Gastrointestinal Bleeding Secondary to Splenic Artery Pseudoaneurysm: A Delayed Complication of a Lumen-Apposing Metal Stent

Abstract

Lumen-apposing metal stents (LAMSs) have been widely used for drainage of peripancreatic collections. A 71-year-old woman with a history of necrotizing pancreatitis who underwent LAMS placement 3 months ago for symptomatic pancreatic fluid collection presented with hematochezia and hemodynamic instability. Computed tomographic angiography of the abdomen showed concerns for stent erosion into the splenic artery. Esophagogastroduodenoscopy revealed a large pulsating nonbleeding vessel within the LAMS. She underwent a mesenteric angiogram, which showed splenic artery pseudoaneurysm, and coil embolization was performed. Gastrointestinal bleeding secondary to pseudoaneurysm should be considered in patients with recent LAMS placement who present with signs of gastrointestinal bleeding.

INTRODUCTION

An encapsulated fluid collected (PFC) with necrotic debris is a late-phase complication of acute necrotizing pancreatitis, better known as walled-off necrosis (WON).¹ Drainage is indicated in patients with infected necrosis or symptomatic WON. Surgical necrosectomy was once the primary treatment of infected necrotic pancreatic collections. However, surgical management has higher risk of complications and is associated with prolonged length of hospital stay. Endoscopic cyst gastrostomy and endoscopic debridement have emerged as preferred means of management of PFCs.^2,3 Lumen-apposing metal stents (LAMSs) or double-pigtail plastic stents (DPPSs) are commonly used for this indication. DPPSs demonstrate good technical success and are more affordable, although a smaller diameter often necessitates the use of multiple stents and runs the risk of stent occlusion. Compared with a DPPS, the wider lumen of a LAMS better facilitates drainage of the viscous material characteristic to WON while the unique biflanged design minimizes peritoneal fluid leak. However, LAMS may be associated with adverse events, such as stent migration or dislodgement, perforation, and bleeding.^4,5

Pseudoaneurysm (PSA) formation and rupture is a feared complication of LAMS placement. Theoretically, as the volume of a PFC decreases, it approximates 2 lumens, which may create tension on surrounding vessels, leading to PSA formation and concomitant bleeding.⁴ Current European Society of Gastrointestinal Endoscopy guidelines recommend LAMS removal at 4 weeks to decrease the risk of stent-related adverse events.^3,6 We present a case of upper gastrointestinal (GI) bleeding and hemodynamic instability secondary to splenic artery PSA that resulted from an indwelling LAMS, promptly identified and treated by collaborative endoscopic and interventional radiology-guided therapy.

CASE REPORT

A 71-year-old woman with a history of necrotizing pancreatitis, complicated by splenic vein thrombosis on warfarin therapy, underwent LAMS placement for a symptomatic WON (Figure 1). A significant reduction in the fluid collection was noted on follow-up imaging at 6 weeks. However, the LAMS was not removed because the patient was recently started on anticoagulation for splenic vein thrombosis. The LAMS was intended for removal after completion of 3 months of anticoagulation therapy. Three months later, she presented with acute melena and hematochezia. On evaluation, she was hypotensive and tachycardic. Laboratory workup revealed hemoglobin 6.1 g/dL (12.0–15.3 g/dL) from a baseline of 12 g/dL and international normalized ratio 3.86 (0.84–1.14). Computed tomographic angiography did not show active GI bleeding, but was suggestive of stent erosion into the splenic artery, and PSA was suspected.

Figure 1.: Axial, coronal, and sagittal contrast-enhanced computed tomography (venous phase) images of the abdomen demonstrating the walled-off necrosis about the body and tail of the pancreas, abutting the stomach and splenic artery.

Interventional radiology was consulted, and a combined endoscopic/radiologic procedure was performed. Esophagogastroduodenoscopy revealed a large pulsating nonbleeding vessel within the LAMS (Figure 2). A mesenteric angiogram was completed before endoscopic intervention. This confirmed a splenic artery PSA, which was then embolized with coils (Figure 3). She underwent repeat esophagogastroduodenoscopy immediately after the coil embolization with successful removal of LAMS. No further bleeding was noted after stent removal (Figure 4). Repeat computed tomography (CT) imaging at 2 weeks (Figure 5) demonstrated numerous wedge-shaped peripheral defects compatible with splenic infarcts and resolution of the WON.

