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Biliary pneumonitis after proximal stent migration
Biliary pneumonitis after proximal stent migration Lutz Liebich-Bartholain, MD, Ulrich Kleinau, MD, Harry Elsbernd, MD, Reinhard Büchsel, MD
Endoscopic stent insertion is commonly used to treat biliary and pancreatic diseases. Reported complications after stent placement include pancreatitis, GI bleeding, perforation, stent occlusion, cholangitis, cholecystitis, and stent fracture.1-3 Additionally, migration of stents is an important complication that occurs in about 5% of patients after insertion of plastic stent.3 Distal migration with stent dislocation from the bile duct (BD) occurs in 6% and rarely presents a problem, although there are sporadic reports of small bowel perforation,4 stent impaction,5-7 colonic diverticular perforation,8 duodenocolic fistula,9 GI bleeding,3 and bowel obstruction.10 Proximal migration occurs in about 5% of cases and most often compromises bile drainage with resultant icterus and cholangitis. However, almost half of the patients with proximally migrated stents remain asymptomatic and the complication is discovered incidentally.3 This is an unusual case of proximal stent migration presenting with biliary pneumonitis, a consequence of migration that has not been previously reported. CASE REPORT An 88-year-old woman was admitted for evaluation of right upper abdominal pain associated with nausea, chronic diarrhea, and weight loss. Conventional cholecystectomy had been performed for cholelithiasis many years previously. There was no history of cardiopulmonary or other disease. On physical examination, there was evidence of general wasting, weight loss, moderate icterus, and mild right abdominal tenderness. Further examination was unremarkable. Laboratory studies disclosed cholestasis (bilirubin 285 µmol/L; normal 1.7-20.5 µmol/L), thrombocytosis (platelet count 448/nL; normal 150-400/nL) and mild leukocytosis (white blood cell count 12/nL; normal 4.3-10.0/nL). Abdominal US revealed marked dilatation of the BD caused by a hypoechoic mass in the head of the pancreas. ERCP disclosed a pancreatic tumor infiltrating the papilla. Endoscopic sphincterotomy (ES) was performed, and a 7F, 10 cm long standard polyethylene stent was inserted. After the procedure, there was rapid resolution of symptoms and normalization of biochemical parameters, allowing the patient to be discharged. Histopathologic evaluation of From the Department of Medicine II, DRK Kliniken Mark Brandenburg, Berlin, Germany. Reprint requests: Liebich-Bartholain, MD, DRK-Kliniken Mark Brandenburg, Drontheimer Strasse 39-40, D 13359 Berlin, Germany. Copyright © 2001 by the American Society for Gastrointestinal Endoscopy 0016-5107/2001/$35.00 + 0 37/4/113646 doi:10.1067/mge.2001.113646 382
GASTROINTESTINAL ENDOSCOPY
Figure 1. Chest radiograph showing bilateral infiltrates, right pleural effusion, and the previously placed stent within the chest cavity. endoscopic biopsy specimens from the tumor yielded a diagnosis of mucinous adenocarcinoma. Three months later the patient was readmitted with symptoms of cough, hoarseness, expectoration of yellowish sputum, diarrhea, and weakness. On admission she was profoundly weak. Auscultation over both lungs revealed bronchitic sounds. There was yellowish discoloration of the tongue and throat. An abdominal mass was not palpable. Chest radiograph demonstrated bilateral infiltrates and a right pleural effusion. Additionally, proximal migration of the stent with penetration through the liver and diaphragm was suspected (Fig. 1). Laboratory examination revealed normal values for total bilirubin, alkaline phosphatase and gamma glutamyl-transferase. C reactive protein was elevated (16 mg/dL; normal 0-0.8 mg/dL) and thrombocytosis was again noted (674/nL). Bilateral hemorrhagic bronchitis was noted on flexible bronchoscopy. Biliary secretions with blood were aspirated from the right lower lobe. Total bilirubin and bile acids were markedly elevated in aspirated bronchial secretions (136 mol/L and 50 mol/L, respectively). Although specific bacteria could not be cultured from material obtained by bronchoalveolar lavage, antibiotic therapy (ampicillinsulbactam, metronidazol, and gentamicin) was initiated. Abdominal US demonstrated progression of the pancreatic mass with cystic structures and penetration of the stent through the right diaphragm into the pleural space. These findings were confirmed by abdominal CT (Fig. 2). Because endoscopic retrieval of the stent was impossible, laparotomy with extraction of the stent, closure of liver and diaphragmatic perforations, and choledochojejunostomy with roux-Y anastomosis were performed. The postoperative course was uneventful. VOLUME 54, NO. 3, 2001
Biliary pneumonitis after proximal stent migration
L Liebich-Bartholain, U Kleinau, H Elsbernd, et al.
