Usefulness of an algorithm for endoscopic retrieval of proximally migrated 5Fr and 7Fr pancreatic stents

Shanghai, China

Usefulness of an algorithm for endoscopic retrieval of proximally migrated 5Fr and 7Fr pancreatic stents

Biao Gong, Bo Sun, Li-Xiao Hao and Like Bie

Shanghai, China

BACKGROUND: Proximal migration of pancreatic stent (PMPS) is an infrequent event but its management can be technically challenging and there are no standard retrieval methods. This study aimed to determine the results of an endoscopic stent retrieval algorithm in terms of feasibility and efficacy of the endoscopic procedure.

METHODS: During the period from January 2008 to December 2009, 15 patients (8 women and 7 men with a mean age of 51.9 years) with PMPS were included in this study. Stent retrieval was approached initially with balloon extraction followed by rattooth forceps and basket. A rescue approach such as using a stent retriever was attempted when other approaches failed.

RESULTS: All the PMPSs (six 5Fr, nine 7Fr) were retrieved successfully within one ERCP session. Balloon extraction was successful in 9 (60%) patients. In the 6 failed cases of balloon extraction, wire-guided rat-tooth forceps grasp was successful in 4, and stone extraction basket grasp was successful in 1 in whom forceps grasp failed. One stent was finally rescued with a stent retriever when balloon extraction, forceps and basket grasp all failed. In patients with successful balloon extraction, 44.4% (4/9) developed post-ERCP hyperamylasemia but none of them developed post-procedure pancreatitis.

CONCLUSIONS: With this algorithm, 5Fr and 7Fr PMPS were successfully retrieved in all of the patients. Most PMPSs can be safely retrieved with the commonly-used approaches in this study. Those less used approaches can be used as a rescue method.

(Hepatobiliary Pancreat Dis Int 2011; 10: 196-200)

algorithm; endoscopic retrieval; pancreatic stents

Introduction

Endoscopic pancreatic stenting is commonly performed in the treatment of a variety of pancreatic disorders.[1-4]Among the complications of pancreatic stenting, proximal (upstream) migration of pancreatic stents occurs with a reported incidence of 5.2% and may induce morphological changes of the pancreatic duct and pancreatitis if left without retrieval.[5-10]Similar to extraction of migrated biliary stents, more than 80% of proximally migrated pancreatic stents (PMPSs) can be retrieved endoscopically by indirect traction with stone extraction balloon or direct traction with foreign body grasp forceps, snares, or basket.[11-15]In difficult cases, several retrieval techniques have been successfully applied and introduced in case reports, including the wire-guided snare lasso technique,[16]using a Soehendra stent retriever, SpyGlass assisted stent retrieval[17]and interventional cardiology accessories.[18]However, retrieving PMPSs may pose a more technical challenge than extraction of migrated biliary stenting, and some cases may finally need surgical retrieval when repeated endoscopic retrieval methods have failed. This leads to increased morbidity and cost. Although balloon extraction appears to be the most commonly used approach, there is no standard endoscopic retrieval approach and the choice of approach depends on the availability of facilities. The personal preference and experience of the endoscopist may also play a role in selection of retrieving devices and approaches. Hence, we conducted this study to assess the results of an endoscopic PMPS retrieval algorithm combining both the most commonly and least commonly used and less used approaches available in our center for feasibility and efficacy of stent retrieval.

