Where it is given in Sabiston textbook of gen surgery regarding third space endoscopy
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Third space endoscopy refers to techniques like POEM (Per-Oral Endoscopic Myotomy) and STER that access the submucosal "third space" between the mucosa and muscularis. Let me locate this in the Sabiston textbook now.
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The results are from Fischer's and Harrison's, but not Sabiston. Let me search specifically within Sabiston.
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Let me search for POEM and submucosal endoscopy in Sabiston, and also check block2.md where the bariatric endoscopy section mentions it:
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Now let me read the key section in block2.md where "Third Space Endoscopy" is discussed in Sabiston:
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I can see the section now. Let me read a bit more to find the "third space" terminology specifically and then also check what chapter/context this is in:
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Now let me check what chapter number and heading this block belongs to, and also find the specific "third space" term within this chapter:
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Let me read the top of block2.md to identify the chapter name:
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The block starts at pages 133-225 but contains multiple chapters. Let me find the chapter heading right before the POEM section by reading around line 2540:
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I see this is a new chapter starting at page 196 (the outline lists the POEM section). Let me look just slightly before line 2567 to find the chapter title:
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The chapter title seems to be right before page 196 marker. Looking at the block structure (pages 133-225 = block 2), I need to find the chapter heading. The outline at line 2570 lists "Per Oral Endoscopic Myotomy" as a subsection - this is Chapter 12 based on figure references seen earlier (Fig. 12.5). Now I have enough information to give a comprehensive answer.
Here is what the Sabiston Textbook of Surgery covers regarding third space endoscopy:
Third Space Endoscopy in Sabiston Textbook of Surgery
Where to Find It
Third space endoscopy in Sabiston is found in Chapter 12 (pages ~196 onwards, within block pages 133-225), in the section titled "PER ORAL ENDOSCOPIC MYOTOMY" and adjacent subsections. The phrase "third space" is used in the context of the submucosal tunnel that separates the mucosa from the muscularis - the anatomical "third space" accessed during these procedures.
Key Sections and Content
1. PER ORAL ENDOSCOPIC MYOTOMY (POEM) (line 2640, p. ~196)
"Per oral endoscopic myotomy (POEM) is a therapeutic endoscopic technique with origins from the late 1970s and popularized in its current methodology by Dr. Haruhiro Inoue and colleagues in 2008. In their series, POEM was performed in 17 patients with achalasia using a long submucosal tunnel to divide the circular muscles of the gastroesophageal junction (GEJ)."
2. Indications for POEM (line 2654)
- Primary indication: Esophageal achalasia (incidence 0.03-1.63 per 100,000/year), characterized by absent LES relaxation and abnormal esophageal motility
- Expanded indications: Hypercontractility disorders of the esophagus (spastic and nonrelaxing LES disorders) - POEM has been used successfully in diffuse esophageal spasm, Jackhammer esophagus, etc.
3. POEM Technique - The four-step submucosal (third space) access:
- Submucosal injection and mucosal incision (~10-12 cm above GEJ)
- Creation of the submucosal tunnel
- Myotomy of circular muscle fibers
- Closure of the mucosotomy with clips or sutures
4. Zenker Diverticulotomy (Z-POEM) (line 2751) - applying the same third space principle:
"As with POEM, carbon dioxide is used for insufflation because of its rapid absorption by the body. The submucosal tunnel is continued along the length of both sides of the septum until the circular and longitudinal muscular fibers of the esophagus are encountered... A myotomy is created over the entire length of the cricopharyngeus muscle."
5. Per Oral Pyloromyotomy (POP / G-POEM) (line 2785)
- First performed in 2013 by Dr. Mouen Khashab for gastroparesis
- Applies the same submucosal third space tunneling approach to the pylorus
Summary Table of Third Space Endoscopy Procedures in Sabiston
| Procedure | Indication | Access |
|---|---|---|
| POEM | Achalasia, spastic esophageal disorders | Esophageal submucosal tunnel |
| Z-POEM | Zenker's diverticulum | Cricopharyngeal submucosal tunnel |
| G-POEM / POP | Gastroparesis | Gastric submucosal tunnel to pylorus |
Note on Terminology
Sabiston uses the term "submucosal tunnel" throughout to describe what is collectively called "third space endoscopy" in other texts. Fischer's Mastery of Surgery explicitly uses the term "Endoscopic Intramural Surgical techniques or Third Space Endoscopy techniques" - Sabiston covers all the same procedures but tends to describe the anatomy (submucosal layer/tunnel) rather than using the "third space" label by name.
- Sabiston Textbook of Surgery, Chapter 12, pp. 196-225 (9780443124341_block2.md)
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