DISCUSSION The insertion of plastic stent in the BD is accepted treatment for patients with malignant biliary disease who are not candidates for curative resection.1-2 With long-term stent therapy, migration is one of the most important complications, along with stent obstruction and ascending cholangitis.3 To our knowledge this case is the first published report of proximal stent migration presenting with biliary pneumonitis. This unusual occurrence raises the question of whether there were specific circumstances that facilitated proximal stent migration in this case. The risk of proximal stent migration has been reported to be increased with malignant strictures, as well as with the use of larger diameter (>10 F) and shorter stents (<7 cm).3 The stent used in the present case was small in diameter (7F) and longer than 7 cm (10 cm). Therefore, the size and length of the stent used may not have contributed to the degree of migration according to the reported risk factors for migration. With regard to malignant strictures, only those due to cholangiocarcinoma in the study of Johanson et al.3 were strongly associated with an increased risk of proximal migration. Strictures caused by pancreatic cancer, as in our case, were not associated with a higher migration rate.3 The explanation for this difference is unclear. Few data are available as to whether ES before placement of a biliary stent increases the risk for migration. Johanson et al.3 did not find that ES had a significant impact on the frequency of stent migration, but did identify a trend toward a higher migration rate in patients who had undergone ES. Surprisingly, in a recently published retrospective study, Margulies et al.11 reported a higher frequency of stent migration in patients who had stents placed without ES. The higher migration rate in these patients was because of distal migration, whereas the incidence of proximal stent migration was not influenced by ES. Thus, the performance of ES before stent placement cannot be regarded as a proven risk factor for proximal stent migration. Based on available data, the unusual degree of migration in our case cannot be explained by known risk factors for stent migration. It is possible that expansion of the primary tumor may have pushed the stent proximally in the dilated BD. In addition, it is possible that diaphragmatic atrophy caused by generalized cachexia may have facilitated stent penetration into the pleural space. Might stent migration be avoided by using another type of stent? There are no other types of plastic stent with a documented lower rate of migration. In a recently published study comparing a TanVOLUME 54, NO. 3, 2001
Figure 2. Abdominal CT reconstruction demonstrating that the stent has penetrated through the liver and diaphragm and into the right pleural space.
nenbaum Teflon stent (Wilson-Cook Medical, Inc. Winston-Salem, N.C.) with multiple anchoring flaps and the standard “Cotton-Huibregtse” polyethylene stent in distal malignant biliary stenosis, there was no significant difference in the rates of migration.12 Since 1989, self-expanding metal stents have been increasingly used for palliation of patients with malignant biliary obstruction.13-19 Such stents have a considerably higher patency rate than polyethylene stents and an extremely low rate of migration.17,19,20 Their use is limited by their high cost, the possibility of tumor ingrowth, and the impossibility of removing or repositioning the stent after placement.19 Thus, placement of a polyethylene stent is still widely accepted as an initial approach to management of patients with malignant biliary strictures.16 Patients with longer life expectancy (more than 3 months), slow-growing tumors, proximally located strictures, and impending duodenal obstruction are typically candidates for metal stent insertion.16,17,19 Our patient, presenting with distal biliary stenosis caused by pancreatic carcinoma without duodenal obstruction, was considered to have a poor prognosis with a life expectancy of less than 3 months. A self-expanding metal stent was not inserted because the probability of successful palliation with a single polyethylene stent was thought to be high. The majority of proximally migrated stents can be retrieved endoscopically; success rates in the range of 85% have been reported.21-23 Endoscopic devices frequently used for this purpose are the Dormia basket, extraction balloon, grasping forceps, and the Soehendra stent retrieval device.3,21-23 At times, extraordinary techniques with simultaneous GASTROINTESTINAL ENDOSCOPY
383
L Liebich-Bartholain, U Kleinau, H Elsbernd, et al.
