Pancreaticoduodenectomy (PD) is the standard treatment for tumors of the pancreatic head, distal bile duct, duodenum, and ampulla of Vater. With advances in surgical experience and instrumentation, the mortality rate of PD has decreased to below 5% in high-volume pancreatic centers. However, the postoperative complication rate remains high at 25%-50%, limiting the development and application of PD.

The main postoperative complications of PD are postoperative pancreatic fistula (POPF), delayed gastric emptying (DGE), post-pancreatectomy hemorrhage (PPH), and biliary leakage (BL). POPF, BL, and the subsequent abdominal infection, PPH, etc. are the main causes of death during hospitalization. Even in large, relatively mature pancreatic centers, the incidence of POPF remains as high as 10%-40%. In recent years, various methods have been used to prevent and treat POPF and BL after PD, such as pancreatic duct stent external drainage and external biliary drainage.

To date, there have been many studies by domestic and foreign scholars on the advantages and disadvantages of biliary and pancreatic duct external drainage versus internal drainage in PD in terms of perioperative POPF incidence, mortality rate, etc., but the research results are not consistent. Overall, pancreatic duct stent external drainage is only recommended for patients with a high risk of pancreatic fistula during PD. Currently, there have been a few relevant studies exploring and verifying the preventive effect of pancreatic duct stent external drainage on pancreatic fistula in patients with high risk of pancreatic fistula. For example, a retrospective study of 98 patients with soft pancreatic parenchyma by Teruyuki Usub et al. found that there was no significant difference between groups with and without pancreatic duct stent in preventing pancreatic fistula. However, due to the low level of evidence, only a few risk factors such as pancreatic texture and pancreatic duct diameter were included, and the risk of POPF was not systematically evaluated. Further clinical exploration and verification are needed. In 2013, Mark P Callery et al. proposed a pancreatic fistula risk score (The fistula risk score, FRS) based on the pancreatic fistula standard defined by the International Pancreatic Fistula Study Group, which included pancreatic texture, pathological type, pancreatic duct diameter, and intraoperative blood loss. This model can be used to systematically and quantitatively evaluate the risk of POPF. Previous studies did not have a clear stratification for patients undergoing pancreatic duct stent external drainage, which may have included too many patients with a low risk of pancreatic fistula, resulting in inaccurate results. Therefore, it is necessary to re-evaluate the effectiveness of pancreatic duct stent external drainage in preventing clinically relevant pancreatic fistula based on stratification of pancreatic fistula risk and disease type. At the same time, pancreatic juice contains a variety of digestive enzymes, of which pancreatic lipase, trypsin, and chymotrypsin all need to be activated by bile to play a role in digesting and decomposing fat and protein. Theoretically, biliary and pancreatic juice diversion may be able to reduce the incidence of pancreatic fistula and its related complications in PD patients.

Thus, the investigators design the present study to evaluate the impact of main pancreatic duct and biliary duct external drainage on postoperative complication, especially POPF.