Palliative management of malignant gastric outlet obstruction with endoscopically inserted self-expanding metal stents

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1 /2008/100/6/ REVISTA ESPAÑOLA DE ENFERMEDADES DIGESTIVAS Copyright 2008 ARÁN EDICIONES, S. L. REV ESP ENFERM DIG (Madrid) Vol N. 6, pp , 2008 ORIGINAL PAPERS Palliative management of malignant gastric outlet obstruction with endoscopically inserted self-expanding metal stents J. García-Cano, N. Sánchez-Manjavacas, M. Viñuelas Chicano, C. Jimeno Ayllón, R. Martínez Fernández, C. J. Gómez Ruiz, J. I. Pérez García, E. Redondo Cerezo, M. J. Morillas Ariño, M. G. Pérez Vigara and A. Pérez Sola Gastroenterology Department. Virgen de la Luz Hospital. Cuenca, Spain ABSTRACT Aim and background: the insertion of self-expanding metal stents to palliate malignant gastric outlet obstruction is a minimally invasive procedure that is being increasingly used. We discuss experience with this technique in a level-ii hospital in the Spanish National Health System. Patients and methods: a retrospective five-year study ( ) was conducted in 23 patients who underwent 27 procedures aimed at resolving malignant gastric outlet obstruction (mean, 0.45 procedures per month) using endoscopically inserted noncovered stents (Wallstent and Wallflex ). Results: insertion was technically feasible in all 27 (100%) attempts, with satisfactory clinical results in 25 cases (92.5%). Endoscopy alone was used 10 times (37%), and both endoscopy and fluoroscopy on 17 (63%) occasions. After stent insertion, one patient was intervened for treatment, and a patient with an unsuccessful prosthesis received a palliative surgical bypass. Four stents became obstructed by tumoral ingrowth, and patency was reestablished by inserting a new stent. Obstructive jaundice caused by stents covering the papilla of Vater occurred in three cases. There were no other complications or mortality due to the procedure. Mean survival was 104 days (range , SD ± 94). Conclusions: in our experience endoscopic insertion of selfexpanding metal stents appears to be a safe and efficient palliative method for malignant gastric outlet obstruction, and can be performed successfully in a center with our characteristics. Key words: Enteral stent. Gastrojejunostomy. Malignant gastric outlet obstruction. Palliative treatment. Pancreatic cancer. RESUMEN Antecedentes y objetivo: la inserción de prótesis metálicas autoexpandibles para paliar la obstrucción tumoral del vaciamiento gástrico es un procedimiento mínimamente invasivo, que cada vez se utiliza con más frecuencia. Presentamos la experiencia de esta técnica en un hospital de nivel II del Sistema Nacional de Salud. Pacientes y métodos: estudio retrospectivo de un periodo de cinco años ( ), en los que se trató de resolver la obstrucción tumoral del vaciamiento gástrico en 27 ocasiones a 23 pacientes (media de 0,45 procedimientos por mes), mediante la inserción endoscópica de prótesis no recubiertas (Wallstent y Wallflex ). Resultados: la inserción fue técnicamente posible en el 100% de los 27 intentos. Se obtuvo un buen resultado clínico en 25 ocasiones (92,5%). Se utilizó sólo endoscopia 10 (37%) veces y en las otras 17 (63%) también fluoroscopia. Tras la inserción de la prótesis se intervino a un paciente con intención curativa y a otro, en el que la prótesis no funcionó, para realizar una derivación paliativa. Cuatro prótesis se obstruyeron por crecimiento tumoral, recanalizándose mediante la inserción de nuevas prótesis. En tres ocasiones se produjo ictericia obstructiva en prótesis que cubrían la papila de Vater. No hubo otras complicaciones. Tampoco mortalidad derivada del procedimiento. La media de supervivencia fue de 104 días (rango , DE ± 94). Conclusiones: en nuestra experiencia, la inserción endoscópica de prótesis metálicas autoexpandibles parece un método seguro y eficaz en el tratamiento paliativo de la obstrucción tumoral del vaciamiento gástrico y puede llevarse a cabo con éxito en un centro de nuestras características. Palabras clave: Prótesis enterales. Gastroyeyunostomía. Obstrucción tumoral del vaciamiento gástrico. Tratamiento paliativo. Cáncer de páncreas. García-Cano J, Sánchez-Manjavacas N, Viñuelas Chicano M, Jimeno Ayllón C, Martínez Fernández R, Gómez Ruiz CJ, Pérez García JI, Redondo Cerezo E, Morillas Ariño MJ, Pérez Vigara MG, Pérez Sola A. Palliative management of malignant gastric outlet obstruction with endoscopically inserted self-expanding metal stents. Rev Esp Enferm Dig 2008; 100: Received: Accepted: Correspondence: Jesús García-Cano. Sección de Aparato Digestivo. Hospital Virgen de la Luz. Hermandad de Donantes de Sangre, Cuenca, Spain. j.garcia-cano@terra.es

