- Email: [email protected]
Gastrointestinal Stenting: Indications and Techniques
tallic stents in benign strictures. Semin Intervent Radiol 1991; 8:321. 23. Shapiro M], Eschelman D], Bonn], Sullivan KL, Alden ME, Gardiner GA. Malignant biliary duct obstruction: long term experience with Gianturco stents and radiation therapy. Presented at RSNA Annual Meeting, Chicago, Ill., Dec. 4, 1996.
24. Sakaguehi H, Uchide H, Matsuo N, Sakaguehi S, Anai H, Yoshioka T. Combined interventional therapy of metallic stent, radiation, and intracranial chemotherapy for hepatic bilar bile duct cancer. Presented at SCVIR Annual Meeting, Washington, D.C., March 11, 1997. 25. Pakisch B, Schmidt F, Hausegger KA, Stuecklschweiger G, Gahrleitner N, Hackl A. HDR brachytherapy with and without external beam irradiation after permanent stent placement for the treatment of malignant bile duct obstruction. Presented at RSNA Annual Meeting, Chicago, IlL, Dec. 4, 1996. 26. Bezzi M, Panzetti C, Bonomo G, Pedicini V, Salvatori FM, Rossi P: Plastic covered Wallstents in malignant biliary obstructions: evaluation in 17 patients. Presented at SCVIR Annual Meeting, Seattle, WA, March, 1996. 27. Born P, Neuhaus H, Rosch T, et al. Experience with a new partially covered Wallstent for malignant biliary obstruction. Endoscopy 1996; 28:699-702. 28. Cwikiel W, Harnek], Zoucas E: Electrolytic stents: experimental study in rats and pigs. Presented at SCVIR Annual Meeting, Seattle, WA, March, 1996. 29. Machan LS, Hunter W: Prevention of malignant tumor overgrowth by an angiogenesis inhibiting stent coating. In press. 8:25 am
Gastrointestinal Stenting: Indications and Techniques Andreas Adam, FRCR SELF-EXPANDING metallic stents are now used frequently in many organs, including the biliary tract, tracheobronchial tree and vascular system. Within the upper gastrointestinal tract they are most frequently employed in the esophagus, though gastric antral/pyloric, and duodenal stenting have also been described.
110
Esophageal Stenting The majority of esophageal stents are inserted for palliation of inoperable malignant dysphagia, but they are occasionally required to treat tumor recurrence at surgical anastomoses, and in benign strictures which are unresponsive to balloon dilatation. Tracheo-esophageal fistulae and esophageal leaks can also be successfully treated with covered stents. Esophageal carcinoma is a relatively common disease with a poor prognosis, accounting for 3,500 deaths per
year in the United Kingdom (1). At the time of presentation 75% of patients will have disease spread to lymph nodes (2), and approximately 500/0---60% of patients are not suitable for attempted curative surgical resection. Available palliative treatments include surgery, radiotherapy, chemotherapy, rigid plastic tubes, laser therapy and self expanding metallic esophageal stents. A variety of covered and uncovered stents are available. The three most commonly used are the Wallstent (Schneider AG, Zurich, Switzerland), the Strecker stent (Medi-tech/Boston Scientific Corporation, Watertown, MA, USA), and the Gianturco stent (William Cook Europe, Bjaeverskov, Denmark). An initial esophagogram is performed to delineate the site and length of stricture. The patient lies on the fluoroscopic table in the left lateral position. Lidocaine spray is applied to the pharynx, and the patient is sedated with an intravenous agent such as midazolam. Suitable catheters and guide wires are used to cross the stricture. The catheter and guide wire are manipulated into the duodenum to provide as stable a position as possible, and the guide wire is changed for an Amplatz stiff exchange wire. A IS-mm-diameter balloon is used to predilate the stricture prior to stent deployment. We aim to deploy the stent with approximately 60% of its length above the middle of the stricture in an effort to minimize the incidence of distal stent migration. Long strictures may require the use of more than one overlapping stent. Immediately after the procedure, nonionic contrast medium is introduced into the esophagus via the catheter to look for any procedural complication, especially esophageal perforation, and to confirm stent patency. Patients remain in hospital overnight, and once they have recovered from the effects of the sedation, they are allowed to take small volumes of clear fluids orally. The following day a further esophagogram is performed with a view to proceeding to any further intervention that may be required. For example, a stent may show persistent narrowing, requiring balloon dilatation, or there may have been migration, requiring the insertion of an additional stent coaxially within the first endoprosthesis and overlapping with it to prevent further slip. If the esophagogram shows good stent position and function patients are allowed a normal diet. They are advised to cut their food into small pieces, to chew it thoroughly and to have carbonated beverages after each meal in order to clear the stent of any food debris. In any patient in whom a stent has been placed across the gastro-esophageal junction, reflux of gastric contents will inevitably occur. The symptoms are controlled by the administration of omeprazole, which is started routinely after the procedure.
