Background

Less than 10% of patients with gastro-esophageal cancer survive 5 years (Lee, 2001). Oral intake of nutrition is vital in maintaining quality of life for these patients, particularly when considered by the multidisciplinary team (MDT) to be suitable for palliative treatment only. The development of significant dysphagia to solids and, more particularly, liquids as a result of occlusive neoplastic stricturing requires palliation that is effective and minimally invasive (Box 22.1). In this section, it is intended to review upper gastrointestinal (GI) tract stenting.

BOX 22.1 Management options to palliate dysphagia resulting from occlusive neoplastic stricturing

Laser ablation

Photodynamic therapy

Argon therapy

Ethanol injection

Brachytherapy

Radiotherapy on its own or chemoradiotherapy

Self-expanding metal stent (SEMS)

History

Historically, palliation of dysphagia resulting from occlusive malignancy has required surgical intervention. Celestin (1959) described a traction technique that required endoscopic guidance of an introducer and a mini laparotomy to gain entry high in the stomach; this enabled the tube (Figure 22.1) to be pulled through. Subsequently, the Nottingham introducer precluded the requirement for a laparotomy.

Figure 22.1 Insertion size of the Celestin tube (top) compared with the delivery system for SEMS (underneath), with two SEMS types expanded.

The alternative pulsion technique was one where a tube, such as the Atkinson or Soutter tubes, was pushed through the neoplastic stricture, often following bougie dilatation.

These intubation procedures took less than an hour to perform but required a general anesthetic and hospitalization of between three and ten days (Celestin, 1959; Davis, 1972; Bancewicz, 1979; Unruh and Pagliero, 1985; Kratz et al., 1989; Dunn and Rawlinson, 1992).

Self-expanding metal stent (SEMS) structure

The most common material used to form GI SEMS mesh weave is Nitinol, an abbreviation of ‘Nickel Titanium Naval Ordinance Laboratory’. Discovered in 1961 by William Buehler, Nitinol is one of the shape memory alloys. It has the property, particularly when warm, of generating a force returning it to a predetermined shape. Nitinol’s property and its strength make it an ideal material to be fashioned into the wire that forms SEMS. The membrane of the covered GI stent is most commonly made of silicone or polyurethane:

The vast majority of upper GI SEMS insertions are associated with neoplastic occlusion or tracheo-esophageal fistula. SEMS have also been used for benign conditions, such as achalasia, where other management options, such as myotomy, balloon dilatation or the injection of botulinum toxin, have failed. In a number of papers, the use of stents is not recommended for benign strictures (De Palma et al., 2001). Ackroyd (2001) suggests that SEMS should be used for benign strictures with caution as they can make matters worse, potentially making a stricture inoperable. The indications for upper GI SEMS insertion are given in Box 22.2.

BOX 22.2 Indications for upper GI SEMS insertion

Palliation of malignant occlusion

Palliation of tumor overgrowth in an in situ stent

Occlusion of tracheo-esophageal fistula

Esophageal perforation predominantly as a result of:

stricture dilatation

iatrogenic endoscopic trauma

anastomotic tumor recurrence or leak

benign esophageal stricturing

Stricturing resulting from extrinsic neoplastic compression

Removable SEMS

If a temporary stent is being considered, subsequent removal is undertaken endoscopically (Nam et al., 2006; Shin et al., 2008). Removable stents have a lasso woven into their proximal end. Under endoscopic control, forceps are used to grasp the lasso, tension will draw the proximal end of the stent closed and away from the esophageal wall. Maintaining hold of the lasso, the scope and forceps are then drawn out together with the stent.

