Yi Jia1, Syed M. Abbas Fehmi2, and Michael L. Kochman1 1 University of Pennsylvania Health System, Philadelphia, PA, USA 2 University of California San Diego, San Diego, CA, USA “Dilation” when mentioned by a gastroenterologist refers to widening or opening an intraluminal stricture in a segment of the gastrointestinal (GI) tract. A stricture is an abnormal narrowing or constriction of the luminal GI tract, which may be in the form of an intraluminal, intrinsic mural, or extramural process. The focus of this chapter will be on the technique of performing effective and safe dilation in the luminal GI tract. We will comment on the skill set required to perform this procedure, how to best acquire this skill set, and pearls on mastering the technique and propose some measures to assess the proficiency of an endoscopist in performing dilation. We will concentrate on making the concepts of dilation clear rather than focusing on any specific device type. The small differences that exist between similar devices manufactured by different companies and between the categories of devices are always changing, and as long as the technique is understood, one can easily adapt to new technology device iterations. Lastly, we shall not be covering dilation of the pancreaticobiliary system as this will be covered in a dedicated chapter. Likewise, discussion regarding the management of complications, the efficacy data of different techniques, and techniques for stricture management other than dilation are beyond the scope of this chapter. Dilators can be divided into two basic types: semirigid fixed‐diameter push‐type “bougie” dilators and the pneumatic through‐the‐scope (TTS) balloon dilators. The polyvinyl chloride wire‐guided dilators are available from various manufacturers. An excellent summary of different designs can be found in the technology status evaluation report from the ASGE [1]. The differences between manufacturers are not of substantive importance, but familiarity with the device that will be utilized is needed. These differences include the designs (wire guided or not), length of the dilator (usually 70–100 cm), the length of the distal taper, the calibers measured in either millimeter or French (usually 15–60 Fr), and the cost. The radiopaque markers may be either focally embedded (the proximal marker usually marking the site of maximal dilating caliber, Savary‐Gilliard dilators, Cook Medical, Winston‐Salem, North Carolina, USA) or with barium impregnation throughout the entire dilator (American Dilation System dilators, ConMed, Utica, New York, USA; SafeGuide dilators, Medovations, Milwaukee, USA). The length of the bougie dilators is measured in two different ways, and both are marked on some dilators: the American system measures the distance from the distal tip of dilator, while the European measures from the point of maximal diameter (size) of the dilator. The wire (available separately and in different lengths) used with these dilators is typically marked for distance (usually one mark every 20 cm) and should be kept kink‐free. The traditional bougie dilators include the liquid metal‐filled Maloney dilators. Given the concerns of mercury exposure via rupture or disposal and the clear limited life of this type of dilator, most have been replaced by tungsten for gravity assistance with much the same feel. These push‐type dilators are quite flexible, tend to easily curl at the tip during use, and have a higher complication rate when used in complex strictures and sedated patients. Overall they are used less frequently than in the past and are now primarily used in the setting of low‐risk dilation of Schatzki’s rings and by non‐sedated patients for self‐dilation in the upright position. The balloon dilators are typically made of inflatable thermoplastic polyethylene, with or without a wire guide to facilitate placement. Balloon dilators are available from a variety of manufacturers. A summary of the various designs can be found in the technology status evaluation report from the ASGE [1]. The differences between manufacturers include cost, a single fixed‐diameter or multidiameter balloon, the balloon length, the required endoscope channel size, the guide wire diameter, and the different pressures required for achieving the marked nominal size. Wire‐guided TTS balloon dilators are passed through the endoscope accessory channel and over a guide wire. The balloons may be filled with water or with radiopaque contrast for improved fluoroscopic visualization. Achalasia balloon dilators are larger size diameter (30, 35, and 40 mm) balloon dilators primarily used for dilation in patients with achalasia [2]. These large dilators are wire guided and do not pass through the working channel of the endoscope. Push‐type dilators may be reprocessed, while most balloon dilators are single use only. Cost‐effectiveness ultimately depends upon local reprocessing costs and the acquisition costs of the dilators from the vendor. Balloon dilators do not have the “tactile feel” that fixed‐diameter push‐type dilators do, though the push‐type dilators require experience to be able to recognize the contribution of the stricture to resistance of passage. Balloon dilators do allow real‐time visualization of stricture dilation under direct endoscopic view and under fluoroscopic control of the dilation if filled with contrast, while the fixed‐diameter push‐type dilators can be observed under fluoroscopic control. Some feel that the availability of multidiameter balloon dilators can make the dilation process more time effective. These also provide the ability to perform the “continuous access technique” (see “Continuous access technique” section for detail), which can be extremely helpful under certain conditions (e.g., traversing malignant and complex obstructions). Multidiameter balloons have been shown to compare favorably with fixed‐diameter balloons with regard to diameter consistency and dilating force [3]. Both types of dilators are most commonly used in the esophagus, and current data does not suggest any difference in technical success or perforation rates between various types of dilators [4–7]. The exception to this is the use of blind non‐wire‐guided bougie (Maloney‐type) dilators in the setting of complex strictures that are associated with a higher perforation rate [7,8]. These are typically devices used during biliary endoscopy (biliary guide wires, catheters, and dilators). Their rare application in luminal dilation is in order to facilitate traversing and dilating tight complex strictures. These will be discussed later in the chapter. Other devices are also available for unique situations (incision techniques for refractory esophageal strictures and the use of endoprosthetics). These tools are not being discussed in this dilation chapter. Table 17.1 Endoscope outer diameter and channel size. Endoscopists should be familiar with the endoscope outer diameter/tip diameter and channel size to best plan the dilation procedure and the type and size of dilator selected. Representative information for the Olympus series as available at their website is shown (Table 17.1). Similar information for the Pentax or Fujinon endoscopes can be found on their representative websites. Occasionally the adjunctive use of bronchoscopes may be helpful. This is not required for simple strictures but is extremely useful in selected cases, especially when dilation is initially being performed in the setting of a complex non‐traversed stricture. The use of fluoroscopy can help the endoscopist successfully overcome the complex stricture associated with angulation, luminal irregularity, or a compromised lumen that may preclude passage of endoscope, including those with a large hiatus hernia or a diverticulum. Without fluoroscopy, safe passage of a guide wire or dilator can be extremely difficult, if not impossible. Fluoroscopy can also help in successful intubation of the esophagus when strictures are located proximally, making adequate visualization difficult. The esophagus is easily visualized on fluoroscopic images as an air column immediately posterior to the trachea and anterior to the spine. Fluoroscopy can also help affirm that the push‐type dilator’s maximal diameter has traversed the stricture. It can help in the positioning of a balloon dilator, to check if a “waist” is present, and to document relief of the stricture during the procedure. In a tertiary care referral center with referral for complex strictures, fluoroscopy may be used in up to 33% of all dilation procedures [9]. Fluoroscopy benefits are well established when using various dilators, where fluoroscopy is associated with a reduction in the risk of perforation [7,10,11]. The topic of training in the use of fluoroscopy is addressed in more detail in another chapter in this volume (see Chapter 13). All dilators use radial shear force to dilate the stricture zone. This concept is easy to understand especially when using the multidiameter balloon dilators with fluoroscopy. The Maloney and polyvinyl dilators are inserted with a longitudinal pushing force that is converted to radial expansible shear force by the distal ramp slope. This is relatively inefficient, and one can actually push a stricture distally (and potentially perforate proximal to the stricture) if the resistance of the stricture in the radial vector is greater than the resistance of the esophagus to movement in the longitudinal vector (shear force). Non‐wire‐guided bougie dilators may curl proximal to a stricture and not actually engage it, also potentially causing a proximal perforation. It is important to have a good understanding of terms used to describe strictures as they will be used throughout this chapter [5,7,8,12]. These are symmetric or concentric, straight, short (<2 cm), and allow passage of a diagnostic upper endoscope or visualization of the distal lumen, such as Schatzki’s rings, esophageal webs, and peptic strictures. Analogously, these are asymmetric; there is an inability to pass diagnostic upper endoscope, length (>2 cm), multiple, angulated, or accompanied by a significant hiatal hernia or esophageal diverticulum. We have proposed and published the following definition, which is being utilized in current clinical studies: “an anatomic restriction because of cicatricial luminal compromise or fibrosis that results in the clinical symptom of dysphagia in the absence of endoscopic evidence of inflammation. This may occur as the result of either an inability to successfully remediate the anatomic problem to a diameter of 14 mm over 5 sessions at 2‐week intervals (refractory) or as a result of an inability to maintain a satisfactory luminal diameter for 4 weeks once the target diameter of 14 mm has been achieved (recurrent). This definition is not meant to include those patients with an inflammatory stricture (which will not resolve successfully until the inflammation subsides) or those with a satisfactory diameter who have dysphagia on the basis of neuromuscular dysfunction (e.g., those with postoperative and post‐radiation therapy dysphagia)” [13]. Strictures are most commonly encountered in the esophagus, and as such the video illustrating the technique of dilation also features a prototypical esophageal stricture. Patients should be informed of the possibility of several sessions to achieve resolution of dysphagia before the first procedure. The technique and concepts are applicable to all strictures in the GI luminal tract unless otherwise indicated in the text and discussed separately (e.g., achalasia). Once it has been confirmed that luminal dilation is required (after review of history and all available imaging studies) and there are no absolute contraindications, dilation of the stricture is performed with a preliminary determination as to whether it is a simple or complex stricture. These dilators (the commonly ones used are American or Savary‐Gilliard) are polyvinyl chloride, latex‐free cylindrical solid tubes with a central channel designed to accommodate a soft spring‐tip metal guide wire. The use of the guide wire technique (whether rigid or balloon dilators) allows for both proximal and distal control of the stricture, which is felt to decrease the likelihood of a perforation. The first step is to position the tip of guide wire distal to the stricture, in the case of esophageal stricture preferably in the gastric antrum. If the stricture allows the passage of regular upper endoscope, this can be performed under direct visual guidance. However, if the endoscope cannot traverse the stricture, fluoroscopy can be used to direct passage of the guide wire tip into the gastric lumen. The spring tip should remain straight and not be allowed to coil, and there should not be significant resistance felt to the passage of wire. As the wire passes the GE junction and the diaphragm into the gastric body, the passage of wire along the greater curve of the stomach can be visualized under fluoroscopy as confirmation of wire placement intraluminally into the gastric body. Step two is removal of the endoscope while maintaining the wire positioned in the stomach. If fluoroscopy is being used, the wire position can be confirmed radiographically as well. An assistant should be poised at the mouth to hold the wire in place as the endoscope is withdrawn. Care must be taken that the sharp proximal tip of the guide wire does not hit the assistant, patient, or physician. Before completely removing the endoscope, the endoscopist should affirm optimal positioning of the wire by checking the marks on the guide wire that indicate its location. Each mark represents 20 cm of the wire. Three marks are typically seen at the incisors in a patient with an intact UGI tract, which would indicate 60 cm of wire in esophagus and stomach. Step three is passing the bougie dilator over the wire after the endoscope has been removed. The physician should check the size on the dilator to make sure it is what was requested. When using the commonly used push‐type Savary‐Gillard (size shown in millimeter) or American Dilation System (size shown in French) dilators, there may be two sets of markings on the dilator. The American system measures the distance from the tip of dilator, while the European measures from the point of maximal diameter of the dilator. Optimal patient position during this part of the procedure is very important. The patient should be left lateral with neck slightly hyperextended in the “sword‐swallowing position.” The physician’s stance is important: feet shoulder width apart with position at the level of the head or slightly above with the right hand holding the wire stably against the physician’s hip or chest and the dilator being grasped with the fingers of the left hand and advanced gently. A small amount of lubrication on the dilator may help. A stable position should be maintained on the guide wire with the right hand held against the physician’s body so that it is stable and does not inadvertently migrate distally. If fluoroscopy was being used, additional confirmation of a stable position of the wire and documentation of traversing of the stricture with the dilator may be obtained. Removal of dilator to allow the passage of additional dilators over the wire is analogous to the removal of the endoscope. If no further dilation is being performed, gently withdraw the wire through the dilator until the tip gently impacts the tip of dilator and then withdraw as a unit. “Rule of Threes”: After moderate resistance is felt on the dilator, it is often stated that the size of dilator should not be increased more than two additional consecutively sized dilators for a total of three dilators. It is recommended that endoscopists to be cognizant of and aware of the application of the above “rule.” However, this generally practiced technique has not been confirmed to improve safety and efficacy by studies [14]. If a total loss of resistance is felt after moderate resistance was first appreciated, resistance at the subsequent larger diameter dilator will not be felt, giving a false impression of safety to continue dilations; the earlier loss of resistance may not be due to stricture remediation and may represent a tear in the muscularis propria layer; further dilation should not be performed until this is investigated.
17
Luminal Dilation Techniques (Strictures, Achalasia, Anastomotic, IBD)
Introduction
Equipment
Fixed‐diameter push‐type or “bougie” dilators
Balloon dilators
Differences between fixed‐diameter push‐type and balloon dilators
Ancillary devices
Outer diameter (mm)
Channel size (mm)
Olympus GIF‐HQ190 (standard upper endoscope)
9.9
2.8
Olympus GIF‐1TH190 (therapeutic upper endoscope)
10.0
3.7
Olympus GIF‐XP190N (pediatric upper endoscope)
5.9
2.2
Olympus TJF‐Q190V (therapeutic ERCP scope)
11.3
4.2
Olympus PCF‐Q190DL/I (pediatric colonoscope)
11.7
3.2
Olympus CF‐Q190L/I (adult colonoscope)
12.8 (tip 13.2)
3.7
Olympus GF‐UE160AL5 (radial echoendoscope)
11.8 (tip 13.8)
2.2
Olympus GIF‐N180 (transnasal endoscope)
4.9
2.0
Endoscope key points to remember
Fluoroscopy
Mechanism of dilation
Terminology
Simple stricture
Complex stricture
Refractory or recurrent stricture (esophagus)
Technique of dilation
Fixed‐diameter push‐type or “bougie” dilation
TTS balloon dilation
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