Endoscopic retrograde cholangiopancreatography (ERCP)-related procedures were performed in 2136 cases at the Division of Gastroenterology and Hepatology of the St. Marianna University School of Medicine Hospital between April 2008 and August 2013. In our department, biliary cannulation is first attempted using the conventional contrast-assisted cannulation (CC) method. However, in cases where bile duct cannulation is difficult to perform using CC but in which a guidewire can be placed in the pancreatic duct, P-GW is employed as the procedure of first choice to achieve biliary cannulation. A second cannula was passed into the same working channel of the scope alongside the guidewire using the two-devices-in-one-channel method[12], and biliary cannulation was attempted.

Of the 2136 patients who underwent ERCP-related procedures during the study period, 1454 had a native papilla. After 316 patients who did not undergo biliary cannulation or who had pancreatic diseases were excluded, 1138 patients remained. Biliary cannulation was achieved using CC in 977 of these patients. Then, among the 161 patients who experienced difficult biliary cannulation using CC, P-GW was attempted in 144, and successful biliary cannulation was achieved in 122 patients. Among these 122 patients with successful biliary cannulation using P-GW, EST was performed in 55, endoscopic papillary balloon dilation (EPBD) was performed in 18, and no papillary procedure was performed in 49 patients. EST was performed using an electrosurgical generator in the 120-Watt Endocut mode (ICC 200: ERBE Corp., Tuebingen, Germany). Following EST, a pancreatic duct stent was placed in 24 patients (stent group), whereas no pancreatic stenting was performed in the remaining 31 cases (no-stent group) (Figure 1). The pancreatic duct stents used were all 5-Fr, 3-cm-long spontaneous dislodgement stents with a single duodenal pigtail (Pit-stent, Gadelius Medical, Tokyo, Japan).

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Figure 1 Flow chart showing the clinical courses of the patients. EST: Endoscopic sphincterotomy; P-GW: Pancreatic duct guidewire placement; ERCP: Endoscopic retrograde cholangiopancreatography; PD: Pancreatic duct; EPBD: Endoscopic papillary balloom dilation.

Decisions regarding whether pancreatic stenting was necessary were left to the discretion of the endoscopist performing each procedure. All the procedures were supervised by a single expert, who performs approximately 500-600 ERCPs per year. Because our hospital is an educational institution, trainees performed approximately half of the procedures. However, when deep cannulation of the bile duct was not achieved within 15 min, the expert took over the procedure. In all cases, 600 mg of gabexate mesilate was administered on the day of the procedure to prevent PEP. The patients’ serum amylase levels (normal range: 37-124 IU/L) were measured prior to, 3 h after, and 1 d after the ERCP procedure.

The stent group (n = 24), in which pancreatic stenting was performed after EST, and the no-stent group (n = 31), in which no pancreatic duct stent was placed after EST, were retrospectively compared in terms of patient characteristics (age, sex, primary disease, history of pancreatitis, and peripapillary diverticulum), endoscopic procedures (diameter of the pancreatic duct guidewire, range of EST incision, biliary maneuver, and procedure time), incidence of PEP, complication rate, and serum amylase levels. Moreover, univariate and multivariate logistic regression analyses were performed to identify the risk factors for PEP in patients undergoing EST after biliary cannulation by P-GW.

The ranges of the EST incisions were defined as follows: an incision up to the hooding fold was considered a small incision, an incision up to the upper border of the oral protrusion was a large incision, and an incision with a range between those of small and large incisions was an intermediate incision. The diagnosis of pancreatitis and the determination of its severity were based on consensus guidelines proposed by Cotton et al[13]. Moreover, complications, such as bleeding, perforation, and cholangitis, were also diagnosed according to the consensus guidelines proposed by Cotton et al[13].

The statistical analysis was performed using Fisher’s exact test or Welch’s t-test, as appropriate. To identify risk factors for post-ERCP pancreatitis, variables found to be possibly significant (P < 0.2) by univariate analysis were entered into a multiple logistic regression model. P values < 0.05 were regarded as denoting significance. The statistical analysis was performed using the Prism 5 program (GraphPad Software, Inc., CA, United States) and SPSS (version 19; SPSS, Chicago, IL, United States).