use of guidewires, balloons, and baskets are necessary for successful stent retrieval.5 In our case, none of these endoscopic procedures would have been suitable because the stent had migrated too far proximally, in fact, through the liver into the pleural space. In addition, therapy was urgently needed for respiratory symptoms, and simultaneous removal of the migrated stent and the establishment of biliary drainage were necessary. Therefore, surgical management of the complication was necessary; the patient tolerated this well despite the underlying malignant disease. This case demonstrates that proximal migration of biliary stents does not always present with signs of biliary obstruction and that even pulmonary symptoms are possible. Because the use of stents continues to increase, it is necessary to be cognizant of all potential complications of this form of therapy. REFERENCES 1. Huibregtse K, Katon RM, Coene PP, Tytgat GNJ. Endoscopic palliative treatment in pancreatic cancer. Gastrointest Endosc 1986;32:334-8. 2. Naggar E, Krag E, Matzen P. Endoscopically inserted biliary endoprosthesis in malignant obstructive jaundice—a survey of the literature. Liver 1990;10:321-4. 3. Johanson JF, Schmalz MJ, Geenen JE. Incidence and risk factors for biliary and pancreatic stent migration. Gastrointest Endosc 1992;38,341-6. 4. Esterl RM, St Laurent M, Bay MK, Speeg KV, Halff GH. Endoscopic biliary stent migration with small-bowel perforation in a liver transplant recipient. J Clin Gastroenterol 1997;24:106-10. 5. Mergener K, Baillie J. Retrieval of distally migrated, impacted biliary endoprotheses using a novel guidewire/basket “lasso” technique. Gastrointest Endosc 1999;50:93-5. 6. Shapiro AM, Scudamore CH, July LV, Buczkowski AK, Chung SW, Gul S, et al. Calcific intra-pancreatic stent necessitating surgical removal—a danger of chronic endoscopic retrograde pancreatic stent placement. Gastrointest Endosc 1999;50:860-2. 7. Brown KA, Carpenter S, Barnett JL, Williams DM. Proximal migration of a biliary stent: treatment by combined percutaneous/endoscopic approach. Gastrointest Endosc 1995;41:611-2. 8. Lenzo NP, Sci B, Garas G. Biliary stent migration with colonic diverticular perforation. Gastrointest Endosc 1998;47:543-4. 9. Ang BK, Wee S-W, Kaushik SF, Low C-H. Duodenal-colic fis-
384
GASTROINTESTINAL ENDOSCOPY
Biliary pneumonitis after proximal stent migration
10.
11.
12.
13.
14.
15.
16.
17.
18.
19. 20. 21.
22.
23.
