Endoscopic stenting-Where are we now and where can we go?

Best Practices in Esophageal, Gastroduodenal, and Colonic Stenting

Endoscopic stenting is an area of endoscopy that has witnessed noteworthy advancements over the last decade, resulting in evolving clinical practices among gastroenterologists around the world. Indications for endoscopic stenting have progressively expanded, becoming a frequent part of the management algorithm for various benign and malignant conditions of the gastrointestinal tract, from esophagus to rectum. In addition to expanded indications, continuous technological enhancements and development of novel endoscopic stents have resulted in an increased success of these approaches and, in some cases, allowed new applications. This review aimed to summarize best practices in esophageal, gastroduodenal, and colonic stenting.

Recent Updates in Gastrointestinal Stent Placement from the Esophagus to the Colon: A Radiological Perspective

Fluoroscopic-guided stent placement has become an advantageous treatment option for diverse gastrointestinal disorders. In addition to palliative stent placement in patients with inoperable cancers, stenting has gradually expanded to other conditions, including as a bridge to surgery, as well as in patients' benign lesions and anastomotic strictures or leaks. This narrative review describes the indications, efficacy and safety of stent placement from the esophagus to the colon, including current recommendations, recent updates, and novel stents.

Endoscopic Management of Malignant Colonic Obstruction

Advanced colorectal cancer can cause acute colonic obstruction, which is a life-threatening condition that requires emergency bowel decompression. Malignant colonic obstruction has traditionally been treated using emergency surgery, including primary resection or stoma formation. However, relatively high rates of complications, such as anastomosis site leakage, have been considered as major concerns for emergency surgery. Endoscopic management of malignant colonic obstruction using a self-expandable metal stent (SEMS) was introduced 20 years ago and it has been used as a first-line palliative treatment. However, endoscopic treatment of malignant colonic obstruction using SEMSs as a bridge to surgery remains controversial owing to short-term complications and longterm oncological outcomes. In this review, the current status of and recommendations for endoscopic management using SEMSs for malignant colonic obstruction will be discussed.

Stents for colorectal obstruction: Past, present, and future

Since the development of uncovered self-expanding metal stents (SEMS) in the 1990s, endoscopic stents have evolved dramatically. Application of new materials and new designs has expanded the indications for enteral SEMS. At present, enteral stents are considered the first-line modality for palliative care, and numerous types of enteral stents are under development for extended clinical usage, beyond a merely palliative purpose. Herein, we will discuss the current status and the future development of lower enteral stents.

Advances in Flexible Endoscopy

Flexible endoscopy, a minimally invasive diagnostic and potentially therapeutic tool, has become more available over the past decades. A fiberscope is used to visualize the lumen of the area of interest and collect tissue or fluid samples for evaluation. Samples can be submitted for histopathology, cytologic analysis, and bacterial culture. Flexible endoscopy is being investigated. This article provides a brief review of equipment and basic flexible endoscopy followed by an overview of advanced flexible endoscopic procedures that focuses on the gastrointestinal tract. The procedures included here may become more readily available and improve diagnosis and treatment.

Fabrication and evaluation of polymer-based esophageal stents for benign esophagus stricture insertion

In benign esophageal strictures, polymeric lines and membranes were chosen to knit an esophageal stent for relieving esophageal lesions caused by esophageal stenosis and obstruction.

Recent Advances in Gastrointestinal Stent Development

Endoscopic stenting is increasingly being used in the management of gastrointestinal luminal obstruction, and has become the current treatment of choice for the palliation of blockage caused by malignant or benign growths. A variety of stents have been developed to enhance the efficacy of the procedure, and improvements are ongoing. In this article, we review the history of, and recent advances in, gastrointestinal stenting. We describe the rationale behind the design as well as the resulting outcome for each stent type.

Recent Advances in Gastrointestinal Stent Development

Endoscopic stenting is increasingly being used in the management of gastrointestinal luminal obstruction, and has become the current treatment of choice for the palliation of blockage caused by malignant or benign growths. A variety of stents have been developed to enhance the efficacy of the procedure, and improvements are ongoing. In this article, we review the history of, and recent advances in, gastrointestinal stenting. We describe the rationale behind the design as well as the resulting outcome for each stent type.

Endoscopic stenting for recurrence-related colorectal anastomotic site obstruction: Preliminary experience

AIM: To evaluate the efficacy of stents in treating patients with anastomotic site obstructions due to cancer recurrence following colorectal surgery.

