Colonic strictures, both benign and malignant, are commonly encountered in clinical practice. Benign strictures are most commonly treated by balloon dilation and less frequently with stents. Balloon dilation can help forestall or obviate surgery in some patients. Colonic strictures of malignant etiology generally need to be managed by stents and/or surgery. This article reviews endoscopic approaches to the management of colonic strictures.
Key points
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Colonic strictures, both benign and malignant, are common.
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Dilation of benign colonic strictures, most notably caused by inflammatory bowel disease, is safe and effective, and can obviate surgery in some patients.
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Malignant colonic strictures rarely respond to dilation.
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Malignant colonic strictures are typically treated by stents and/or surgery.
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Colonic stents are safe and effective for malignant large bowel obstruction and can play a role in certain benign colonic strictures, notably anastomotic strictures.
Introduction
Colonic strictures, both benign and malignant, are commonly encountered in clinical practice by both gastroenterologists and surgeons. Benign strictures are most commonly treated by balloon dilation and less frequently with stents. The opposite is true for malignant strictures, whether they are intrinsic or extrinsic to the colon. This article reviews the endoscopic management of colonic strictures.
Introduction
Colonic strictures, both benign and malignant, are commonly encountered in clinical practice by both gastroenterologists and surgeons. Benign strictures are most commonly treated by balloon dilation and less frequently with stents. The opposite is true for malignant strictures, whether they are intrinsic or extrinsic to the colon. This article reviews the endoscopic management of colonic strictures.
Endoscopic balloon dilation of benign colonic strictures
Endoscopic dilation of colonic strictures is primarily used for benign indications: anastomotic strictures, strictures from inflammatory bowel disease (IBD) (usually Crohn’s disease), colopathy induced by nonsteroidal anti-inflammatory drugs, and, rarely, diverticular strictures that develop following acute diverticulitis. There is only a limited role for dilation of malignant strictures, as the duration of effect is typically short lived.
Dilation of strictures is typically performed by using through-the-scope (TTS) balloons. Passage dilators are largely reserved for very distal strictures and are uncommonly used in current practice. The technique for balloon dilation is relatively simple. The endoscope (usually a colonoscope) is advanced to the level of the colonic stricture. It is not mandatory to traverse the stricture with the endoscope. TTS balloons are available in over-the-wire and non–guide wire based formats, and both are equally effective. TTS balloons used in this context are typically esophageal, pyloric, or colonic balloons; there are no data to support the superiority of one type over another. If the stricture is tortuous, it is recommended that a guide wire be advanced across the stricture under fluoroscopic and endoscopic guidance. Fluoroscopy can confirm the presence of the wire in the proximal large bowel. An estimate of the required balloon size can be made and a balloon selected. Most TTS balloons are available in multiple size formats (ie, 12-, 13.5-, and 15-mm diameters when inflated with varying amounts of fluid). The TTS balloon can be advanced over the wire (if a wire was used) and across the stricture. The balloon can then be inflated with saline, contrast, or a mixture thereof. Contrast is only required if fluoroscopy is to be used.
The time required to keep the balloon inflated is not standardized. Individual preferences vary, and inflation times of 30, 60, and 120 seconds are all commonly used, with no data to suggest the superiority of one specific duration. Once the balloon is deflated the stricture can be evaluated for improvement in luminal diameter, the need for further dilation, and for any complications (most notably bleeding and/or perforation).
Almost all of the currently available data on balloon dilation of benign colonic strictures come from the IBD literature, wherein the procedure has been reported for several years. The technique is recognized as being relatively safe and an alternative to surgery (or at least a temporizing measure in patients who are not surgical candidates at the time of endoscopy). Most studies have reported on patients with small and large bowel strictures, and mix pure intestinal strictures with anastomotic strictures.
A representative study was published by Foster and colleagues in 2008. A variety of strictures were identified in the small and large bowel of 24 patients, most of whom had Crohn’s disease (22 of 24). Overall, 71 dilations were performed in 29 strictures. Of note, 46 dilations for 17 strictures were performed with a simultaneous injection of triamcinolone to increase the duration of effect. Mean follow-up was 32 months. The investigators reported results in 1 stomal, 12 anastomotic, and 16 de novo strictures. There were no complications in 22 of 24 patients; bleeding and perforation occurred in 1 patient and rupture of a paracolonic abscess developed in another with a sigmoid stricture. Two patients failed endoscopic therapy and ultimately required surgery.
Hoffman and colleagues reported their results in 25 patients with Crohn’s disease who underwent TTS dilations. Thirty-nine colonoscopies with 51 dilations were performed, and 52% became asymptomatic after a single dilation while 48% needed further dilations or surgery. Mild bleeding (that did not require transfusion) occurred in 3 out of 39 colonoscopies, and there was 1 perforation. The investigators found that significant negative prognostic factors were active smoking and ulcerated strictures ( P <.05 each).
