Endoscopic mucosal resection (EMR) is preferred to standard polypectomy for the resection of non-polypoid lesions because these lesions can be technically difficult to capture with a snare; furthermore, without submucosal injection the underlying muscularis propria may be excessively coagulated or even inadvertently resected. Because the resection plane of EMR is in the middle or deeper part of the submucosa, EMR allows the precise depth of the lesion to be evaluated. Although the majority of non-polypoid lesions are adenomatous, non-polypoid colorectal neoplasm has a high association with advanced pathology, irrespective of size. Using EMR, a complete pathologic specimen is obtained, the risk of lymph node metastasis can be accurately assessed based on the depth of invasion, and patients can be suitably managed. Used according to its indications, EMR provides curative resection, and obviates the higher morbidity, mortality, and cost associated with surgical treatment.
Endoscopic mucosal resection (EMR), rather than standard polypectomy, is the preferred resection method of non-polypoid lesions because these lesions can be technically difficult to capture with a snare; furthermore, without submucosal injection the underlying muscularis propria may be excessively coagulated or even inadvertently resected. In addition, because the resection plane of EMR is in the middle or deeper part of the submucosa, EMR allows the precise depth of the lesion to be evaluated. Although the majority of non-polypoid lesions are adenomatous, non-polypoid colorectal neoplasm (NP-CRN) has a high association with advanced pathology, irrespective of size. Thus, using EMR, a complete pathologic specimen is obtained, the risk of lymph node metastasis can be accurately assessed based on the depth of invasion, and patients can be suitably managed. Used according to its indications, EMR provides curative resection, and obviates the higher morbidity, mortality, and cost associated with surgical treatment.
Indications for colorectal EMR
EMR is indicated for the treatment of non-polypoid colorectal lesions when removal at the submucosal level is required to obtain accurate pathology, and ascertain endoscopic cure. For lesions suspected to have high-grade dysplasia or superficial submucosal invasive cancer, EMR is an appropriate strategy and an attempt should be made to remove the lesion en bloc. On the other hand, if piecemeal EMR is technically necessary to remove such lesions with advanced pathology, then the endoscopist should minimize the number of pieces and consider submucosal dissection technique or surgical management. EMR is not indicated when the endoscopist does not believe that he or she can remove the entire lesion in one session ( Fig. 1 ). EMR can be safe and efficacious but requires knowledge, expertise, time, and a team; without them, EMR can in fact be dangerous ( Fig. 2 ). Thus, EMR is not indicated when the endoscopist does not have the expertise to perform it or is not willing to follow the principles of safe practice of EMR. The indications of colonoscopic mucosal resection are shown in Box 1 .
- 1.
Without advanced/massive submucosal invasive pathology
- 2.
Any size:
Lesion requiring resection at the submucosa to ensure cure
Suspicious high-grade dysplasia/superficial spreading melanoma that can be removed en bloc using the technique
- 3.
Pathology:
United States: high-grade dysplasia or intramucosal adenocarcinoma
Japan: well-differentiated adenocarcinoma without lymphovascular involvement up to 1000 μm from the muscularis mucosa
Estimation of the depth of invasion
Colonoscopic assessment of the most likely pathology and estimation of the depth of invasion is important in planning an EMR of the colon and rectum. Neoplasm limited to the mucosa is the best target lesion. Lesions with minimal or moderate likelihood to contain submucosal invasion can be treated with EMR for diagnostic and therapeutic purposes, provided that the endoscopist believes that the lesion can be safely removed in its entirety, and that the potential benefits of endoscopic treatment outweigh the risks. Patients whose lesions are strongly suggestive of invasion should be referred to surgery after a confirmatory biopsy, as endoscopic resection will expose them to unnecessary risks. For example, colonoscopic resection of neoplasms with massive submucosal invasive cancer is generally difficult to accomplish and has a high risk of bleeding, perforation, recurrence, and metastasis. It is appropriate, after assessment of the lesion, to reschedule the patient for a dedicated resection procedure. This rescheduling allows appropriate discussion of the risks and benefits with the patient, and ensures adequate planning for the necessary equipment, time, and personnel for the procedure.
Estimation of the depth of invasion
Colonoscopic assessment of the most likely pathology and estimation of the depth of invasion is important in planning an EMR of the colon and rectum. Neoplasm limited to the mucosa is the best target lesion. Lesions with minimal or moderate likelihood to contain submucosal invasion can be treated with EMR for diagnostic and therapeutic purposes, provided that the endoscopist believes that the lesion can be safely removed in its entirety, and that the potential benefits of endoscopic treatment outweigh the risks. Patients whose lesions are strongly suggestive of invasion should be referred to surgery after a confirmatory biopsy, as endoscopic resection will expose them to unnecessary risks. For example, colonoscopic resection of neoplasms with massive submucosal invasive cancer is generally difficult to accomplish and has a high risk of bleeding, perforation, recurrence, and metastasis. It is appropriate, after assessment of the lesion, to reschedule the patient for a dedicated resection procedure. This rescheduling allows appropriate discussion of the risks and benefits with the patient, and ensures adequate planning for the necessary equipment, time, and personnel for the procedure.