Approaches to esophageal and gastro-esophageal SEMS insertion

SEMS provide a significant benefit in palliating malignant dysphagia, but there is broad discussion as to the best method to employ for their insertion. The literature suggests a bias towards a joint endoscopic/fluoroscopic approach to SEMS insertion. Ramirez et al. (1997) reported that 83% of those members of the American Society of Gastrointestinal Endoscopy (ASGE) who responded to a survey used a combined endoscopic/fluoroscopic approach for the deployment of SEMS. Described by Sarper et al. (2003) and others, the joint approach uses endoscopy to pass the guide wire across the stricture, the subsequent stent deployment being undertaken using fluoroscopic guidance. Singhvi et al. (2000) suggest fluoroscopy is not necessary, advocating the use of a thin gastroscope, possibly in conjunction with a dilator such as the Savrey buginage, to assist with tight strictures. The routine use of general anesthetic for endoscopic SEMS insertion has also been reported (Singhvi et al., 2000; Sarper et al., 2003; Sabharwal et al., 2003; Soussan et al., 2005a, 2005b). The literature, however, also supports the use of fluoroscopy alone for deployment (Laasch et al., 2002; Saranovic et al., 2005; Law, 2008). The technical and clinical success rates for the deployment of esophageal SEMS are reported as similar whether using an endoscopic/fluoroscopic technique or fluoroscopic alone (Petruzziello and Costamagna, 2002).

Some units use endoscopy alone for the insertion of SEMS, but the advantages of this approach are limited. It can be used where there is limited access to fluoroscopy (Rathore et al., 2006). Singhvi et al. (2000) report using endoscopy alone as being a quick procedure (15 minutes) and resorting to the use of fluoroscopy is not routinely needed.

Points to consider:

Figure 22.2 (A) Contrast passing through a tumor via an esophagogastric fistula; (B) the strictured true lumen adjacent to the fistulous tract.

Fluoroscopically guided SEMS insertion: technique

Fluoroscopy could be considered the optimum approach to esophageal SEMS insertion; it is quick, safe and cost effective. A suggested alternative would be to employ the endoscopic/fluoroscopic approach only in particularly problematic situations and the endoscopy only approach should not be used.

Fine bore intubation is a natural skill progression for GI radiographers or radiologic technologists experienced in demonstrating esophageal pathology. (The techniques and benefits of technician performed fine bore intubation are described as a service development in Chapter 11.) In performing complicated fluoroscopically guided naso/orogastric intubation, GI radiographers and radiologic technologists are ideally placed to be involved in a joint approach with a clinician (gastroenterologist, surgeon or radiologist) in performing the first part of SEMS deployment by transgressing the esophageal lumen strictured by tumor (Law, 2008). Suggested protocol inclusions prior to upper GI SEMS insertion are offered in Box 22.3.

BOX 22.3 Pre-upper GI SEMS insertion protocol

Histological confirmation of a malignancy

The tumor must be staged

The patient should have been discussed at the upper GI multidisciplinary team (MDT) meeting and considered suitable for palliation only

A barium swallow performed to confirm that the degree of dysphagia justifies stenting. (If due to clinical need, stenting is required at short notice, evaluation of the neoplastic stricture with barium can be performed immediately prior to the stent procedure)

Patient preparation

The protocol for upper gastrointestinal SEMS insertion should include:

The barium swallow

Figure 22.3 Barium outline of neoplastic stricture. A radiopaque rule can help approximate measurement.

Intubation across the stricture

Figure 22.4 (A) Anteroposterior view of the fine bore tube across stricture and into the stomach. (B) Lateral image of tube across lesion and sited in the stomach.

Figure 22.5 A stiff wire sited into the stomach and the tube being withdrawn over the wire.

Figure 22.6 (A) SEMS released from delivery system. Proximal, middle and distal markers visible, guidewire in situ. (B) SEMS deployed.

High esophageal stricture

Technically, there is nothing to preclude fluoroscopically guided stenting of malignant strictures close to the upper esophageal sphincter. Verschuur et al. (2007), in reporting the safety and effectiveness of stenting high in the esophagus, note that its limitations can include patient intolerance due to pain or globus sensation. Sihoe et al. (2004) reported that, due to the close proximity of the trachea and the upper esophagus, consideration should be given to pre-empt airway stenosis or fistulation by inserting a tracheal stent prior to the insertion of a high esophageal stent. Wyn et al. (2006), although supporting this premise, suggest that airway compression is rare.

