Naohisa Yoshida, MD, PhD; Ken Inoue, MD, PhD; and Yoshito Itoh, MD, PhD
Endoscopic mucosal resection (EMR) has become a standard therapy for the management of most colorectal polyps worldwide.1 The main limitation of EMR is the difficulty in achieving en bloc resection for lesions ≥ 20 mm with EMR is reported to be around 30%.2,3 Hence, piecemeal resection is often performed for these larger lesions, which in turn is associated with a higher risk for recurrence.4 Endoscopic submucosal dissection (ESD) is an endoscopic technique introduced in Japan for the en bloc resection of superficial gastrointestinal neoplastic lesions irrespective of size.4,5 However, the uptake of ESD, particularly for colorectal lesions, has been slowed by the steeper learning curve and higher risk for severe complications when compared to EMR. As such, EMR remains the first-line therapy for the resection of most benign colorectal lesions.
EMR has continued to evolve with the introduction of new modified techniques along with the development of new snares and longer-lasting lifting solutions. The introduction of stiff snares and viscous solutions, such as hyaluronic acid, have significantly improved EMR outcomes in terms of en bloc and R0 resection rates.6–8 However, en bloc resection of large lesions with EMR is still limited by the size of the snare and the variable submucosal lift prior to resection. More recently, precutting EMR has been introduced as a modified technique that allows the more consistent en bloc resection of large colorectal lesions. In this chapter, we will provide an overview of the technical aspects and clinical outcomes of precutting EMR.
Precutting Endoscopic Mucosal Resection
Precutting EMR is preferably used for lesions in which en bloc resection with standard EMR is not feasible. Lesions ≥ 20 mm in size can be en bloc excised with precutting EMR, albeit caution should be exercised for lesions. Precutting EMR may also be a viable technique for the en bloc resection of lesions in which underlying fibrosis may hinder an adequate submucosal lift. This may include the following: (1) resection of lesions after incomplete EMR and polypectomy, (2) those with submucosal fibrosis due to extensive diagnostic biopsies, (3) lateral spreading nongranular lesions, (4) lesions with superficial submucosal invasion, or (5) lesions around the appendiceal orifice, ileocecal valve, or around an angulated fold.9 A small rectal submucosal tumor such as a carcinoid is also an indication. Precutting EMR can also be helpful when enough elevation by conventional submucosal needle injection is not achieved unexpectedly, even if it measures less than 20 mm in size. Before precutting EMR, magnified observation with Blue Light Imaging (BLI, Fujifilm) in the West and Blue Laser Imaging (BLI, Fujifilm) in other Asian countries including Japan and South America, and Narrow Band Imaging (Olympus) is performed for accurate diagnosis.
Precutting Endoscopic Mucosal Resection Technique
Different lifting solutions can be used for precutting EMR. In our institution, the injection solution is 0.13% hyaluronic acid solution prepared with 0.4% hyaluronic acid solution (MucoUp; Boston Scientific or Seikagaku Corporation) including a small amount of 0.2% indigo carmine (final concentration: 0.02% indigo carmine).6 This viscous solution with dye facilitates a sustained lift and also lesion margin identification and the accurate resection with enough margin. Injection of hyaluronic acid is administered with a 25-gauge high-flow needle (TOP Co). Hyaluronic acid is viscous and thereby a high-flow needle may facilitate its injection when compared to normal saline. CO2 insufflation is used for preventing severe abdominal fullness and minimizing the difficulty of manipulation. Regarding electrosurgical units, a VIO300D high-frequency generator (Erbe) is used and our routine precutting EMR setting is described below. Circumferential incision is performed with ENDO CUT I mode (effect: 2, duration: 2, interval: 2), and snare resection is performed with swift coagulation (effect 3, 40 W). Stiff snares, such as DuaLoop (Medicos Hirata) and Captivator II 25 mm (Boston Scientific), are used. Hemostatic forceps can be used when bleeding occurs during incision and after resection. Endoscopic clipping (EZ Clip, Olympus) is performed when procedural perforation or coagulation of proper muscle layer occurs. Additionally, we use a novel lens cleaner (Cleash, Fujifilm and Nagase Medicals), which was developed by our group and is created mainly of 2 harmless, nonionic surfactants for preventing lens cloudiness during procedures.10
Case Illustration for Precutting Endoscopic Mucosal Resection
We present 4 precutting EMR cases to illustrate the indications and resection techniques. The first case was a 79-year-old woman and the lesion was a nonpolypoid lesion 15 mm in size on the ascending colon (Figure 17-1A). Previous biopsy caused a slight depression and scarring. We diagnosed this lesion as a low-grade adenoma based on white-light and magnifying endoscopy using BLI. A lower gastrointestinal endoscope with a single channel (EC-L600ZP, Fujifilm; PCFH290I, Olympus) was utilized. Mucosal injection using 0.13% hyaluronic acid with a small amount of indigo carmine was performed (Figure 17-1B). However, an adequate elevation could not be achieved because of scarring from a previous biopsy. Thus, a full circumferential mucosal incision was performed with the tip of a snare (Figure 17-1C). Circumferential incision subsequently allowed successful snare entrapment followed by en bloc resection (Figure 17-1D). Histology confirmed the lesion to be a low-grade adenoma with negative resection margins.
The second case was a 75-year-old woman with a nonpolypoid lesion 25 mm in size on the ascending colon (Figure 17-2A). BLI magnification showed dilated vessels and dilated crypts consistent with a sessile-serrated adenoma/polyp (SSA/P) (Figure 17-2B). Additonally, the lesion’s irregular vessel and surface pattern suggested high-grade dysplasia (Figure 17-2C). Thus, we diagnosed it as SSA/P with high-grade dysplasia and decided to proceed with precutting EMR. A full circumferential mucosal incision was performed which facilitated en bloc resection (Figures 17-2D through F). Histology confirmed the initial diagnosis of SSA/P with high-grade dysplasia with negative resection margins (Figures 17-3A and B).