Management of anticoagulant and antiplatelet medications
In preparation for a standard polypectomy colonoscopy procedure, the American Society of Gastrointestinal Endoscopy (ASGE) guidelines recommend no interruption of antiplatelet medications, such as aspirin or nonsteroidal anti-inflammatory drugs, though they do recommend the discontinuation of platelet aggregation inhibitors, such as ticlopidine and clopidogrel, for 7 to 10 days. The ASGE advises that patients on anticoagulation at relatively low risk of thromboembolic complications can discontinue warfarin 5 days before the procedure. The international normalized ratio (INR) should be 1.4 or less, although we (T.K. and R.S., the authors of this article) prefer a normal INR before an EMR. High-risk patients, such as those with atrial fibrillation and concomitant valvular disease, should receive either standard intravenous heparin until approximately 6 hours before the procedure or low-molecular-weight heparin until approximately 24 hours before the procedure. Of note, in patients who are on short-term antiplatelet or anticoagulation therapy, we defer the resection procedure until they no longer require such agents, if possible.
In the absence of robust data or specific guidelines for the postresection management of large or complex colon lesions, we typically individualize care for the reinstitution of antiplatelet or anticoagulation therapy, considering both the patient’s thromboembolic risk and postresection bleeding potential. After large polypectomy or mucosal resection, we typically use endoscopic clips to close the mucosal defects. We generally instruct patients who have significant risk factors to continue to take aspirin, 81 mg daily. In the rare patient considered to be at high risk for postresection bleeding, we recommend that the patient refrain from taking other nonsteroidal anti-inflammatory drugs, and platelet inhibitors for an additional 7 to 14 days. Warfarin is resumed 10 days after the procedure. In patients at high risk for coagulation, we use intravenous heparin: we resume the heparin infusion 2 to 6 hours after the procedure, until the INR is therapeutic.
In our published experience of colonoscopic resection of small (<1 cm) colorectal lesions in anticoagulated patients, we withheld warfarin for approximately 36 hours only, to avoid supratherapeutic anticoagulation due to dietary restriction and bowel purge. In this retrospective series, using a variety of polypectomy techniques, including cold snare, standard snare with cautery, and inject-and-cut mucosectomy, followed by endoscopic clipping, the risk of major delayed bleeding in the resection of 5.1 ± 2.2 mm lesion was 0.8% (95% confidence interval: 0.1%–4.5%).
Management of high-risk patients for bacterial endocarditis
We follow the ASGE guidelines. In general, antibiotic prophylaxis is not recommended for EMR. Note, however, that there are limited data for EMR of large colorectal lesion, and exception to the recommendation may be necessary for select patients.
EMR Procedure at Palo Alto
We use a standardized endoscopic resection approach that includes lesion assessment, inject-and-cut EMR (for the colon and rectum), and EMR Ligation (for the rectum only) techniques, immediate reassessment and treatment of residual, histologic preparation and assessment, and surveillance, to safely and efficaciously remove non-polypoid lesions. Note that we do not use other EMR techniques such as the EMR Cap or the Double Channel EMR because of the risks of perforations.
Equipment and Tools
We use therapeutic endoscopes equipped with an auxiliary water jet. We typically use an adult high-definition colonoscope, with the accessory channel at the 5-o’clock position, for right colon lesions or alternatively, a therapeutic gastroscope, with the accessory channel at 7-o’clock, for left-sided lesions. The translucent distal attachment device is often a helpful tool to augment stable visualization and resection, particularly of rectal lesions ( Box 2 ).
- 1.
Colonoscope with auxiliary water jet
- 2.
Diagnostic:
Adult colonoscope with high-resolution image (minimum)
Pediatric colonoscope with high-resolution image
- 3.
Therapeutic: adult colonoscope (right sided) or therapeutic upper (left sided)
- 4.
Carbon dioxide regulator
- 5.
Diluted simethicone in 60-mL syringe
- 6.
Indigo carmine in 60-mL syringe
- 7.
Injection needle (diluted indigo carmine in preloaded 10 mL, Spot tattoo)
- 8.
Standard generator (Blend current 35 to 40 W)
- 9.
Stiff snare: 2 types (large and small)
- 10.
Biopsy forceps (cold and hot of standard cup size)
- 11.
Endoscopic clips (naked Resolution, Endoclip). Endoscopic loop. EVL 6 bander
- 12.
Argon plasma coagulator with straight catheter
- 13.
Roth net and multichannel suction trap
Related posts:
Relationship of Non-Polypoid Colorectal Neoplasms to Quality of Colonoscopy
Non-Polypoid Colorectal Neoplasms are Relatively Common Worldwide
Image-Enhanced Endoscopy Is Critical in the Detection, Diagnosis, and Treatment of Non-Polypoid Colorectal Neoplasms
Dynamic Submucosal Injection Technique
Targeted Imaging of Flat and Depressed Colonic Neoplasms
Endoscopic Submucosal Dissection of Non-Polypoid Colorectal Neoplasms
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