Gastric and duodenal SEMS

SEMS insertion can be used to palliate advanced symptomatic malignancy obstructing the stomach or duodenum. It is normally undertaken as a joint endoscopic/fluoroscopic procedure. Symptoms might include vomiting, cachexia and dehydration.

As a precursor to SEMS insertion, location and length of the stricture can be demonstrated fluoroscopically using a water-soluble contrast medium such as Ultravist 240 (Schering Health Care Ltd).

With the patient lying on their right side, the contrast pooling (whether in the stomach or duodenum) has the optimum chance of outlining the strictured lumen (Aviv et al., 2002; Lowe et al., 2007; Van Hooft et al., 2007; Hosono et al., 2007).

Technical considerations

• Stenting is normally performed as a joint endoscopic-fluoroscopic procedure.

• The stomach should be empty, if necessary by the prior insertion of a gastric drainage tube

• The use of an endoscope can help direct the guide wire into the proximal origin of the stricture. It can also prevent the wire coiling in the stomach during advancement

• The potential for the stent to abut the normal anatomy at either end of the stricture (such as the duodenal bulb), should be taken into account when deciding SEMS length

• If a duodenal stricture to be stented transgresses the ampulla, it must be confirmed that no further endoscopic intervention of the pancreas or biliary tree is required as the SEMS will obstruct access to the ampulla

• Lowe et al. (2007) reported a 96.6% technical success rate for gastro duodenal SEMS insertion; 75% of patients were able to be supported at home without tube feeding

• The removal of a retrievable stent can be elective or indicated as a result of complications such as pain, migration, new stricture formation, incomplete expansion, airway compression. Care must be taken with removal, as intramural perforation, major bleeding, pneumomediastinum and even death may result (Yoon et al., 2004; Wyn et al., 2006)

• Where the stomach is not over distended and the stricture is outlined by a water-soluble contrast medium, gastric and duodenal SEMS insertion can be performed using fluoroscopy without the aid of endoscopy. The technique is similar to that used in the esophagus. Figures 22.7A–G demonstrate stenting of an incomplete duodenal occlusion from a carcinoma in the head of pancreas

Figure 22.7 (A) Water-soluble contrast outlining stricture in 2nd part of the duodenum. Metal and plastic stent in the common bile duct; (B) 8fg fine bore tube placed at the proximal origin of stricture; (C) guide wire passed across stricture; (D) guide wire passed into jejunum; (E) stent delivery system passed over guide wire; (F) stent deployed; (G) delivery system withdrawn.

Patient after-care post upper GI SEMS insertion

BOX 22.4 Gastro-esophageal SEMS complications

Chest pain often present as the stent expands

Bleeding, perforation, aspiration, fever, fistula

Covered stent migration, possibly requiring further stenting

Esophageal reflux

Stent impaction

Tracheal compression

The patient experience

Xylocaine spray to the throat will initially taste unpleasant before making the tongue feel as if it has enlarged. Despite local anesthesia, a degree of retching can occur. This can be caused by the initial passage of the tube through the pharynx into the esophagus. With residual fluid collecting above an esophageal occlusion, reflux and possible aspiration is a hazard during the procedure.

The most common experience the patient can expect, particularly in the immediate post SEMS insertion period, is focal chest pain. Pain is caused by the radial force of the stent as it opens. Staying in hospital overnight will allow for monitoring and appropriate analgesia to provide pain relief. Complications are not infrequent. Although not related to large patient groups, literature has reported early complication rates of 13% and late complication rate of 20% (Aviv et al., 2002). A complication rate of 44% has been reported for SEMS placement for distal esophageal tumor stenoses (Sarper et al., 2003). Major complication rates of 37% have also been reported (Ross et al., 2007). Complications are given in Table 22.1.