Methods

Patients

Between January 2008 and December 2009, 191 patients underwent endoscopic pancreatic stenting for various pancreaticobiliary disorders at our tertiary referral center. In total, 15 patients with PMPS were consecutively enrolled: 8 women and 7 men with a mean age of 51.9 years (range 15-83 years). Eight patients with PMPS were found in our center with a migration rate of 4.2% (8/191). Seven patients with migrated stents came from outside institutions. Indications for stenting included chronic pancreatitis (11 patients), pancreas divisum (1), pancreatic sphincter of Oddi dysfunction with sphincterotomy (1), and prevention of post-ERCP pancreatitis (3). The mean interval between placement of the stent and detection of migration was 150 days (range 58-354 days). Among the 11 patients with chronic pancreatitis, 9 had proximal pancreatic duct stricture, 2 had incomplete pancreas divisum, and 9 had a dilated pancreatic duct (range 4-7 mm). Thirteen patients had main pancreatic duct stenting only, one had dorsal pancreatic duct stenting only, and one had both main and dorsal pancreatic duct stenting. Twelve patients (80%) were asymptomatic when the stent migration was identified but 3 (25%) presented with hyperamylasemia. Three patients (25%) presented with pancreatitis with abdominal pain and hyperamylasemia more than three times the normal upper limit. Diameters of stents were 5F in 6 patients and 7F in 9. Lengths of stents were 5 cm in 5 patients, 7 cm in 6, and 9 cm in 4. Fourteen stents were straight stents with flaps at both ends. One stent was single pigtail stent. Fourteen stents migrated into the main pancreatic duct and 1 into the dorsal pancreatic duct. This study was approved by the institutional review board of Shanghai Jiaotong University School of Medicine, and all patients provided written informed consent.

Retrieval algorithm

The patients were sedated with meperidine, midazolam or diazepam with appropriate cardiorespiratory monitoring. Stent retrieval was performed by Dr. Biao Gong who performs more than 1000 ERCP procedures annually for pancreaticobiliary diseases. The existing strictures in the proximal pancreatic duct were dilated with dilation balloon or bougie before stent retrieval. Endoscopic sphincterotomy or dilation was performed on the intact minor papilla if retrieval of the PMPS from the dorsal pancreatic duct was determined.

Fig. 1. Endoscopic retrieval algorithm for proximally migrated pancreatic stent. PD: pancreatic duct; EST: endoscopic sphincterotomy.

All of the PMPSs were retrieved initially with balloon extraction by inflating an over-the-wire stone extraction balloon (Wilson Cook) alongside or above the migrated stent and dragging the stent distally. If balloon extraction failed after five attempts, another accessory was used (Fig. 1).

In patients without pancreatic duct dilation, a rat-tooth forceps (Olympus FG-44NR-1, Japan) was introduced into the pancreatic duct by grasping the guide wire to the distal end or the shaft of the stent. Direct grasping of the stent then was conducted under fluoroscopy. If this approach failed after five attempts, a rescue approach was attempted. In patients with pancreatic duct dilation, retrieval with a rat-tooth forceps was also tried first. If it failed after five attempts, a wire-guided basket (Endoflex, Germany) was used to grasp the stent and a rescue approach was considered after five failed attempts.

Three techniques were available in our center as a rescue approach: 1) retrieval with a stent retriever (7F, Wilson Cook) after cannulating the stent lumen with a guide wire, 2) stent extraction under the direct visualization of pancreatoscopy, and 3) retrieval with an interventional cardiology angioplasty balloon.

Successful retrieval was defined as complete removal of the stent from the pancreatic duct, irrespective of the number of attempts. Patients were followed up prospectively for clinical outcomes and complications after stent retrieval.

Results

Stents were successfully retrieved in all fifteen patients (100%) (Table). The success rate for balloon extraction was 60% (9/15). In one patient, the proximal end of a single pigtail stent was wedged into a side-branchof the main pancreatic duct. An inflated balloon was put alongside the stent and pushed the stent out of the side-branch before retrieval (Fig. 2). In another patient with incomplete pancreas divisum, the proximal end of the stent was wedged into the dorsal pancreatic duct through the communicating duct. The initial attempt to push it back to the main pancreatic duct with an inflated balloon failed. As a result, a sphincterotomy was performed on the minor papilla followed by pulling the stent with an inflated balloon in the main pancreatic duct toward the minor papilla. Finally, the proximal end of the stent was pulled outside of the minor papilla.

Table. Retrieval of proximally migrated pancreatic duct stents

Fig. 2. A: The proximal end of a single-pigtail stent was wedged into a side-branch pancreatic duct; B: The wedged stent was pushed out of the side branch with an inflated balloon.