METHODS: The medical records of patients who underwent endoscopic self-expanding metal stents (SEMS) insertion for colorectal obstructions between February 2004 and January 2014 were retrospectively reviewed. During the study period, a total of 218 patients underwent endoscopic stenting for colorectal obstructions. We identified and examined the patients who underwent endoscopic stenting for obstructions caused by cancer recurrence at the anastomotic site following colorectal surgeries for primary colorectal cancer.

RESULTS: Five consecutive patients [mean age, 56.4 years (range: 39-82 years); 4 women, 1 man] underwent endoscopic stenting for obstructions caused by cancer recurrence at the anastomotic site following colorectal surgeries for primary colorectal cancer. Technical and clinical success was achieved in all 5 patients, without any early complications. During follow-up, 3 patients did not need further intervention, prior to their death, after the first stent insertion; thus, the overall success rate was 3/5 (60%). Perforations occurred in 2 patients who required a second SEMS insertion due to re-obstruction; none of the patients experienced stent migration.

CONCLUSION: SEMS placement is a promising treatment option for patients who develop obstructions of their colonic anastomosis sites due to cancer recurrence.

A novel anchoring system for colonic stents: a pilot in vivo study in a porcine model

BACKGROUND

Colorectal stents have a proven role in colorectal cancer as palliative care or a bridge to surgery. However, their efficacy and anchoring to the tissue varies according to stent design with stent migration rates up to 50 %. We present preliminary in vivo results of a new end-luminal anchoring system for stent fixation to the rectal canal. The aim was to assess the efficacy and safety of the stent using the anchoring system while subjecting the device to daily abdominal pressures related to daily activities in a porcine animal model.

METHODS

Ex vivo anatomical and physical studies were performed to improve the system's structure and safety. Four female pigs were followed for the acute and chronic (16 weeks) period. Two animals were euthanized and underwent en-bloc pelvic visceral excision and histopathological examination. Device fixation time, animal behavior, device patency, anoscopic examination and histopathological features were assessed.

RESULTS

Mean anchoring time was 13.83 weeks (standard error ± 1.38 weeks). One of the animals experienced early device expulsion with no complications. No obstruction was noted in any of the animals. Macroscopic examination revealed mild focal submucosal scarring in one animal and a normal examination in the other. Hematoxylin and eosin staining revealed mucosal ulceration and mixed inflammatory cell infiltrate, with no signs of granulomata, foreign body giant cell reaction or microabscess formation.

CONCLUSIONS

A novel fixation device designed for long-term intrarectal implantation was well tolerated and maintained anal canal patency without migration. Larger studies are needed before its implementation in humans.

Imaging evaluation of dogs and cats with Dysphagia

The current literature is reviewed in this paper regarding the application of diagnostic imaging in the evaluation of swallowing disorders of the dog. The applications of radiography, contrast radiography, and contrast videofluoroscopy are discussed with pertinent case examples provided for emphasis. The indications for image-guided interventions are also described.

Use of bio-degradable stents for the treatment of refractory benign gastrointestinal stenoses

Bio-degradable stents are be made of different synthetic polymers (like polylactide or polyglycolide) or their co-polymers (polydioxanone). They can be used for treating benign stenoses of the small and large intestine, particularly in Crohn's disease. Endoscopic introduction of bio-degradable stents into small and large intestinal stenoses is feasible and relatively simple. Initial results are encouraging and the complication rate is low. However, there are still some difficulties that need to be overcome. The rate of early stent migration is still rather high (up to one third of patients). This might be solved by changes in the shape or rigidity of the stents as well as by further improvement in the design. Proof of long-term efficacy and safety requires further studies.

Modulating malignant epithelial tumor cell adhesion, migration and mechanics with nanorod surfaces

The failure of tumor stents used for palliative therapy is due in part to the adhesion of tumor cells to the stent surface. It is therefore desirable to develop approaches to weaken the adhesion of malignant tumor cells to surfaces. We have previously developed SiO₂ coated nanorods that resist the adhesion of normal endothelial cells and fibroblasts. The adhesion mechanisms in malignant tumor cells are significantly altered from normal cells; therefore, it is unclear if nanorods can similarly resist tumor cell adhesion. In this study, we show that the morphology of tumor epithelial cells cultured on nanorods is rounded compared to flat surfaces and associated with decreased cellular stiffness and non-muscle myosin II phosphorylation. Tumor cell viability and proliferation was unchanged on nanorods. Adherent cell numbers were significantly decreased while single tumor cell motility was increased on nanorods compared to flat surfaces. Together, these results suggest that nanorods can be used to weaken malignant tumor cell adhesion, and therefore potentially improve tumor stent performance.