Table 22.1 SEMS complications

Introduction

About 20 000 people die in the UK each year from colorectal malignancy (Starkey, 2002; Steele, 2006). Currently, most incidents of colorectal cancer occur in patients in their seventh and eighth decades of life when other comorbidities, such as vascular disease, may limit treatment options. Most patients with colorectal cancer present with colonic symptoms (see Chapter 10), while others may present with disease as a consequence of metastatic spread. A significant number of patients with colorectal cancer present with acute large bowel obstruction (Stipa et al., 2008) and it is in this group of patients where colonic stenting is particularly appropriate (Alcantara et al., 2007; Farrell, 2007; Dionigi et al., 2007).

The morbidity and mortality for elective surgery for colorectal cancer is quite low, while urgent surgery for the patient who presents with acute colonic obstruction is significantly higher. Concerns may include:

Most colorectal cancers which cause intestinal obstruction are on the left side of the colon, where the diameter of the colon is less and the consistency of feces is harder. It has been hypothesized that the relatively high mortality of urgent surgery can be avoided by placing a stent across the obstructing tumor and allowing the colon to decompress and the patient to return to a normal physiological state before elective surgery is undertaken. This, it is believed, returns the patient to the risk level for morbidity and mortality associated with elective surgery. Additionally, the use of colorectal stenting in the emergency situation might simplify the type of surgery. In an acutely obstructed patient, it may be necessary to perform colostomy to decompress the colon, closing the distal colonic stump. In some circumstances, it may not even be possible to remove the primary tumor at this time. The patient is then left with a colostomy and probably the need for further surgery at some time in the future when the urgent situation has passed. If a stent is placed and elective surgery is undertaken, then a primary colocolic anastomosis may be undertaken and the tumor removed, thereby improving the quality of the patient’s existence and reducing the need for second surgery. Under some circumstances, for example, where the patient is not fit even for elective surgery or has extensive metastatic disease, colonic stenting may be definitive therapy in the acutely obstructed patient, thereby avoiding the need for potentially futile surgery (Athreya et al., 2006; Soto et al., 2006; Small et al., 2008).

Other indications

While the majority of colorectal stenting is undertaken for the obstructed patient with colonic cancer, other indications exist. Colonic strictures from diverticular disease or from Crohn’s disease may be treated with stenting when the patient is too unfit for the surgical option. The presence of a fistula between the colon and other structures, such as the bladder, small bowel and vagina, can lead to extremely debilitating symptoms for the patient and may be effectively treated by stenting (Laasch et al., 2003; Small et al., 2008).

One of the uncertainties regarding the use of colorectal stenting at present is whether pre-emptive stenting in the patient with a left-sided colonic tumor who is unfit for surgery might be of value. It is tempting to try to prevent the onset of colonic obstruction by stenting the patient who appears to have a narrow lumen through the tumor at the time of diagnosis. Opinions here are divided. It is clearly logical to try to avoid an episode of acute large bowel obstruction with its associated morbidity and mortality, but colorectal stenting itself carries a risk and there are no clear predictors that indicate the likelihood of large bowel obstruction in colonic cancer patients. The risk, therefore, is that patients are exposed to the risks of stenting for no clear clinical value. Most intestinal stents have a limited life span eventually becoming obstructed themselves. It may be inappropriate to use a proportion of this lifespan before it is clinically necessary.

Patient preparation

For the patient who presents with acute colonic obstruction, full clinical biochemical, hematological and radiological evaluation is important to reduce risk. Clinical assessment is important to determine the presence of comorbidities, particularly cardiac and respiratory disease. Hematological assessment is necessary because the patient may be anemic as a consequence of bleeding from the tumor and this may need correcting. Biochemical abnormality may be present because of dehydration, vomiting and renal failure. These deficiencies need to be corrected. It is rare that colorectal stenting is required so urgently that the patient cannot be adequately resuscitated from a hematological and biochemical standpoint prior to stenting. While radiological evaluation is most commonly undertaken using a plain film of the abdomen to determine the presence of obstruction, CT of the abdomen at least is essential. It may be valuable to add a CT of the chest in order to determine the presence of metastatic disease.