One of the largest studies regarding endoscopic dilation for strictures in Crohn’s disease comes from Gustavsson and colleagues, who reported on a 22-year institutional history. Between 1987 and 2009, this group performed 776 endoscopic dilations for benign strictures (80% were for anastomotic strictures) in 178 patients (94 of whom were women) with Crohn’s disease. The median age of the patients was 45 years, with median disease duration of 16 years. Technical success was achieved in 689 of 776 patients (89%), and rates of patients undergoing surgery at 1, 3, and 5 years were 13%, 28%, and 36%, respectively. Complications occurred in 41 of 776 dilations (5.3%) and included bowel perforation (n = 11, 1.4%), bleeding requiring blood transfusion (n = 8, 1.0%), minor bleeding (n = 10, 1.3%), and abdominal pain or fever (n = 12, 1.5%). Ten patients required surgery to treat complications, usually perforation.
Overall, balloon dilation for benign colonic strictures is considered to be safe and effective, but generally requires repeated treatments.
Endoscopic self-expanding metal stents for the treatment of malignant colonic strictures
Malignant strictures are largely treated in current endoscopic practice through the use of self-expanding metal stents (SEMS). These devices, once only used in tertiary referral centers, are now in widespread use in both academic and general gastrointestinal practices. Stents are most commonly placed by gastroenterologists, but some surgeons and interventional radiologists also perform the procedure. SEMS are most commonly used to treat malignant large bowel obstructions.
Malignant colonic obstructions can occur as a result of primary colorectal cancer causing intrinsic obstruction, or extrinsic lesions that compress the colon. Most extrinsic lesions arise from primary pelvic malignancies such as bladder, ovarian, and uterine cancer, but can also arise from metastatic lesions to the pelvis. In general, patients with extrinsic malignant colonic obstruction usually have incurable disease and are not good candidates for surgeries beyond a decompressing colostomy. Dedicated stents for use in the large bowel are all uncovered metal mesh devices that embed in the stricture site. These devices are usually placed without intent of future endoscopic removal. Fully covered esophageal stents can be used in an off-label manner to treat colonic anastomotic strictures and diverticular strictures.
SEMS are typically used in 2 settings: preoperative (as a bridge to surgery) and palliative (in patients with primary colorectal cancers who are not candidates for surgery because of metastatic disease or overall debility).
SEMS are available as TTS and non-TTS stents. TTS stents are much more commonly used in North America, but non-TTS devices still play an important role. TTS stents can be used anywhere in the colon that can be reached by an endoscope, including the very proximal colon or across the ileocecal valve. Non-TTS stents are largely confined to use in the left colon, as they cannot be advanced more proximally because of their limited catheter length and the relatively high rigidity of these same deployment catheters.
Self-Expanding Metal Stents for Malignant Colonic Obstruction in the Preoperative Setting
Many patients with primary colon cancer will have obstruction as their presenting symptom. It must be stressed that patients who present with acute malignant colonic obstruction are almost always ill. Patients tend to be dehydrated, have electrolyte abnormalities, and a distended proximal colon (full of stool), and may have respiratory compromise owing to limited diaphragmatic excursion from a distended abdomen. These patients are generally poor surgical candidates in the acute setting, and surgeons may be reluctant to take such patients for emergency surgery if other options are available.
The management of patients with acute colonic obstruction arising from colon cancer includes both surgical and endoscopic approaches. Patients can undergo placement of a colonic SEMS or surgery. The surgical options are similar to what they were in years past: surgery with creation of a loop colostomy or loop ileostomy and subsequent resection (2- or 3-staged procedure), a primary resection with end colostomy (Hartmann procedure), or a primary tumor resection with creation of an internal anastomosis at the time of the primary surgery. This last option often requires on-table lavage and, though often discussed, is rarely performed given the complexity involved.
One should pay special attention to how many of the aforementioned surgical options include a temporary or permanent ostomy creation, which most patients would prefer to avoid. The use of a SEMS for acute colonic obstruction has several advantages for patients who ultimately undergo surgery. Placement of a colonic SEMS can serve as a bridge to surgery because it allows bowel decompression via the normal route, patient stabilization, correction of electrolyte abnormalities, hydration, and proper preoperative care. Placement of a SEMS before surgery allows time for a complete oncologic evaluation and cancer staging. Of importance, patients who undergo SEMS placement in the setting of an acute colonic obstruction can undergo standard bowel preparation via ingestion of an oral purgative. Once this is accomplished, most patients who proceed to surgery can undergo a 1-stage procedure whereby the primary tumor is removed and an internal colocolonic anastomosis is created, thus avoiding the need for an ostomy.
Many high-quality prospective studies have been performed to evaluate the technical and clinical success rates for SEMS placement in the preoperative setting for acute colonic obstruction. Technical success (defined as successful placement of 1 or more stents across the stricture) is common, occurring in 75% to 100% of patients, and clinical success (defined as successful bowel decompression and patient stabilization) is seen in 84% to 100% of patients.
