The endoscopic cap that can (with videos)

TECHNICAL REVIEW

The endoscopic cap that can (with videos) Andres Sanchez-Yague, MD,1,2 Tonya Kaltenbach, MD,1 Hironori Yamamoto, MD,3 Andrew Anglemyer,4 Haruhiro Inoue, MD,5 Roy Soetikno, MD1

“I . . . think . . . I . . . can . . . I . . . thought . . . I . . . could . . . I . . . thought . . . I . . . could. I thought I could. I thought I could. I thought I could.” And singing its triumph, it (the Little Engine) rushed on down toward the valley. —Reverend Charles S. Wing, 1906 The endoscopic caps often bridge the can to the could. It is among the best inventions in endoscopy. The cap adds practical functionality to the endoscope – some of which cannot be accomplished without it. Indeed caps have been used for more than 2 decades for a variety of indications, and are available in different materials, sizes, shapes, and features (Fig. 1; Table 1). Worldwide, endoscopic caps have been used routinely for variceal ligation1 and, increasingly, for endoscopic mucosal resection (EMR).1-3 In Japan, caps have been used for a wider range of diagnostic and therapeutic applications, such as for detailed magnification endoscopy and to maintain the precise dissection plane during submucosal dissection.4,5 Recently, an increasing body of literature examines the potential utility of caps to augment mucosal examination behind folds or at angulations for screening colonoscopy.6-30 This review summarizes the science and the art of use of the endoscopic cap and, most importantly, provides practical examples of its use

Abbreviations: ADR, adenoma detection rate; ESD, endoscopic submucosal dissection; NOTES, natural orifice transluminal endoscopic surgery; POEM, peroral endoscopic myotomy; STER, submucosal tunneling endoscopic resection. DISCLOSURE: H. Yamamoto has received honoraria, grants, and royalties from and holds patents related to Fujifilm Corporation. H. Inoue received a research grant from Olympus. R. Soetikno holds U.S. and Canadian patents for a clip device and the protective covering. No other financial relationships relevant to this publication were disclosed. See CME section; p. 159.

Use your mobile device to scan this QR code and watch the author interview. Download a free QR code scanner by searching ‘QR Scanner’ in your mobile device’s app store. Copyright © 2012 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 http://dx.doi.org/10.1016/j.gie.2012.04.447

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in day-to-day endoscopic practice. Thus, we will focus on caps that are commercially available in the United States.

REVIEW METHOD We searched the MEDLINE and Evidenced Based Medicine Reviews (Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Review) computerized databases through November 1, 2011 by using the keywords cap, cap-fitted, distal attachment, hood, colonoscopy, and endoscopy; manually reviewed the references; and obtained those that contained relevant information. We ranked the strength of reported evidence and recommendations based according to “Evidence Based Gastroenterology and Hepatology”31 (Appendix 1, available online at www.giejournal.org). More importantly, in order to provide an objective review of the literature on the application of caps for screening colonoscopy; we performed a meta-analysis comparing the quality of colonoscopy with and without a distal attachment cap (Appendix 2, available online at www.giejournal.org).

TECHNICAL ASPECTS Cap types and their attachment to the endoscopes Caps are transparent, opaque, or colored hollow cylinders that can be attached to the distal tip of the endoscope (Video 1, available online at www.giejournal.org). They are available in a variety of sizes and forms and are made of different materials. The proximal part of the cap fits the outer aspect of the distal end of the endoscope. To prevent displacement or even dislodgement of the cap, the cap can be secured to the endoscope by using waterproof adhesive tape (Hy-Tape pink tape; Hy-Tape International, Patterson, NY). The distal part of the cap is its working part. It can be conic, straight, or funnel-shaped with a horizontal or oblique end, which, in turn, may be rounded or internally beveled. Some caps have one or more side holes designed to prevent fluid accumulation within the cap. The cap designed for EMR has a small cut on the rim of the bevel that is used to align its placement with the direction of the working channel. Retractable caps have been described but are not commonly used. The depth of the cap is important for its diagnostic and therapeutic applications (Video 1). Although some caps Volume 76, No. 1 : 2012 GASTROINTESTINAL ENDOSCOPY 169

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have predetermined depth, the distal attachment caps (Olympus America, Inc, Center Valley, Pa) can be adjusted. The depth of the cap may be classified as short (1-2 mm), medium (3-4 mm), and long (⬎4 mm).

Mechanisms of function Caps have a number of mechanical functions (Table 2). They keep mucosa within range of the focal depth of the endoscope. They also are useful to push aside folds, angulations, or tissues. Caps can stabilize positioning of the tip of the endoscope (Fig. 2). The caps can help align the target for therapy with the axis of the working channel. When caps are used to allow visualization of a diseased area for snaring or clipping, the cap must be positioned with enough depth to allow housing the snare or clip within the cap and, at the same time, to keep the mucosa away from the lens. The cap also can provide stability and housing for an endoscopic accessory. For example, a needle-knife can be used within the cap in order to allow a very precise cut, and clips can be stationed within the cap while awaiting the target tissue to be suctioned.5 Another major function of the cap is that it extends the capability of the endoscope to suction selectively to within its opening. This is particularly useful for aspirating tissues or foreign bodies and holding them within the cap, either partially or fully, for removal. Gentle suctioning with concomitant washing through a water jet can be performed to view a bleeding site.32 The long cap is required to invert a bleeding diverticulum (eg, using the straight cap for EMR with cap, the variceal ligation cap, or the distal attachment cap placed in the “long” position). The depth of the cap allows the bleeding vessel at the dome to be suctioned into an awaiting open clip.32

