Pancreatectomy

As for CP patients with less dilated duct and fibrotic pancreatic tissues，especially calcified ones，pancreatectomy should be taken.On the basis of pathological region and extent，the resection is classified as follows.

1.Pancreatoduodenectomy or pylorus-preserving pancreatoduodenectomy

Since the classical pancreatoduodenectomy（PD）and Pylorus-preserving pancreatoduodenectomy（PPPD）were respectively proposed in 1946 and 1978，they have increasingly been used in the treatment of patients with CP with the continuous improvement in their safety.PD and PPPD are applied to CP patients with no dilated ducts，especially to those whose lesions locating in pancreatic head and unciform process，with a low surgical mortality rate and a high long-term pain relief rate（Büchler and Warshaw 2008；Jimenez et al.2000）.

2.Duodenum-preserving pancreatic head resection

In 1972，Beger performed the first duodenumpreserving pancreatic head resection（DPPHR），also called the Beger procedure.The neck of the pancreas is separated over the portal vein，and the head and uncinate process are subtotally excised preserving the duodenum and the intrapancreatic bile duct.The advantage of Beger procedure is long-term pain relief with the preservation of pancreatic body and tail，the physiologic function of the stomach，duodenum，and common bile duct.It is a safe and effective procedure in some patients with an expanded inflammatory mass in the head of the pancreas associated pain in CP.In 1987，Frey modified the procedure into side to side pancreaticojejunostomy incorporatedwith a local resection of pancreatic head，which is a combination of DPPHR and drainage.When CP patients have pancreatic duct obstruction and small inflammatory masses at the pancreatic head，the Frey procedure can be considered.Compared with the standard resections such as the Whipple operation，Begerand Frey operations can get a better global quality of life（Yin et al.2012）and a lower postoperative morbidity（Farkas et al.2006）.Therefore，these tend to better the outcome following organ-preserving surgery compared to the traditional operations.The Berne procedure is to aim at the condition of portal hypertension in certain patients with CP（Gloor et al.2001），involving a local pancreatic head resection，without complete removal of the pancreas and without lateral pancreaticojejunostomy.Moreover，Izbicki et al.developed the Hamburg procedure specialized for patients with“small duct”pancreatitis（pancreatic duct diameter＜3 mm）（Kutup et al.2010）.The key point of the operation is to resect ventral pancreas in a V shape and perform a Roux-en-Y anastomosis，in order to adequately drainage the second and third pancreatic branches.(https://www.daowen.com)

3.Distal pancreatectomy

A distal pancreatectomy（DP）can be applied in patients with normal proximal pancreatic tissues and main pancreatic duct stenosis，with a reported hospital mortality of 0-3.8%and a morbidity of 15-31%（Sakorafas et al.2001）.Besides，normal duct but with hydatoncus in pancreatic tail is indication for DP.The procedure can safely preserve spleen and delaythe attack of diabetes mellitus.

4.Total pancreatectomy

As total pancreatectomy heavily destroys pancreatic endocrine and exocrine functions，it is only chosen when lesion involves the whole pancreas or abdominal pain sustains after conducting limited pancreatectomy as well as drainage.Several studies reported this procedure successfully reduced pain under stable glycemic control and improved quality of life（Wilson et al.2015a，b），but long-term prognosis should be further studied.Moreover，to restore the endocrine function，total pancreatectomy should be conducted with the combination of islet autologous transplantation and selection criteria remain to be fulfilled（Bellin et al.2015）.In view of the high postoperative ulcer incidence and severe metabolic disorders，TP should only be considered once other surgical treatment options proved to be useless or unlikely to improve symptoms（Bramis et al.2012）.