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Endoscopic retrograde cholangiopancreatography  (ERCP) is commonly performed to relieve biliary obstruction in patients with periampullary carcinoma or carcinoma head of pancreas undergoing pancreatico-duodenectomy (PD). Post-ERCP pancreatitis may pose significant challenges during PD due to obliteration of tissue planes and adhesions as well as necrosis in the root of the mesentery. The study aimed to compare postoperative outcomes in patients with and without preoperative post-ERCP acute pancreatitis. (PAP).

We retrospectively analysed 20 patients who underwent PD from January 2015 to July 2017. Among these patients, two had preoperative PAP following endoscopic biliary drainage for cholangitis. This group was compared with the remaining 18 patients in the control groupin terms of demographic profile, intraoperative variables such as operative time, blood loss, blood transfusions received, pancreatic texture(soft vs hard), pancreatic duct size, and postoperative outcomes such as ICU and hospital stay, pancreatic fistula, delayed gastric emptying and postoperative haemorrhage.Pancreatic fistula and delayed gastric emptying were defined and graded according to international consensus definitions^1,2 and complications were graded according to the Clavien-Dindo classification³.

The number of complications was higher in the PAP group (8/2) compared to the control group (20/18). The demographic profile and operative variables in the PAP group (n=2) and control group (n=18) are shown in Table 1. 

Each patient in the PAP group had moderately severe acute pancreatitis according to the revised Atlanta classification (2012)⁴. 18 patients underwent classical PD and 2 underwent pylorus-preserving pancreaticoduodenectomy (PPPD). The postoperative outcomes and complications with ClavienDindo grading are shown in Table 2. 

The duration of ICU and post-operative stay and the incidence of delayed gastric emptying (DGE) were higher in the PAP group. There was one perioperative mortality due to grade C pancreatic fistula in the control group. 9/20 patients underwent endoscopic biliary stenting preoperatively. Complication rates in stented and non-stented patients are shown in Table 3.

The risk factors for pancreatic fistula were analysed. Follow up was available for 18 patients. The mean follow up duration was 15 months. Tumour recurrence-locoregional and distant each with pancreatic head adenocarcinoma occurred in 2 patients. Among these patients, one patient expired at 8 months and the other at 10 months following surgery.

Although the role of diagnostic ERCP has diminished, it is still being performed for preoperative endoscopic biliary decompression in patients with obstructive jaundice when indicated.  Whereas the overall incidence of post-ERCP pancreatitis ranges from 1% to 6%, the incidence of post-ERCP pancreatitis may exceed 30% in patients considered to be high risk^5-7. Younger patients, difficult cannulation, a precut or dilated papilla, and injection of contrast into the pancreatic duct more than once are associated with post-ERCP pancreatitis⁸.

The data on PD in the setting of preoperative post-ERCP acute pancreatitis is sparse. Studies have shown that this is feasible, albeit with higher morbidity^9,10.

The timing of surgery for PD after PAP is crucial. An interval of 4-6 weeks may be advisable to allow any local complication of acute pancreatitis like necrosis, pseudocyst or abscess to develop. This also permits sepsis control and optimization of general condition especially in patients with severe PAP. Preoperative contrast enhanced computed tomography (CECT) abdomen just before surgery must exclude these local complications and ensure viable (non-necrotic) pancreatic parenchyma as well to ensure a healthy pancreatic stump for anastomosis. In our study, one patient was operated at 33 days and the other one after 64 days of ERCP. Mean serum bilirubin was 7.5 mg/dL before endoscopic biliary stenting.

The key intraoperative challenges encountered include inflammatory adhesions and necrosis in the peripancreatic region and the root of the mesentery leading to difficulty in retropancreatic tunnel formation and bleeding from the gastrocolic trunk or the SMV itself (Figure 2). Indeed,higher blood loss and operative time were reported in the study by Hirashita et.al¹⁰. Occasionally, a fused lesser sac precluding access may mandate abandoning the procedure itself. Operative tips to perform the procedure successfully in this setting include  identifying the inferior border of the pancreas and dissecting close to the pancreatic head, to lead to the retropancreatic tunnel.

Each of the 2 patients in the PAP group had a higher rate of complications (Table 2), and longer hospital and ICU stay. One patient had pus in the peritoneal cavity which was not identified on preoperative imaging. As the patient was stable, surgery was completed. Postoperatively, the patient had hypotension requiring inotropic support and escalation of antibiotics. Similar findings have been reported previously^9,10. In the study by Hirashita et.al, PD in the setting of PAP was associated with longer operative time, higher blood loss, elevated CRP and delayed gastric emptying10. In another study by Chen et.al, PAP was associated with a higher rate of severe complications (Clavien grade 3 or higher) and prolonged hospital stay. Moreover, PAP was an independent risk factor for postoperative pancreatic fistula⁹. As the numbers in our study are low, the impact of PAP on postoperative pancreatic fistula and other complications (Table 2) is difficult to assess.Nevertheless, delayed gastric emptying, prolonged hospital and ICU stay were associated with the PAP group.

Delayed gastric emptying is one of the most common complications after PD^11,12. The pathophysiology has been poorly understood. The association between delayed gastric emptying and postoperative complications, such as pancreatic fistula, postoperative pancreatitis, and overall complications has been reported previously^13,14. In our study, both patients developed delayed gastric emptying with one of them having a severity of grade C requiring nasogastric tube for 22 days postoperatively. Residual local peripancreatic sepsis or collections may lead to delayed gastric emptying in this setting.

Although preoperative endoscopic biliary stenting is not associated with major morbidity postoperatively in patients undergoing PD, infectious complications such as wound infection occur more frequently in stented patients, especially when bile is infected^15-19. In our study, 9 out of 20 patients were stented. In contrast to the aforementioned studies, overall and wound infections were not statistically significant in either group. This observation could be due to small numbers in each group. 

The risk factors for pancreatic fistula can be classified into disease-related factors,such as a soft pancreas, non dilated ducts, ampullary, duodenal, cystic or islet-cell pathology; patient-related factors like age more than 70 years, comorbidities like coronary artery disease and duration of biliary obstruction; or operative risk factors like excessive blood loss²⁰. In our study, pancreatic fistula occurred in 6/20 patients(30%), of which clinically relevant fistula formation (grade B or C) occurred in 4/20 (20%). We analysed the risk factors for pancreatic fistula (Table 4) and found that soft pancreas and non-dilated pancreatic duct are risk factors for pancreatic fistula. PAP was not statistically associated with pancreatic fistula in contrast to the study from Chen et.al⁹.

To conclude, PD in the setting of PAP is feasible, albeit challenging and associated with more frequent complications, prolonged ICU and hospital stay.