Figure 1. A general representation of the available caps in the United States. A, The Disposable Distal Attachment caps (DAC, Olympus America, Center Valley, Pa) are available with 2-mm and 4-mm working distance types, which are intended for maintaining the optimal field of view and keeping the correct depth of field, respectively. An anal intraepithelial neoplasm was imaged under water with a 2-mm DAC in place for magnification. The cap was slightly visible under standard view (see inset). On ⫻1.2 digital magnification, the cap was not visible. The irregular microvessels were observed. B, A recurrent adenoma on an EMR scar was examined by using the DAC, which was placed at 4 mm from the tip of the endoscope. The DAC obscured the periphery of the visual field. C, The oblique hard endoscopic mucosal resection cap (Olympus) was used to suction a bleeding diverticulum from its dome. The cap housed a previously opened clip, which was awaiting the bleeding vessel before it was clipped. Complete hemostasis was achieved. D, A large oblique soft EMR was used to suction a 2-cm hemangioma in the sigmoid colon, while an endoloop was being applied. E, The cap of the endoscopic variceal ligation (Cook Medical, Salem, NC) was used to remove pancreatic phlegmon from inside a pseudocyst. F, The Halo cap (Barrx Medical, Sunnyvale, Calif), a frosted soft silicone cap that was designed to facilitate removal of coagulated esophageal tissue after radiofrequency ablation, was used to keep the gastroesophageal junction open in order to allow detailed examination.

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TABLE 1. Commercially available endoscopic caps in the United States

Device

Company

Material

Shape

End

Rim

Side hole

Outer diameter (mm)

Price (USD)

Distal attachment for screening colonoscopy

Olympus

Soft clear

Straight

Straight

No

Yes

11.3-15.7

$335*

Olympus

Soft clear

Straight

Straight

No

Yes

12.1-16.7

$335*

D-201-10704, D-201-11304, D-201-11804, D-201-12704, D-201-13404, D-201-14304, D-201-15004 Distal attachment for magnification colonoscopy D-201-11802, D-201-12402, D-201-16403 Caps included in EMR kits

Olympus

$310†

MH-593, MH-594, MH-595, MH-596, MH597, MH-598, D-402-13212, D-402-14212, D-405-15514, D-406-15514

Hard clear

Straight

Straight

Yes

No

12.9-16.1

MAJ-289, MAJ-290, MAJ-291, MAJ-292, MAJ-293, MAJ-294, MAJ-295, MAJ-296, MAJ-297

Hard clear

Straight

Oblique

Yes

No

12.8-19.1

D-206-01, D-206-02, D-206-03 D-206-04, D-206-05

Soft clear

Funnel

Oblique

Yes

No

18.0

DT series

Hard clear

Straight

Straight

No

No

11.8

$359†

MBL series

Hard clear

Straight

Straight

No

No

11.6-12.7

$351†

Soft frosted

Straight

Oblique

No

No

10.5-11.8

$300†

Multi-Band

HALO Cap

Cook

BarrX

CP-001A, CP-002A Enteroscope caps

Fujinon

$281†

DH-14EN

Soft dark

Straight

Straight

No

No

10.8

DH-17EN

Soft clear

Straight

Straight

No

No

11.5

USD, United States dollars. *Units: 10 per box. †Units: per kit (1 cap).

Limitations The cap may reduce the endoscope angle of view and maneuverability, and it can be costly. The cap can decrease the direct wide-angle of view of endoscopes from 170° to as little as 130°. It can add length and width to the endoscope tip, which may complicate insertion through narrowed areas or bends and retroflexion. The large (18 mm outer diameter) funnel-shaped caps, made for EMR with cap, despite being made from a more pliable plastic, can be difficult to insert through the esophageal sphincters. A number of studies, however, have shown that use of caps does not lead to increased difficulty of insertion or risk of colonoscope used for screening for colorectal neoplasms.7,8,12,14,22 Last, but not least, the caps for variceal ligation and kits for EMR with cap are marketed as singleuse devices for specific purposes and with additional accessories and thus can be costly. www.giejournal.org

APPLICATIONS AND OUTCOMES The reported applications of the caps are many. Some applications have been reported as randomized, clinical trials and case series—the science; others have illustrated unique uses—the art. The distal attachment cap, caps for EMR, and band ligation caps with the bands removed have been applied to assist in a variety of difficult diagnostic and therapeutic endoscopies, which in some cases otherwise would have been impossible to accomplish. We illustrate the applications of caps in Figure 3 by using our own experience.

Improving visualization Visualization of the diseased and normal mucosa of the hypopharynx, esophageal sphincters, pylorus, and the small and large bowels behind the folds and turns may be improved with using endoscopic caps. Use of caps has been Volume 76, No. 1 : 2012 GASTROINTESTINAL ENDOSCOPY 171

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TABLE 2. Mechanisms of caps Purpose Improving visualization

Mechanism Maintaining the optimal field of view and keeping the correct depth of field; pushing aside folds, angulations, tissues, or sphincters; and stabilizing the position of the tip of the endoscope

Distancing the tip of the endoscope to Placing the target of therapy en face, rather than tangential, at the ideal and constant distance the ideal distance for delivering for delivering treatment treatment Aligning the target of therapy with the Pushing aside folds, angulations, tissues, or the wall of the GI tract axis of the accessory channel Diagnosis and treatment of diverticular bleeding

Inverting a diverticulum for examination of its dome and treatment of a bleeding vessel

Improving suction capability

Enlarging the area of suction to the opening of the cap rather than the opening of the channel

Creating a submucosal tunnel

Pushing aside submucosal tissues

Housing for an accessory

Placing an accessory within the cap allows protection of the surrounding tissue and keeps the target of treatment in view

Figure 2. Use of an endoscopic cap to treat a large duodenal ulcer with a visible clot. A, Injection of diluted epinephrine to 4 quadrants surrounding the clot was difficult because the clot could be approached only tangentially. B, A diagram showing the potential benefits gained by using a cap in the treatment of a duodenal ulcer—the cap stabilizes the position of the tip of the endoscope and positions the ulcer en face. C, The endoscope has been equipped with a disposable distal attachment cap, which was placed at about 4 mm from the tip of the endoscope. The cap was used to push the wall proximal to the vessel, thus making the visible vessel almost en face. D, The lumen was suctioned to bring the distal part of the vessel further en face. Suction brought the vessel onto an awaiting open clip. E, The vessel had been captured by the clip, and the clip had been closed. F, The clip was precisely placed on the vessel. Illustration by Justin Greene ([email protected]).