Abdominal CT can be carried out without any oral or rectal bowel preparation, but with intravenous contrast medium administration and CT examination carried out during the portal phase of contrast flow.

The CT will demonstrate:

Stent placement technique

Colonoscopy or not?

It is generally true to say, with upper GI or lower GI enteral stenting, that the further the lesion from the point of access, the more appropriate it is to use endoscopy. Obstructing tumors in the rectosigmoid can usually be traversed and stented using fluoroscopic guidance alone, without colonoscopy (Athreya et al., 2006). However, with more proximal tumors, in the descending colon up to the transverse colon, colonoscopy has a definite advantage in that it allows more rapid access to the tumor and therefore reduces radiation dose to the patient, but most importantly to staff (Figures 22.8,22.9A,22.9B).

Figure 22.8 Obstructive carcinoma descending colon.

Figure 22.9 (A) Endoscope passed to descending colon; (B) wire passed through stricture.

Fluoroscopic stent placement technique

It is appropriate to have a variety of hydrophilic catheters and guide wires to hand. With the patient in the left lateral position, a catheter (such as the Headhunter 1, Bernstein or Law 2) loaded with a guide wire is inserted into the rectum and negotiated slowly up to the level of the tumor. This is generally not difficult but can be time consuming. Once arrival at the distal margin of the tumor is achieved, it may be appropriate to inject water-soluble contrast in order to outline the tumor (Figure 22.10).

Figure 22.10 Water-soluble contrast infused through catheter to outline tumor.

The catheter and guide wire can then be negotiated across the tumor into the dilated colon above (Figures 22.11 and 22.12). This can occasionally be very difficult or impossible and there is a variety of tricks to improve success. Access across the tumor is most easily achieved using a standard non-stiff, straight tipped, hydrophilic guide wire. Occasionally, stiff or angled wires may be helpful. A change of catheter should be considered if difficulty is encountered. The more curved (cobra) or even straight catheters may be successful when the primary choice of catheter fails. Intravenous Buscopan to reduce peristalsis may help, as might insufflation of the rectum and distal colon with gas. The placement of a stiffening sheath into the rectum and sigmoid can help to prevent tube looping, but this also removes the effectiveness of the anal sphincter in maintaining continence.

Figure 22.11 Catheter negotiated across tumor lumen.

Figure 22.12 Guide wire advanced across tumor lumen into dilated colon.

If the proximal margin of the tumor has not been outlined, with the catheter passed through the tumor lumen into dilated colon, the guide wire can be removed and a water-soluble contrast infused. A relatively long, relatively stiff, nitinol plastic coated guide wire should then be passed into the proximal segments of colon. As much wire as possible should be inserted beyond the stricture (Figure 22.13). It may be necessary to allow a soft guide wire to loop its passage through the stricture (Figure 22.14). However, depending on the configuration of the colon, the length of wire passed across the stricture may, by force of circumstances, be short (Figure 22.15).

Figure 22.13 Law 2 tube showing guide wire passed into proximal descending colon.

Figure 22.14 Using joint colonoscopic/fluoroscopic guidance a soft wire is allowed to loop to pass across the strictured lumen.

Figure 22.15 Maximum position of guide wire due to a tight loop of bowel immediately proximal to the tumor site.

Short (90 cm) non-endoscopic stent delivery systems are available, as well as long (150 cm) delivery systems for endoscopic use. While short systems cannot be used with an endoscope, it is possible to use long (more cumbersome) delivery systems without an endoscope. The well-lubricated and flushed stent system is passed gently over the guide wire under fluoroscopic control, until it lies in an acceptable position.

If the delivery system does not easily pass through the stricture due to the tightness or rigidity of the lumen, pulling the wire to place it under tension can assist in railroading the delivery system into place. If the wire is to be placed under tension, the amount of free wire across the stricture must be very closely monitored as the tension will draw the wire out. Should the amount of wire extracted give concern, stop the advance of the delivery system and reinsert the wire.

