Endoscopic Intermuscular Dissection (EID): Advancing Minimally Invasive Rectal Cancer Treatment
The new frontier of endoscopy: removing deep rectal tumours without open surgery, without a stoma, and without external scars.
EID allows us to reach "one layer deeper" while preserving the rectum.
TL;DR (quick summary)
What it is:
- • An endoscopic technique that dissects between the two muscle layers of the rectum.
- • Removes deeper tumours than classic ESD, without open surgery.
What it is used for:
- • T1 rectal cancer with deep submucosal invasion (sm2–sm3).
- • Recurrent fibrotic lesions or small GIST/neuroendocrine tumours.
- • Discharge at 24 h, no stoma, no external scars.
Endoscopic Intermuscular Dissection (EID) is an advanced endoscopic technique that I offer my patients, and it is changing the way we treat rectal tumours. Instead of operating "from the outside" by opening the abdomen or removing part of the rectum, we pass the endoscope through the natural route and dissect precisely between the two muscle layers of the rectal wall, taking the tumour with a deep safety margin — while leaving the rectum in place.
Quick contents
What is EID and why is it different?
Picture the rectal wall as a layered sandwich: on the inside you have the mucosa (where most polyps arise), then the submucosa, and then two muscle layers — the inner circular muscle and the outer longitudinal muscle. Fat lies on the outside.
Classic Endoscopic Submucosal Dissection (ESD) works above the muscle: it lifts the tumour from the submucosal plane. It works brilliantly when the tumour is "superficial", but once the cancer has invaded a little deeper, ESD is insufficient and the patient would normally be referred for surgery.
EID goes one step further: it dissects between the two muscle layers. The inner circular muscle is taken en bloc with the tumour, while the outer longitudinal muscle is left intact, acting as a "safety floor". The result: clean deep margins without perforating the rectal wall. 1
When is EID used?
Main indications
- 1. T1 rectal cancer with deep submucosal invasion (sm2–sm3 / T1b) without lymph node involvement on imaging. 1 2
- 2. Lesions with severe fibrosis or scarring (e.g. after a previous resection attempt or radiotherapy) where classic ESD is not feasible. 3 4
- 3. Small subepithelial rectal tumours: GISTs or neuroendocrine tumours located within the inner muscle layer. 5 6
Before planning an EID I always perform a full staging work-up: MRI, endoscopic ultrasound and detailed chromoendoscopy. Without accurate staging there is no safe endoscopic resection.
What the evidence says (no smoke and mirrors)
EID is a young technique, but the published data are already remarkably solid for a recently described procedure. Here are the key points every patient should know:
- In the initial prospective cohort by Moons et al. (2022), involving 67 patients with deep T1 cancer, the R0 resection rate was 81%, with 12% minor adverse events. 1
- The 3-year multicentre study by Van der Schee et al. (Gut, 2025), with 188 patients, reported R0 of 82.5% and recurrence rates of 7–13% in low/intermediate-risk cases, all salvageable and with no distant metastases. 2
- In the Chinese series by Yang et al. (2025) on T1b lesions, EID achieved 100% vertical R0, a technical success rate of 91.7%, and no recurrences at a median follow-up of 9 months. 7
- In fibrotic benign lesions (recurrences, radiation proctitis), EID achieves en-bloc resection with negative margins and good healing at 6 months. 3 8
What this means for patients:
In expert hands and with careful patient selection, EID achieves complete tumour removal (with clear margins) in approximately 80–100% of cases, and when early recurrences do appear, they can be rescued. That is crucial: it means EID does not burn bridges — it keeps all surgical options open if needed down the line.
If you would like to see more real-world advanced endoscopy cases, visit my dedicated advanced endoscopy section.
A real clinical case (unfiltered)
Patient with recurrent rectal lesion and fibrosis
- • Lesion type: rectal recurrence with high-grade dysplasia.
- • Size: 3 cm.
- • Particularity: severe fibrosis from a previous resection attempt.
- • Technique used: Endoscopic Intermuscular Dissection (EID).
- • Procedure duration: 35 minutes.
- • Complications: none.
- • Hospital discharge: at 24 hours.
This is precisely the type of case where EID shines. A recurrent fibrotic lesion is the nightmare of classic ESD: scar tissue does not lift properly, the tissue planes are obliterated, and the perforation risk rises sharply. By dissecting below the submucosa, between the two muscle layers, EID lets us work in a clean and predictable plane.
If you have been told that "surgery is the only option", let us review your case together before you decide.
Benefits for the patient
- Rectal preservation: no stoma (no bag) and no surgical resection.
- Early discharge: typically within 24 hours.
- No external scars: everything is done endoscopically via the natural route.
- Complete specimen for pathology: the pathologist can examine the entire piece and tell us whether the resection was curative or whether additional treatment is warranted.
- No bridges burned: if the pathology report reveals high-risk features, surgery remains fully possible afterwards.