proposed for detailed examination of the anal canal33 and to assist examination of the rectum34 behind the folds. Visualization during high magnification requires the mucosa to be within the depth of field (the distance between the nearest 172 GASTROINTESTINAL ENDOSCOPY Volume 76, No. 1 : 2012

and farthest point that appear acceptably sharp) of the endoscope; typically the short cap (2 mm) is used. Gentle suction is applied to bring the target into focus and avoid pressing the tip of the endoscope onto the mucosa.35 www.giejournal.org

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Screening for colorectal neoplasms The mechanical function of caps to deflect folds was initially thought to be useful in the colon to increase the completeness of colonoscopy and to reduce examination times. Tada et al27 performed the first randomized controlled trial in 1996 on the use of caps during colonoscopy. Thirteen other groups have since published their results since that time.7-12,14,17,24-26,29,30 The more recent studies have primarily focused on its potential use to increase the adenoma detection rate. We performed a meta-analysis on 4 studies that provided adequate data for analysis of the adenoma detection rate.9,10,25,29 A total of 1629 patients (see Methods in Appendix 2) were included in our analysis. The pooled

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adenoma detection rate (ADR) in patients who underwent colonoscopy with a cap was 46.6% (385/827) versus 40.3% (323/802) without cap. The pooled risk ratio was 1.14 (95% confidence interval [CI], 1.03-1.27; P ⫽ .01) and the number needed to treat was 16.6 patients. The heterogeneity between studies was low (I2 ⫽ 8%). The mean number of adenomas detected per participant was marginally higher when a cap was used (mean difference 0.43; 95% CI, ⫺0.03 to 0.89; P ⫽ .07; I2 ⫽ 73%). The quality of evidence for both the ADR and mean number of adenomas detected was determined to be moderate. Although the use of cap significantly increased the number of patients with at least one adenoma compared to the patients who underwent standard colonoscopy, the difference was in the detection of diminutive adenomas—the cap had no significant impact on the detection of adenomas in the right side of the colon, those 5 mm or larger, or on the mean number of advanced adenomas detected per participant (R Grade A). The use of the cap to reach the cecum in difficult colonoscopy also has been studied (R Grade A). Kondo et al12 found the short transparent cap significantly better to improve intubation times in difficult cases, while Lee et al13 demonstrated a higher rescue rate in cecal intubation by using a cap after a failed standard colonoscopy (66.7% vs 21.1%; P ⫽ .003).12 Nakamura et al36 reported the use of a gastroscope with a short black cap to facilitate cecal intubation in patients with an anticipated difficult colonoscopy.

Figure 3. Composite examples of a variety of use of caps. A, A nonpolypoid colorectal neoplasm was difficult to visualize without the cap. B, Visualization significantly improved after the endoscope was equipped with a 4-mm distal attachment cap. The cap was used to push down the fold, thus bringing the lesion into view. C, In this case of Barrett’s esophagus with early cancer, the mucosa closest to the endoscope was out of focus. D, After we placed the cap, the mucosa was kept at the optimal distance for in-depth examination. E, The large, soft, oblique cap for EMR with cap (EMRC) can be useful for removing large foreign body impactions in the esophagus (Video 2, available online at www.giejournal.org). F, The same type of cap was used to remove a fish bone that had penetrated the esophagus at two opposite sides. The cap allowed the wall of the esophagus to be pushed to the side while the bone was gently released from the puncture site (Video 3, available online at www.giejournal.org). G, A straight, hard cap of the EMRC kit was used to treat a bleeding arteriovenous malformation in the distal duodenal bulb. The bleeding was profuse but the lesion was clearly seen given the use of a water jet and gentle suction simultaneously. H, The bleeding vessel was suctioned into a waiting open clip within the cap. Clipping was successful in stopping the bleeding. I, An ERCP of a patient with Roux-en-Y anatomy by using a pediatric colonoscope equipped with a cap from a variceal ligation kit. The axis of the bile duct was made coaxial with the direction of the therapeutic channel by pushing the wall distal to the ampulla laterally. J, Sphincteroplasty was subsequently performed, thus allowing successful removal of a bile duct stone. Illustrations by Justin Greene ([email protected]).

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Removal of food impaction, foreign bodies, and resected tissue The cap can assist in foreign body removal by pushing the wall to free up the sharp edge of a foreign body and also for protecting the wall from sharp or pointy edges (Videos 2 and 3, available online at www.giejournal.org). Saeed et al37 described in 1990 the use of a prototype cap to remove food boluses (R Grade C). A modification of this technique featured the use of a Dormia basket to grasp the impacted food and bring it into the cap (R Grade C).38 The cap can be useful to remove pieces of resected tissues while the suction is kept on.

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TABLE 3. Indications for use of band ligation in patients with esophageal varices Primary prophylaxis

In patients who have contraindication or intolerance to ␤-blocker: any size varix with high-risk stigmata In patients who have contraindication or intolerance to ␤-blocker: large varix without high-risk stigmata

Secondary prophylaxis

Band ligation every 1-2 weeks until obliteration, then every 6-12 months for surveillance

