Patients with acute colonic obstruction and synchronous metastatic disease pose specific challenges. Such patients often present in a debilitated state and have a limited life expectancy. While surgical intervention can be undertaken under such circumstances, less invasive treatment can be beneficial in this group of patients (Table 19.1). Lee and colleagues reviewed their experience with SEMS and found clinical success comparable to surgical intervention; however, SEMS was associated with fewer complications compared to palliative surgery [4]. Despite improved short-term morbidity and mortality, a shorter hospital stay, avoiding stoma formation, and better quality of life, several studies have shown no long-term survival advantage in patients treated with SEMS compared to those treated surgically. It is important to note that one study by Súarez et al. reported a significant survival advantage in patients with incurable colorectal cancer treated with SEMS [5].

Colon perforation , a well-known complication of stenting, also occurs in a minority of patients who receive chemotherapy, especially bevacizumab-based chemotherapy. For this reason, stent placement in patients who will undergo palliative chemotherapy remains controversial and patients should be counseled regarding the potential risk of perforation.

Despite the short-term advantages of SEMS , the long-term benefits of SEMS for palliation have not been well established. Lee et al. compared the long-term outcomes of SEMS placement with those of palliative surgery and documented that the patency of the first stent and duration of decompression was shorter but that decompression after a second stent was comparable with surgery [4]. In another study by Small et al., 24.4% of patients decompressed with SEMS experienced long-term complications such as perforation, occlusion, and migration [6]. Fernández-Esparrach et al. showed a long-term clinical failure rate of 51%, with a mean stent patency duration of only 145 days [7].

SEMS in patients with incurable colorectal cancer can improve quality of life with a relatively low risk for early complications and should be considered in patients with limited life expectancy (Table 19.2). However, surgical intervention should be considered in patients who are better operative candidates, who have longer life expectancy, and who are candidates for chemotherapy.

Endoluminal colonic stenting as “bridge-to-surgery” can be considered in patients with potentially curable colorectal malignancy. Up to 30% of patients with colorectal cancer present with acute colonic obstruction, which would otherwise require surgery. Emergency decompressive surgery carries significant risks of morbidity (30–60%) and mortality (15–35%).

The technical success rate of SEMS with “bridge-to-surgery” intent has been reported between 46.7 and 100% with a clinical success rate ranging from 40 to 100% (Table 19.3). For obstructed patients without proper cancer staging and in the setting of malnutrition, SEMS is an attractive option. Endoluminal decompression with a stent also allows for preoperative medical evaluation and optimization. Emergency decompression with SEMS can also allow for bowel preparation and increases the likelihood of single-stage elective resection. A systematic review by Brehant et al. comparing emergency surgery with SEMS insertion as a bridge to surgery showed a higher primary anastomosis rate, shorter hospital stay, and a lower colostomy rate in the SEMS group [8]. Another meta-analysis by Tilney et al. comparing colorectal stenting with surgery showed similar results with fewer medical complications in the bridge-to-surgery group [9]. Similarly, Tan and colleagues reviewed controlled and randomized trials and reported a higher primary anastomosis rate and lower stoma formation rate in patients undergoing SEMS [10]. However, the permanent stoma rate, morbidity and mortality rates were not significantly different between patients undergoing SEMS compared to those treated surgically.

The possible impact of SEMS on oncologic outcome has been questioned in several studies where the long-term oncologic outcome of stent insertion as a bridge to surgery was associated with a higher recurrence rate compared to emergency resection. In a study by Kim et al., multiple stent insertions were identified as a risk factor for subsequent surgical failure [11]. Perhaps most concerning, stent perforation can lead to peritoneal tumor seeding that upstages the patient and changes a potentially curable situation into an incurable one, as shown in several studies.

While the overall survival rates in several studies did not show significant differences between groups of patients treated with stenting or surgery, the recent guidelines by the European Society of Gastrointestinal Endoscopy do not recommend the use of metallic stents as bridge to surgery because of concerns about oncological safety [12]. This recommendation was endorsed by the Governing Board of the American Society for Gastrointestinal Endoscopy . Thus, emergency stenting in left-sided and potentially curable malignant obstruction can be considered as an alternative to emergency surgery in high-risk patients with increased risk of postoperative mortality. In right-sided colonic obstruction, resection with a primary anastomosis without the need for a diverting stoma is usually possible. Emergency surgery is preferable instead of stent insertion as a bridge to surgery in such subgroup of patients.

