a patient with an acute rupture of a splenic artery aneurysm lies largely in making the diagnosis and urgent surgical consultation. Standard resuscitative maneuvers (insertion of two large-bore IV catheters, initiation of cardiac monitoring, and administration of supplemental oxygen) are required. Fluid resuscitation is needed if the patient is hemodynamically unstable. However, caution should be taken to avoid over-resuscitation which will potentially cause more bleeding if bleeding is still not under control.

Imaging modalities for diagnosing splenic artery aneurysm include ultrasound, pulsed Doppler, CT, MRI, and abdominal aortic arteriography, which is the gold standard [16]. In our case, bedside ultrasound findings suggested rupture of the aneurysm, and subsequent CT scan confirmed the diagnosis of rupture of splenic artery pseudoaneurysm.

Rapid bedside ultrasound is useful to demonstrate the aneurysm and associated free fluid inside the abdomen. It is ideal for patients in an unstable condition who cannot undergo CT scanning. Emergency ultrasound is noninvasive, can be rapidly deployed, and does not entail removal of the patient from the resuscitation area [17]. Ultrasound is also radiation-free, thus particularly useful in pregnancy. However, it is operator independent and its sensitivity is significantly degraded in the presence of obesity, gaseous distension, arteriosclerosis, and small aneurysms [3].

CT scanning with IV contrast material is useful to demonstrate the anatomic details of the aneurysm in three-dimensions, associated retroperitoneal hemorrhage, and associated underlying diseases. CT scanning should be obtained in patients in stable condition.

The management of ruptured SAA is similar to that of ruptured abdominal artery aneurysm (AAA). Emergency physicians are familiar with using ultrasound to diagnose AAA. With the wide availability of ultrasound in EDs nowadays, SAA can be readily picked up under appropriate clinical settings. However, pitfalls should be borne in mind to differentiate SAA from AAA (Fig. 5). In our case, color Doppler sonography showed a large mass with strong Doppler flow inside, suggestive of an aneurysm. To differentiate a visceral artery aneurysm from an AAA, the aneurysm should be discrete, and no continuity should be demonstrated when chasing the entire abdominal aorta down to bifurcation into both common iliac arteries.

SAA with features suggestive of low risk for rupture may be successfully managed without intervention. Radiological follow-up with six monthly ultrasound or CT scans should be mandatory to assess progression of the aneurysm. Active intervention should be considered if the aneurysm is symptomatic, enlarging, more than 2 cm in diameter or if found in pregnancy or childbearing age. All false aneurysms of the splenic artery should be treated as soon as possible, irrespective of size, symptoms, or rupture [3].

The therapeutic options are either surgical or endovascular intervention.

Endovascular procedure, which includes embolization or stent graft application, is considered as a first choice of treatment for splenic artery aneurysm [18]. The choice between embolization and stent grafting should be dependent on the shape, size, and site of the SAA as well as the local expertise [3].

Surgical intervention is considered the conventional option of treatment in most centers especially in case of rupture [14]. The options include excision, ligation, or revascularization, with or without splenectomy [12]. Laparoscopic approach may be considered if radiation exposure is contraindicated, such as pregnancy, or where endovascular techniques either fail or are not available [3].