Treatment of bleeding Endoscopic caps have been used to help in visualizing the source of the bleeding behind folds, turns, tissues, or structures and to stabilize the tip of the endoscope. Use of the caps has been reported in cases of bleeding gastric and duodenal ulcers and after polypectomy and sphincterotomy (R Grade C). Bleeding arising in the posterior wall of the stomach can be difficult to manage endoscopically because of its tangential relationship to the forwardviewing endoscope. A cap can help modify the angle of approach (R Grade B). In a case series involving 74 patients with bleeding gastric lesions, the use of the cap allowed successful clip placement in 18 cases where the bleeding site could not initially be approached. Initial hemostasis was similar in patients with and without the cap, although notably the cap was used in those cases where a standard approach was unsuccessful.39 Similarly, bleeding from the duodenal bulb can be challenging to treat. The duodenal bulb is often short, and bleeding can be either too close to the pylorus or on a tangent. The frequent endoscope retraction into the stomach adds to the difficulties. Successful treatment of duodenal ulcers by using a cap-fitted endoscope has been described (R Grade C).40,41 Caps also have been used in combination with detachable snares to loop a large pedicle of a short pedunculated polyp after polypectomy42 or to obtain a frontal view of the papilla (R Grade C) to successfully treat postsphincterotomy bleeding 48 hours after ERCP.43

Diagnosis and treatment of colon diverticular bleeding We recently described the use of caps to diagnose and treat diverticular bleeding in the colon (R Grade B) (Video 4, available online at www.giejournal.org).32 The source of diverticular bleeding was within the dome in approximately one-third of cases; the stigmata of which would not have be visualized without use of the cap. The distal cap attachment facilitates both the identification and treatment of the bleeding stigmata through irrigation, suctioning, and dislodgement of fibrin clots in the diverticula as well as improving the ability to inspect behind folds and at the diverticular neck and dome. 174 GASTROINTESTINAL ENDOSCOPY Volume 76, No. 1 : 2012

Using the cap to examine the diverticular dome, for example, allows for the diverticulum to be everted with slight suction and thus thoroughly inspected and treated. Once the bleeding source is diagnosed, the cap permits housing of an endoscopic clip that can be reopened and closed to target precise mechanical hemostasis. Others have described the use of banding ligation to treat diverticular bleeding (R Grade B).44,45

Band ligation Endoscopic variceal ligation is an established procedure; a review has been published.46 A summary of the indications of band ligation in the management of esophageal varices is, however, shown in Table 3. Band ligation also has been used to treat Dieulafoy’s lesion,47,48 MalloryWeiss tear,49,50 inflammatory polyps, and gastric antral vascular ectasia.51

EMR and submucosal dissection Caps are used extensively in EMR and endoscopic submucosal dissection (ESD). The Distal Attachment Caps are often used during the inject and cut EMR technique because it allows improved visualization of the tumor and placing it within the axis of the accessory channel. In EMR with cap, EMR with ligation52 and multiple ligation,2 specialized caps are inherent parts of the technique. The use of caps in these EMR techniques allows the target tissues, which are typically too flat to be snared, to be made into a mushroom-shape and captured by the snare (R Grade B).3 Caps are particularly useful during ESD.5 In ESD, the medium depth cap functions to separate the dissected tissue from the wall; thus exposing the submucosa for precise dissection. It keeps tissue from touching the endoscope lens, thus allowing constant visualization during dissection. Caps also can be used to press on a bleeding vessel in order to provide temporary tamponade.53

Use of cap during enteroscopy During deep enteroscopy, the use of a cap attached to the endoscope tip allows prevention of “red-out” and www.giejournal.org

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facilitates insertion by the slalom technique with minimum air insufflation (Video 5, available online at www. giejournal.org). Overinsufflation hampers effective shortening of the small intestine that is necessary for deep intubation of an enteroscope. A short cap (1 mm from the endoscope tip), which does not interfere with the endoscopic viewing field, is used for regular procedures. For more complicated therapeutic procedures, a longer transparent cap (4 mm from the endoscope tip) is useful to ensure a good view of the lumen as well as the targeted tissue while accessory devices such as injection needles,

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snares, and argon-plasma-coagulation probes are used (Video 5) (R Grade C).54

ERCP ERCP in patients who have had Billroth II or Roux-en-Y surgeries can be particularly challenging. When approached from the distal duodenum by using a forwardviewing endoscope, the ampulla and the direction of the bile duct may not be aligned with the axis of the therapeutic channel. The cap, which is fitted to the tip of a

Figure 4. The use of an endoscopic cap is an integral part of peroral endoscopic myotomy for esophageal achalasia. A, After submucosal injection of diluted indigo carmine solution at approximately 10 cm proximal to the esophagogastric junction, the first cut of the mucosa was performed by using the Triangle Tip knife (Olympus Corp, Tokyo, Japan). A longitudinal mucosal incision was made distally to create an entry for a submucosal tunnel. B, The endoscopic cap was used during dissection of the submucosa. It was critical to keep the mucosal layer intact in order to prevent leakage of luminal content into the mediastinum. C, On the left side, the mucosa with a longitudinal palisade vessel was seen. On the right side, the circular muscularis propria was observed. D, Myotomy of this layer in the submucosal tunnel was started 2 cm distal from the mucosal incision and continued toward the gastric side. Without the cap it was difficult to keep an appropriate distance to the targeted tissue. After the myotomy was completed, the mucosal entry was closed with hemostatic clips. A complete incision of a tight lower esophageal sphincter is the primary aim of this procedure.

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forward-viewing endoscope, can be used to push the wall of the duodenum slightly distal to the papilla, thus permitting cannulation of the bile duct (R Grade B). Lee55 described the first case, in which a patient with a Billroth II gastrectomy had a papilla that faced toward the proximal duodenum, thus making it impossible to cannulate by using a duodenoscope or a forward-viewing endoscope. ERCP was successfully performed by using the forwardview endoscope with a hard, transparent cap attached to the tip. The papilla was cannulated, and a plastic stent was placed for drainage. A case series featuring 10 patients with Billroth II gastrectomy and bile duct stones or a bile duct stricture in which ERCP was performed by using a cap fitted onto a forward-viewing endoscope demonstrated the feasibility of the approach further (R Grade B).56 Successful intubation of the afferent loop, cannulation of the bile duct, and therapeutic maneuvers were achieved in all cases, and there were no serious complications.