tula resulting from migration of a biliary stent: a case report. Gastrointest Endosc 1998;48:80-3. Yoshida EM, Steinbrecher UP. Abdominal pain and rectal bleeding as a complication of biliary stent migration in a liver transplant recipient. Gastrointest Endosc 1998;47:418-20. Margulies C, Siqueira ES, Silverman WB, Lin XS, Martin JA, Rabinovitz M, et al. The effect of endoscopic sphincterotomy on acute and chronic complications of biliary endoprotheses. Gastrointest Endosc 1999;49:716-9. Terruzzi V, Comin U, De Grazia F, Toti GL, Zambelli A, Beretta S, et al. Prospective randomized trial comparing Tannenbaum Teflon and standard polyethylene stents in distal malignant biliary stenosis. Gastrointest Endosc 2000;51:23-7. Huibregtse K, Cheng J, Coene PPLO, Fockens P, Tytgat GNJ. Endoscopic placement of expandable metal stents for biliary strictures—a preliminary report on experience with 33 patients. Endoscopy 1989;21:280-2. Knyrim K, Wagner HJ, Pausch J, Vakil N. A prospective, randomized, controlled trial of metal stents for malignant obstruction of the common bile duct. Endoscopy 1993;25:207-12. Hoepffner N, Foerster EC, Hvgemann B, Domschke W. Longterm experience in Wallstent therapy for malignant choledochal stenosis. Endoscopy 1994;26:597-602. O’Brien S, Hatfield ARW, Craig PI, Williams SP. A three year follow-up of self expanding metal stents in the endoscopic palliation of longterm survivors with malignant biliary obstruction. Gut 1995;36:618-21. Prat F, Chapat O, Ducot B, Ponchon T, Pelletier G, Fritsch J, et al. A randomized trial of endoscopic drainage methods for inoperable malignant strictures of the common bile duct. Gastrointest Endosc 1998;47:1-7. Vitale GC, Larson GM, George M, Tatum C. Management of malignant biliary stricture with self-expanding metallic stent. Surg Endosc 1996;10:970-3. Rösch T. Metal stents for benign and malignant bile duct strictures. Endoscopy 1998;30(suppl):A247-52. Wong SY, Ng FH. Lower intestinal hemorrhage due to a dislodged metallic stent. Endoscopy 1997;29:407-8. Tarnasky PR, Cotton PB; Baillie J, Branch MS, Affronti J, Jowell PS, et al. Proximal migration of biliary stents: attempted endoscopic retrieval in forty-one patients. Gastrointest Endosc 1995;42:513-9. Chaurasia OP, Rauws EA, Fockens P, Huibregtse K. Endoscopic techniques for retrieval of proximally migrated biliary stents: the Amsterdam experience. Gastrointest Endosc 1999;50:780-5. Lahoti S, Catalano MF, Geenen JE, Schmalz MJ. Endoscopic retrieval of proximally migrated biliary and pancreatic stents: experience of a large referral center. Gastrointest Endosc 1998;47:486-91.
VOLUME 54, NO. 3, 2001
Endoscopic stent insertion is commonly used to treat biliary and pancreatic diseases. Reported complications after stent placement include pancreatitis, GI bleeding, perforation, stent occlusion, cholangitis, cholecystitis, and stent fracture.1-3 Additionally, migration of stents is an important complication that occurs in about 5% of patients after insertion of plastic stent.3 Distal migration with stent dislocation from the bile duct (BD) occurs in 6% and rarely presents a problem, although there are sporadic reports of small bowel perforation,4 stent impaction,5-7 colonic diverticular perforation,8 duodenocolic fistula,9 GI bleeding,3 and bowel obstruction.10 Proximal migration occurs in about 5% of cases and most often compromises bile drainage with resultant icterus and cholangitis. However, almost half of the patients with proximally migrated stents remain asymptomatic and the complication is discovered incidentally.3 This is an unusual case of proximal stent migration presenting with biliary pneumonitis, a consequence of migration that has not been previously reported. CASE REPORT An 88-year-old woman was admitted for evaluation of right upper abdominal pain associated with nausea, chronic diarrhea, and weight loss. Conventional cholecystectomy had been performed for cholelithiasis many years previously. There was no history of cardiopulmonary or other disease. On physical examination, there was evidence of general wasting, weight loss, moderate icterus, and mild right abdominal tenderness. Further examination was unremarkable. Laboratory studies disclosed cholestasis (bilirubin 285 µmol/L; normal 1.7-20.5 µmol/L), thrombocytosis (platelet count 448/nL; normal 150-400/nL) and mild leukocytosis (white blood cell count 12/nL; normal 4.3-10.0/nL). Abdominal US revealed marked dilatation of the BD caused by a hypoechoic mass in the head of the pancreas. ERCP disclosed a pancreatic tumor infiltrating the papilla. Endoscopic sphincterotomy (ES) was performed, and a 7F, 10 cm long standard polyethylene stent was inserted. After the procedure, there was rapid resolution of symptoms and normalization of biochemical parameters, allowing the patient to be discharged. Histopathologic evaluation of From the Department of Medicine II, DRK Kliniken Mark Brandenburg, Berlin, Germany. Reprint requests: Liebich-Bartholain, MD, DRK-Kliniken Mark Brandenburg, Drontheimer Strasse 39-40, D 13359 Berlin, Germany. Copyright © 2001 by the American Society for Gastrointestinal Endoscopy 0016-5107/2001/$35.00 + 0 37/4/113646 doi:10.1067/mge.2001.113646 382