Four patients (4/6) had the stent successfully retrieved with a rat-tooth forceps after balloon extraction failed. In one of the patients with incomplete pancreas divisum, the proximal end of the stent was wedged into the communicating duct between the main and dorsal ducts. An inflated balloon failed to push the stent out of the communicating duct, so a rat-tooth forceps was subsequently used to grasp the stent shaft and finally retrieve it from the main pancreatic duct. The use of balloon and rat-tooth forceps accounted for 86.7% (13/15) of the successfully retrieved PMPS in our series. Neither balloon extraction nor rat-tooth forceps grasping was successful in one patient with significant pancreatic duct dilation. The stent was finally retrieved with a wire-guided stone extraction basket. Balloon extraction, forceps grasp and basket extraction all failed in one patient, where the PMPS was finally retrieved with a 7F stent retriever.

A 3-cm long, 5F pigtail pancreatic stent (Wilson Cook) was inserted after stent retrieval in 12 patients to prevent post-procedure pancreatitis. All stents had a spontaneous passage within two weeks confirmed by abdominal plain films. Two patients underwent stent replacement with a 7F (7 cm) strait pancreatic stent. One patient with pancreas divisum underwent stent replacement with a 7F (12 cm) single pigtail stent.

Among the patients with successful balloon extraction, 4 (4/9, 44.4%) developed post-ERCP hyperamylasemia but none of them developed pancreatitis. One patient developed acute edematous pancreatitis after stent retrieval with a rat-tooth forceps after balloon extraction failed. He underwent conservative treatment and the recovery process was uneventful. After stent retrieval, abdominal pain and hyperamylasemia disappeared in all 3 patients with prior pancreatitis, and serum amylase returned to normal in 2 of the 3 asymptomatic patients with prior hyperamylasemia. Three of the remaining 9 asymptomatic patients developed hyperamylasemia after stent retrieval but remained asymptomatic.

Discussion

Proximal migration of stents is one of the late complications of pancreatic stenting and has gained awareness among endoscopists due to its potentially serious consequences. In this study, the proximal migration rate of pancreatic duct stents in our center during the study period was 4.2%, with the majority (78.6%) of patients asymptomatic upon presentation. Retrieval of PMPS has previously been reported in some studies with a success rate of more than 75%.[14,15]To retrieve the PMPS, multiple attempts with various accessories may be tried but there is no standard retrieval method and the rationale for selection of accessories has not been well documented. We therefore proposed to perform an intention-to-treat analysis with a prospective design including the different endoscopicretrieval approaches to determine whether the use of this algorithm might bring a high success rate in endoscopic retrieval of PMPS. In the present study, all PMPSs (5Fr and 7Fr) were successfully retrieved (100%) and all patients required only one session of ERCP. Dilation of a downstream pancreatic duct stenosis by pancreatic sphincterotomy or dilation was performed prior to retrieval, which contributed to the success. Only one patient developed acute edematous pancreatitis after stent retrieval. Prophylactic pancreatic stent placement or replacement of a pancreatic stent may help to reduce the risk of pancreatitis associated with repeated stent extraction.

Balloon extraction was the first method used to retrieve PMPS in this series. First, balloon extraction is the most commonly used approach to pancreatic duct stent retrieval.[14]Second, we believe an inflated balloon within the relatively small pancreatic duct could provide enough shearing strength against the stent when dragging it distally. Third, other accessories (basket, snare, and grasping forceps) may cause more mechanical injury to the pancreatic duct. In this series, the majority of PMPSs were successfully retrieved by balloon extraction (9/15, 60%). In addition, there was no acute pancreatitis after a successful balloon extraction. This supports the recommendation of Price et al that stent retrieval should be initially approached with balloon extraction.[14]However, hyperamylasemia occurred in 44.4% of those who underwent balloon extraction only. The potential damage to the pancreatic duct by balloon extraction still needs to be evaluated by future larger-scale studies.

