Analysis of occluded pancreatic stents and juices in patients with chronic pancreatitis.

BACKGROUND

Pancreatic stents may occlude with time, and there is little information available on the nature of the clogging process.

METHODS

We analyzed the contents of occluded pancreatic polyethylene stents in nine patients with chronic pancreatitis. In the same patients, the protein patterns in the corresponding pancreatic juices were analyzed. The stents had been in place for a mean of 9 weeks (range 2 to 17).

RESULTS

All stents were occluded at both ends, especially around side holes, with thick creamy-white precipitate. The average dry weight of occluding debris was 3 mg per 3.25 cm 10F stent. Total protein content was 50% (SD 16.3) and total calcium 0.8% of dry weight (SD 0.6). Light microscopy showed that proteinaceous material completely filled the stent lumen. Yeasts and plant material were seen in two stents. A variable number of bacteria of mixed species, sometimes in clumps, were patchily scattered in the protein matrix. Cultures of stent contents grew several species of Gram-positive and negative bacteria. Scanning and transmission electron microscopy showed an amorphous protein matrix in all stents, arranged as a network in some areas, but in layers in other areas. Sodium dodecylsulfate polyacrimide gel electrophoresis showed that protein patterns of stent contents were remarkably different from the protein patterns of the juice samples of the same patient. A 66 kD band, identified as albumin, appeared in the protein patterns of stent content, whereas it was lacking in most juice samples.

CONCLUSIONS

Adherence of protein, especially albumin, plays an important role in the process of pancreatic stent clogging. Other factors, such as bacteria, refluxed duodenal contents, and calcium seem to be of less importance.