Peripancreatic fluid collection (PFC) associated with necrotizing pancreatitis, including acute necrotic collection (ANC) or walled-off necrosis (WON), sometimes becomes severe and life-threatening.¹ Therefore, appropriate diagnosis and treatment result in improved prognosis.^2,3 A step-up approach, including conservative treatment, endoscopic treatment, radiological intervention, and surgical treatment, is recommended.⁴ Drainage is indicated and a transgastrointestinal approach is encouraged in cases of antimicrobial agent resistance.⁵ The gastrointestinal tract used depends on PFC location, and most frequently the stomach is selected.⁶ The nearby digestive tract has been reported in a small number of cases with PFC present in the pancreatic head or pelvic region.^7,8 Several ductal organs, such as blood vessels and bile ducts, were observed, especially around the pancreatic head, and evidence for the safety of endoscopic ultrasound (EUS) intervention for PFC is insufficient.⁹ Additionally, a variety of devices were used, varying from plastic to specialized metal stents.^10,11 Multiple plastic stents provide clinical improvement, but their small diameter requires frequent replacement.¹² In contrast, the usefulness of lumen-apposing metal stent (LAMS) for PFC has recently been reported,¹⁰ which can be utilized in a single step, thereby significantly reducing procedure time, and demonstrating a high clinical improvement rate due to the large diameter.¹³ Meanwhile, a large flange sometimes compresses a blood vessel, developing a pseudoaneurysm and causing bleeding.¹⁴

Here, we report a rare case in which a flange of LAMS caused obstructive jaundice after ANC transduodenal drainage.

A 58-year-old male patient with a history of heavy drinking was admitted with alcoholic acute pancreatitis and ANC with a high fever. He had epigastric pain for the previous 4 weeks but without jaundice. Computed tomography (CT) revealed a 65 × 62 mm ANC in the pancreatic head (Fig. 1A). Empiric antibiotic therapy with meropenem was administered, however, the high fever persisted and C-reactive protein elevated (4.5 → 14.3 mg/dL). Endoscopic transduodenal drainage was performed on the infected ANC. Endoscopic ultrasonography from the superior duodenum angulus detected the ANC, which was filled with low echoic fluid with no solid components (Fig. 1B). The duodenal lumen was edematous due to the inflammatory effects of pancreatitis, which was needed the balloon dilation and thus endoscopy was unstable. The LAMS (10 mm bore diameter, Hot AXIOS system; Boston Scientific Corp.) placement facilitated the drainage of a large volume of pus (Fig. 1C). Abdominal pain and fever immediately improved, but the patient’s obstructive jaundice worsened 3 days postintervention. CT and endoscopic retrograde cholangiopancreatography revealed that the distal flange of the LAMS smoothly compressed the distal common bile duct, causing biliary obstruction and jaundice (Fig. 2A, 2B). A plastic stent was temporarily inserted into the common bile duct, which promptly improved obstructive jaundice. The LAMS was removed without bleeding or perforation on day 15, leaving behind the plastic stent in the bile duct. The plastic stent was removed after 4 months, and the benign biliary stricture had improved without biliary fistula formation (Fig. 2C). Thereafter, abdominal symptoms, laboratory data and CT scans were monitored every 3 months, and PFC recurrence was observed after 1 year of follow-up.

Figure 1. (A) Computed tomography confirms a 65 × 62 mm acute necrotic collection in the pancreatic head. (B, C) Endoscopic transduodenal drainage with lumen-apposing metallic stent (10 mm bore diameter, Hot AXIOS system; Boston Scientific Corp.) was performed.

Figure 2. (A) Computed tomography with coronal reconstruction showing lumen-apposing metal stent in close proximity to the distal bile duct (white arrow head). (B) Endoscopic retrograde cholangiopancreatography revealed that the abscess side flange of the lumen-apposing metallic stent had compressed the common bile duct (white arrow head), and (C) benign biliary stricture was improved after 4 months of conservative treatment with plastic stent placement.