No significant differences in age, sex, distribution of primary diseases, history of pancreatitis, or presence/absence of peripapillary diverticulum were observed between the Stent and no-stent groups (Table 1). Moreover, the analysis of endoscopic procedure-related variables revealed no significant differences in the diameter of the pancreatic duct guidewire, range of EST incision, biliary maneuver, or procedure time between the Stent and no-stent groups (Table 2).

The incidence of PEP was 4.2% (1/24) in the stent group and 29.0% (9/31) in the no-stent group, with the no-stent group having a significantly higher incidence (P = 0.031) (Table 3). The PEP severity was mild for all the patients in the stent group. In contrast, among the 9 PEP patients in the no-stent group, 8 had mild PEP and 1 had moderate PEP. Intermediate EST incisions were performed in all the patients in the stent group with PEP, whereas among the 9 patients in the no-stent group with PEP, 3 received small incisions, 5 received intermediate incisions, and 1 received a large incision. Conservative therapy without additional endoscopic procedures resulted in improvement in all the patients.

With regard to complications other than PEP, bleeding was observed in 2 patients each in the stent group (2/24; 8.3%) and the no-stent group (2/31; 6.5%), with no significant difference in incidence between the two groups (P = 1.000). No other complications, such as perforation or cholangitis, were observed in either group. The overall complication rate, including PEP, was 12.5% (3/24) in the stent group and 35.5% (11/31) in the no-stent group. Although the difference was not significant, the rate tended to be higher in the no-stent group (P = 0.067) (Table 3).

The serum amylase levels (means ± SD) in the stent group were 118 ± 116.9 IU/L before ERCP, 183.1 ± 136.7 IU/L 3 h after ERCP, and 209.5 ± 208.7 IU/L one day after ERCP; the corresponding values in the no-stent group were 85.5 ± 56.0, 463.6 ± 510.4 and 684.4 ± 759.3 IU/L, respectively. Although no significant difference in the serum amylase levels before ERCP was observed between the Stent and no-stent groups (P = 0.238), the levels 3 h after and one day after ERCP were significantly higher in the no-stent group (P = 0.006 and P = 0.002, respectively) (Figure 2).

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Figure 2 Comparison of serum amylase levels between the Stent and no-stent groups.

The univariate analysis identified the absence of pancreatic duct stenting (P = 0.031; OR, 9.4; 95%CI: 1.1-81) and the incidence of endoscopic nasobiliary drainage (P = 0.047; OR, 5.3; 95%CI: 1.1-26) as significant risk factors for PEP (Table 4). The multivariate analysis identified the absence of pancreatic stenting (P = 0.045; OR, 9.7; 95%CI: 1.1-90) as the only significant risk factor (Table 5).

The pancreatic duct guidewire placement method is reported to be effective in patients with difficult biliary cannulation. However, difficult biliary cannulation is associated with a high incidence of post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP).

The efficacy of pancreatic stenting to prevent PEP in patients with difficult cannulation has been reported. However, endoscopic sphincterotomy (EST) is also considered effective for preventing PEP because it facilitates the outflow of pancreatic juice.

The authors examined the incidence of PEP in patients with difficult cannulation for whom the bile duct was cannulated using P-GW with or without pancreatic stenting. The incidence of PEP was 4.2% and 29.0% in the stent and no-stent groups, respectively, with the incidence in the no-stent group being significantly higher. A multivariate analysis identified the absence of pancreatic stenting as a significant risk factor for PEP.

In patients with difficult cannulation for whom the bile duct is cannulated using P-GW, a pancreatic stent should be placed even if EST has been performed.

The authors report the incidence of post-endoscopic retrograde cholangiopancreatography (ERCP)-pancreatitis in patients with difficult ERCP undergoing the pancreatic duct guidewire placement method of biliary cannulation with or without a PD stent. This is an interesting study.