Results of Esophageal Stenting in Malignant Disease The degree of dysphagia can be assessed by the use of a dysphagia score, where 0 is equivalent to no dysphagia and 4 indicates total dysphagia (Table). The immediate technical success in virtually 100%,
Table 1 Dysphagia Score
Degree of Dysphagia
o
No dysphagia Able to swallow semi-solid food only Able to swallow liquids only Difficulty in swallowing liquids and saliva Complete dysphagia
1
2
3
4
with improvement in the dysphagia score in 830/0-100% of patients (3-5). Uncovered stents are prone to tumor ingrowth (200/030%), compared to only 2% of patients treated with covered stents. The lack of an outer covering probably also accounts for the absence of migration with this type of stent. Stent migration occurs in 30% of covered Wallstents and 100/0-15% of Gianturco stents. Covered stents are particularly liable to migrate when positioned at the gastro-esophageal junction, with a free end lying in the stomach. Wallstents rely on the uncovered portion at either end to prevent migration, and if one end lies free in the stomach this mechanism is compromised. In cases of complete and symptomatic stent migration, the stent can be removed by surgical gastrotomy. In cases of partial migration, the covered stent can be stabilized by the placement of a coaxially-placed, uncovered stent through its proximal end. Because of the propensity of covered stents placed over the gastro-esophageal junction to migrate, we now elect to deploy uncovered stents at this site, although as the new Wallstents with an inner plastic covering become available our practice may change. Recurrence of dysphagia secondary to tumor ingrowth or overgrowth can be successfully managed either with endoscopic laser therapy, or by the placement of additional stents. Food bolus impaction is easily cleared endoscopically. Rigid plastic tubes, usually inserted under general anesthesia, have declined in popularity in many centers. The overall complication rate has been reported to be as high as 36%, with a mortality of 20/0-16%. The reported complications include a perforation rate of 4.20/0-10.5%, hemorrhage in 1.50/0-5%, tumor overgrowth in 8.5%, tube migration in 22%, and pressure necrosis of the esophageal wall in 4% (6,7). The small luminal diameter leads to problems with food impaction in around 6.5%. The use of a general anesthesia and the requirement for admission to hospital for a few days also makes this treatment expensive. Laser therapy has been shown in a number of studies to provide excellent palliation in malignant esophageal obstruction (8,9). With the use of laser therapy, more than 80% of patients can be maintained on a solid or
semi-solid diet (8,9). The main drawback of this modality is the requirement for multiple treatments, which need to be repeated every 4-8 weeks. In a series of 189 patients with inoperable esophageal carcinoma, a mean of 3.3 procedures per patient were required (9). The complication rate is low (50/0-9%) (8,9), and is mainly related to esophageal perforation during pretreatment dilation. The other main complication is hemorrhage, but this can be easily controlled by local laser photocoagulation. Both laser therapy and self expanding metallic stents are used in our center for the palliation of malignant dysphagia. We have conducted a triple randomized study comparing Wallstents, Strecker stents, and laser therapy. The results demonstrated statistically significantly better palliation with metallic stents than with laser therapy (10). However, there are certain morphological types of tumor in which esophageal stents are best avoided: in situations where the tumor is very exophytic, or where the esophagus is very dilated above the stricture, the free end of the stent will not lie closely adjacent to the esophageal wall, and food or fluid will tend to pool between the stent and the mucosa. In this situation, palliation will be suboptimal, and there is a risk of aspiration. We, therefore, find that esophageal stents and laser therapy are complementary treatments, and that each case should be treated on its own merits.
Esophageal Stents in Benign Disease In the majority of patients with malignant disease the application of esophageal stents presents few long-term problems, as most individuals have a fairly short survival. The management of benign disease is different, as in the long-term one cannot be entirely certain of the difficulties that may be encountered. Generally, we avoid the use of stents in this situation, but there are occasions when repeated dilation produces progressively shorter periods of relief of dysphagia, in which there is little choice other than to employ a stent or submit the patient to major surgery. In addition, there are rare occ~sions when it is simply not possible to dilate benign strictures successfully. In general, we restrict the use of self-expanding stents in benign strictures to patients who are not fit for surgery. Clearly, the use of a stent does not preclude surgery at a later date should that become necessary, and should the patient's clinical condition improve sufficiently with adequate nutrition. The technique employed for deploying esophageal stents across benign strictures is essentially the same as that in malignant disease, although we consider uncovered stents more appropriate as they are less likely to migrate, and in this clinical setting there is no potential for tumor ingrowth, making the stent covering superfluous. An additional advantage of using uncovered stents is that after a few months the stent is completely covered by epithelium and becomes incorporated into the wall of the esophagus. A number of cases of the use of metallic stents in benign strictures are reported in the literature, and the results indicate a good response of dysphagia
111
(11-13). However, the major problem in the long-term is the occurrence of epithelial hyperplasia related to the stent. This is amenable either to balloon dilation, or to laser treatment. The hyperplastic epithelium is considerably easier to deal with than the original benign stricture, so although stents are not ideal for the treatment of benign disease, they do at least help to make an almost unmanageable situation manageable.
