Main Pancreatic Duct Strictures

MPD（main pancreatic duct）strictures occur due to a previous embedded stone or the necroinflammatory process surrounding the duct.Insertion of a pancreatic duct stent leads to ductal decompression and pain relief.This is best seen in patients with strictures located within the head of pancreas and associated with upstream ductal dilation（Cremer et al.1991）.Other predictors of good outcome after MPD stenting include absence of pancreas divisum and non-alcoholic aetiology of chronic pancreatitis（Cremer et al.1991；Eleftherladis et al.2005）.

Endotherapy for MPD strictures include pancreatic sphincterotomy，stricture dilation and ductal stenting with a temporary stent.While pancreatic sphincterotomy alone may improve ductal drainage in patients with juxtapapillary strictures，most other strictures would need some form of dilation as they are usually very tight and fibrotic（Fig.9.3a-c）.When dilation with radial expansion balloons or dilator bougies fail，the Soehendra stent retriever may be used as a boring tool for difficult strictures（Ziebert and DiSario 1999）.

Itoi et al.described a novel technique using wire-guided snare forceps to incise a refractory stricture.Although successful in the two described cases，the risk of severe complications of perforation，bleeding and pancreatic parenchymal injury is present（Itoi et al.2010）.

Fig.9.3　（a）Pancreatography showing a tight pancreatic duct stricture at the head region.（b）Balloon dilation of the stricture.（c）Plastic stent insertion with drainage of the pancreatic duct(https://www.daowen.com)

Stents may be inserted in a single or multiple fashion.The types of available stents include plastic or self-expanding metallic stents.The overall aim is to eventually remove the stents and confirm the resolution of the stricture via pancreatography.If a dominant stricture persists，the patient is unlikely to be pain-free without continual stenting.A dominant stricture is defined as presence of at least one of the following features:upstream MPD dilation of≥6 mm in diameter；prevention of contrast medium outflow alongside a 6-Fr catheter inserted upstream from the stricture；or abdominal pain during continuous infusion of a nasopancreatic catheter inserted upstream from the stricture with 1L saline for 12-24 h（Dumonceau et al.2012）.Practically，we perform threemonthly assessments for stricture resolution；observing for good contrast outflow，smooth passage of a 7-Fr catheter within the duct and diminished focal narrowing.Once these are confirmed，we remove the stents and observe the patient clinically in the coming months.

MPD stenting is successful in 85-98%of patients，with immediate pain relief in 65-95%（Dumonceau et al.2012）.Over a follow-up period of 14-58 months，pain relief is seen in 32-68%.Surgery may still be required in 4-26%of patients，due to non-response to treatment or complications（Eleftherladis et al.2005；Vitale et al.2004；Binmoeller et al.1995）.Complications occur in 6-39%of patients，including mild pancreatitis（most common），stent migration and pancreatic sepsis（Dumonceau et al.2012；Eleftherladis et al.2005；Vitale et al.2004；Binmoeller et al.1995）.