Zenker diverticulotomy Use of a transparent cap during Zenker diverticulotomy (R Grade B) can be useful for exposing the septum for resection within a single session.57 Housing the cutting device or argon-plasma-coagulation probe within the cap can prevent accidental injury to the posterior wall of the diverticulum. Sakai et al58 described the use of a transparent oblique mucosectomy cap in 10 patients, allowing for complete incision of the septum in a single session in all cases. A confirmatory study has been reported (R Grade B).59,60 The use of caps to assist Zenker diverticulotomy can make the procedure more available. Others have advocated the use of a diverticuloscope, although such a device is not largely available in endoscopy units.60

Submucosal tunneling: peroral endoscopic myotomy and submucosal tunneling endoscopic resection Submucosal tunneling was initially devised for peritoneal access as part of natural orifice transluminal endoscopic surgery (NOTES) procedures.61 Current clinical applications include the use for peroral endoscopic myotomy (POEM) and submucosal tunneling endoscopic resection (STER). The most cutting edge application of the cap is its use for POEM (Fig. 4). The concept of POEM62 was established by Inoue et al63 to treat patients with achalasia. In brief, after submucosal injection, a mucosal incision is made toward the submucosa space approximately 10 cm proximal to the esophageal sphincter. A submucosal tunnel is then created to approximately 3 cm distal to the esophagogastric junction. The hard-oblique cap of EMR with cap is used to keep the field of view clear, although other caps (short cap, tapered cap, etc.) also may be used. Endoscopic myotomy of the inner circular muscle bundle is performed by using the triangle tip 176 GASTROINTESTINAL ENDOSCOPY Volume 76, No. 1 : 2012

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knife followed by closure of the mucosa entry by using multiple endoscopic clips.64 For classic achalasia, myotomies of at least 7 cm in the esophageal side and 3 cm in the gastric side are performed. For vigorous achalasia with chest pain, a longer myotomy with an elongated submucosal tunnel is carried out. The total length of myotomy is decided according to data from manometry, barium swallow, and endoscopic findings. Case series involving a large number of patients have been reported (R Grade B).65-67 The STER technique has been reported for the treatment of submucosal lesions in the esophagus and cardia. Essentially, a 2-cm longitudinal or transverse incision is made 5 cm from the lesion, and then a cap-fitted endoscope is used to access the submucosa, create the tunnel, and remove the lesion.68-70

Other uses A wide variety of other applications of caps have been described. Caps have been used to get a more stable position to facilitate taking biopsies,40 for puncturing the gastric wall prior to pseudocyst drainage,71 or for argon plasma coagulation of radiation proctitis located close to the dentate line.72 A dedicated cap was devised to perform mucosal scraping after the first set of radiofrequency ablation for the treatment of Barrett’s esophagus,73 whereas the small-caliber-tip transparent hood has been used to perform direct visualization bougienage of esophageal strictures.74 The over-the-scope clip features a mounting cap that is used to aspirate the edges of a perforation to achieve tissue approximation before clipping.75,76

CONCLUSIONS Caps are useful endoscopic accessories in a variety of endoscopic procedures. When used for screening for colorectal neoplasms, the distal attachment cap increases the ADR, although the increase was achieved primarily by improving the detection of adenomas smaller than 5 mm. The use of distal attachment caps does not improve adenoma detection in the right side of the colon, adenomas 5 mm or larger, or the average number of advanced adenomas. More importantly, however, caps can be very useful for many other indications and, in some cases, opening new possibilities to efficaciously and efficiently perform endoscopy. Simple is hard, but hard can be made simple—the endoscopic cap often can facilitate. REFERENCES 1. Inoue H, Endo M, Takeshita K, et al. A new simplified technique of endoscopic esophageal mucosal resection using a cap-fitted panendoscope (EMRC). Surg Endosc 1992;6:264-5. 2. Soehendra N, Seewald S, Groth S, et al. Use of modified multiband ligator facilitates circumferential EMR in Barrett’s esophagus (with video). Gastrointest Endosc 2006;63:847-52.