Results The number of patients reported in the literature is currently small, but results indicate that immediate technical success can be expected in 890/0-100%, with successful palliation of symptoms in 780/0-100%. No major complications have been described. Given the relatively narrow stents that are used, a soft diet is often advised.
References Treatment ofMalignant Esophageal Leaks and Fistulae Esophageal leaks or perforations may occur due to tumor invasion, or be iatrogenic secondary to esophageal dilatation or biopsy. Fistulae to the respiratory tract may be caused by a tumor arising either from the esophagus or from the tracheobronchial tree, or may be a complication of surgery or esophageal stenting. Although perforations and leaks are generally treated conservatively in the first instance, those of malignant etiology will usually not heal. In cases of malignancy where conservative therapy has failed, management is fairly straightforward, with deployment of a covered stent, most commonly in the esophagus, though covered tracheal stents are also useful. Treatment of malignant esophageal fistulae with covered self-expanding stents is very successful in covering the fistulae and preventing leakage either into the mediastinum or respiratory tract (14). In addition, nearly all patients return either to a soft or completely normal diet, as would be expected from the results of larger series of experience of esophageal stenting of tumors.
112
Gastric Antral and Duodenal Stenting Gastric outlet obstruction is most commonly caused by malignancy arising either from the gastric antrum, or from duodenal stricture or obstruction secondary either to direct invasion or extrinsic compression or invasion from pancreatic carcinoma. Gastric outlet obstruction is usually palliated with a gastroenterostomy, and stenting is generally only carried out in patients deemed unfit for surgery. Insertion of stents via gastrostomy (15) or the peroral route has been described (16). Endoscopy is frequently used, though is not strictly necessary, although there is an absolute requirement for fluoroscopic screening. We favor the peroral route under fluoroscopic guidance. Mter the administration of intravenous sedation, a catheter and guide wire are passed through the esophagus down to the level of the stricture in either the gastric antrum or duodenum. The catheter is manipulated across the stricture, and the guide wire changed for an Amplatz super-stiff exchange guide wire. The stricture is predilated to 10 mm in diameter, and an appropriate sized stent is deployed. We favor the Wallstent because of its greater inherent outward radial force and prefer to use uncovered stents, to minimize the risk of migration. We have used 16-mm-diameter stents (16), which are probably the best compromise between a desirable large diameter and flexibility.
1. Earlam R. Oesophageal cancer treatment in North East Thames region in 1981: medical audit using hospital activity analysis data. Br Med ] 1984; 288: 1892-1894. 2. Rankin S, Mason R. Staging of oesophageal carcinoma. Clin Radiol 1992; 461:373-377. 3. Cwikiel W, Stridbeck H, Tranberg KG, et al. Malignant esophageal strictures: treatment with a self expanding nitinol stent. Radiology 1993; 187:661-665. 4. Saxon RR, Barton RE, Katon RM, et al. Treatment of malignant esophageal obstructions with covered metallic Z stents: long term results in 52 patients. ]VIR 1995; 6:747-754. 5. Song HY, Do YS, Han YM, et al. Covered, expandable esophageal metallic stent tubes: experiences in 119 patients. Radiology 1994; 193:689-695. 6. Tytgat GN]. Endoscopic therapy of esophageal cancer: possibilities and limitations. Endoscopy 1990; 22:263-267. 7. Gasparri G, Casalegno PA, Camadona M, et al. Endoscopic insertion of 248 prostheses in inoperable carcinoma of the esophagus and cardia: short-term and long-term results. Gastrointestinal Endoscopy 1987; 33:354-356. 8. Sander RR, Poesl, H. Cancer of the oesophagus: palliation, laser treatment and combined procedures. Endoscopy 1993; 25CSuppl):679-682. 9. Mason RC, Bright N, McColl 1. Palliation of malignant dysphagia with laser therapy: predictability of results. Br] Surg 1991; 78:1346-1347. 10. Adam A, Ellul], Watkinson AF, et al. Palliation of inoperable esophageal carcinoma: a prospective randomized trial of laser therapy and stent placement. Radiology 1997; 202:344-348. 11. Cwiekel W, Willen R, Stridbeck H, et al. Self expanding stent in the treatment of benign esophageal strictures: experimental study in pigs and presentation of clinical cases. Radiology 1993; 187:667-671. 12. Foster DR. Use of a Strecker oesophageal stent in the treatment of benign oesophageal stricture. Australasian Radiol 1995; 39:399-400. 13. Tan BS, Kennedy C, Morgan R, Owen W, Adam A. Uncovered metallic endoprostheses for recurrent benign esophageal strictures: preliminary experience. A]R (In Press).