2 Vol N. 6, 2008 PALLIATIVE MANAGEMENT OF MALIGNANT GASTRIC OUTLET OBSTRUCTION 321 WITH ENDOSCOPICALLY INSERTED SELF-EXPANDING METAL STENTS INDRODUCTION Obstruction is a pathological phenomenon common to all tubular organs of the body. Pathophysiological consequences vary in relation to the anatomical location of the obstruction. Technological advances allow the use of different materials to build self-expanding metal prostheses or stents (SEMS). SEMS are meshed cylindrical tubes of various lengths and widths that can be inserted folded. This property allows their passage beyond severe strictures, usually without the need for previous dilation. Once inside the obstructed area, SEMS are opened by a release mechanism that provides sufficient diameter to re-canalize the stenosed area. SEMS can be modified according to anatomic locations, and are used to achieve patency in the obstruction of tubular structures such as the coronary arteries, trachea, and most of the digestive tract and bile duct (1). SEMS are being used to palliate malignant gastric outlet obstruction (MGOO) since the nineteen-nineties (2-8). Due to technological improvement, stent models can now be specifically designed to re-canalize tumoral obstructions of the gastric outlet (antrum, pylorus, and duodenum). The term enteral SEMS includes prostheses for the treatment of MGOO and malignant colorectal obstructions (MCRO). Usually, the design in both cases is similar, although the prosthesis has an end wider than the rest of the stent, which is located orally in relation to the obstruction to help prevent SEMS migration. Since stents for MGOO are inserted by upper endoscopic techniques, and colorectal ones via the anus, this wider portion is already located in the folded prosthesis in a different end. SEMS for MGOO as opposed to stents for MCRO (9) are usually inserted with a palliative purpose (10). The concept of using SEMS as a bridge to surgery is not yet clearly established for the stents for MGOO. Unlike acute colonic obstruction, which needs urgent treatment, obstruction of the gastric outlet can be managed with nihil per os (NPO), with sometimes aspiration by a nasogastric tube if surgery is not delayed too much. This study describes the palliative management of MGOO using SEMS insertion in our center. PATIENTS AND METHODS Patients with MGOO and treated by SEMS insertion were analysed retrospectively over a five-year period ( ). MGOO was diagnosed by gastroscopy in patients having typical clinical symptoms (vomiting and food intolerance). Radiological barium contrast studies were also performed occasionally. According to the Surgery and Oncology departments, when a surgical procedure was not possible, MGOO was palliated by the insertion of SEMS. The gastric cavity was cleaned of retained food as much as possible to facilitate the endoscopic procedure and to avoid aspiration. The patient was on NPO and occasionally had a nasogastric tube. The most critical step for SEMS insertion is the passage of a guidewire through the tumoral stricture to place it beyond the tumor, in healthy tissue. The undeployed stent is then glided over this guidewire and may then be opened inside the tumor thus solving the obstruction. To ensure that the guidewire was properly positioned, two techniques were used: 1. Fluoroscopy was used if a fluoroscopic device was available (Fig. 1). The endoscope with a therapeutic working channel (usually a colonoscope, because a therapeutic gastroscope was not available) was located in the proximal part of the tumor. A guidewire of inches (0.875 mm) in diameter fitted with an atraumatic hydrophilic tip was passed through the working channel to make it through the whole stenosed segment. This passage was confirmed by fluoroscopy. A biliary catheter used for endoscopic retrograde cholangiopancreatography (ERCP) was introduced over the guidewire and the obstruction was delineated by contrast injection. The catheter was then withdrawn and the prosthesis was always inserted over the guidewire. Once the SEMS was inside the stricture, it was gradually opened up to place it correctly with proximal and distal ends located in healthy areas. The proximal end of the stent was always located in the prepyloric distal antrum, which is called the transpyloric position (Fig. 2), except when the obstruction was in the more distal duodenum (Fig. 3). Both types of stents were inserted, stainless steel Wallstent and nitinol Wallflex (both from Boston Scientific). They had lengths of 6 or 9 cm, and minimal diameters of mm once fully open. 2. The second technique was the use of an ultrathin endoscope (UTE) able to go beyond strictures. The difficulty that many gastroenterologists face is having appropriate fluoroscopy devices to help in performing endoscopic procedures safely, which has led to develop only endoscopic methods that can provide the reassurance fluoroscopy brings. Several models of very small caliber endoscopes are available that can go beyond many strictures in the digestive tract. According to our previously described technique (11), once the tumor is traversed by a 6 mm diameter endoscope (Pentax EG-1870 K) a guidewire is left in place through the UTE working channel. Subsequently the UTE is removed, leaving the guidewire in place beyond the stenosis. This guidewire is then inserted in a retrograde manner in the therapeutic endoscope working channel, and a SEMS is placed over it. The SEMS that were employed (Wallstent and Wallflex ) have no cover over the mesh, and this allows the tumor to penetrate the metal cells, thus decreasing migration. However, a tumor can grow into the stent and obstruct it over time. After SEMS insertion, patients were usually kept in hospital for 24 hours, and their tolerance to liquids was tried the next day. Clinical improvement in patients was assessed, and possible complications were evaluated. Patients received instructions to start a normal diet gradually.

