Prevention of late complications with coverage agents in endoscopic resection of colorectal lesions: Current landscape in gastrointestinal endoscopy

Advances in Hydrogel Adhesives for Gastrointestinal Wound Closure and Repair

Millions of individuals undergo gastrointestinal (GI) tract surgeries each year with common postoperative complications including bleeding, perforation, anastomotic leakage, and infection. Today, techniques such as suturing and stapling seal internal wounds, and electrocoagulation stops bleeding. These methods induce secondary damage to the tissue and can be technically difficult to perform depending on the wound site location. To overcome these challenges and to further advance wound closure, hydrogel adhesives are being investigated to specifically target GI tract wounds because of their atraumatic nature, fluid-tight sealing capability, favorable wound healing properties, and facile application. However, challenges remain that limit their use, such as weak underwater adhesive strength, slow gelation, and/or acidic degradation. In this review, we summarize recent advances in hydrogel adhesives to treat various GI tract wounds, with a focus on novel material designs and compositions to combat the environment-specific challenges of GI injury. We conclude with a discussion of potential opportunities from both research and clinical perspectives.

Preventing Postendoscopic Mucosal Resection Bleeding of Large Nonpedunculated Colorectal Lesions

The most common major adverse event of endoscopic mucosal resection (EMR) is clinically significant post-EMR bleeding (CSPEB), with an incidence of 6%-7% in large lesions. Repeat colonoscopy, blood transfusions, or other interventions are often needed. The associated direct costs are much higher than those of an uncomplicated EMR. In this review, we discuss the aspects related to CSPEB of large nonpedunculated polyps, such as risk factors, predictive models, and prophylactic measures, and we highlight evidence for preventive treatment options and explore new methods for bleeding prophylaxis. We also provide recommendations for steps that can be taken before, during, and after EMR to minimize bleeding risk. Finally, this review proposes future directions to reduce CSPEB incidence.

Endoscopic management of difficult laterally spreading tumors in colorectum

Due to the advent of the screening programs for colorectal cancer and the era of quality assurance colonoscopy the number the polyps that can be considered difficult, including large (> 20 mm) laterally spreading tumors (LSTs), has increased in the last decade. All LSTs should be assessed carefully, looking for suspicious areas of submucosal invasion (SMI), such as nodules or depressed areas, describing the morphology according to the Paris classification, the pit pattern, and vascular pattern. The simplest, most appropriate and safest endoscopic treatment with curative intent should be selected. For LST-granular homogeneous type, piecemeal endoscopic mucosal resection should be the first option due to its biological low risk of SMI. LST-nongranular pseudodepressed type has an increased risk of SMI, and en bloc resection should be mandatory. Underwater endoscopic mucosal resection is useful in situations where submucosal injection alters the operative field, e.g., for the resection of scar lesions, with no lifting, adjacent tattoo, incomplete resection attempts, lesions into a colonic diverticulum, in ileocecal valve and lesions with intra-appendicular involvement. Endoscopic full thickness resection is very useful for the treatment of difficult to resect lesions of less than 20 up to 25 mm. Among the indications, we highlight the treatment of polyps with suspected malignancy because the acquired tissue allows an exact histologic risk stratification to assign patients individually to the best treatment and avoid surgery for low-risk lesions. Endoscopic submucosal dissection is the only endoscopic procedure that allows completes en bloc resection regardless of the size of the lesion. It should therefore be indicated in the treatment of lesions with risk of SMI.

Prevention of late complications of endoscopic resection of colorectal lesions with a coverage agent: Current status of gastrointestinal endoscopy

Endoscopic ectomy of large nonpedunculated colorectal lesions (≥ 20 mm) might cause significant adverse incidents, such as delayed perforation and delayed bleeding, despite the closure of mucosal lesions with clips. The conventional utilization of prophylactic clipping has not decreased the risk of postprocedural delayed adverse events, and additional outcomes and cost-effectiveness research is needed for patients with proximal lesions ≥ 20 mm, in whom prophylactic clipping might be useful. Coverage of the wound after endoscopic excision offers shield protection against delayed concomitant diseases.

Prior endoscopic resection does not affect the outcome of secondary surgery for T1 colorectal cancer, a systematic review and meta-analysis

BACKGROUND

It remains unclear the effect of prior endoscopic resection (ER) on the secondary surgery (SS) for T1 colorectal cancer (CRC). This study aimed to compare the short- and long-term outcomes between primary surgery (PS) and ER followed by SS for T1 CRC.

METHODS

A systematic literature search was performed in PubMed and Ovid for studies comparing PS with ER followed by SS for T1 colorectal cancer. The last search was performed on 18 May 2021. The primary outcomes were surgical parameters and the secondary outcomes were survival indicators. The meta-analysis was performed with Review Manager Software (version 5.3).

RESULTS

A total of fifteen studies published between 2013 and 2021 with 4349 patients were included in this meta-analysis finally. No significant difference was observed between the two groups for operative time (P = 0.75, WMD = 3.16, 95%CI [-15.88, 22.19], I² = 64%), blood loss (P = 0.86, WMD = 12.33, 95%CI [-122.99, 147.65], I² = 95%), and postoperative complications (P = 0.59, OR = 0.93, 95%CI [0.71, 1.22], I² = 0%). Besides, the two groups showed comparable survival outcomes, including overall recurrence rate (P = 0.15, OR = 0.78, 95%CI [0.56, 1.09], I² = 23%) and 5-year overall survival (P = 0.76, OR = 0.86, 95%CI [0.33, 2.25], I² = 0%). In the subgroup analysis for studies with propensity matching score or lesions located in the rectum, the results were not changed.

CONCLUSION

ER followed by SS is feasible for T1 CRC with high-risk factors. The prior ER would not bring additional adverse effects to the SS. More advanced tools should be developed to improve the diagnostic accuracy for the high-risk factors before treatment for T1 CRC.

Temporary In Situ Hydrogel Dressings for Colon Polypectomies

Currently, no dressings are utilized after removal of polyps during a colonoscopy rendering these tissue sites susceptible to bleeding, sepsis, and perfusion. We report the design specifications, synthesis, and ex vivo evaluation of in situ polymerized hydrogels as colon wound dressings post polypectomy. The hydrogels exhibited varied properties to include moduli between 100 and 16 000 Pa, dissolution times between 4 h to 7 days or longer, swelling up to 200%, and adhesion to colon tissue from 0.1 to 0.4 N/cm². The hydrogels displayed minimal cytotoxicity, prevented the migration/spread of bacteria, and exhibited rapid gelation, a requirement for application to the lumen of the colon via an endoscope. This work highlights the structure-property relationship of hydrogels prepared from N-hydroxysuccinimide functionalized PEG cross-linkers and hyperbranched polyethylenimines or 4-arm PEG-NH₂ star polymers, and their potential as colon wound dressings.