14. Watkinson A, Ellul], Entwistle K, et a1. Plastic-covered metallic endoprostheses in the management of oesophageal perforation in patients with oesophageal carcinoma. Clin Radiol 1995; 50:304-309. 15. Keymling M, Wagner H-J, Vakil N, Knyrim K. Relief of malignant doudenal obstruction by percutaneous insertion of a metal stent. Gastrointestinal Endoscopy 1993; 39:439-441. 16. Scott-Mackie P, Morgan R, Farrugia M, Glynos M, Adam A. Malignant duodenal obstruction: a role for metallic stents. Br J Radiol (In Press). 8:50 am
Management of Chronic Ureteral Obstruction Parvati Ramchandani, MD URETERAL obstruction comes to clinical attention when patients present with flank or abdominal pain, azotemia or urinary tract infection or when imaging studies demonstrate hydroureteronephrosis; the etiology spans the spectrum from neoplastic disease to benign causes. Neoplastic obstruction usually occurs in the setting of advanced malignant disease and it can be related either to primary urothelial neoplasms or to extrinsic compression by primary or metastatic retroperitoneal or pelvic malignancies. The goal of treatment in these patients is to provide renal drainage so that renal function can be maintained. Benign ureteral strictures are most apt to be iatrogenic in origin with urological, gynecological and general surgical procedures accounting for 42%, 34%, 34%, and 24% of ureteral injuries respectively in a recent series (1). The widespread use of upper urinary tract endoscopy for the minimally invasive diagnosis and treatment of a myriad of pathologies has had the paradoxical result of making endourological procedures the single most common cause of ureteral injuries, which reportedly occur in 3%-18% of patients undergoing ureteroscopy (1,2). In Selzman's series (1), 79% of urological ureteral injuries occurred during an endoscopic procedure (attempted stone removal being the most frequent), while 21% occurred during an open procedure such as uretro or nephrolithotomy, radical retropubic prostatectomy, or lymph node dissection. Abdominal hysterectomy and salpingo oopherectomy accounted for 86% of the gynecological injuries and colorectal surgery accounted for 67% of all general surgical injuries. Laparoscopic surgery is also becoming an increasingly frequent cause of iatrogenic ureteral injuries (3). Other causes of ureteral strictures include recurrent stone passage in patients with chronic calculous disease, penetrating abdominal trauma, particularly high velocity gun shot wounds, radiation therapy, and infections such as tuberculosis and bilharziasis. Strictures that occur at the uretero-enteral anastomotic site in patients with urinary diversion are particularly refractory to treatment. Therapeutic options in the management of chronic ureteral obstruction range from percutaneous nephros-
tomy drainage alone to ureteral stenting, either denovo or preceded by balloon dilation. Percutaneous nephrostomy is almost universally successful in draining obstructed, dilated kidneys, allowing for immediate renal decompression in patients with obstruction complicated by urosepsis or azotemia (4,5). In ureteral obstruction due to benign disease, the decision to perfonn the procedure is straightforward. In patients with terminal malignancies where the obstruction is irremediable, the need for drainage is likely to be pennanent. The burden posed by the presence of a drainage catheter should be carefully weighed against the benefit of extending life for a few months, a dilemma that should be openly discussed with the referring physician, the patient and the family. Long-tenn survival after palliative diversion for malignant ureteral obstruction is poor and determined largely by the type and stage of the underlying neoplasm, and its potential for further treatment. Median survival after nephrostomy drainage in one group of 77 patients with pelvic malignant disease was 26 weeks (6) and only 25% of patients were alive at 1 year in another series (7). Unless aggressive chemotherapeutic treatment is planned, unilateral drainage usually suffices and bilateral drainage confers no additional benefit. However, patients with hormone responsive prostate cancer tend to live longer than patients with other pelvic malignancies and bilateral drainage may be a preferable option in these patients, particularly if they are young (8). Percutaneous nephrostomy should not be the first procedure to be considered for renal drainage unless the patient has urosepsis; it should ideally be reserved for patients in whom retrograde renal drainage is either unsuccessful or infeasible. Locking loop 8- or 10-F drainage catheters are the catheters of choice for long-term drainage with a reported dislodgment rate of less than 1% (4).