The optimal timing for surgical intervention following SEMS depends on several patient factors like the degree or success of decompression and the need for medical optimization and cancer staging. A significant delay between stenting and surgery should be avoided as this can potentially increase the risk of stent-related complications. A study by Sirikurnpiboon et al. suggested that the optimal bridging time to surgery should be within 5 days and other studies recommend resection 5 to 10 days after stent insertion [13]. Patients with unique factors and patients with locally advanced rectal cancer who undergo neoadjuvant chemoradiation require a longer interval and surgery may be delayed for several weeks.

Most cases of the colonic obstruction are due to intrinsic occlusion by colorectal malignancy, benign stenosis due to an inflammatory process such as diverticulitis or anastomotic stricture. However, extra-colonic conditions can also cause extrinsic compression resulting in obstruction. In such patients, SEMS may be considered as an alternative to surgical intervention; however, the technical success rate of stenting for colorectal obstruction due to extrinsic malignancy ranges from 42 to 100% with a reported clinical success rate of 25–87% [14, 15].

Luigiano et al. showed a lower patency rate in patients with extrinsic obstruction compared to intrinsic malignancy [16]. Trompetas et al. reported 12 stent procedures carried out in 11 patients with colonic obstruction from extra-colonic malignancy with technical and clinical success rates of 42 and 25%, respectively [17]. Importantly, in this study, the 30-day mortality was 36%, the colostomy formation rate was 45%, and the median survival rate was only 2 months. The clinical outcomes of stent placement in patients with extra-colonic causes of the colonic obstruction are less favorable compared to patients with intrinsic obstruction from colorectal cancer. Nonetheless, SEMS should be considered in such patients if technically feasible due to the limited life expectancy of patients with metastatic cancer causing extrinsic compression.

Most of the available data on the use of SEMS in the setting of benign colonic strictures is derived from case reports or case series. Etiologies of benign strictures include diverticulitis, strictures after pelvic abscesses, radiation-related strictures, inflammatory bowel disease strictures, and ischemia. Stenting has also been described for treating colonic fistulas and anastomotic complications.

A case series of benign colorectal strictures treated with SEMS by Small et al. demonstrated a technical success rate of 95% but the major complication rate was 38% and included stent migration, obstruction, and perforation [18]. Another case series by Keränen et al. reported outcome of SEMS used for anastomotic stricture, diverticular disease, and radiation-induced stricture and documented a clinical success rate of 76% with a 43% complication rate [15]. Most of the complications occurred in patients with diverticular disease. A retrospective review by Pommergaard et al. reported results of SEMS in both malignant and benign colonic obstructions [19]. In this study, the technical success rate was 97%, the complication rate was 21%, and the mortality rate was 2.6% in patients with malignant stricture while in the benign group, the technical success rate was 86%, complications occurred in 71% of patients, and the mortality rate was 28%.

Colovesical fistulas are most often treated surgically; however, in high-risk patients, the placement of a covered stent may provide symptomatic control. Ahmad et al. reported a case of colovesical fistula secondary to malignancy, which was successfully treated with SEMS [20]. Similarly, the technique of SEMS placement in patients with colovaginal fistula has been described.

Anastomotic leak and complications after colorectal resection are challenging clinical problems that often require reintervention and the potential need for diverting stoma formation. There is a paucity of data on the use of colonic stenting for such indications. Abbas first described the use of a covered stent in two patients with anastomotic complications [21]. More recently, Lamazza et al. reported the long-term results after stent placement in 22 patients with symptomatic anastomotic leak after colorectal resection [22]. The technical success rate was 100%, 15 patients (62%) required diverting ileostomy, and the anastomotic leak healed in 19 patients (86%). In two patients with recurrent rectovaginal fistula, stent placement controlled the symptoms of the leak allowing for a subsequent successful surgery with advancement flap and only one patient required a permanent stoma.

Modern colorectal stents such as SEMS are made of radio-opaque, woven, uncovered metal mesh and have a cylindrical shape that result in self-expanding forces. There are two major SEMS delivery systems, through-the-scope stents (TTS) and over-the-wire stents (OTW) . TTS stents are small enough to fit through the working channel of an adult endoscope and OTW stents are passed alongside the endoscope. After deployment, stents continue to expand and reach their full expansion diameter within a couple of days. Stent specifications include length, diameter, and proximal flare. The most common lengths used vary from 8 to 11 cm, the most common diameters used are between 18 and 25 mm, and the maximum proximal flare is 30 mm. Partially covered or fully covered colonic stents are not currently available in the United States.