The question of whether a patient with acute colonic obstruction should undergo surgery or SEMS placement is central to management, and has been evaluated in several prospective studies and high-quality meta-analyses with comparable overall results. A recent Cochrane meta-analysis of patients with acute malignant colon obstruction reviewed 5 randomized trials that included a total of 207 patients. This study compared outcomes between colonic stenting in 102 patients and emergency surgery in 105 patients. With regard to SEMS, technical success was achieved in 86% of patients. The perforation rate was 5.88% and the migration rate was 2.13%. There was no statistically significant difference in the overall complication rate or 30-day mortality rate between the patients who underwent stenting or surgery. The mean hospital stay was shorter in the patients who underwent SEMS placement than in those who underwent emergency surgery (11.5 vs 17.2 days). This study can be interpreted as arguing for SEMS placement over emergency surgery in patients who are candidates for endoscopic therapy.
A 2012 meta-analysis that included 2 randomized studies and 6 retrospective studies compared outcomes between SEMS placement as a bridge to surgery with emergency surgery in patients who presented with obstruction in the setting of colon cancer. Patients who underwent SEMS placement had overall lower mortality, fewer postoperative anastomotic leaks, and a lower rate of initial stoma creation in comparison with those undergoing emergency surgery.
In practice, the decision to place a SEMS or operate in a patient with acute malignant obstruction should be made by joint consultation between patients, gastroenterologists, and surgeons, with risks and benefits weighed carefully. Some patients are not candidates for endoscopy and are best treated via emergency surgery, whereas others are better treated by endoscopy with SEMS placement followed by surgery. The current environment of multidisciplinary care should foster active discussion as to what is the best option for individual patients.
Self-Expanding Metal Stents for Malignant Obstruction in Patients Who Are Not Surgical Candidates
The presence of widespread or disseminated peritoneal or solid organ metastatic disease, malignant ascites, or significant comorbidity may preclude surgery in some patients with malignant colonic obstruction. Placement of a SEMS in these patients is performed for palliation of symptoms of obstruction and improvement in their quality of life. These patients usually have short survival, and stents are often placed before a referral for hospice care to ensure bowel patency.
As previously mentioned, some patients with malignancies of nongastrointestinal origin (ie, bladder, ovarian, and uterine cancer) can develop colonic obstruction attributable to extrinsic compression from primary tumors, malignant adenopathy, or metastases. Patients with extrinsic malignant colonic obstruction will not have a visible mass in the colonic lumen in most cases, but rather a smooth-walled area of obstruction. Extrinsic colonic obstructions are more likely to occur in the left colon and are most commonly seen in the distal large bowel.
A prospective multicenter study of SEMS placement for malignant colonic obstruction in 44 nonsurgical patients showed a technical success rate of 95% with a clinical success rate of 81%. There were no perforations or SEMS-related mortality. Another retrospective study of 168 palliative colon SEMS placements reported a technical success of 96%, with 99% of these patients reported to have immediate clinical success with regard to bowel decompression.
A multicenter retrospective study involving 5 tertiary care centers and 201 patients evaluated the use of palliative SEMS placement for colorectal obstruction. Technical success was seen in 91.5% of patients, and clinical success was achieved in 89.7%. Fully three-quarters of enrolled patients were able to avoid undergoing creation of a colostomy. Major complications occurred in 11.9% of patients: 11 migrations, 12 perforations, and 1 reobstruction. This study noted an association between the humanized monoclonal antibody/angiogenesis inhibitor bevacizumab and perforation, the risk of which was increased 19.6-fold. Other studies have noted this risk with this agent.
Most of the published literature comparing surgery with SEMS placement is based in the preoperative setting. Only limited data exist to compare the use of SEMS with surgery in the palliative setting.
A retrospective cohort study of 144 patients with inoperable and/or metastatic colon cancer included 73 patients who underwent surgery and 71 who underwent SEMS placement. Patients who had SEMS placed developed early complications (15.5% vs 32.9%, respectively). Overall, major complication rates were not significantly different. Fully 39.7% of patients in the surgical group had an ostomy created, again emphasizing a potential benefit of stenting when feasible.
A retrospective study of 55 patients (29 SEMS, 26 surgery) who were treated in a palliative manner for left-sided large bowel obstruction was published in 2008. Hospital stay was significantly shorter for patients who underwent SEMS placement (4 vs 13.5 days, P <.0001). Four of the patients in the SEMS group eventually required surgery. Creation of a stoma was needed in 12 of 26 patients who underwent surgery and 4 of 29 patients who had a SEMS placed. Survival among patients in both groups was similar.
The only published randomized trial of SEMS placement versus surgery in the palliative setting was stopped prematurely because of an unusually high number of perforations in the stent group. There were 10 patients in the surgical treatment group and 11 in the SEMS group, with 6 perforations occurring in the SEMS group. It should be noted that this is an exceptionally high perforation rate that is inconsistent with the existing colonic stent literature.
As mentioned previously in the context of stent placement in the preoperative setting, the ultimate decision on SEMS or surgery in patients with incurable disease should be made through a multidisciplinary and individualized approach.
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