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3. Soetikno RM, Gotoda T, Nakanishi Y, et al. Endoscopic mucosal resection. Gastrointest Endosc 2003;57:567-79. 4. Oyama T, Tomori A, Hotta K, et al. Endoscopic submucosal dissection of early esophageal cancer. Clin Gastroenterol Hepatol 2005;3:S67-70. 5. Yamamoto H, Koiwai H, Yube T, et al. A successful single-step endoscopic resection of a 40 millimeter flat-elevated tumor in the rectum: endoscopic mucosal resection using sodium hyaluronate. Gastrointest Endosc 1999;50:701-4. 6. Dafnis GM. Technical considerations and patient comfort in total colonoscopy with and without a transparent cap: initial experiences from a pilot study. Endoscopy 2000;32:381-4. 7. Dai J, Feng N, Lu H, et al. Transparent cap improves patients’ tolerance of colonoscopy and shortens examination time by inexperienced endoscopists. J Dig Dis 2010;11:364-8. 8. Harada Y, Hirasawa D, Fujita N, et al. Impact of a transparent hood on the performance of total colonoscopy: a randomized controlled trial. Gastrointest Endosc 2009;69:637-44. 9. Hewett DG, Rex DK. Cap-fitted colonoscopy: a randomized, tandem colonoscopy study of adenoma miss rates. Gastrointest Endosc 2010;72:775-81. 10. Horiuchi A, Nakayama Y. Improved colorectal adenoma detection with a transparent retractable extension device. Am J Gastroenterol 2008;103: 341-5. 11. Horiuchi A, Nakayama Y, Kato N, et al. Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging. Clin Gastroenterol Hepatol 2010;8:379-83. 12. Kondo S, Yamaji Y, Watabe H, et al. A randomized controlled trial evaluating the usefulness of a transparent hood attached to the tip of the colonoscope. Am J Gastroenterol 2007;102:75-81. 13. Lee YT, Hui AJ, Wong VW, et al. Improved colonoscopy success rate with a distally attached mucosectomy cap. Endoscopy 2006;38:739-42. 14. Lee YT, Lai LH, Hui AJ, et al. Efficacy of cap-assisted colonoscopy in comparison with regular colonoscopy: a randomized controlled trial. Am J Gastroenterol 2009;104:41-6. 15. Matsushita M, Danbara N, Fukui T, et al. Much colonic surface visualization by a standard colonoscope with a transparent hood. Am J Gastroenterol 2008;103:1568; author reply 1568-9. 16. Matsushita M, Danbara N, Fukui T, et al. Total colonoscopy with a transparent hood for trainees. Am J Gastroenterol 2007;102:2355-6. 17. Matsushita M, Hajiro K, Okazaki K, et al. Efficacy of total colonoscopy with a transparent cap in comparison with colonoscopy without the cap. Endoscopy 1998;30:444-7. 18. Matsushita M, Omiya M, Uchida K, et al. Narrow-band imaging colonoscopy with a transparent hood for more polyp detection. J Gastroenterol 2008;43:809; author reply 809-10. 19. Matsushita M, Omiya M, Uchida K, et al. More polyp detection: narrowband imaging or a transparent hood? Gut 2008;57:1334. 20. Matsushita M, Omiya M, Uchida K, et al. Narrow-band imaging in addition to a transparent hood for much more polyp detection. Gastrointest Endosc 2009;69:189-90; author reply 189-90-1. 21. Matsushita M, Tanaka T, Sekimoto G, et al. A retrograde-viewing device or a transparent hood for improving colorectal adenoma detection. Gastrointest Endosc 2011;73:637-8; author reply 637-8. 22. Matsushita M, Yamagata H, Wakamatsu T, et al. Colonoscopy with a transparent hood: simple technique for improved quality of colonoscopy. Am J Gastroenterol 2009;104:527. 23. Pohl H. Cap-assisted colonoscopy: Does it hinder or help adenoma detection? Am J Gastroenterol 2009;104:2111-2; author reply 2111-2. 24. Prachayakul V, Aswakul P, Limsrivilai J, et al. Benefit of “transparent softshort-hood on the scope” for colonoscopy among experienced gastroenterologists and gastroenterologist trainee: a randomized, controlled trial. Surg Endosc 2011;26:1041-6. 25. Rastogi A, Bansal A, Rao DS, et al. Higher adenoma detection rates with cap-assisted colonoscopy: a randomised controlled trial. Gut 2012;61: 402-8. 26. Shida T, Katsuura Y, Teramoto O, et al. Transparent hood attached to the colonoscope: Does it really work for all types of colonoscopes? Surg Endosc 2008;22:2654-8.

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27. Tada M, Inoue H, Yabata E, et al. Feasibility of the transparent cap-fitted colonoscope for screening and mucosal resection. Dis Colon Rectum 1997;40:618-21. 28. Takeuchi Y, Inoue T, Hanaoka N, et al. Surveillance colonoscopy using a transparent hood and image-enhanced endoscopy. Dig Endosc 2010; 22(suppl 1):S47-53. 29. Takeuchi Y, Inoue T, Hanaoka N, et al. Autofluorescence imaging with a transparent hood for detection of colorectal neoplasms: a prospective, randomized trial. Gastrointest Endosc 2010;72:1006-13. 30. Tee HP, Corte C, Al-Ghamdi H, et al. Prospective randomized controlled trial evaluating cap-assisted colonoscopy vs standard colonoscopy. World J Gastroenterol 2010;16:3905-10. 31. McDonald JWD. Evidence-based gastroenterology and hepatology, 3rd ed. Chichester, West Sussex: John Wiley & Sons; 2010. 32. Kaltenbach T, Watson R, Shah J, et al. Colonoscopy with clipping is useful in the diagnosis and treatment of diverticular bleeding. Clin Gastroenterol Hepatol 2012;10:131-7. 33. Oono Y, Fu K, Nakamura H, et al. Narrow band imaging colonoscopy with a transparent hood for diagnosis of a squamous cell carcinoma in situ in the anal canal. Endoscopy 2010;42(suppl 2):E183-4. 34. Lee YT. Improve anorectal examination by the cap-assisted colonoscopy method. Gastrointest Endosc 2010;71:433. 35. Urita Y, Nishino M, Ariki H, et al. A transparent hood simplifies magnifying observation of the colonic mucosa by colonoscopy. Gastrointest Endosc 1997;46:170-2. 36. Nakamura H, Fu K, Yamamura A. Magnifying gastroscopy using a soft black hood for difficult colonoscopy. Surg Endosc 2011;25:3016-21. 37. Saeed ZA, Michaletz PA, Feiner SD, et al. A new endoscopic method for managing food impaction in the esophagus. Endoscopy 1990;22:226-8. 38. Patel NC, Fry LC, Monkemuller KE. Modified suction cap technique for endoscopic management of esophageal food impaction. Endoscopy 2003;35:548. 39. Kim JI, Kim SS, Park S, et al. Endoscopic hemoclipping using a transparent cap in technically difficult cases. Endoscopy 2003;35:659-62. 40. Yap CK, Ng HS. Cap-fitted gastroscopy improves visualization and targeting of lesions. Gastrointest Endosc 2001;53:93-5. 41. Kaltenbach T, Friedland S, Barro J, et al. Clipping for upper gastrointestinal bleeding. Am J Gastroenterol 2006;101:915-8. 42. Zachaus M, Kunzel U, Halm U. Bleeding prophylaxis after polypectomy by colonoscopic application of a detachable snare with a mucosectomy cap. Endoscopy 2008;40(suppl 2):E159. 43. Leal-Salazar JA, Gonzalez-Gonzalez JA, Garza-Galindo AA, et al. Use of a gastroscope armed with a transparent cap in the treatment of bleeding after endoscopic sphincterotomy. Endoscopy 2009;41(suppl 2):E91. 44. Ishii N, Setoyama T, Deshpande GA, et al. Endoscopic band ligation for colonic diverticular hemorrhage. Gastrointest Endosc 2012;75:382-7. 45. Farrell JJ, Graeme-Cook F, Kelsey PB. Treatment of bleeding colonic diverticula by endoscopic band ligation: an in-vivo and ex-vivo pilot study. Endoscopy 2003;35:823-9. 46. Garcia-Tsao G, Sanyal AJ, Grace ND, et al. Prevention and management of gastroesophageal varices and variceal hemorrhage in cirrhosis. Hepatology 2007;46:922-38. 47. Soetikno RM, Piper J, Montes H, et al. Use of endoscopic band ligation to treat a Dieulafoy’s lesion of the esophagus. Endoscopy 2000;32:S15. 48. Gerson LB, Yap E, Slosberg E, et al. Endoscopic band ligation for actively bleeding Dieulafoy’s lesions. Gastrointest Endosc 1999;50:454-5. 49. Gunay K, Cabioglu N, Barbaros U, et al. Endoscopic ligation for patients with active bleeding Mallory-Weiss tears. Surg Endosc 2001;15:1305-7. 50. Park CH, Min SW, Sohn YH, et al. A prospective, randomized trial of endoscopic band ligation vs epinephrine injection for actively bleeding Mallory-Weiss syndrome. Gastrointest Endosc 2004;60:22-7. 51. Wells CD, Harrison ME, Gurudu SR, et al. Treatment of gastric antral vascular ectasia (watermelon stomach) with endoscopic band ligation. Gastrointest Endosc 2008;68:231-6. 52. Suzuki H. Endoscopic mucosal resection using ligating device for early gastric cancer. Gastrointest Endosc Clin N Am 2001;11:511-8.