Endoscope-assisted brachytherapy for pancreatic cancer: From tumor killing to pain relief and drainage

Locally advanced or metastatic pancreatic cancer has been a long-term challenge to clinicians, due to the poor overall survival rate compared with that of other gastrointestinal malignancies. Recently, with the emerging applications of therapeutic endoscopic ultrasonography (EUS), EUS- guided fine needle injection with antitumor agents is considered a promising modality. In this review, we summarize recently published data on the efficacy of endoscope guided interventional procedures with radioactive seeds. Firstly, EUS-guided iodine-125 seed implantation was reported to have a short-term efficacy on pancreatic cancer, with a three-month partial remission rate of 13.6% to 27%. Thereafter, feasibility of celiac ganglion radiation was tested in animal models to achieve pain relief. Recently, a seed-based stent has been introduced in the endoscopic retrograde cholangio-pancreatography (ERCP) drainage of biliary obstruction caused by pancreatic cancer, with a response rate of 72.7%. In addition, we discuss the potential of radioactive seed-based, endoscope-assisted interventional treatment of patients with locally advanced pancreatic cancer. Further studies should focus on the precise amount and distribution of seeds with the aim to improve the survival rate as well as the quality of life.

Malignant gastric outlet obstructions: treatment with self-expandable metallic stents

Unresectable malignant gastric outlet obstruction (GOO) severely affects the quality of life, with complications that include nausea, vomiting, aspiration, pain, and malnutrition. Although palliative surgical procedures have been traditionally performed, they are associated with high morbidity and mortality rates. Placing self-expandable metallic stents is associated with higher clinical success rates, lower morbidity, shorter time from the procedure to starting oral intake, lower incidence of delayed gastric emptying, and a shorter hospital stay than palliative surgery. Fluoroscopic or endoscopic placement of either bare or covered self-expandable metallic stents is a safe, nonsurgical, palliative treatment option for unresectable malignant GOOs, with a high clinical success rate and a low rate of serious complications. Stent obstruction and migration are the most common complications, but most can be managed by interventional treatments. Although there have been substantial developments in stent design over the past decade, large prospective, randomized studies are required to determine the ideal stent for malignant GOOs.

Stenting of the upper gastrointestinal tract: current status

Minimally invasive image-guided insertion of self-expanding metal stents in the upper gastrointestinal tract is the current treatment of choice for palliation of malignant esophageal or gastroduodenal outlet obstructions. A concise review is presented of contemporary stenting practice of the upper gastrointestinal tract, and the procedures in terms of appropriate patient evaluation, indications, and contraindications for treatment are analyzed, along with available stent designs, procedural steps, clinical outcomes, inadvertent complications, and future technology. Latest developments include biodegradable polymeric stents for benign disease and radioactive or drug-eluting stents for malignant obstructions.

Endoscopic treatment of colonic obstruction

PURPOSE OF REVIEW

Over the past 15 years, great strides have been made in the nonsurgical management of malignant large bowel obstruction. Progress continues, particularly in the area of self-expanding metal stents. The purpose of this review is to assess the available endoscopic techniques for colonic decompression and document the inexorable trend toward supremacy of the self-expanding metal stent in this arena.

RECENT FINDINGS

Stents are being designed with the structure and function of the colon in mind allowing better and longer-lasting palliation. Improvement in the design of the colonic decompression tube allows a low-tech approach to the palliation of colonic obstruction. Argon plasma coagulation is helpful in restoring continuity of the obstructed colonic lumen in certain circumstances.

SUMMARY

As a consequence of technological innovation and growing expertise in the community, gastroenterology is becoming the go to specialty in the early management and palliation of malignant bowel obstruction.

Advances in research of esophageal stents

Esophageal stents were used initially in the palliative treatment of esophageal carcinoma to improve the life quality of the patients in the advanced stage. Along with the appearance of many new kinds of esophageal stents, esophageal stents have been used in the management of the benign esophageal strictures, and clinical effectiveness has been made. This article reviews the application of the esophageal stents in the benign and malignant esophageal strictures.

Application progress of stent placement in esophageal malignant and benign stenosis

Stent placement is widely used for palliation of dysphagia caused by advanced esophageal carcinoma. As the development of technology, many new stents are being used for clinical therapy. Some stents are added with anti-reflux valve or retrievable device, some are loaded with ¹²⁵I; the biodegradable stent are even invented. Improvement of sents can decrease many complications while elevate survival rates. Several nonsurgical palliative modalities including endoluminal laser therapy, photodynamic therapy, electrocoagulation and brachytherapy are available to recanalize malignant stenosis, but the fastest palliative method is stent placement. Reports about treating benign esophageal stricture with stents are increasing, and temporary and biodegradable stents have a better effect.