Metallic stent placement in the pancreatic duct: an experimental study in the normal dog pancreas.

PURPOSE: To evaluate radiologic and histologic changes in the pancreatic duct and parenchyma after placement of metallic stents in normal dog pancreatic ducts.

MATERIALS AND

METHODS

Eight dogs underwent duodenotomy and placement of a balloon-expandable metallic stent 1.5 mm in diameter and 1 cm in length in the main pancreatic duct. Two dogs each were killed at 1 day and 1, 3, and 5 months after stent placement. Pancreatic duct injection images were obtained before and immediately after stent placement and just before and after sacrifice. Macroscopic and microscopic examinations were also performed.

RESULTS

Pancreatic duct injection images revealed mild dilation of pancreatic ducts related to the procedure immediately and 1 day after stent placement. Microscopically, denudation of the ductal epithelium and small foci of fat necrosis were observed. At 1 month or later, ductal stricture (n = 4) and occlusion (n = 2) were found at the downstream edge of the initially stent-implanted region associated with dilation of the duct upstream. Epithelial hyperplasia was observed at the sites of ductal stricture and occlusion at 1 and 3 months. Stents remained in the region in which they were initially placed until 1 month. However, stents had moved downstream from their initial positions at 3 and 5 months. One stent had migrated into the duodenum at 5 months. Stone formation was found in the ductal lumen and around the stents at 3 and 5 months. Ducts and parenchyma became fibrotic proportional to the period of stent implantation.

CONCLUSION

Metallic stent placement in the pancreatic duct causes ductal and parenchymal damage related to the procedure and reaction to the stent in the normal dog pancreas.