3 322 J. GARCÍA-CANO ET AL. REV ESP ENFERM DIG (Madrid) Fig. 1. Insertion technique of a self-expanding metal stent to palliate a duodenal obstruction secondary to pancreatic cancer. A. Endoscopic view of the stricture in the bulbar apex crossed by a guide wire. B. Radiological view. The guidewire is located at the angle of Treitz is passing the tumor. C. To open the whole stricture, two overlapped Wallstent prostheses were used from the pylorus up to the third portion of the duodenum. Previously, a Zilver stent had been placed in the common bile duct to palliate the patient s obstructive jaundice. Fig. 2. A Wallflex stent immediately after release. The yellow rod in which it was mounted and folded may be seen. The end is in the gastric antrum outside the pylorus. This is called the transpyloric position for stents located for duodenal strictures. This kind of stent has blunt ends to avoid damaging the mucosa. The resolution of gastric outlet obstruction syndrome after stent insertion without significant complications such as need for surgery was considered a clinical success. RESULTS Twenty-seven enteral SEMS insertions were attempted in 23 patients during a study period of 60 months (0.45 procedures per month). There were 15 men (65%) and 8 (35%) women with a mean age of 75 years (range 46-19, SD ± 12). Patient characteristics are depicted in table I. Tumor obstruction was due to primary gastric adenocarcinomas in 16 (69.5%) patients. The rest of cancers corresponded to three duodenal neoplasms, two pancreatic neoplasms, and two common bile duct cholangiocarcinomas that had extended into the duodenum. Obstructions were antropyloric (14 patients or 61%), duodenal (6 or 23%), and pyloroduodenal (3 or 13%) (Fig. 4). Endoscopy alone was used in 10 (37%) procedures according to the UTE method. Endoscopy with fluoroscopic monitoring was used in the other 17 (53%). SEMS were inserted successfully in the obstructed zone in all 27 (100%) attempts. In general, conscious sedation with midazolam was employed but occasionally dolantine and sometimes buscapine were added to relax gastroduodenal motility. Two overlapped SEMS were needed in three patients to completely open the stricture in its entire length. No significant complications (hemorrhage or perforation) were observed during the first few days after the procedure, and patients did not need any special analgesia. Complete clinical improvement of the MGOO syndrome was achieved on 25 (92.5%) occasions. However, in one patient improvement was partial and in another a palliative gastrojejunostomy had to be performed due to total lack of improvement. SEMS were inserted as a definitive palliative treatment in all patients. Nevertheless, a patient with a duodenal tumor was re-evaluated after stent insertion in another hospital and underwent surgery several months later. Meanwhile he was able to have a normal diet. Mean survival was of 104 days (range , SD ± 94) excluding surgically intervened patients. In three patients the stent

4 Vol N. 6, 2008 PALLIATIVE MANAGEMENT OF MALIGNANT GASTRIC OUTLET OBSTRUCTION 323 WITH ENDOSCOPICALLY INSERTED SELF-EXPANDING METAL STENTS Fig. 3. A. A patient with a tumoral stricture in the inferior duodenal angle. The barium contrast also reveals the common bile duct. B. A Wallstent immediately after placement between the second and third duodenal portions. Three patients with stents covering the papilla of Vater area showed jaundice several weeks after the insertion. No therapeutic procedure was performed because of their advanced condition and according to the wishes of patients and their families. DISCUSSION Fig. 4. Location and causes for our 23 patients with tumoral strictures of the gastric outlet. was re-obstructed by tumor ingrowth, and they were treated with repeat SEMS insertion. A third stent was needed for a 91-year-old patient (Table I) who survived for 400 days (Fig. 5). Patients with MGOO show a significant decline in their quality of life. Initially, the symptoms of MGOO syndrome, such as nausea, vomiting, dehydration and weight loss, can be mistakenly attributed to advanced neoplastic disease and to various oncology treatments (chemotherapy, opiates, etc.). Due to stomach distension the diagnosis of MGOO is sometimes delayed. Traditionally the only choices for MGOO patients were surgical palliative techniques. Derivative surgery, usually a gastrojejunostomy, does not offer satisfactory results, and has high morbidity and mortality rates (12). Moreover, these patients usually have a very poor clinical condition that is contraindicative for a surgical procedure. The therapeutic management of MGOO has progressively changed since the 1990s, when SEMS were beginning to be used to palliate neoplastic gastric outlet obstruction. A review on the use of stents to palliate MGOO that included 606 patients showed that stents were inserted correctly in 97% of cases while clinical improvement with the possibility of oral intake was achieved in 89% of cases (13). Nowadays, insertion of SEMS is the palliative treatment of choice for MGOO. When compared to surgery, stents are at least as efficient as gastrojejunostomy, although the cost of the procedure is lower. Patients have to stay in hos-

5 324 J. GARCÍA-CANO ET AL. REV ESP ENFERM DIG (Madrid) Table I. Characteristics of patients with tumoral obstruction of the gastric outlet palliated by the endoscopic insertion of selfexpanding metal stents Patient Gender/age (1) Location of the Type of Stent type/ Clinical stricture (2) tumor lenght (cm) success 1 M/78 Antropyloric Gastric Wallstent 6 cm Yes 2 M/55 Pyloroduodenal Duodenal Wallstent 9 cm Yes 3 M/67 Duodenum Cholangio Wallstent 9 cm Yes 4 M/87 Antropyloric Gastric Wallstent 9 cm Yes 5 F/91 Antropyloric Gastric Wallstent 9 cm Yes 6 M/77 Duodenum Pancreas Wallstent 9 cm Yes 7 F/85 Antropyloric Gastric Wallstent 6 cm Yes 8 M/77 Duodenum Duodenal Wallstent 9 cm Yes 9 F/84 Pyloroduodenal Gastric Wallstent 9 cm Yes 10 F/90 Antropyloric Gastric Wallstent 9 cm Yes 11 M/46 Antropyloric Gastric Wallstent 9 cm Yes 12 M/79 Antropyloric Gastric Wallstent 9 cm Yes 13 M/78 Antropyloric Gastric Wallstent 9 cm Yes 14 M/91 Duodenum Duodenal Wallstent 6 cm Yes 15 F/87 Pyloroduodenal Gastric Wallflex 9 cm Yes 16 F/62 Antropyloric Gastric Wallflex 6 cm Yes 17 M/80 Antropyloric Gastric Wallflex 6 cm Yes 18 M/86 Antropyloric Gastric Wallflex 9 cm Partial 19 M/78 Duodenum Pancreas 2 Wallstent 9 cm Yes 20 M/72 Antropyloric Gastric 2 Wallflex 9 cm No 21 M/62 Antropyloric Gastric 2 Wallflex 6 cm Yes 22 M/78 Antropyloric Gastric Wallflex 6 cm Yes 23 F/53 Duodenum Cholangio Wallflex 6 cm Yes In four cases stents became obstructed and new ones were inserted to solve the obstruction, for a total number of procedures of 27. (1) M = male, F = female. (2) Gastric and duodenal tumors were carcinomas originating in these organs. Cholangio (cholangiocarcinomas) corresponded to duodenal extension of tumors originated in the common bile duct. Fig. 5. When a stent becomes obstructed the easier way to re-canalize is by inserting another stent within the initial one. This image corresponds to the patient in figure 2, who lived more than a year after the insertion of the first stent. It then became obstructed and was re-canalized. pital for a shorter period and after the endoscopic procedure they can start oral diets earlier after SEMS insertion than after surgery (10,14-17). In Spain, a multicenter study performed at 13 centers showed that the annual mean number of stent insertions for MGOO treatment was 0.45 stents per month (18). Our center s stent insertion rate is similar. It is important to keep in mind that our hospital is a level-ii site in the National Health System (and may be considered a community hospital), whereas some hospitals that participated in the study are tertiary referral centers. If surgical and oncology teams understand the advantages of this minimally invasive procedure to solve gastric outlet obstruction by means of stents, the use of this technique is likely to proliferate even further. Endoscopic SEMS insertion, at either the gastroduodenal, colonic (9) or esophageal (19) level, in the context of the difficulties that every interventional technique implies, seems to us a simpler procedure than ERCP (20). SEMS insertion has a shorter learning curve. However, to obtain acceptable success rates (successful rate insertions around 100%) special dedication is needed. Taking into consideration that, in our institution, the mean rate of gastroduodenal stent insertions is slightly less than one

