| | Double Balloon Enteroscopy: TechniquesDouble balloon endoscopy realized endoscopists’ dream of observing the small intestine and providing treatment without excessive stress on patients. Stabilization of the intestine by gripping the intestinal wall with a balloon attached to the distal end of a flexible overtube enables the endoscope to go deeper through the tube by preventing further extension even with bending or looping of the intestine, which is the principle of the double balloon method. In addition, another balloon was attached to the endoscope tip to prevent the withdrawal of the endoscope tip during the advancement of the overtube, resulting in the double balloon endoscope. The endoscope moves forward using two balloons in sequence while folding and shortening the long intestine onto the overtube and making a concentric circle with its shaft. In this article, we will describe the insertion principle, the basis for development of the double balloon endoscope, and detailed insertion procedures with some tips and devices. Although endoscopic observation of the small intestine had been tried from the early stage of the era of fiberoscopy, the insertion method of enteroscopy did not make remarkable progress for about 30 years. Push enteroscopy had been the standard procedure of enteroscopy during this time period. Push enteroscopy, however, has a limitation in the range of insertion, which is at most 100 cm beyond the ligament of Treitz.1 As a consequence, most parts of the small intestine had been beyond the reach of a standard enteroscopic examination. Double balloon endoscopy (DBE) was developed using a novel idea of endoscopic insertion, namely the double-balloon method.2 The idea occurred to one of the authors (Yamamoto) in 1997 when he saw an examination of push enteroscopy which resulted in vain without reaching the lesion despite considerable efforts of both the endoscopist and the patient. The first prototype of DBE was developed by himself. Then Fujinon Company started collaboration in 2000, and the first product of DBE (EN-450P5; Fujinon Corp., Saitama, Japan) was released to the market in November 2003. The detail of the principle of the method is described below. Technique: Principle of DBE  Simple insertion of an endoscope into the small intestine may lead to bending and the formation of loops, and further insertion may extend the bent intestine so that the endoscope tip will not move forward. In other words, even with bends and loops, the endoscope can move forward if no further stretching of the intestine occurs. The double balloon method was developed focusing attention on this factor.2, 3 An overtube equipped with a soft balloon holds the bent intestine in one position. Inflating the balloon holds the intestine internally and proximally to prevent it from coming (or sliding) off the overtube. Insertion of the endoscope thus will not cause further stretching of the intestine even if it is bent. This effectively transmits the insertion distance to the endoscope tip, enabling the endoscope to move further from the balloon on the distal end of the overtube as the fixation point (Fig. 1A and B). To insert the endoscope further, another balloon is attached to the tip of the endoscope. Inflating the balloon on the endoscope tip at the furthest point of one stroke of insertion to hold the intestine prevents the endoscope from coming off during insertion of the overtube. This effectively makes the intestine fold up on the overtube for the length of every insertion stroke, enabling further insertion of the endoscope. Technique: Instruments The DBE system consists of a dedicated endoscope which can mount a balloon at its distal end, an overtube with a balloon, and a balloon controller to inflate or deflate the balloons (Fig. 2). Currently, three types of DBE are available from Fujinon Company: diagnostic type (EN-450P5; Fujinon, Saitama, Japan), therapeutic type (EN-450T5; Fujinon), and shorter version of therapeutic type (EC-450BI5; Fujinon). The endoscopes of all the types have the air channel inside for the balloons. They are used in combination with a flexible overtube, mounted with a balloon at the distal end (Fig. 3). The inner and outer surfaces of the tube are hydrophil-coated. Both endoscope and overtube balloons are made of latex, which is 0.1 mm thick and very soft, and can be inflated or deflated by a dedicated balloon controller (PB-20; Fujinon) with one-touch controls, while monitoring the air pressure (Fig. 4). The balloons are used at 45 mm Hg, which is the lowest possible pressure to hold the intestine for endoscope insertion and designed not to cause pain or discomfort to subjects due to balloon inflation. The differences among the three types of DBE are in the length and diameter. The working length of EN-450P5 and EN-450T5 is 200 cm, and the working length of EC-450BI5 is 152 cm. EN-450P5 is a thin endoscope with external diameter of 8.5 mm, and forceps channel diameter of 2.2 mm; it is used with an overtube that has an external diameter of 12.2 mm and an internal diameter of 10 mm. Both EN-450T5 and EC-450BI5 have an external diameter of 9.4 mm and forceps channel diameter of 2.8 mm. EN-450T5 is used with a 145-cm overtube that has an external diameter of 13.2 mm and an internal diameter of 11 mm. EC-450BI5 is used with a 105-cm overtube that has an external diameter of 13.2 mm and an internal diameter of 11 mm (Table 1). | | |  | Endoscope | EN-450P5/20 | EN-450T5/W | EC-450BI5 | |
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| Outer diameter (mm) | 8.5 | 9.4 | 9.4 | | | Accessory channnel (mm) | 2.2 | 2.8 | 2.8 | | | Working length (mm) | 2000 | 2000 | 1520 | | | Total length (mm) | 2300 | 2300 | 1820 | | | | |
The shorter DBE, EC-450BI5, is useful for colonoscopy and for ERCP in patients with Roux-en-Y anastomosis. Most accessory devices for colonoscopy and ERCP can be used with this endoscope. Routes of Insertion DBE can be done either orally or transanally. Oral insertion alone may allow, but less frequently, observation of the entire small intestine. To ensure observation of the total small intestine, transanal insertion that provides the subject with less discomfort is normally performed initially, and a tattoo is made at the furthest point reached by the endoscope. If the tattoo can be found during the next oral insertion, then observation of the total small intestine is confirmed. Although clipping requires an accessory channel diameter of 2.8 mm, if observation in the reverse direction is scheduled within a few days, a marking clip may be used in addition to or in place of tattooing. In a case of suspected stenosis in the small intestine, an abdominal CT before the endoscopy may be useful. Intestinal dilation at the oral side of the stenosis can be useful in localizing the stenotic lesion. Careful readings of the CT may allow us to follow the full length of the small intestine, permitting us to determine the route of insertion (Fig. 5). If a long decompression tube is already inserted orally, Gastrografin contrast radiography through the tube may be useful. In some cases, a long decompression tube can be used as a guide to insert an overtube followed by insertion of an endoscope.4 When DBE will be performed to determine the cause of bleeding in the small intestine, route selection may differ between elective endoscopy and that for ongoing bleeding. For elective endoscopy, the location of the lesion is assumed according to the clinical course and the results of other laboratories in choosing a route closer to the lesion. We can also roughly localize the site of bleeding according to the color of the feces.5 Red to dark red feces often indicates bleeding in the lower small intestine, and transanal insertion should be chosen. Black feces may indicate bleeding in the esophagus, stomach, and upper small intestine, but care should be taken because, in the case of constipation, feces can be black due to prolonged retention in the intestine even with bleeding in the lower small intestine. In addition, capsule endoscopy is useful for determining the route. For ongoing bleeding, oral insertion without bowel preparation should basically be chosen. In the small intestine under physiological conditions, unlike in the colon, regurgitation of intestinal fluid seldom occurs; therefore, the source of bleeding can often be identified in proximity to bloody intestinal fluid during oral insertion. During transanal insertion, bloody intestinal fluid may cause poor visibility, and the air supply associated with insertion of an endoscope may cause oral regurgitation of bloody intestinal fluid, leading to very difficult identification of the source of bleeding. When an examination will be conducted for a neoplastic lesion using DBE, the results obtained from other modalities (eg, CT, contrast radiography of the small intestine, and capsule endoscopy) should be comprehensively evaluated to choose the easier route of insertion. When multiple lesions are expected, in case of some types of tumors such as carcinoid and lymphoma, observation of the entire small intestine should be scheduled. Detailed Insertion Procedure for DBE It is important when inserting a DBE to arrange the intestine (concentrically) for easier insertion by effectively shortening it to move the endoscope tip forward with the minimum force necessary. In order for the balloon to hold the intestine, as well as for the intestine to shorten effectively, air in the intestine will be an obstacle. Therefore, the minimum amount of air should be supplied into the intestine during insertion of a DBE. An endoscope tip hood (DH-14EN, DH-17EN; Fujinon) is useful for insertion with the minimum air supply necessary (see “Hood” below for details). Oral Insertion Before insertion of the endoscope, adequate lubricant is applied to the tip and the balloon, and a lens cleaner is applied to the lens. Initially, both balloons are deflated. Until reaching the stomach, one operator inserts only the endoscope with the overtube fixed at the most retracted position (Fig. 6A). When the endoscope reaches between the antrum and the gastric angle, the operator takes a step back so the assistant can insert the overtube along the endoscope until the proximal end of the overtube passes the white line as the distance marker at 155 cm on the endoscope shaft (Figs. 6B and 7). At this time, adequate lubricant should be applied to minimize the stimulus to the pharynx. Then, the operator inserts the endoscope to the horizontal part of the duodenum and inflates the endoscope tip balloon (Fig. 6C and D), after which the assistant moves the overtube to the white line along with the endoscope and inflates the balloon on the overtube (Fig. 6E and F; there is an opinion that balloon inflation in the descending part of the duodenum should be avoided to prevent the complication of pancreatitis, although no causal relationship has been found). For the first stroke after entry into the duodenum, shortening procedure of the intestine is not necessary before the second stroke of insertion. The balloon on the tip of the endoscope is deflated for moving to the jejunum through the duodenum as far as possible, followed by inflation of the balloon on the tip of the endoscope to hold the intestinal wall (Fig. 6G–I). In many cases, the endoscope goes over the ligament of Treitz (duodenojejunal junction) during the second stroke. After the balloon on the overtube is deflated, the overtube is again advanced to pass the white line where the overtube balloon is inflated again (Fig. 6J–L). When the endoscope is pulled together with the overtube with both balloons inflated to hold the intestine, any bending of the endoscope will straighten in the stomach, and the range of the small intestine through which the overtube has been inserted is folded (Fig. 6M and N). Simultaneously, the anal side of the intestine is simplified morphologically. If any resistance is felt, further shortening should be stopped. Excessive shortening may cause the endoscope to come off when the pulling force exceeds the holding strength of the balloons. In addition, a vagal reflex may occur. The endoscope should be inserted further through the small intestine by repeating the above procedure (Fig. 6O and P). At the beginning of the training, operators may insert the endoscope and overtube with fluoroscopic guidance for confirmation of its shape, whereas it is less necessary for more skilled operators. In an oral insertion, an endoscope can be inserted in either a clockwise or counterclockwise manner. It can be inserted in the direction that goes more smoothly so that it follows a concentric circle with a larger diameter. Transanal Insertion Before transanal insertion, bowel preparation similar to that for colonoscopy is needed; in particular, thorough preparation without remaining feces is desired for the transanal DBE. In some facilities, bowel preparation is performed the day before endoscopy. Preparation the day before endoscopy may make it difficult to insert the endoscope because of mucosal secretions attached to the colon wall by the time of endoscopy, which causes poor fixation of the balloons. Therefore, for transanal DBE, bowel preparation should be performed on the morning of the endoscopy. Insertion in the Colon DBE insertion will be much easier with fixation using the balloons even when the endoscope is passed through the colon. Since inflation of the balloon for DBE is not determined by diameter but by internal pressure, the balloon can be inflated adequately in the colon as well. It is difficult to insert the DBE into the cecum, like colonoscopy, without using the balloons, which should be avoided. In addition, an excessive amount of air may make it difficult to shorten the intestine, leading to poor insertion of the endoscope. Therefore, even when the endoscope is passed through the colon, insertion with a minimum amount of air is preferable. The practical insertion procedure is as follows. Initially, one operator inserts the endoscope about 45 cm from the anus, similar to the usual colonoscopy, without the overtube (Fig. 8A). In a case with no adhesion and a relatively short sigmoid colon, even the thin, flexible DBE can often be inserted linearly to the splenic flexure. In a case with a loop formed in the sigmoid colon, the endoscope is initially inserted to the sigmoid-descending junction. Then, the balloon on the tip of the endoscope is inflated to hold the colon internally followed by insertion of the overtube along with the endoscope to pass the white line at the distance of 155 cm by an assistant (Fig. 8B). The hydrophilic coating on the internal surface of the overtube enables nonresistant insertion if water is injected through a water supply route into the overtube. However, since residues in the colon, when invading the overtube, may make further insertion difficult due to increased friction, an assistant should frequently add water, especially during transanal insertion. Then, the balloon on the overtube is inflated to hold the colon (Fig. 8C). Without complete straightening of the sigmoid colon, the overtube prevents bending and stretching of any loops, which maintains the obtuse angle of the sigmoid-descending junction (Fig. 8D). With the balloon on the tip of the endoscope deflated, the endoscope is passed through the descending colon to the splenic flexure (Fig. 8E). When the endoscope tip reaches the splenic flexure, the balloon on the tip of the endoscope is inflated. Then, the balloon on the overtube is deflated to make the overtube move forward (Fig. 8F). If any resistance is felt due to a loop in the sigmoid colon, the overtube should be moved forward after the loop is released and straightened. Holding the splenic flexure by the balloon on the overtube tip inflated, the endoscope tip balloon is deflated to move toward the transverse colon (Fig. 8G). In some cases, it can be inserted easily into the cecum. In a case with ptosis of the mid-transverse colon, for example, the endoscope tip, followed by the overtube, is moved close to the hepatic flexure, and the transverse colon can be pulled up and straightened by pulling the endoscope and overtube with both balloons inflated and fixed to the hepatic flexure (Fig. 8H). Then, the endoscope balloon is deflated to move the endoscope forward, and it can be inserted easily through the obtuse hepatic flexure to the cecum (Fig. 8I). How to Go Over the Ileocecal Valve In general, the endoscope can be passed easily through the ileocecal valve. To make passage through the ileocecal valve easier, the following procedures can be used: the endoscope should be inserted into the colon with a minimal amount of air; insertion should be performed in the supine position; and the endoscope tip is straightened before further insertion after the endoscope tip goes over the ileocecal valve. In rare cases, it is difficult for the endoscope to go over the ileocecal valve even with the above procedures. When the angle is acute between the ascending colon and terminal ileum, even if the endoscope can be inserted into the terminal ileum by adjusting the angle of the endoscope, it may come off into the cecum during further insertion. To overcome this problem, there are two methods for going over the ileocecal valve: one is to insert the endoscope after pulling the overtube toward the anus in the ascending colon with its balloon inflated making the inlet angle at the ileocecal valve to the terminal ileum obtuse (Fig. 9), and the other method is to push the endoscope after turning over in the cecum. In addition, when the endoscope cannot go over easily in the supine position, it may be useful to move the patient into the left or right lateral position or manually compress the left inferior abdomen. The former method should be tried initially, and if it is still difficult, then the other method should be tried. Further Insertion into the Ileum After passing through the ileocecal valve, the endoscope is inserted as far as possible, and the endoscope tip balloon is inflated and fixed to the ileum (Fig. 8I and J). Then, the overtube is inserted to the white line, and the overtube balloon is inflated (Fig. 8K). No shortening is conducted after the first stroke after entry into the ileum, and then followed by the second stroke. Again, the endoscope tip balloon is deflated to move the endoscope further into the ileum (Fig. 8M). The endoscope tip balloon is inflated at the furthest fixation point in the ileum, and then the overtube balloon is deflated to insert the overtube to the white line. The ileum is folded on the overtube by pulling the whole apparatus with both balloons inflated (Fig. 8N and O). The endoscope is inserted further into the small intestine by repeating this procedure (Fig. 8P). Measurement of the Insertion Distance In a small intestine as long as 7 m, no “Merkmal” (marking) is available to identify location. In addition, the jejunum–ileum junction is not anatomically clear. Consequently, we record estimated insertion distances for each stroke and add them up for an estimation of the location of the lesion or the furthest point reached by the endoscope in the small intestine (eg, first stroke, 20 cm; second stroke, 30 cm; third stroke, 25 cm; total, 75 cm). May and coworkers conducted a study using the Erlangen Model and reported that such estimated insertion distances corresponded almost to the actual distance of insertion.6 For orally inserted endoscopy, the length of insertion from the pylorus ring should be recorded, whereas that from the ileocecal valve should be recorded for transanally inserted endoscopy. Insertion in a Case of Difficult Endoscope Insertion In patients with inflammatory bowel diseases, including Crohn’s disease, and in postoperative conditions, insertion may be difficult due to intestine–abdominal wall or intestine–intestine adhesion. The DBE apparatuses for the small intestine include the EN-450P5 with an outside diameter of 8.5 mm and the EN-450T5 with an outside diameter of 9.4 mm. Despite the approximately 1-mm difference, the EN-450P5 is more appropriate for further insertion in a patient with intestinal adhesion who would not undergo such procedures as dilation which require a bigger accessory channel. Basically, a DBE should be inserted concentrically. For smoother insertion, the endoscope should be inserted so that it follows the larger loop. Adhesion may create a highly bent lumen, and the endoscope tip will follow the shape; therefore, the endoscope makes a smaller loop or an S-shaped configuration. If insertion becomes stuck, the insertion loop should be observed with fluoroscopy to insert the endoscope as it follows the larger loop. If one cannot avoid an S-shaped endoscope, abdominal compression may be useful. During operation of the endoscope, when trying to go over a highly bent point by force, the endoscope will not move forward but the overtube will move backward if the inserting force exceeds the holding strength. Therefore, it is important to be careful to avoid a sharp angulation of the endoscope tip and to ensure that the insertion force is transmitted to the endoscope tip by jiggling. In addition, similar to colonoscopy with adhesion, small bendings should be passed through by shortening it linearly using a slalom technique. Other Considerations Hood As is the case with colonoscopy, a hood on the tip of the endoscope may facilitate insertion and observation. Although the small intestine has many bends that will obscure the direction in which to move, the hood provides some clearance from the mucosa to facilitate detection of Kerckring’s fold, orthogonal to which is the direction to move. During observation, the hood is useful for finding micro lesions, such as angioectasia, because observation behind Kerckring’s folds can be made by pressing gently on the fold with the hood. For the procedures in the biliary system using the DBE, a longer transparent hood of about 4 mm in length may facilitate cannulation into the biliary tracts through the papilla of Vater or choledochojejunostomy. In case of removing the endoscope with the overtube left, for retrieval of polyps, dilation,7, 8 and stenting,9 the balloon should be fixed with thread with no tip hood.10 Controlling Air Volume As described above, it is important to avoid an excessive amount of air during insertion of the DBE more than in colonoscopy. Greater air volumes may decrease the force for the balloon to hold the intestine, leading to difficulty in shortening. In addition, increased abdominal pressure may cause nausea and a vagal reflex. The endoscope should be inserted using the minimum air supply necessary. Lubricant As described above, the overtube is coated by hydrophilic material; therefore, it shows little frictional resistance with injected water, although residue in the intestine may increase the frictional force and make insertion difficult. Frequent water supply to the overtube will be needed. If the frictional force is still too great, a mixture of water with a lubricant gel may reduce it, which is worthwhile to try. References 1. 1Landi B, Tkoub M, Gaudric M, et al. Diagnostic yield of push-type enteroscopy in relation to indication. Gut. 1998;42:421–425. MEDLINE 2. 2Yamamoto H, Sekine Y, Sato Y, et al. Total enteroscopy with a nonsurgical steerable double-balloon method. Gastrointest Endosc. 2001;53:216–220. Abstract | Full Text |
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3. 3Yamamoto H, Sugano K. A new method of enteroscopy: the double-balloon method. Can J Gastroenterol. 2003;17:273–274. MEDLINE 4. 4Yano T, Yamamoto H, Kita H. Technical modification of the double-balloon endoscopy to access to the proximal side of the stenosis in the distal colon. Gastrointest Endosc. 2005;62:302–304. Abstract | Full Text |
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5. 5Gary RZ, Dan RT, Thomas MS, et al. An objective measure of stool color for differentiating upper from lower gastrointestinal bleeding. Dig Dis Sci. 1995;40:1614–1621. MEDLINE |
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6. 6May A, Nachbar L, Schneider M, et al. Push-and-pull enteroscopy using the double-balloon technique: method of assessing depth of insertion and training of the enteroscopy technique using the Erlangen Endo-Trainer. Endoscopy. 2005;37:66–70.
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7. 7Sunada K, Yamamoto H, Kita H, et al. Case report: successful treatment with balloon dilatation in combination with double-balloon enteroscopy of a stricture in the small bowel of a patient with Crohn’s disease. Dig Endosc. 2004;16:237–240. 8. 8Sunada K, Yamamoto H, Kita H, et al. Clinical outcomes of enteroscopy using the double-balloon method for strictures of the small intestine. World J Gastroenterol. 2005;11:1087–1089. MEDLINE 9. 9Hayashi Y, Yamamoto H, Kita H, et al. Non-steroidal anti-inflammatory drug-induced small bowel injuries identified by double-balloon endoscopy. World J Gastroenterol. 2005;11:4861–4864. MEDLINE 10. 10In: Sugano K, Yamamoto H, Kita H editor. Double-Balloon Endoscopy: Theory and Practice. Tokyo: Springer; 2006;. Division of Gastroenterology, Department of Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan.  Address reprint requests to Hironori Yamamoto, MD, Department of Medicine, Division of Gastroenterology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan.
Hinori Yamamoto, MD, has applied for the patent in Japan on double balloon endoscopy described in this manuscript and belongs to a department funded by Fujinon Corporation, the manufacturer of the double balloon endoscopy system described in this report. PII: S1096-2883(08)00003-X doi:10.1016/j.tgie.2008.01.002 © 2008 Elsevier Inc. All rights reserved. | |
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