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53. Yamamoto H. Endoscopic submucosal dissection of early cancers and large flat adenomas. Clin Gastroenterol Hepatol 2005;3:S74-6. 54. Sato H, Yano T. Specific procedures for insertion. In: Sugano K, Yamamoto H, Kita H, editors. Double-balloon endoscopy: theory and practice. Tokyo: Springer; 2006. p. 35-42. 55. Lee YT. Cap-assisted endoscopic retrograde cholangiopancreatography in a patient with a Billroth II gastrectomy. Endoscopy 2004;36:666. 56. Park CH, Lee WS, Joo YE, et al. Cap-assisted ERCP in patients with a Billroth II gastrectomy. Gastrointest Endosc 2007;66:612-5. 57. Hashiba K, de Paula AL, da Silva JG, et al. Endoscopic treatment of Zenker’s diverticulum. Gastrointest Endosc 1999;49:93-7. 58. Sakai P, Ishioka S, Maluf-Filho F, et al. Endoscopic treatment of Zenker’s diverticulum with an oblique-end hood attached to the endoscope. Gastrointest Endosc 2001;54:760-3. 59. Costamagna G, Mutignani M, Tringali A, et al. Treatment of Zenker’s diverticulum with the help of a plastic hood attached to the endoscope. Gastrointest Endosc 2002;56:611-2; author reply 611-2. 60. Costamagna G, Iacopini F, Tringali A, et al. Flexible endoscopic Zenker’s diverticulotomy: cap-assisted technique vs. diverticuloscope-assisted technique. Endoscopy 2007;39:146-52. 61. Sumiyama K, Gostout CJ, Rajan E, et al. Submucosal endoscopy with mucosal flap safety valve. Gastrointest Endosc 2007;65:688-94. 62. Ortega JA, Madureri V, Perez L. Endoscopic myotomy in the treatment of achalasia. Gastrointest Endosc 1980;26:8-10. 63. Inoue H, Minami H, Kobayashi Y, et al. Peroral endoscopic myotomy (POEM) for esophageal achalasia. Endoscopy 2010;42:265-71. 64. Inoue H, Tianle KM, Ikeda H, et al. Peroral endoscopic myotomy for esophageal achalasia: technique, indication, and outcomes. Thorac Surg Clin 2011;21:519-25. 65. Inoue H, Kudo SE. Per-oral endoscopic myotomy (POEM) for 43 consecutive cases of esophageal achalasia[in Japanese]. Nihon Rinsho 2010;68: 1749-52. 66. von Renteln D, Inoue H, Minami H, et al. Peroral endoscopic myotomy for the treatment of achalasia: a prospective single center study. Am J Gastroenterol 2012;107:411-7. 67. Zhou PH, Cai MY, Yao LQ, et al. Peroral endoscopic myotomy for esophageal achalasia: report of 42 cases. Zhonghua Wei Chang Wai Ke Za Zhi 2011;14:705-8. 68. Inoue H, Ikeda H, Hosoya T, et al. Submucosal endoscopic tumor resection for subepithelial tumors in the esophagus and cardia. Endoscopy 2012;44:225-30.

69. Xu MD, Cai MY, Zhou PH, et al. Submucosal tunneling endoscopic resection: a new technique for treating upper GI submucosal tumors originating from the muscularis propria layer (with videos). Gastrointest Endosc 2012;75:195-9. 70. Gong W, Xiong Y, Zhi F, et al. Preliminary experience of endoscopic submucosal tunnel dissection for upper gastrointestinal submucosal tumors. Endoscopy 2012;44:231-5. 71. Gonzalez-Gonzalez JA, Mendoza-Fuerte E, Garza-Galindo AA, et al. Use of a transparent cap for endoscopic drainage of a pancreatic pseudocyst. Endoscopy 2008;40(suppl 2):E206. 72. Coriat R, Wolfers C, Chaput U, et al. Treatment of radiation-induced distal rectal lesions with argon plasma coagulation: use of a transparent cap. Endoscopy 2008;40(suppl 2):E270. 73. Pouw RE, Sharma VK, Bergman JJ, et al. Radiofrequency ablation for total Barrett’s eradication: a description of the endoscopic technique, its clinical results and future prospects. Endoscopy 2008;40:1033-40. 74. Itaba S, Nakamura K, Akiho H, et al. Endoscopic bougienage for a recurrent esophageal web using a small-caliber-tip transparent hood. Endoscopy 2008;40(suppl 2):E198. 75. Kirschniak A, Traub F, Kueper MA, et al. Endoscopic treatment of gastric perforation caused by acute necrotizing pancreatitis using over-thescope clips: a case report. Endoscopy 2007;39:1100-2. 76. Repici A, Arezzo A, De Caro G, et al. Clinical experience with a new endoscopic over-the-scope clip system for use in the GI tract. Dig Liver Dis 2009;41:406-10.