6 Vol N. 6, 2008 PALLIATIVE MANAGEMENT OF MALIGNANT GASTRIC OUTLET OBSTRUCTION 325 WITH ENDOSCOPICALLY INSERTED SELF-EXPANDING METAL STENTS every two months, the performance of this technique should be limited to few physicians. In addition, the experience with instruments used for ERCP such as catheters and guidewires is very useful for a successful insertion of digestive stents (21). Also, in contrast to acute colonic obstruction, a stent is never urgently needed for MGOO. In our opinion, the endoscopic insertion of stents should always be performed with fluoroscopic monitoring. Nonetheless, gastroenterologists experience frequent difficulties in using adequate radiological devices. Until this problem is eventually solved, UTEs may be an alternative method (11). Also, it would be very useful that every center had a gastroscope with therapeutic channel for insertion techniques and many other endoscopic procedures (such as higher aspiration capacity in gastrointestinal hemorrhage). Serious complications of stent insertion are few, but if a gastroduodenal perforation occurs during insertion, an urgent procedure will probably be needed under difficult conditions. Recently, the closure of a perforation due to a gastroduodenal SEMS by means of another covered SEMS has been reported (22). The obstruction of stents by tumor growth into mesh cells can be easily solved endoscopically by the insertion of new stents (Fig. 5). Occasionally, covered stents, which prevent or delay such obstruction, can be used, but their tendency to migrate is higher (23). In our study we used uncovered bared Wallstents and Wallflex stents, and no migration was recorded. Three of our patients developed obstructive jaundice several weeks after the insertion. Bile flow obstruction through the papilla due to epithelial covering of the prosthesis some time after its placement cannot be discarded as a cause. Insertion of a biliary transpapillary stent through the duodenal prosthesis is usually very difficult and frequently needs the use of transhepatic techniques (interventional radiology) or, nowadays, transhepatic ultrasonographically-guided biliary drainage from the upper body of the stomach. Our patients conditions were clinically unstable and, therefore, other bile drainage interventions were not considered. In conclusion, gastroduodenal SEMS insertion to treat MGOO was possible in 100% of cases. Complete clinical improvement was achieved with 92.5% of insertions, and only two patients showed no relief. One patient required surgical gastrojejunoscopy while another patient had a complete liquid diet and prokinetics administered. No immediate complications occurred after the procedures. Radiologists can also place gastroduodenal SEMS (24). Although no comparative study between efficacies after endoscopic or radiological insertions has been conducted, according to radiological studies published the effectiveness seems to be similar. The endoscopic insertion of gastroduodenal stents may be easier due to the stability that an endoscope provides in passing guidewires, catheters, and prostheses themselves. Also, if no endoscopes with therapeutic channels in which stents may fit are available, endoscopes with a diagnostic caliber can be useful to advance stents to the obstruction (25). This is also useful for placing esophageal stents that cannot be introduced in any endoscope working channels. In view of the good results achieved by this and previous studies, the insertion of self-expanding metal stents may generally be considered the treatment of choice for malignant gastric outlet obstruction. This technique can be performed successfully in a center such as ours. REFERENCES 1. Baron TH. Expandable metal stents for the treatment of cancerous obstructions of the gastrointestinal tract. N Engl J Med 2001; 344: Keymling M, Wagner JH, Vakil N, Krynim K. Relief of malignant duodenal obstruction by percutaneous insertion of a metal stent. Gastrointest Endosc 1993; 39: Howell