Limitations (in the spirit of honesty)
EID is a powerful technique, but it is not magic. These are its real limitations today:
- • Almost all evidence comes from case series and cohorts; head-to-head randomised trials against surgery are still lacking. 2
- • It requires a highly experienced endoscopist and a trained multidisciplinary team.
- • Patient selection is critical: if lymph node involvement is suspected, surgery remains the standard of care.
- • Not all tumours are candidates: very large, deeply infiltrating or endoscopically unfavourable lesions should be referred for surgery.
For context, if you would like to understand the differences between the main endoscopic techniques, the following two related posts complement this article well:
Related posts
Where I perform EID
I perform Endoscopic Intermuscular Dissection at Hospital Universitario La Paz, where we are part of the Complex Endoscopy team and serve as a national reference centre for ESD, EID and EMR. We work closely with colorectal surgery, oncology, radiology and pathology so that every case is discussed both before and after the procedure. I also see patients in private practice at INMEQ, where we can review your case, evaluate previous studies and design a personalised treatment plan.
For a deeper technical overview, visit my endoscopic submucosal dissection section and the advanced endoscopy pages to see how we apply these techniques day to day.
A personal note
Behind every EID case there are hours of planning, a large multidisciplinary team and a genuine desire to do things right. When a patient goes home 24 hours after the procedure — no stoma, clean margins — that is the perfect day in the endoscopy suite.
FAQ: quick questions about EID
Is EID painful?
No. It is performed under deep sedation or anaesthesia. Most patients report only mild discomfort on waking, and by the following day they are back to virtually normal activity.
Can EID replace rectal surgery in every case?
Not in all cases. Yes, in many carefully selected T1 deep or complex lesions. The decision is made by a multidisciplinary tumour board. 2
What if the specimen shows high-risk features?
Surgery or oncological treatment can be added. EID never closes doors — it opens them.
How long does the procedure take?
Between 30 and 90 minutes, depending on the size and difficulty. In the case described in this post, 35 minutes.
Do I need a long hospital stay?
Discharge at 24 hours is the norm when there are no complications.
References (clickable)
- Moons LMG, Bastiaansen BAJ, Richir MC, et al. Endoscopic intermuscular dissection (EID) for deep submucosal invasive cancer in the rectum: a new endoscopic approach. Endoscopy (2022). DOI: 10.1055/a-1748-8573
- Van der Schee L, Albers S, Didden P, et al. Results of endoscopic intermuscular dissection for deep submucosal invasive rectal cancer: a three-year follow-up study. Gut (2025);74:1995–2003. DOI: 10.1136/gutjnl-2024-334612
- Tribonias G, Komeda Y, Leontidis N, et al. Endoscopic intermuscular dissection (EID) for removing early rectal cancers and benign fibrotic rectal lesions. Techniques in Coloproctology (2023);27:1393–1400. DOI: 10.1007/s10151-023-02862-7
- Latorre G, Pérez-Valenzuela J, Silva F, et al. Rescue of a recurrence of rectal adenoma using the endoscopic intermuscular dissection technique. Rev Gastroenterol Peru (2025);45(3):295–299. PubMed
- Ichita C, Sasaki A, Kawachi J, et al. Endoscopic intermuscular dissection for a lower rectal gastrointestinal stromal tumor. Endoscopy (2022);55:E258–E259. DOI: 10.1055/a-1974-8823
- Liao S, Li B, Huang L, et al. Endoscopic intermuscular dissection in the management of a rectal neuroendocrine tumor. Endoscopy (2023);55:E977–E979. DOI: 10.1055/a-2139-4310
- Yang T, Qi J, Lin X, et al. Short-term outcomes of endoscopic intermuscular dissection for early rectal cancer with deep submucosal infiltration: a single-center experience from China. Techniques in Coloproctology (2025);29. DOI: 10.1007/s10151-025-03237-w
- Tribonias G, Christoulakis M, Zachou M, et al. EID of a severely fibrotic benign rectal lesion in an area affected by radiation proctitis. Endoscopy International Open (2023);11:E733–E734. DOI: 10.1055/a-2109-8166
- Hochberger J, Loss M, Kruse E, Kouladouros K. Endoscopic Resection Techniques for Widespread Precancerous Lesions and Early Carcinomas in the Rectum. J Clin Med (2025);14. DOI: 10.3390/jcm14103322
- Safi M, Rönnow C, Thorlacius H. Endoscopic intermuscular dissection of early rectal cancer. British Journal of Surgery (2025). DOI: 10.1093/bjs/znaf149.078
- Mascarenhas A, Franco A, Mendes R, et al. Endoscopic intermuscular dissection of a rectal GIST. ESGE Days (2023). DOI: 10.1055/s-0043-1765293
- Fan D, Huang L, Qi J, et al. Application of endoscopic intermuscular dissection for diagnostic resection of early rectal cancer. Zhonghua Wei Chang Wai Ke Za Zhi (2024);27(6):630–633. DOI: 10.3760/cma.j.cn441530-20240314-00098
Have you been told you need rectal surgery?
Before making a decision, let us review your case. In many carefully selected patients, EID makes it possible to remove the tumour without sacrificing the rectum.
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