Ureteral Stenting Ureteral stent placement provides the benefits of urine drainage and diversion without the necessity for a drainage bag and is therefore preferred to nephrostomy drainage in most patients. However, if the urinary bladder is markedly contracted or diseased (as in patients with radiation cystitis, hemorrhagic cystitis, tuberculous cystitis or tumor invasion of the bladder) or in patients with urinary incontinence or vesical fistulae, percutaneous nephrostomy drainage is preferable to ureteral stenting. Nephrostomy drainage may also be the only option in patients with extensive bulky pelvic disease that causes ureteric or bladder compression-antegrade urine drainage often fails in such patients despite patency of the ureteral stent, presumably due to a decrease in the pressure differential between the renal pelvis and the bladder. Ureteral stents can be inserted in one of three ways: (1) percutaneously (antegrade), (2) retrograde transure-
113
24. Sakaguehi H, Uchide H, Matsuo N, Sakaguehi S, Anai H, Yoshioka T. Combined interventional therapy of metallic stent, radiation, and intracranial chemotherapy for hepatic bilar bile duct cancer. Presented at SCVIR Annual Meeting, Washington, D.C., March 11, 1997. 25. Pakisch B, Schmidt F, Hausegger KA, Stuecklschweiger G, Gahrleitner N, Hackl A. HDR brachytherapy with and without external beam irradiation after permanent stent placement for the treatment of malignant bile duct obstruction. Presented at RSNA Annual Meeting, Chicago, IlL, Dec. 4, 1996. 26. Bezzi M, Panzetti C, Bonomo G, Pedicini V, Salvatori FM, Rossi P: Plastic covered Wallstents in malignant biliary obstructions: evaluation in 17 patients. Presented at SCVIR Annual Meeting, Seattle, WA, March, 1996. 27. Born P, Neuhaus H, Rosch T, et al. Experience with a new partially covered Wallstent for malignant biliary obstruction. Endoscopy 1996; 28:699-702. 28. Cwikiel W, Harnek], Zoucas E: Electrolytic stents: experimental study in rats and pigs. Presented at SCVIR Annual Meeting, Seattle, WA, March, 1996. 29. Machan LS, Hunter W: Prevention of malignant tumor overgrowth by an angiogenesis inhibiting stent coating. In press. 8:25 am
Gastrointestinal Stenting: Indications and Techniques Andreas Adam, FRCR SELF-EXPANDING metallic stents are now used frequently in many organs, including the biliary tract, tracheobronchial tree and vascular system. Within the upper gastrointestinal tract they are most frequently employed in the esophagus, though gastric antral/pyloric, and duodenal stenting have also been described.
110
Esophageal Stenting The majority of esophageal stents are inserted for palliation of inoperable malignant dysphagia, but they are occasionally required to treat tumor recurrence at surgical anastomoses, and in benign strictures which are unresponsive to balloon dilatation. Tracheo-esophageal fistulae and esophageal leaks can also be successfully treated with covered stents. Esophageal carcinoma is a relatively common disease with a poor prognosis, accounting for 3,500 deaths per
year in the United Kingdom (1). At the time of presentation 75% of patients will have disease spread to lymph nodes (2), and approximately 500/0---60% of patients are not suitable for attempted curative surgical resection. Available palliative treatments include surgery, radiotherapy, chemotherapy, rigid plastic tubes, laser therapy and self expanding metallic esophageal stents. A variety of covered and uncovered stents are available. The three most commonly used are the Wallstent (Schneider AG, Zurich, Switzerland), the Strecker stent (Medi-tech/Boston Scientific Corporation, Watertown, MA, USA), and the Gianturco stent (William Cook Europe, Bjaeverskov, Denmark). An initial esophagogram is performed to delineate the site and length of stricture. The patient lies on the fluoroscopic table in the left lateral position. Lidocaine spray is applied to the pharynx, and the patient is sedated with an intravenous agent such as midazolam. Suitable catheters and guide wires are used to cross the stricture. The catheter and guide wire are manipulated into the duodenum to provide as stable a position as possible, and the guide wire is changed for an Amplatz stiff exchange wire. A IS-mm-diameter balloon is used to predilate the stricture prior to stent deployment. We aim to deploy the stent with approximately 60% of its length above the middle of the stricture in an effort to minimize the incidence of distal stent migration. Long strictures may require the use of more than one overlapping stent. Immediately after the procedure, nonionic contrast medium is introduced into the esophagus via the catheter to look for any procedural complication, especially esophageal perforation, and to confirm stent patency. Patients remain in hospital overnight, and once they have recovered from the effects of the sedation, they are allowed to take small volumes of clear fluids orally. The following day a further esophagogram is performed with a view to proceeding to any further intervention that may be required. For example, a stent may show persistent narrowing, requiring balloon dilatation, or there may have been migration, requiring the insertion of an additional stent coaxially within the first endoprosthesis and overlapping with it to prevent further slip. If the esophagogram shows good stent position and function patients are allowed a normal diet. They are advised to cut their food into small pieces, to chew it thoroughly and to have carbonated beverages after each meal in order to clear the stent of any food debris. In any patient in whom a stent has been placed across the gastro-esophageal junction, reflux of gastric contents will inevitably occur. The symptoms are controlled by the administration of omeprazole, which is started routinely after the procedure.
