Decompression and Drainage

The procedure is the firstline surgical treatment for patients with dilated main pancreatic duct（≥7 mm）（Büchler and Warshaw 2008）and no inflammatory masses at the pancreatic head（Parekh and Natarajan 2015）.Nowadays，while the causes of pain from CP remain controversial，it probably has something to do with the combination of pancreatic duct obstruction and parenchymal hypertension，leading to ischemia and accumulation of H+（Poulsen et al.2013）.As for this，several procedures have developed.

1.DuVal procedure

In orderto reduce high pressure in main pancreatic duct，in 1954，DuVal and Zollinger et al.performed the pancreatic tail resection alongwith splenectomy and pancreaticojejunostomy of the residual pancreatic end and jejunum.However，this anastomotic method will bring about countercurrent of pancreatic juice，and inconspicuous decompression will sustain in a long run.Therefore，DuVal procedure is almost abandoned in clinical practice.

2.Duodenal papilla plasty(https://www.daowen.com)

In 1956，Doubilet reported duodenal papilla plasty，during which operation duodenal was incised and then duodenal papilla together with orifices of pancreatic duct was shaped.But when the main duct dilates like beads（that is multiple narrow），both of the methods couldnot attain perfect drainage effect.

3.Side-to-side pancreaticojejunostomy

As the two procedure are less effective on decompression，Puestow and Gillesby developed a technique that combining a longitudinal incision of the pancreatic duct and a pancreaticojejunostomy with the pancreatic tail and spleen resection.The Puestow procedure can be applied to multiple strictures pancreatolithiasis but it also bring patients severe trauma.Shortly thereafter，Partington and Rochelle modified this procedure by extensively opening the duct to clear stones and then performing only a side-to side pancreaticojejunostomy without a distal pancreatectomy.The procedure preserves substantial pancreatic parenchyma，which is important for maintaining pancreatic function（Issa et al.2014），therefore，it is the most widely applied CP decompression procedure in clinic.However，Puestow procedure and Partington procedure are not indicated in patients with an inflammatory mass in the head of the pancreas，small duct disease，hereditary chronic pancreatitis，and idiopathic pancreatitis who do not have marked dilated ducts（Parekh and Natarajan 2015）.Once patients have the conditions mentioned above，Partington procedure could not have adequate drainage at the pancreatic head，thus resection or combined procedures are recommended.