With tumors above the rectosigmoid junction, it is probably best to place the middle of the stent in the middle of the tumor, so that there are equal lengths of stent above and below the tumor (Figure 22.16). It is appropriate to use a length of stent so that at least 2, preferably 3 or 4 cm, of stent lie above and below the margins of the tumor. This allows for any slippage or movement during placement (Figure 22.17).

Figure 22.16 Stent delivery system sited across the strictured lumen in the descending colon.

Figure 22.17 Stent deployment (note change in position of delivery system markers from Figure 22.16).

Stent types

As described for esophageal stents (see Part 1) nitinol or stainless steel stents are available. The most appropriate stent in current use has smooth wire ends and no sharp edges. Stents range from 22 to 30 mm in diameter and up to 14 cm in length. Colorectal stents are most commonly uncovered because of the better bowel wall grip achieved. Tumor in-growth is of less concern in the colon due to the bowel lumen diameter that can be achieved post stenting. However, covered stents may be appropriate in patients with fistula (Laasch et al., 2003; Shin et al., 2008; Small et al., 2008).

Post-procedural management

Generally, the feces at the level of obstruction are liquid and pass readily through the opening stent. A successful procedure is generally indicated by the patient needing a bedpan as they are wheeled out into the recovery area of the interventional suite. Again, it is important to maintain adequate fluid balance for the patient although, once the obstruction is dealt with, oral intake can resume quite quickly. In some patients, solid stool is present above the stent and this may make stent dysfunction a problem. Gentle enemas and orally administered stool softeners, such as Lactulose, may be helpful in these circumstances. Once the abdominal distension begins to decompress through the stent, oral intake, both liquid and solid, can resume. It may be wise to keep the patient on an orally administered stool softener indefinitely.

Outcomes

Stent placement and technical success is expected in about 90% of cases (Sebastian et al., 2004; Baraza et al., 2008). Failure occurs most commonly because of inability to negotiate either the catheter or colonoscope through the colon up to the level of the tumor. This may be because of tortuosity of the bowel or the presence of diverticular disease or stricture. Failure to negotiate a catheter or guide wire across the stricture may occur because the stricture is very tight (uncommon) or because of an adverse relationship of the lumen of the colon and the lumen of the tumor. Once the guide wire has been placed across the tumor into the proximal colon, failure to place a stent is extremely rare.

Complications

Apart from failure to complete the procedure, complications are few. Perforation of the distal colon or perforation of the tumor can occur and, in some series, appear quite common. If the position markers are not held rigidly in place during SEMS deployment, as the stent opens the radial force can migrate the stent into the more proximal colon (Figure 22.18). Stent migration appears to be less common in the colon than at the gastro-esophageal junction, perhaps a function of the use of uncovered stents more frequently in the colon. In experienced hands, perforation is uncommon. Failure of a technically well placed stent to function adequately is most likely because of impaction of solid feces into the stent and enemas, together with oral stool softeners, may resolve the situation (Athreya et al., 2006; Pericoli Ridolfini et al., 2007; Shin et al., 2008).

Figure 22.18 Stenting sited around a tight strictured loop, due to stent migration: malignancy not optimally covered.

Late complications

Stent migration can occur late, but is less common than immediate migration. Stent occlusion is the most common later sequel and is usually due to tumor through-growth, although fecal impaction may occur. Late perforation is reported (Salvi et al., 2004; Pericoli Ridolfini et al., 2007).

Post-stent course

In the majority of patients who undergo colorectal stenting for acute colonic obstruction as a bridge to surgery, further clinical and radiological assessment for the detection of metastatic disease or preliminary treatment with chemotherapy or radiotherapy may be appropriate under certain circumstances. Elective surgery can then be undertaken, the stent being removed with the surgical specimen. There does not appear to be any disadvantage to the surgeon caused by the presence of the stent. Some anxieties have been raised about the possibility that the presence of the stent causes dissemination of tumor cells with a possible increased risk of metastatic liver disease (Maruthachalam et al., 2007), but these concerns have yet to be confirmed.

Summary