Results of Esophageal Stenting in Malignant Disease The degree of dysphagia can be assessed by the use of a dysphagia score, where 0 is equivalent to no dysphagia and 4 indicates total dysphagia (Table). The immediate technical success in virtually 100%,
Table 1 Dysphagia Score
Degree of Dysphagia
o
No dysphagia Able to swallow semi-solid food only Able to swallow liquids only Difficulty in swallowing liquids and saliva Complete dysphagia
1
2
3
4
with improvement in the dysphagia score in 830/0-100% of patients (3-5). Uncovered stents are prone to tumor ingrowth (200/030%), compared to only 2% of patients treated with covered stents. The lack of an outer covering probably also accounts for the absence of migration with this type of stent. Stent migration occurs in 30% of covered Wallstents and 100/0-15% of Gianturco stents. Covered stents are particularly liable to migrate when positioned at the gastro-esophageal junction, with a free end lying in the stomach. Wallstents rely on the uncovered portion at either end to prevent migration, and if one end lies free in the stomach this mechanism is compromised. In cases of complete and symptomatic stent migration, the stent can be removed by surgical gastrotomy. In cases of partial migration, the covered stent can be stabilized by the placement of a coaxially-placed, uncovered stent through its proximal end. Because of the propensity of covered stents placed over the gastro-esophageal junction to migrate, we now elect to deploy uncovered stents at this site, although as the new Wallstents with an inner plastic covering become available our practice may change. Recurrence of dysphagia secondary to tumor ingrowth or overgrowth can be successfully managed either with endoscopic laser therapy, or by the placement of additional stents. Food bolus impaction is easily cleared endoscopically. Rigid plastic tubes, usually inserted under general anesthesia, have declined in popularity in many centers. The overall complication rate has been reported to be as high as 36%, with a mortality of 20/0-16%. The reported complications include a perforation rate of 4.20/0-10.5%, hemorrhage in 1.50/0-5%, tumor overgrowth in 8.5%, tube migration in 22%, and pressure necrosis of the esophageal wall in 4% (6,7). The small luminal diameter leads to problems with food impaction in around 6.5%. The use of a general anesthesia and the requirement for admission to hospital for a few days also makes this treatment expensive. Laser therapy has been shown in a number of studies to provide excellent palliation in malignant esophageal obstruction (8,9). With the use of laser therapy, more than 80% of patients can be maintained on a solid or
semi-solid diet (8,9). The main drawback of this modality is the requirement for multiple treatments, which need to be repeated every 4-8 weeks. In a series of 189 patients with inoperable esophageal carcinoma, a mean of 3.3 procedures per patient were required (9). The complication rate is low (50/0-9%) (8,9), and is mainly related to esophageal perforation during pretreatment dilation. The other main complication is hemorrhage, but this can be easily controlled by local laser photocoagulation. Both laser therapy and self expanding metallic stents are used in our center for the palliation of malignant dysphagia. We have conducted a triple randomized study comparing Wallstents, Strecker stents, and laser therapy. The results demonstrated statistically significantly better palliation with metallic stents than with laser therapy (10). However, there are certain morphological types of tumor in which esophageal stents are best avoided: in situations where the tumor is very exophytic, or where the esophagus is very dilated above the stricture, the free end of the stent will not lie closely adjacent to the esophageal wall, and food or fluid will tend to pool between the stent and the mucosa. In this situation, palliation will be suboptimal, and there is a risk of aspiration. We, therefore, find that esophageal stents and laser therapy are complementary treatments, and that each case should be treated on its own merits.
Esophageal Stents in Benign Disease In the majority of patients with malignant disease the application of esophageal stents presents few long-term problems, as most individuals have a fairly short survival. The management of benign disease is different, as in the long-term one cannot be entirely certain of the difficulties that may be encountered. Generally, we avoid the use of stents in this situation, but there are occasions when repeated dilation produces progressively shorter periods of relief of dysphagia, in which there is little choice other than to employ a stent or submit the patient to major surgery. In addition, there are rare occ~sions when it is simply not possible to dilate benign strictures successfully. In general, we restrict the use of self-expanding stents in benign strictures to patients who are not fit for surgery. Clearly, the use of a stent does not preclude surgery at a later date should that become necessary, and should the patient's clinical condition improve sufficiently with adequate nutrition. The technique employed for deploying esophageal stents across benign strictures is essentially the same as that in malignant disease, although we consider uncovered stents more appropriate as they are less likely to migrate, and in this clinical setting there is no potential for tumor ingrowth, making the stent covering superfluous. An additional advantage of using uncovered stents is that after a few months the stent is completely covered by epithelium and becomes incorporated into the wall of the esophagus. A number of cases of the use of metallic stents in benign strictures are reported in the literature, and the results indicate a good response of dysphagia
111
(11-13). However, the major problem in the long-term is the occurrence of epithelial hyperplasia related to the stent. This is amenable either to balloon dilation, or to laser treatment. The hyperplastic epithelium is considerably easier to deal with than the original benign stricture, so although stents are not ideal for the treatment of benign disease, they do at least help to make an almost unmanageable situation manageable.