Received December 12, 2011. Accepted April 12, 2012. Current affiliations: Endoscopy Unit (1), Veterans Affairs Palo Alto and Stanford University, Palo Alto, California, USA, Gastroenterology Unit (2), Hospital Costa del Sol, Marbella, Spain, Department of Endoscopic Research and International Education (3), Jichi Medical University Hospital, Tochigi, Japan, Cochrane HIV/AIDS Group, Institute for Global Health (4), University of California, San Francisco, California, USA, Showa University International Training Center for Endoscopy (5), Showa University, Northern Yokohama Hospital, Yokohama, Japan. Reprint requests: Roy Soetikno, MD, Veterans Affairs Palo Alto Health Care System, Endoscopy Unit, 3801 Miranda Ave, GI111, Palo Alto, CA 94304.

Registration of Human Clinical Trials Gastrointestinal Endoscopy follows the International Committee of Medical Journal Editors (ICMJE)’s Uniform Requirements for Manuscripts Submitted to Biomedical Journals. All prospective human clinical trials eventually submitted in GIE must have been registered through one of the registries approved by the ICMJE, and proof of that registration must be submitted to GIE along with the article. For further details and explanation of which trials need to be registered as well as a list of ICMJE-acceptable registries, please go to http://www.icmje.org.

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APPENDIX 1. Grading of recommendations and levels of evidence Grade A - Evidence from large randomized clinical trials or systematic reviews of multiple randomized trials, which collectively have at least as much data as one single well-defined trial. - Evidence from at least one ”All or None” high-quality cohort study; in which ALL patients died/failed with conventional therapy and some survived/succeeded with the new therapy (e.g., chemotherapy for tuberculosis, meningitis, or defibrillation for ventricular fibrillation); or in which many died/failed with conventional therapy and NONE died/failed with the new therapy (e.g., penicillin for pneumococcal infections). - Evidence from at least one moderate-sized RCT or metaanalysis of small trials, which collectively only has a moderate number of patients - Evidence from at least one RCT Grade B - Evidence from at least one high-quality study of nonrandomized cohorts who did and did not receive the new therapy. 9 Evidence from at least one high-quality case control study. - Evidence from at least one high-quality case series Grade C - Opinions from experts without reference or access to any of the foregoing (e.g., argument from physiology, bench research, or first principles). The evidence may not completely fit into neat compartments and extrapolations to another study may be warranted. In such situations, a combination of grading, for example, Grade A/C, may be used. In addition, the nonrandomized data can be so overwhelmingly clear and biologically plausible that it would be reasonable to be given as Grade A. Adapted and modified from McDonald et al.

APPENDIX 2. To cap or not to cap during screening colonoscopy: a meta-analysis Material and methods We searched published randomized controlled clinical trials comparing the use of distal attachments versus

Category

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standard colonoscopy through MEDLINE and Evidence Based Medicine Reviews (Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Review) through November 1, 2011 and included studies in English that compared use of white light colonoscopy with and without cap. In addition, we manually reviewed the reference lists of all retrieved articles. Two independent reviewers extracted data. We evaluated the association of the use of cap in screening colonoscopy with adenoma detection rate (ADR), mean number of adenomas per patient, location of adenomas (right and left-sided) and size of adenomas (⬍ 5 mm and ⬎⫽ 5 mm), compared to standard colonoscopy. We calculated pooled Risk Ratios (RR) and Mean Differences (MD) using a DerSimonian Laird random effects model with 95% confidence intervals (CI), and the number needed to treat (NNT) using Review Manager 5.1 software and assessed study heterogeneity using the Cochran Q␹2 test and I2 statistic. The quality of evidence was evaluated using GRADEPro.

Results We identified 14 unique studies and summarized the meta-analysis findings in the Table. The ADR was studied in 1629 patients. The pooled ADR in patients who underwent colonoscopy with a cap was 46.6% (385/ 827) versus 40.3% (323/802) without cap. The pooled RR was 1.14 (CI 95% 1.03 to 1.27, P ⫽ 0.01) and the NNT was 16.6 patients. The heterogeneity between studies was low (I2 ⫽ 8%). The mean number of adenomas detected per subject was marginally higher when a cap was used (MD ⫽ 0.43 (95% CI ⫽ ⫺0.03 to 0.89, p ⫽ 0.07; I2 ⫽ 73%). The quality of evidence for both the ADR and mean number of adenomas detected was determined to be moderate. Though the use of cap significantly increased the number of patients with at least one adenoma compared to the patients who underwent standard colonoscopy, the difference was in the detection of diminutive adenomas–the cap had no significant impact on the detection of adenomas in the right colon, those 5 mm or larger or on the mean number of advanced adenomas detected per subject (see Table).

Risk Ratio [95% CI]

Heterogeneity

Adenoma detection rate

1.14 [1.03-1.27]

8%

Polyp detection rate

1.04 [0.93-1.17]

58%

Detection of adenoma in the right-side

1.33 [0.94-1.87]

86%

Detection of adenoma in the left-side

1.25 [0.99-1.58]

73%

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Adenoma ⬉ 5 mm

1.35 [1.05-1.72]

82%

Adenoma ⬎ 5 mm

1.14 [0.75-1.75]

84%

Mean Difference [95% CI] Average number of adenoma per subject

0.43 [⫺0.03-0.89]

73%

Average number of polyp per subject

0.29 [⫺0.19-0.76]

83%

Average number of advanced adenoma per subject

0.07 [⫺0.03-0.17]

69%

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