Figure 2.: Esophagogastroduodenoscopy revealing a large pulsating nonbleeding vessel within the lumen-apposing metal stent.

Figure 3.: (A) Digital subtraction angiogram of the celiac artery demonstrating luminal irregularity and dilation, consistent with pseudoaneurysm of the main splenic artery, adjacent to the inferior margin of the lumen-apposing metal stent. (B) Angiogram of the splenic artery after proximal coil embolization. There is no further filling of the splenic artery or the pseudoaneurysm.

Figure 4.: Esophagogastroduodenoscopy after lumen-apposing metal stent removal was negative for bleeding.

Figure 5.: Axial, coronal, and sagittal contrast-enhanced computed tomography (venous phase) images of the abdomen demonstrating resolution of the walled-off necrosis status post AXIOS stent placement. Note the stent abutting the splenic artery on the sagittal images.

DISCUSSION

A PSA, or false aneurysm, is a vascular abnormality that arises secondary to inflammation or traumatic insult. The arterial outflow contained outside intimal layers of a vessel wall is at high risk of shearing and rupture, regardless of size.^7,8 PSA rupture can manifest with severe abdominal pain, hemodynamic instability, or GI bleeding. If suspected, a CT angiogram is the best test for initial diagnosis.

Few cases of bleeding PSAs have been reported in the literature secondary to LAMS placement.^9,10 Gajjar et al⁹ reported a case of upper GI bleeding in a patient with a history of LAMS placement for drainage of a pseudocyst. Successful coil embolization of the splenic artery was able to control the bleeding. Similarly, Flynn et al¹⁰ also reported successful coil embolization of the splenic artery in a patient with suspected splenic artery erosion secondary to LAMS who presented with upper GI bleeding.

LAMSs are increasingly favored for the treatment of PFCs; however, as noted previously, they are associated with several procedure-related risks. Although the initial use of intraprocedural Doppler minimizes the risk of stent placement near vessels, it is unclear where the stent will reside as the PFC decreases in size. In a study by Bang et al,⁵ approximately 50% of patients with LAMSs demonstrated adverse events at 6 weeks. As such, European Society of Gastrointestinal Endoscopy guidelines recommend imaging twice, once at the time of placement and, again, 4 weeks later.³ A prospective analysis by Bhandari et al¹¹ sought to protocolize this recommendation. All patients underwent arterial-phase CT before stent placement; 17% were found to have an unrecognized PSA before stent placement. Similarly, imaging studies 4 weeks after stent placement demonstrated complete resolution of the PFC in 90% of patients. Careful consideration for imaging should occur before and 4 weeks after stent placement.

Our patient was imaged before stent placement, at which time no PSA was noted. Owing to recurrent symptoms, repeat imaging 3 weeks after stent placement demonstrated persistent WON and a new splenic vein thrombosis (SVT), for which the patient started oral anticoagulation (OAC). Pancreatitis has a well-known association with splenic vein thrombosis, but the use of OAC remains controversial. Some literature describes the spontaneous resolution of SVT without anticoagulation.¹² Alternatively, progression of the thrombus can result in increased portal hypertension and portosystemic collaterals, which may necessitate OAC. However, no clear literature or guidelines exist. A meta-analysis by Sissingh et al¹³ compared therapeutic anticoagulation against no intervention in those with SVT secondary to acute pancreatitis and was ultimately unable to prove a benefit in mortality, rates of recanalization, or formation of varices in either group. Further randomized clinical trials are needed to illustrate the benefit of anticoagulation in these cases.

In summary, ruptured PSA from LAMS is a feared complication and should be considered in patients with recent stent placement who present with signs of upper GI bleeding. Prompt reimaging at 4 weeks may prevent this life-threatening complication altogether. Potential interventions should ideally be performed by an expert multidisciplinary team of providers at high-volume centers with interventional radiology and surgical capability because this will decrease poor patient outcomes.

DISCLOSURES

Author contributions: All authors listed above were responsible for substantial contributions for this case report, including the conception process/writing, literature review, revisions, analysis, and final approval. They also agreed to be held accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. A. Moin is the article guarantor.

Financial disclosure: None to report.

Previous presentation: This case report was presented at the ACG Annual Scientific Meeting, October 20–26, 2022; Charlotte, NC.

Informed patient consent was obtained for this case report.