Stents wedged in the dorsal pancreatic duct or embedded into a side-branch of the main duct are a technical challenge for retrieval.[19,20]Some patients need more than one attempt or finally require surgery to remove the stent.[15]In our experience, the embedded stent can be pushed out of the side-branch duct or dorsal duct with an inflated balloon or grasped with a forceps. When the proximal end of the stent migrated into the dorsal pancreatic duct through the communication duct in incomplete pancreas divisum, the stent can be extracted through the minor papilla with balloon extraction after minor papilla sphincterotomy or dilation. If this fails, the stent shaft can be grasped with a rat-tooth forceps in the main pancreatic duct and retrieved. However, we feel more comfortable using this technique when there is significant pancreatic duct dilation considering that the stent is in a curled, doubled position. We successfully removed three stents by using these methods. This may provide a useful clue in the selection of retrieval devices for similar conditions. If balloon and grasping forceps fail, direct extraction with pancreatoscopy may facilitate removal of the embedded stent.

The choice of other accessories in this series when the initial balloon extraction failed was determined by the condition of the pancreatic duct. We chose rattooth forceps partly due to our experience in using this accessory. In patients without pancreatic duct dilation, especially if it is difficult to place the guide-wire or catheter alongside the stent, an over-the-wire snare or basket is difficult to manipulate due to the limited space. In this circumstance, we prefer to cannulate the stent lumen with a guide-wire, and then the wire is grasped by a rat-tooth forceps which can be advanced to the proximal end of the stent to grasp it. We successfully removed a PMPS using this method after the balloon sweep failed. However, this method can be difficult or impossible to use when facing an occluded stent. In patients with significant pancreatic duct dilation, grasp forceps, snare or basket can all be tried but a rat-tooth forceps seems to have difficulty grasping the stent sometimes due to the two-dimensional view under a fluoroscope. Direct forceps grasp failed in 2 patients (2/6) in our series.

The major limitation of this study was the small study sample. The data in our study may not be applicable to 3Fr pancreatic stents since no patients with such stents were included. Their smaller diameter and lack of a dedicated 3Fr stent retrieval device make these stents more difficult to retrieve. It is also difficult to compare the effectiveness and complication rates among different retrieval approaches. Other retrieval methods such as trapping the distal flap with a sphincterotome cautery wire, insertion of an inflated dilating balloon above or within the stent lumen, intraductal endoscopy or interventional cardiology accessories all may play a role in solving difficult cases based on the performer's experience and availability of equipments. The effectiveness of these techniques is left to be discussed and debated in future studies. The SpyGlass visualization system has been recently introduced and successfully used for removal of a PMPS when conventional accessories failed.[17]It appears an attractive method especially when the stent lumen is too narrow to allow passing a guide-wire or when the pigtail of the stent migrates into a side-branch. Further studies are needed to evaluate the role of SpyGlass in retrieval of PMPS.

In conclusion, based on our algorithm, PMPS retrieval was successfully achieved in all patients. Balloon extraction appeared safe and can be used as an initial approach for retrieval of PMPS with a relativelyhigh success rate. Most PMPSs can be retrieved with commonly-used accessories. A variety of techniques with other accessories play a rescue role when these approaches fail. Large-scale, randomized studies are needed to compare the effectiveness and complications among different retrieval techniques.

Acknowledgment

We thank Dr. Bill Tu of the Parkway Health Medical Center (North Asia) for his review of this manuscript.

Funding: None.

Ethical approval: Not needed.

Contributors: GB proposed the study. SB wrote the first draft. HLX and BL analyzed the data. All authors contributed to the design and interpretation of the study and to further drafts. GB is the guarantor.

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Competing interest: No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

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Received October 19, 2010

Accepted after revision January 13, 2011

Author Affiliations: Department of Gastroenterology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China (Gong B and Bie L); Department of Gastroenterology, Shanghai Gleneagles Medical Center, Parkway Health (North Asia), Shanghai 200003, China (Sun B); Department of Hepatobiliary Surgery, No. 455 Hospital, Shanghai 200025, China (Hao LX)

Biao Gong, MD, Department of Gastroenterology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China (Tel: 86-21-64370045ext600918; Fax: 86-21-64370045ext 600926; Email: gb-ercp@vip.sina.com)

? 2011, Hepatobiliary Pancreat Dis Int. All rights reserved.