A 14-year-old boy with recent idiopathic acute severe pancreatitis, presented 6 weeks later with large (137 × 114 mm) symptomatic walled off pancreatic necrosis (WON) in body and tail region of pancreas. He underwent EUS-guided trans-gastric drainage of WON using a fully covered, 16-mm diameter, 2-cm long bi-flanged metal stent (BFMS) (NAGI stent, Taewoong Medical, Gyeonggi-do, South Korea) (Fig. 1a). He had rapid clinical improvement, with significant reduction (more than 75%) in size of the collection on computed tomography (CT) scan at 48 h.

Cystogastric stent placement and migrated stent (a) trans-gastric drainage of walled off necrosis (WON) drainage bi-flanged metal stent (BFMS); (b) erect abdominal x-ray showing BFMS in transverse colon; (c) computed tomography showing small residual collection post EUS drainage of WON; (d) impacted flange of BFMS in the wall of transverse colon with dilated proximal colonic loops filled with fecal matter.

Two weeks later, he presented with acute pain abdomen and vomiting. Abdominal x-ray on erect portion showed BFMS in right upper quadrant with dilated transverse colonic loops (Fig. 1b). CT abdomen showed a small (4.5 × 1 cm) residual collection (Fig. 1c) and impacted flange of BFMS in the wall of transverse colon with dilated proximal colonic loops filled with fecal matter (Fig. 1d). Colonoscopy confirmed an impacted BFMS in transverse colon (Fig. 2a), which was removed with biopsy forceps by holding the purse string attachment at one end of the BFMS after disimpaction (Fig. 2b). There was no obvious underlying colonic pathology. He improved symptomatically after removal of BFMS.

Colonoscopic removal of impacted bi-flanged metal stent (BFMS). (a) Colonoscopy showing an impacted BFMS in descending colon which is held by biopsy forceps through the purse string attachment; (b) disimpacted BFMS brought out into sigmoid colon.

Endoscopic ultrasound (EUS) guided cysto-gastric drainage using dedicated fully covered self-expandable stents (FCSEMSs) has emerged as an effective treatment modality for pancreatic fluid collections (PFC). Spontaneous migrations have been described with tubular shaped FCSEMS (meant originally for biliary stricture). Most external stent migrations into GI lumen are insignificant. Spontaneous migration of lumen apposing metal stents (LAMS) have also been reported into colon. But most of the earlier reports did not cause colonic obstruction and was managed either conservatively or by sigmoidoscopic removal. Spontaneous external migrations of BFMS (Nagi SEMS) after EUS-guided drainage of PFC causing GI lumen obstruction have not been reported earlier. The relative small colonic caliber of a 14-year-old child could be the plausible explanation for this complication. Maximum transverse colonic diameter in adults is less than 6 cm whereas it can vary from 3.6 to 4.4 cm in pediatric patients between 10 and 15 years of age. This is the potential reason why 2-cm long NAGI stent with flared ends (20 mm each) got impacted in colon in this case. This patient with BFMS impacted in colon large bowel obstruction was managed by colonoscopic removal of stent. However, this report could raise the potential “relative contra-indication” for the use of BFMS for drainage of pancreatic fluid collections in pediatric population.