DA, Bosco JJ, Muggia RA. Endoscopic double bypass: Duodenal metal expandable stenting late in malignancy. Gastrointest Endosc 1994; 40: 40A. 4. Feretis C, Benakis P, Dimopoulos C, et al. Palliation of malignant gastric outlet obstruction with self-expanding metal stents. Endoscopy 1996; 28: Maetani I, Inoue H, Sato M, et al. Peroral insertion techniques of self-expanding metal stents for malignant gastric outlet and duodenal stenoses. Gastointest Endosc 1996; 44: Feretis C, Benakis P, Dimopoulos C. Self-expanding endoprostheses for palliation of duodenal obstruction. Gastrointest Endosc 1997; 46: Bethge N, Breitkreutz C, Vakil N. Metal stents for palliation of inoperable upper gastrointestinal stenoses. Am J Gastroenterol 1997; 93: Montes López C, Marinelli Ibarreta A, Tejero Cebrián E, Romeo Martínez J, Vázquez Echarri J, Martín Ramiro J, et al. Expandable stents in obstructive unresectable carcinoma of the gastric antrum. Rev Esp Enferm Dig 1999; 91: García-Cano J, González-Huix F, Juzgado D, Igea F, Pérez-Miranda M, López-Rosés L, et al. Use of self-expanding metal stents to treat malignant colorectal obstruction in general endoscopic practice (with videos). Gastrointest Endosc 2006; 64: Espinel J, Sanz O, Vivas S, Jorquera F, Muñoz F, Olcoz JL, et al. Malignant gastrointestinal obstruction: Endoscopic stenting versus surgical palliation. Surg Endosc 2006; 20: García-Cano J. Use of an ultrathin gastroscope to allow endoscopic insertion of enteral wallstents without fluoroscopic monitoring. Dig Dis Sci 2006; 51: Lillemoe KD, Barnes SA. Surgical palliation of unresectable pancreatic carcinoma. Surg Clin North Am 1995; 75: Dormann A, Meisner S, Verin N, Wenk Lang A. Self-expanding metal stents for gastroduodenal malignancies: Systematic review of their clinical effectiveness. Endoscopy 2004; 36: Wong YT, Brams DM, Munson L, et al. Gastric outlet obstruction secondary to pancreatic cancer: Surgical vs. endoscopic palliation. Surg Endosc 2002; 16: Maetani I, Akatsuka S, Ikeda M, et al. Self-expandable metallic stent placement for palliation in gastric outlet obstructions caused by gastric cancer: A comparison with surgical gastrojejunostomy. J Gastroenterol 2005; 40: Johnsson E, Thune A, Liedman B. Palliation of malignant gastroduodenal obstruction with open surgical bypass or endoscopic stenting: Clinical outcome and health economic evaluation. World J Surg 2004; 28: Fiori E, Lamazza A, Volpino P, et al. Palliative management of malignant antro-pyloric strictures. Gastroenterostomy vs. endoscopic

7 326 J. GARCÍA-CANO ET AL. REV ESP ENFERM DIG (Madrid) stenting. A randomized prospective trial. Anticancer Res 2004; 24: Pérez-Miranda M, Espinós J, Juzgado D, González-Carro P, García- Cano J, Igea F, et al. Palliation of malignant gastric outlet obstruction (GOO) with through-the-scope (TTS) expandable metal stents (EMS): A multicenter descriptive study. Gastrointest Endosc 2005; 61: AB García-Cano J. Endoscopic insertion of oesophageal stents without fluoroscopic guidance. Scand J Gastroenterol 2005; 40: García-Cano Lizcano J, González Martín JA, Morillas Ariño J, Pérez Sola A. Complications of endoscopic retrograde cholangiopancreatography. A study in a small ERCP unit. Rev Esp Enferm Dig 2004; 96: Adler DG, Baron TH. Endoscopic palliation of malignant gastric outlet obstruction using self-expanding metal stents: experience in 36 patients. Am J Gastroenterol 2002; 97: Small AJ, Petersen BT, Baron TH. Closure of a duodenal stent-induced perforation by endoscopic stent removal and covered self-expandable metal stent placement (with video). Gastrointest Endosc 2007; 66: Kim JH, Song HY, Shin JH, Choi E, Kim TW, Jung HY, et al. Metallic stent placement in the palliative treatment of malignant gastroduodenal obstructions: Prospective evaluation of results and factors influencing outcome in 213 patients. Gastrointest Endosc 2007; 66: Lopera JE, Brazzini A, Gonzales A, Castaneda-Zuniga WR. Gastroduodenal stent placement: Current status. Radiographics 2004; 24: Rábago LR, Castro JL, Joya D, Montes C, Gea F, Mora P, Blesa C. Treatment of inoperable malignant gastric stenosis with self-expanding prothesis. Gastroenterol Hepatol 1999; 22: