Pancreatic endoprostheses in chronic pancreatitis: criteria to predict stent occlusion

Background Good clinical results of main pancreatic duct (MPD) stent placement in chronic pancreatitis (CP) are clouded by early stent occlusion. The aim of this study was to increase knowledge about stent occlusion and its effects on clinical symptoms, and to define criteria that enable the prediction of clogging. Methods A total of 100 pancreatic endoprostheses of 47 patients (32 men, 15 women; mean age, 53 years; standard deviation, 9 years) suffering from CP were bench tested by simulating the pathophysiologically increased MPD pressure. The main study parameter was the reduction of water flow through clogged stents in comparison with native endoprostheses of identical type, length, and diameter. Major stent occlusion was defined as flow reduction by ≥75%. The association between time to stent occlusion and stent- or patient-related variables was evaluated. Results Occlusion took place in nearly all endoprostheses (97%). No significant association of occlusion with clinical or blood parameters was found. Multifactorial analysis proved 4 risk factors for major stent occlusion: (A) stent diameter >8.5F, (B) stent length >8 cm, (C) female gender, (D) exocrine pancreatic insufficiency that required regular oral enzyme supplementation. According to the relative risk, these factors were given the following scores: A, 3 points; B to D, 2 points. Stents in patients with a score sum >5 showed a significantly higher risk of major stent occlusion within 90 days. Conclusions Stent clogging in CP seems to be an inevitable phenomenon. Because clinical and laboratory data do not reliably indicate clogging, stent removal or exchange should be performed in high-risk patients (score sum >5) within 3 months.