Bleeding, in both early and late stages, is the most prevalent complication of LAMS.¹⁵ This is due to the unique morphology of LAMS, which causes peptic ulceration due to proximal^16,17 and bleeding due to distal flanges compressing the surrounding vessels.¹⁸ In particular, prolonged placement beyond 3 weeks is a high-risk factor for adverse events.¹⁹ Additionally, the effects of distal flange are not limited to the vessels but can extend to surrounding organs, such as the bile ducts.²⁰ Bang et al²¹ revealed three cases of WON with distal bile duct obstruction 5 or 6 weeks after LAMS placement via the duodenal bulb. To the best of our knowledge, no studies have reported bile duct stenosis caused by plastic stent placement for PFC. Therefore, there was also the option of a plastic stent in this case as well. However, the procedure was performed via a superior duodenum angle, which made the procedure difficult, especially in this case. The drainage route to the ANC was limited to one point to avoid blood vessels, and the scope position was the semi-push position. The duodenum was strongly stenotic because of post-pancreatitis, and the scope could not be manipulated smoothly. Therefore, we expected that the scope position would be easily displaced during stent release. EUS drainage via the superior duodenal angle is extremely unstable in scope position, and the LAMS is more suitable because it requires easy release with a single step, especially when limited to technicalities under the specific conditions of this case.

In this case, the distal bile duct was not located along the drainage route, based on the EUS observation, although biliary compression occurred after LAMS placement. However, the preoperative CT revealed the biliary tract and ANC in proximity, indicating that the risk of compression following the intervention should have been considered high.²² Additionally, we should predict that the distance between the surrounding organs and the distal flange will be closer after the abscess has become smaller. In the present case, jaundice developed 3 days after LAMS placement and occurred as an early complication in contrast to previous reports.²¹ It has been reported that the time for reduction depends on the contents of the abscess. The ANC in this case consisted mostly of fluid with minimal necrotic materials, leading to rapid ANC reduction. In such cases, LAMS compression may occur earlier, and this complication could be prevented by selecting a plastic stent. Several guidelines have suggested different types of stents for the treatment of PFC.^23,24 Plastic stents are widely used for because of their low cost and fewer complications. In contrast, self-expandable metal stent (SEMS) offers a larger diameter and can be delivered in a single step. SEMS is a good indication for improving the efficiency of WON treatment or when a short procedure is required, as in this case. In summary, although LAMS was selected due to technical factors in this case, a plastic stent should generally be the first choice for the stent considering the complications. If LAMS is selected because of technical challenges, it is important that check the anatomy carefully with imaging modality before the procedure, closely monitor for postoperative jaundice, liver function, and conduct imaging examinations closely.

Generally, a LAMS placement is recommended for 3–5 weeks.^21,25 Early LAMS removal within 4 weeks is associated with treatment failure (odds ratio: 24.0).²⁶ Meanwhile, Bang et al²¹ reported in their randomized trial that LAMS-related adverse events were observed in 32.3% of cases, with complications, including bleeding, occurring more frequently after 3 weeks of placement. Therefore, they also suggested removal at 3 weeks if the fluid collection has resolved. Dhillon et al²⁷ reported that the LAMS was removed at a median of 19 days (interquartile range 14 to 22 days) as in our case, with a low rate of adverse events (2.4%). In this case, the LAMS was removed after 15 days without complications. However, most reports on the efficacy and safety of LAMS are for transgastric procedures, and there is an urgent need for evidence in the groove region, which includes the bile ducts and blood vessels, is rapidly needed. Perforation is another potential complication that is rare (1%–3%).²⁸ Furthermore, the cause of perforation is often related to dislodgement during placement or direct necrosectomy, rather than removal.^29,30 In this case, LAMS caused mechanical bile duct compression, which likely resulted in bile leakage. In previous reports, bile leakage with LAMS has only been reported when the stent is directly placed into the gallbladder or common bile duct.^31,32 In a case of indirect biliary obstruction 5 weeks after LAMS placement, the LAMS was immediately removed, and no biliary leakage occurred. Conservative treatment with endoscopic sphincterotomy and biliary stenting was also effective. Because the safety of LAMS removal was not established on the third day of placement, as in the present case, the placement of only the biliary stent without LAMS removal may have prevented biliary leakage. Although the mechanical pressure of LAMS is considered strong, but reversible changes can be expected with good infection control and appropriate biliary drainage with temporary plastic stent placement.

In conclusion, interventional EUS via the duodenum is challenging because of issues with endoscope stability and a narrow lumen, which causes poor visibility. However, we should be aware of the unexpected biliary stricture caused by LAMS placement.

None.

The data that support the findings of this study are available from the corresponding author upon reasonable request.

No potential conflict of interest relevant to this article was reported.