Endoscopic Procedures for Gastrointestinal Lesions

Introduction to Endoscopic Techniques

Endoscopic submucosal dissection (ESD) is an advanced endoscopic technique that involves resecting the overlying mucosa along with the lesion itself by dissecting through the submucosal layer using electrocautery knives after submucosal injection, as recommended by the American Gastroenterological Association 1
Endoscopic mucosal resection (EMR) is a technique used for removing colon polyps, with underwater EMR being a preferred alternative when a polyp cannot be raised with submucosal injection, maintaining safety and efficacy without the need for submucosal injection, as supported by the American Gastroenterological Association 2

ESD is primarily indicated for large lesions (>20 mm) where en bloc resection using standard EMR is difficult, lesions suspected to have superficial submucosal invasion, mucosal lesions with fibrosis, local residual early carcinoma after endoscopic resection, and non-polypoid colorectal dysplasia in inflammatory bowel disease patients, according to the American College of Gastroenterology 2
Underwater EMR is specifically indicated for polyps with severe submucosal fibrosis or suspected submucosal invasion, and has a relatively short learning curve for endoscopists experienced in conventional EMR, but requires advanced expertise, as recommended by the American Gastroenterological Association 2
ESD should be selectively used for specific polyps that cannot be adequately removed by conventional polypectomy or EMR, particularly when en bloc resection is necessary for histological assessment of suspected malignancy 2

Carefully evaluate the lesion's characteristics (size, morphology, location) and determine if ESD is appropriate based on suspected depth of invasion, with a 3-4 mm margin of normal surrounding mucosa marked around the lesion 2
Create a complete circumferential mucosal incision around the marked borders to isolate the lesion with surrounding normal mucosa, using specialized ESD knives for precise cutting 2
Dissect through the expanded submucosal layer with an ESD knife, maintaining traction and counter-traction for optimal visualization, until the lesion is completely excavated in one piece 1
Water immersion in underwater EMR causes the mucosa and submucosa to involute as folds while the muscularis propria remains circular, allowing for effective resection, with the technique involving immersing the colon segment with the lesion in water, marking polyp borders using APC or snare tip coagulation, and performing hot snare resection typically using Drycut, effect 5, 60W 2
Submucosal injection solution with contrast agent and low concentration adrenaline is recommended, with sodium hyaluronate or colloidal solutions preferred as they provide longer-lasting lift than normal saline 3

Inspect the resection bed for complete removal of the lesion, potential perforations, and bleeding vessels requiring hemostasis, and consider closure methods when needed (suturing or over-the-scope clips) 1
Consider prophylactic closure of resection defects ≥20mm in the right colon, and ensure availability of full-thickness closure methods (suturing, clips) 1
Check resection site 2-6 months after piecemeal endoscopic resection, and positively identify, photograph, and assess scar with image enhancement techniques, with patients provided with written information about post-procedure complications and recommended actions and an emergency contact number 3

ESD requires extensive training and experience due to its technical complexity, and endoscopists should develop skills progressively from simpler to more complex cases, master submucosal injection and dissection techniques, and be proficient in managing complications, as recommended by the American Society for Gastrointestinal Endoscopy 2
Underwater EMR has a relatively short learning curve for endoscopists experienced in conventional EMR, but requires advanced expertise, as recommended by the American Gastroenterological Association 2

Perforation is the main early adverse event, with ESD having higher perforation rates than EMR, and perforation rates should be monitored as a key performance indicator, with aspirational standards for EMR perforation rate <0.5%, EMR post-procedure bleeding rate <5%, and recurrent/residual polyp at 12 months <5% 3, 4
Underwater EMR has a 2-5% risk of bleeding and rare but reported perforation, particularly in retroflexion, with recurrence rates of 13.6% at median 6 months follow-up, and the right colon is associated with higher complication rates 2
Known or suspected intestinal perforation is an absolute contraindication, and clinically evident intestinal obstruction, neutropenic enterocolitis, hemodynamic instability requiring vasopressors, and severe sepsis with organ failure are also contraindications 5
Caecal location, polyp size ≥40mm, and endoscopist inexperience are also risk factors for complications, and surgical therapy should be considered when malignancy is suspected or concerns about incomplete endoscopic resection exist 3