Polyethylene pancreatic duct stent-induced changes in the normal dog pancreas.

This study was undertaken to evaluate the frequency, severity, and reversibility of stent-induced pancreatic ductal and parenchymal changes in the normal dog pancreas. Six adult mongrel dogs underwent duodenotomy and placement of 5F polyethylene pancreatic duct stents into the main pancreatic duct. After 8 weeks of stenting, the animals were randomly assigned to one of three groups: group I (n = 2), sacrifice; group II (n = 2), stent removal followed by sacrifice after an 8-week recovery period; group III (n = 2), the stent was exchanged and kept in place for an additional 8 weeks. In group III at 16 weeks the stent was removed, and the animals were allowed to recover for 8 weeks before sacrifice. Pancreatograms were obtained at each operation and were normal before stent placement. Gross and histologic evaluation was performed at the time of sacrifice. All stented animals developed radiographic, gross, and histologic abnormalities. Pancreatograms showed duct dilation in the stented region associated with a short stenosis at the mid to upstream segment of the stent. Group III animals had more advanced radiographic changes than group I and II animals. The radiographic findings were associated with gross evidence of fibrosis, which increased proportionately with the length of the stenting period. Group III animals developed moderate to severe pancreas atrophy. Histologic changes of obstructive pancreatitis were present in most experimental dogs. The results of this study suggest that pancreatic stenting may cause permanent damage in the normal dog pancreas. The cause of the damage appears to be related to stent occlusion, perhaps exacerbated by local stent-induced trauma.