Results The number of patients reported in the literature is currently small, but results indicate that immediate technical success can be expected in 890/0-100%, with successful palliation of symptoms in 780/0-100%. No major complications have been described. Given the relatively narrow stents that are used, a soft diet is often advised.
References Treatment ofMalignant Esophageal Leaks and Fistulae Esophageal leaks or perforations may occur due to tumor invasion, or be iatrogenic secondary to esophageal dilatation or biopsy. Fistulae to the respiratory tract may be caused by a tumor arising either from the esophagus or from the tracheobronchial tree, or may be a complication of surgery or esophageal stenting. Although perforations and leaks are generally treated conservatively in the first instance, those of malignant etiology will usually not heal. In cases of malignancy where conservative therapy has failed, management is fairly straightforward, with deployment of a covered stent, most commonly in the esophagus, though covered tracheal stents are also useful. Treatment of malignant esophageal fistulae with covered self-expanding stents is very successful in covering the fistulae and preventing leakage either into the mediastinum or respiratory tract (14). In addition, nearly all patients return either to a soft or completely normal diet, as would be expected from the results of larger series of experience of esophageal stenting of tumors.
112
Gastric Antral and Duodenal Stenting Gastric outlet obstruction is most commonly caused by malignancy arising either from the gastric antrum, or from duodenal stricture or obstruction secondary either to direct invasion or extrinsic compression or invasion from pancreatic carcinoma. Gastric outlet obstruction is usually palliated with a gastroenterostomy, and stenting is generally only carried out in patients deemed unfit for surgery. Insertion of stents via gastrostomy (15) or the peroral route has been described (16). Endoscopy is frequently used, though is not strictly necessary, although there is an absolute requirement for fluoroscopic screening. We favor the peroral route under fluoroscopic guidance. Mter the administration of intravenous sedation, a catheter and guide wire are passed through the esophagus down to the level of the stricture in either the gastric antrum or duodenum. The catheter is manipulated across the stricture, and the guide wire changed for an Amplatz super-stiff exchange guide wire. The stricture is predilated to 10 mm in diameter, and an appropriate sized stent is deployed. We favor the Wallstent because of its greater inherent outward radial force and prefer to use uncovered stents, to minimize the risk of migration. We have used 16-mm-diameter stents (16), which are probably the best compromise between a desirable large diameter and flexibility.
1. Earlam R. Oesophageal cancer treatment in North East Thames region in 1981: medical audit using hospital activity analysis data. Br Med ] 1984; 288: 1892-1894. 2. Rankin S, Mason R. Staging of oesophageal carcinoma. Clin Radiol 1992; 461:373-377. 3. Cwikiel W, Stridbeck H, Tranberg KG, et al. Malignant esophageal strictures: treatment with a self expanding nitinol stent. Radiology 1993; 187:661-665. 4. Saxon RR, Barton RE, Katon RM, et al. Treatment of malignant esophageal obstructions with covered metallic Z stents: long term results in 52 patients. ]VIR 1995; 6:747-754. 5. Song HY, Do YS, Han YM, et al. Covered, expandable esophageal metallic stent tubes: experiences in 119 patients. Radiology 1994; 193:689-695. 6. Tytgat GN]. Endoscopic therapy of esophageal cancer: possibilities and limitations. Endoscopy 1990; 22:263-267. 7. Gasparri G, Casalegno PA, Camadona M, et al. Endoscopic insertion of 248 prostheses in inoperable carcinoma of the esophagus and cardia: short-term and long-term results. Gastrointestinal Endoscopy 1987; 33:354-356. 8. Sander RR, Poesl, H. Cancer of the oesophagus: palliation, laser treatment and combined procedures. Endoscopy 1993; 25CSuppl):679-682. 9. Mason RC, Bright N, McColl 1. Palliation of malignant dysphagia with laser therapy: predictability of results. Br] Surg 1991; 78:1346-1347. 10. Adam A, Ellul], Watkinson AF, et al. Palliation of inoperable esophageal carcinoma: a prospective randomized trial of laser therapy and stent placement. Radiology 1997; 202:344-348. 11. Cwiekel W, Willen R, Stridbeck H, et al. Self expanding stent in the treatment of benign esophageal strictures: experimental study in pigs and presentation of clinical cases. Radiology 1993; 187:667-671. 12. Foster DR. Use of a Strecker oesophageal stent in the treatment of benign oesophageal stricture. Australasian Radiol 1995; 39:399-400. 13. Tan BS, Kennedy C, Morgan R, Owen W, Adam A. Uncovered metallic endoprostheses for recurrent benign esophageal strictures: preliminary experience. A]R (In Press).