GASTROINTESTINAL ENDOSCOPY
Figure 1. Chest radiograph showing bilateral infiltrates, right pleural effusion, and the previously placed stent within the chest cavity. endoscopic biopsy specimens from the tumor yielded a diagnosis of mucinous adenocarcinoma. Three months later the patient was readmitted with symptoms of cough, hoarseness, expectoration of yellowish sputum, diarrhea, and weakness. On admission she was profoundly weak. Auscultation over both lungs revealed bronchitic sounds. There was yellowish discoloration of the tongue and throat. An abdominal mass was not palpable. Chest radiograph demonstrated bilateral infiltrates and a right pleural effusion. Additionally, proximal migration of the stent with penetration through the liver and diaphragm was suspected (Fig. 1). Laboratory examination revealed normal values for total bilirubin, alkaline phosphatase and gamma glutamyl-transferase. C reactive protein was elevated (16 mg/dL; normal 0-0.8 mg/dL) and thrombocytosis was again noted (674/nL). Bilateral hemorrhagic bronchitis was noted on flexible bronchoscopy. Biliary secretions with blood were aspirated from the right lower lobe. Total bilirubin and bile acids were markedly elevated in aspirated bronchial secretions (136 mol/L and 50 mol/L, respectively). Although specific bacteria could not be cultured from material obtained by bronchoalveolar lavage, antibiotic therapy (ampicillinsulbactam, metronidazol, and gentamicin) was initiated. Abdominal US demonstrated progression of the pancreatic mass with cystic structures and penetration of the stent through the right diaphragm into the pleural space. These findings were confirmed by abdominal CT (Fig. 2). Because endoscopic retrieval of the stent was impossible, laparotomy with extraction of the stent, closure of liver and diaphragmatic perforations, and choledochojejunostomy with roux-Y anastomosis were performed. The postoperative course was uneventful. VOLUME 54, NO. 3, 2001
Biliary pneumonitis after proximal stent migration
L Liebich-Bartholain, U Kleinau, H Elsbernd, et al.
DISCUSSION The insertion of plastic stent in the BD is accepted treatment for patients with malignant biliary disease who are not candidates for curative resection.1-2 With long-term stent therapy, migration is one of the most important complications, along with stent obstruction and ascending cholangitis.3 To our knowledge this case is the first published report of proximal stent migration presenting with biliary pneumonitis. This unusual occurrence raises the question of whether there were specific circumstances that facilitated proximal stent migration in this case. The risk of proximal stent migration has been reported to be increased with malignant strictures, as well as with the use of larger diameter (>10 F) and shorter stents (<7 cm).3 The stent used in the present case was small in diameter (7F) and longer than 7 cm (10 cm). Therefore, the size and length of the stent used may not have contributed to the degree of migration according to the reported risk factors for migration. With regard to malignant strictures, only those due to cholangiocarcinoma in the study of Johanson et al.3 were strongly associated with an increased risk of proximal migration. Strictures caused by pancreatic cancer, as in our case, were not associated with a higher migration rate.3 The explanation for this difference is unclear. Few data are available as to whether ES before placement of a biliary stent increases the risk for migration. Johanson et al.3 did not find that ES had a significant impact on the frequency of stent migration, but did identify a trend toward a higher migration rate in patients who had undergone ES. Surprisingly, in a recently published retrospective study, Margulies et al.11 reported a higher frequency of stent migration in patients who had stents placed without ES. The higher migration rate in these patients was because of distal migration, whereas the incidence of proximal stent migration was not influenced by ES. Thus, the performance of ES before stent placement cannot be regarded as a proven risk factor for proximal stent migration. Based on available data, the unusual degree of migration in our case cannot be explained by known risk factors for stent migration. It is possible that expansion of the primary tumor may have pushed the stent proximally in the dilated BD. In addition, it is possible that diaphragmatic atrophy caused by generalized cachexia may have facilitated stent penetration into the pleural space. Might stent migration be avoided by using another type of stent? There are no other types of plastic stent with a documented lower rate of migration. In a recently published study comparing a TanVOLUME 54, NO. 3, 2001
Figure 2. Abdominal CT reconstruction demonstrating that the stent has penetrated through the liver and diaphragm and into the right pleural space.
