Pancreatic endoscopic retrograde cholangiopancreatography

Prophylaxis of post-ERCP pancreatitis: a practice survey (Dumonceau et al., Gastrointest Endosc 2010 [1])
Significant clinical implications of prophylactic pancreatic stent placement in previously normal pancreatic ducts (Bakman et al., Endoscopy 2009 [2])

Placement of prophylactic pancreatic stents has become a cornerstone in the prevention of post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP). There is an increasing body of evidence to support prophylactic pancreatic stent placement to minimize the risk of pancreatitis in high-risk ERCP, including suspected sphincter of Oddi dysfunction (SOD), difficult cannulation, pancreatic guide wire placement to assist biliary access, precut sphincterotomy, and endoscopic ampullectomy [3] [4] [5]. Whereas there is now a reasonable consensus among advanced endoscopists regarding the need for prophylactic stent placement, there is no consensus as to exact indications, or to optimal type or configuration of stent used. The approach to pancreatic stent placement in smaller and community settings is not known [4] [5]. In addition, although pancreatic stent placement can reduce the risk of pancreatitis in the appropriate setting and improve patient outcomes, this is countered by the potential difficulties and risks associated with pancreatic stent placement (e. g. failed or difficult placement, lack of physician familiarity with anatomical variation, stent insertion techniques, and equipment) and possible associated complications (e. g. inward migration of pancreatic stents, stent-induced pancreatic duct injury), which may result in not only short-term complications, but possibly to irreversible pancreatic damage [6] [7]. Insight into patterns of pancreatic stent placement and potential complications are provided by two studies.

Dumonceau et al. report the results of a survey on the use prophylactic pancreatic stent placement among a large audience of endoscopists mostly practicing in a community setting [1]. The authors conducted a survey to assess the use of prophylactic pancreatic stents among 467 endoscopists attending a course on therapeutic endoscopy in Europe. The candidates were given a two-page questionnaire in which they were asked to provide general demographic data and respond to questions regarding prophylactic stent placement in eight clinical settings. The results of completed surveys from 141 doctors (30 %) were reported. The majority of respondents were practicing in community hospital settings (62 %) with an annual ERCP volume of ≥ 500 cases (> 80 %). Over 60 % of respondents reported not placing a pancreatic duct stent in three high-risk settings (at least one deep pancreatic wire pass, more than 10 minutes spent attempting cannulation, and precut sphincterotomy), and over 40 % reported not placing a stent most of the time in patients with suspected SOD and those with a history of previous PEP. A total of 30 respondents (21 %) did not place stents in any setting; 22 (16 %) reported having no experience with pancreatic stent placement and cited this as the reason for never placing a pancreatic stent. On multivariate analysis, respondents with an annual volume of > 500 ERCPs (16 % of respondents) and those who routinely tracked rates of PEP (56 %) were more likely to place a prophylactic pancreatic stent. A number of endoscopists reported placement of 7-Fr or even 10-Fr stents for prophylaxis, which has been associated with significant ductal injury.

Bakman and colleagues provide the first published report of clinically significant and lasting damage to previously normal glands from placement of prophylactic pancreatic stents [2]. The authors reported a series of eight patients referred to a single center for treatment of pancreatic stent-related pancreatic problems, including acute recurrent or chronic pancreatitis. All patients had undergone prophylactic stent placement in previously normal pancreatic ducts for prevention of PEP at a variety of outside centers. Endoscopists ranged from community practitioners to nationally recognized experts. Indications for initial ERCP with pancreatic stent placement at the outside facility included: empiric sphincterotomy for suspected SOD without sphincter of Oddi manometry (n = 5); minor papillotomy for pancreas divisum with acute recurrent pancreatitis (n = 1); and minimally elevated serum lipase (n = 2). Reports or review of the original pancreatogram revealed a normal, small-caliber duct (< 3 mm) in all, and normal configuration (n = 5) or pancreas divisum (n = 3). Six patients had previously been evaluated with endoscopic ultrasound (EUS), which revealed no evidence of chronic pancreatitis. At the time of the initial ERCP at the outside facility, all patients underwent placement of either conventional polyethylene flanged (4-Fr in one patient and 5-Fr in five patients) or unflanged (7-Fr in two patients) stents, all less than 4 cm in length. All stents were in place for less than 4 weeks, except for in one patient who was lost to follow-up with the stent in place for 12 months.

Seven of eight patients developed mild PEP, but the severity of the pancreatitis did not seem sufficient alone to cause subsequent injury. Presentation to the reporting institution occurred at a mean interval of 17.8 months after initial ERCP. All patients reported recurrent abdominal pain, with evidence of new onset acute recurrent and/or chronic pancreatitis in all. In all patients undergoing secretin-enhanced magnetic resonance cholangiopancreatography, there was demonstration of a new main pancreatic duct stricture within the span of the previously placed stent, and a dilated pancreatic duct upstream from the stricture (mean 4.6 mm, range 3 – 8.2 mm). These findings were confirmed by ERCP. All patients were treated with multiple 3-Fr polyethylene or 4-Fr or 5-Fr soft polymer stents. Seven of eight patients required multiple procedures. Five patients had a sustained response (complete pain resolution) and one had a fair response (controlled with opioid analgesics). In two patients repeated endoscopic interventions failed and total pancreatectomy with islet autotransplantation was carried out at the referral center.

These reports raise some interesting points. Although pancreatic stent placement continues to be essential for the prevention of PEP, the devil is in the detail. There needs to be more education for practicing endoscopists regarding pancreatic stent placement, including techniques, equipment, and treatment of subsequent complications. It is likely that many physicians, when beginning the practice of pancreatic stent placement, have never actually seen one placed at a tertiary center. There are many educational DVDs (www.asge.org) and online materials (DAVE project, http://daveproject.org) available that enable at least the observation of such techniques. These study data also raise awareness about the potential for duct injury from conventional polyethylene stents, particularly in small normal pancreatic ducts. Because of concern about duct injury, we have, for many years, avoided placing polyethylene hard-material stents in normal pancreatic ducts, with the exception of occasional very long 3-Fr unflanged single pigtail stents, with only very sporadic evidence of minor duct abnormalities after > 1000 cases. A number of configurations of soft polymer pancreatic stents are available from several manufacturers (Hobbs Medical Inc., Stafford Springs, Connecticut, USA; Cook Endoscopy, Limerick, Ireland). Further research into optimal design and material for prophylactic pancreatic stents is much needed ([Fig. 1]  –  [3]).

Fig. 1 Endoscopic retrograde pancreatography showing ansa loop duct with minimal length of guide wire in duct for placement of short pancreatic stent.

Fig. 2 Endoscopic retrograde pancreatography showing placement of 4-Fr × 2-cm pancreatic stent with complete pancreatic drainage.

Fig. 3 Variety of available pancreatic stents.

References

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