14. Watkinson A, Ellul], Entwistle K, et a1. Plastic-covered metallic endoprostheses in the management of oesophageal perforation in patients with oesophageal carcinoma. Clin Radiol 1995; 50:304-309. 15. Keymling M, Wagner H-J, Vakil N, Knyrim K. Relief of malignant doudenal obstruction by percutaneous insertion of a metal stent. Gastrointestinal Endoscopy 1993; 39:439-441. 16. Scott-Mackie P, Morgan R, Farrugia M, Glynos M, Adam A. Malignant duodenal obstruction: a role for metallic stents. Br J Radiol (In Press). 8:50 am
Management of Chronic Ureteral Obstruction Parvati Ramchandani, MD URETERAL obstruction comes to clinical attention when patients present with flank or abdominal pain, azotemia or urinary tract infection or when imaging studies demonstrate hydroureteronephrosis; the etiology spans the spectrum from neoplastic disease to benign causes. Neoplastic obstruction usually occurs in the setting of advanced malignant disease and it can be related either to primary urothelial neoplasms or to extrinsic compression by primary or metastatic retroperitoneal or pelvic malignancies. The goal of treatment in these patients is to provide renal drainage so that renal function can be maintained. Benign ureteral strictures are most apt to be iatrogenic in origin with urological, gynecological and general surgical procedures accounting for 42%, 34%, 34%, and 24% of ureteral injuries respectively in a recent series (1). The widespread use of upper urinary tract endoscopy for the minimally invasive diagnosis and treatment of a myriad of pathologies has had the paradoxical result of making endourological procedures the single most common cause of ureteral injuries, which reportedly occur in 3%-18% of patients undergoing ureteroscopy (1,2). In Selzman's series (1), 79% of urological ureteral injuries occurred during an endoscopic procedure (attempted stone removal being the most frequent), while 21% occurred during an open procedure such as uretro or nephrolithotomy, radical retropubic prostatectomy, or lymph node dissection. Abdominal hysterectomy and salpingo oopherectomy accounted for 86% of the gynecological injuries and colorectal surgery accounted for 67% of all general surgical injuries. Laparoscopic surgery is also becoming an increasingly frequent cause of iatrogenic ureteral injuries (3). Other causes of ureteral strictures include recurrent stone passage in patients with chronic calculous disease, penetrating abdominal trauma, particularly high velocity gun shot wounds, radiation therapy, and infections such as tuberculosis and bilharziasis. Strictures that occur at the uretero-enteral anastomotic site in patients with urinary diversion are particularly refractory to treatment. Therapeutic options in the management of chronic ureteral obstruction range from percutaneous nephros-
tomy drainage alone to ureteral stenting, either denovo or preceded by balloon dilation. Percutaneous nephrostomy is almost universally successful in draining obstructed, dilated kidneys, allowing for immediate renal decompression in patients with obstruction complicated by urosepsis or azotemia (4,5). In ureteral obstruction due to benign disease, the decision to perfonn the procedure is straightforward. In patients with terminal malignancies where the obstruction is irremediable, the need for drainage is likely to be pennanent. The burden posed by the presence of a drainage catheter should be carefully weighed against the benefit of extending life for a few months, a dilemma that should be openly discussed with the referring physician, the patient and the family. Long-tenn survival after palliative diversion for malignant ureteral obstruction is poor and determined largely by the type and stage of the underlying neoplasm, and its potential for further treatment. Median survival after nephrostomy drainage in one group of 77 patients with pelvic malignant disease was 26 weeks (6) and only 25% of patients were alive at 1 year in another series (7). Unless aggressive chemotherapeutic treatment is planned, unilateral drainage usually suffices and bilateral drainage confers no additional benefit. However, patients with hormone responsive prostate cancer tend to live longer than patients with other pelvic malignancies and bilateral drainage may be a preferable option in these patients, particularly if they are young (8). Percutaneous nephrostomy should not be the first procedure to be considered for renal drainage unless the patient has urosepsis; it should ideally be reserved for patients in whom retrograde renal drainage is either unsuccessful or infeasible. Locking loop 8- or 10-F drainage catheters are the catheters of choice for long-term drainage with a reported dislodgment rate of less than 1% (4).
Ureteral Stenting Ureteral stent placement provides the benefits of urine drainage and diversion without the necessity for a drainage bag and is therefore preferred to nephrostomy drainage in most patients. However, if the urinary bladder is markedly contracted or diseased (as in patients with radiation cystitis, hemorrhagic cystitis, tuberculous cystitis or tumor invasion of the bladder) or in patients with urinary incontinence or vesical fistulae, percutaneous nephrostomy drainage is preferable to ureteral stenting. Nephrostomy drainage may also be the only option in patients with extensive bulky pelvic disease that causes ureteric or bladder compression-antegrade urine drainage often fails in such patients despite patency of the ureteral stent, presumably due to a decrease in the pressure differential between the renal pelvis and the bladder. Ureteral stents can be inserted in one of three ways: (1) percutaneously (antegrade), (2) retrograde transure-
113