nenbaum Teflon stent (Wilson-Cook Medical, Inc. Winston-Salem, N.C.) with multiple anchoring flaps and the standard “Cotton-Huibregtse” polyethylene stent in distal malignant biliary stenosis, there was no significant difference in the rates of migration.12 Since 1989, self-expanding metal stents have been increasingly used for palliation of patients with malignant biliary obstruction.13-19 Such stents have a considerably higher patency rate than polyethylene stents and an extremely low rate of migration.17,19,20 Their use is limited by their high cost, the possibility of tumor ingrowth, and the impossibility of removing or repositioning the stent after placement.19 Thus, placement of a polyethylene stent is still widely accepted as an initial approach to management of patients with malignant biliary strictures.16 Patients with longer life expectancy (more than 3 months), slow-growing tumors, proximally located strictures, and impending duodenal obstruction are typically candidates for metal stent insertion.16,17,19 Our patient, presenting with distal biliary stenosis caused by pancreatic carcinoma without duodenal obstruction, was considered to have a poor prognosis with a life expectancy of less than 3 months. A self-expanding metal stent was not inserted because the probability of successful palliation with a single polyethylene stent was thought to be high. The majority of proximally migrated stents can be retrieved endoscopically; success rates in the range of 85% have been reported.21-23 Endoscopic devices frequently used for this purpose are the Dormia basket, extraction balloon, grasping forceps, and the Soehendra stent retrieval device.3,21-23 At times, extraordinary techniques with simultaneous GASTROINTESTINAL ENDOSCOPY
383
L Liebich-Bartholain, U Kleinau, H Elsbernd, et al.
use of guidewires, balloons, and baskets are necessary for successful stent retrieval.5 In our case, none of these endoscopic procedures would have been suitable because the stent had migrated too far proximally, in fact, through the liver into the pleural space. In addition, therapy was urgently needed for respiratory symptoms, and simultaneous removal of the migrated stent and the establishment of biliary drainage were necessary. Therefore, surgical management of the complication was necessary; the patient tolerated this well despite the underlying malignant disease. This case demonstrates that proximal migration of biliary stents does not always present with signs of biliary obstruction and that even pulmonary symptoms are possible. Because the use of stents continues to increase, it is necessary to be cognizant of all potential complications of this form of therapy. REFERENCES 1. Huibregtse K, Katon RM, Coene PP, Tytgat GNJ. Endoscopic palliative treatment in pancreatic cancer. Gastrointest Endosc 1986;32:334-8. 2. Naggar E, Krag E, Matzen P. Endoscopically inserted biliary endoprosthesis in malignant obstructive jaundice—a survey of the literature. Liver 1990;10:321-4. 3. Johanson JF, Schmalz MJ, Geenen JE. Incidence and risk factors for biliary and pancreatic stent migration. Gastrointest Endosc 1992;38,341-6. 4. Esterl RM, St Laurent M, Bay MK, Speeg KV, Halff GH. Endoscopic biliary stent migration with small-bowel perforation in a liver transplant recipient. J Clin Gastroenterol 1997;24:106-10. 5. Mergener K, Baillie J. Retrieval of distally migrated, impacted biliary endoprotheses using a novel guidewire/basket “lasso” technique. Gastrointest Endosc 1999;50:93-5. 6. Shapiro AM, Scudamore CH, July LV, Buczkowski AK, Chung SW, Gul S, et al. Calcific intra-pancreatic stent necessitating surgical removal—a danger of chronic endoscopic retrograde pancreatic stent placement. Gastrointest Endosc 1999;50:860-2. 7. Brown KA, Carpenter S, Barnett JL, Williams DM. Proximal migration of a biliary stent: treatment by combined percutaneous/endoscopic approach. Gastrointest Endosc 1995;41:611-2. 8. Lenzo NP, Sci B, Garas G. Biliary stent migration with colonic diverticular perforation. Gastrointest Endosc 1998;47:543-4. 9. Ang BK, Wee S-W, Kaushik SF, Low C-H. Duodenal-colic fis-
384
GASTROINTESTINAL ENDOSCOPY
Biliary pneumonitis after proximal stent migration
10.
11.
12.
13.
14.
15.
16.
17.
18.
19. 20. 21.
22.
23.
tula resulting from migration of a biliary stent: a case report. Gastrointest Endosc 1998;48:80-3. Yoshida EM, Steinbrecher UP. Abdominal pain and rectal bleeding as a complication of biliary stent migration in a liver transplant recipient. Gastrointest Endosc 1998;47:418-20. Margulies C, Siqueira ES, Silverman WB, Lin XS, Martin JA, Rabinovitz M, et al. The effect of endoscopic sphincterotomy on acute and chronic complications of biliary endoprotheses. Gastrointest Endosc 1999;49:716-9. Terruzzi V, Comin U, De Grazia F, Toti GL, Zambelli A, Beretta S, et al. Prospective randomized trial comparing Tannenbaum Teflon and standard polyethylene stents in distal malignant biliary stenosis. Gastrointest Endosc 2000;51:23-7. Huibregtse K, Cheng J, Coene PPLO, Fockens P, Tytgat GNJ. Endoscopic placement of expandable metal stents for biliary strictures—a preliminary report on experience with 33 patients. Endoscopy 1989;21:280-2. Knyrim K, Wagner HJ, Pausch J, Vakil N. A prospective, randomized, controlled trial of metal stents for malignant obstruction of the common bile duct. Endoscopy 1993;25:207-12. Hoepffner N, Foerster EC, Hvgemann B, Domschke W. Longterm experience in Wallstent therapy for malignant choledochal stenosis. Endoscopy 1994;26:597-602. O’Brien S, Hatfield ARW, Craig PI, Williams SP. A three year follow-up of self expanding metal stents in the endoscopic palliation of longterm survivors with malignant biliary obstruction. Gut 1995;36:618-21. Prat F, Chapat O, Ducot B, Ponchon T, Pelletier G, Fritsch J, et al. A randomized trial of endoscopic drainage methods for inoperable malignant strictures of the common bile duct. Gastrointest Endosc 1998;47:1-7. Vitale GC, Larson GM, George M, Tatum C. Management of malignant biliary stricture with self-expanding metallic stent. Surg Endosc 1996;10:970-3. Rösch T. Metal stents for benign and malignant bile duct strictures. Endoscopy 1998;30(suppl):A247-52. Wong SY, Ng FH. Lower intestinal hemorrhage due to a dislodged metallic stent. Endoscopy 1997;29:407-8. Tarnasky PR, Cotton PB; Baillie J, Branch MS, Affronti J, Jowell PS, et al. Proximal migration of biliary stents: attempted endoscopic retrieval in forty-one patients. Gastrointest Endosc 1995;42:513-9. Chaurasia OP, Rauws EA, Fockens P, Huibregtse K. Endoscopic techniques for retrieval of proximally migrated biliary stents: the Amsterdam experience. Gastrointest Endosc 1999;50:780-5. Lahoti S, Catalano MF, Geenen JE, Schmalz MJ. Endoscopic retrieval of proximally migrated biliary and pancreatic stents: experience of a large referral center. Gastrointest Endosc 1998;47:486-91.
VOLUME 54, NO. 3, 2001