Recent randomized controlled trials have demonstrated the benefits of utilizing an ES [3, 10, 11, 13, 16]. There are several factors supporting the effectiveness of ES in reducing the occurrence of CR-POPF. Theoretically, an ES has the advantage of diverting pancreatic juice more completely from the pancreaticoenteral anastomosis, thus preventing bile activation by pancreatic enzymes . Stent placement of the pancreatic duct allows for more accurate placement of sutures during pancreaticoenteral anastomosis . Patients who develop CR-POPF can be managed more efficiently and conservatively without requiring reoperation. Thus, ESs prevent the severity of CR-POPF [3, 13]. The results of the present study showed that soft pancreas, non-dilated pancreatic duct, and a higher volume of pancreatic juice prevented early ES removal, which is consistent with clinical factors associated with CR-POPF . Higher serum CRP levels, higher D-AMY levels, and POPF were the postoperative factors associated with the prevention of early ES removal. However, CR-POPF was not associated with early ES removal. In addition, early ES removal was associated with early discharge home or to a rehabilitation hospital. The median duration of postoperative hospital stay was 16 days in the present study, which is shorter than that (29 days [IQR: 21–42 days]) from the National Clinical Database of Japan . Even when early removal of ES was not possible, ES could be used to manage CR-POPF. These results suggest that an ES may suppress the deterioration of CR-POPF.
Potential complications are among the concerns with the use of an ES for pancreaticoenteral anastomosis . It may increase the risks such as local skin infections, subcutaneous abscesses, and local peritonitis after tube removal [12, 18]. Although the ES can be locked earlier in the absence of pancreatic fistula, it has been placed at 3–8 weeks after PD in previous reports [3, 12, 13, 18]. ESs seem uncomfortable for patients who undergo PD and can be inadvertently removed . The present study showed that the ES could be removed within 10 days regardless of the volume of pancreatic juice drained from it. No patient was readmitted or had an intra-abdominal abscess after ES removal. In cases where an intra-abdominal abscess is observed after ES removal, the peripheral part of the jejunum from the biliary anastomosis has been reportedly selected to guide the ES outside the jejunum . Therefore, Development of postoperative intra-abdominal abscess due to ES may be suppressed by selecting the stump of the elevated jejunum to the abdominal wall (Fig. 1b).
An IS does not require additional postoperative management of drainage tubes. However, IS has been reported to cause a variety of stent-induced complications such as bile duct strictures, stones, liver abscesses, intestinal obstruction, and intestinal perforation . In addition, proximal migration of the IS has also been reported . Externalization of the stent prevents complications .
Based on the definition proposed by Connor, the reported rate of POAP was between 53% and 64% . The rate of POPF was 72.3% in the present study. S-AMY levels have been reported to peak at POD 1 and to normalize at POD 4–5 during the postoperative course , which is consistent with the results of the present study. Serum CRP levels peaked at POD 3 and decreased at POD 5–7, and the volume of pancreatic juice from the ES increased until 5 days after PD. These results indicate that POAP may resolve at 5–7 days after PD and the pancreatic remnant may start to recover functionally. The results from the present study showed that POAP was associated with the time to ES removal and the time to intra-abdominal tube removal. However, POAP was not associated with postoperative hospital stay, CR-POPF, or postoperative complications. This suggests that ESs may control POAP in the early postoperative period. Considering the results regarding the clinical pattern of POAP and the purpose of an ES, an ES might be removed earlier, since POAP management needs only 5–7 days after PD.
The present study indicated that early removal of the abdominal tube was the only factor associated with early removal of ES (OR: 8.5, 95% CI: 1.3–69, P=0.03) in the multivariate analysis. Various discussions have been conducted on intra-abdominal drains during PD [20, 21]. Two points should be considered regarding the drainage of amylase-rich ascites: it contains proteases and it can cause infection. Leakage of pancreatic juice from the pancreatic remnant starts intraoperatively . Proteases, rather than amylases in the pancreatic juice, can damage the tissues around the pancreaticoenteral anastomosis, leading to the development of POPF [23, 24]. Particularly, the area of peritoneal fluid collection around the pancreaticoenteral anastomosis has been significantly associated with the development of CR-POPF . Thus, sufficient drainage of amylase-rich ascites through an intra-abdominal tube is essential to prevent POPF. In contrast, an intra-abdominal drain tube can directly injure the pancreaticoenteral anastomosis . In addition, long-term drainage via an intra-abdominal tube can increase the risk of infection, which in turn increases the risk of CR-POPF [21, 27]. Microbial detection in CR-POPF can lead to life-threatening conditions [23, 28]. Early removal of the intra-abdominal tube immediately after the disappearance of amylase-rich ascites is a reasonable strategy to decrease the risk of CR-POPF.
The present study has several limitations. It was a single-institution retrospective analysis with a small number of patients and limited clinical variables. No comparisons were performed with the absence of a pancreatic stent or an IS. Moreover, this study did not perform a comparison between the 10-day removal group and the conventional ≥3-week removal group. The effects of ES on POAP need to be evaluated carefully, since the stent removal period was not based on patients with or without POAP in the present study. A comparative study between an IS group and an early ES removal group among patients with a high risk of POAP is desirable in the future.