Andrew J. Read, MD
Ryan Law, DO
Michael D. Rice, MD
Evaluation of the small bowel is difficult to endoscopically examine due to its length, distensibility, and tortuosity. Early methods for endoscopic evaluation of the small bowel were limited by efficacy. Push enteroscopy, as previously discussed, is suitable for evaluation of the proximal small bowel and distal ileum but is insufficient in visualizing the majority of the jejunum and more proximal ileum. To address this concern, Yamamoto el al. began to develop techniques for device-assisted enteroscopy which permitted evaluation of the entire small bowel and allowed for therapeutic intervention, if necessary. Currently, systems for single-balloon enteroscopy (SBE), double-balloon enteroscopy (DBE), and spiral enteroscopy exist. Use of these techniques is cumbersome, time-consuming, and require special training to perform. Furthermore, each platform includes dedicated equipment, both capital and disposable. This chapter will discuss single-balloon, double-balloon, and spiral enteroscopy including indications, contraindications, and the technical aspects of performing the procedure.
1. Diagnosis and/or therapy for suspected proximal small bowel bleeding
2. Overt gastrointestinal bleeding with a negative upper endoscopy and colonoscopy
3. Occult gastrointestinal bleeding or iron-deficiency anemia with a negative upper endoscopy and colonoscopy
4. Radiographic abnormalities found in the middle to distal small bowel
5. Evaluation of patients with polyposis syndrome
6. Placement of a percutaneous jejunostomy tube
7. Retrieval of foreign bodies
8. Access to altered anatomy (e.g., Whipple, Roux-en-Y gastric bypass, etc.)
9. Diagnosis and/or therapy for video capsule endoscopy findings in the middle to distal small bowel
CONTRAINDICATIONS (SIMILAR TO THOSE OF UPPER ENDOSCOPY)
1. Bowel perforation, known or suspected
2. Bowel obstruction, known or suspected
3. Severe respiratory distress (unless the patient is on mechanical ventilation)
4. Atlantoaxial subluxation
5. Hemodynamic instability
6. Inability to provide adequate sedation
1. Uncooperative patient
2. Acute myocardial infarction
3. Small bowel ileus
4. Latex allergy. The balloons contain latex and thus DBE is contraindicated in severely latex allergic patients. Alternative procedures such as SBE, which are latex free, or premedication should be considered in consultation with anesthesia and/or allergy
a. Elevated international normalized ratio (INR) >1.5
b. Partial thromboplastin time (PTT) 20 seconds over control
c. Bleeding time >10 minutes
d. Platelet count <50,000/mL
1. A dedicated SBE endoscope, 200 cm length with 2.8 mm working channel, and a corresponding overtube (13.2 mm outer diameter) OR DBE enteroscope, 180 to 230 cm length with a working channel ranging from 2.2 mm (pediatric) to 3.2 mm (therapeutic), and a corresponding overtube (range 12.2 to 13.2 mm outer diameter) OR spiral overtube, 118 cm length (22 cm spiral segment and 92 cm working length) with 48F (16 mm) outer diameter, including the locking coupler, green rotational handgrip, and spiral element. The 22 cm spiral segment is 70 cm distal to the green rotation handle. The spiral overtube does not contain latex. (The spiral overtube is intended to be used with 200 cm long enteroscopes with outer diameters between 9.1 and 9.5 mm.)
2. Light source and video system.
3. Balloon control unit.
4. Water supply and carbon dioxide insufflation. Carbon dioxide is highly recommended over room air for improved patient comfort and recovery, given extended duration of deep enteroscopy procedures.
5. Surgical lubricating jelly, gloves, eye protection, gown, shoe covers, and washcloth or gauze.
6. 60-mL syringe for flushes, biopsy forceps, electrocautery equipment (argon plasma coagulation (APC), where available, if bleeding is an indication), hemostatic clips, epinephrine injection, and glucagon.
7. Continuous electrocardiogram, pulse oximetry monitoring, and consideration of continuous waveform capnography monitoring.
1. For an antegrade deep enteroscopy, we typically use 2L polyethylene glycol (PEG) electrolyte solution, taken the evening before the procedure. For a retrograde approach, an excellent colonic bowel preparation is required to maximize technical success of this procedure, and we typically use a 2-day bowel preparation with 6-8L of PEG solution.
2. Patients should fast a minimum of 2 hours from clear liquid ingestion and 6 hours from a light meal.
3. Therapeutic procedures are considered increased risk from a bleeding standpoint, and thus it is important to discontinue anticoagulation or dual antiplatelet therapy per periprocedural anticoagulation guidelines and in consultation with a patient’s cardiologist or hematologist, where applicable.
4. Informed consent should be performed in writing prior to initiation of the procedure.
5. Place an intravenous line for administration of sedation.
6. Antibiotic indications are the same as for standard upper endoscopy or colonoscopy.
7. Sedation: Individual anesthesia plan is developed in conjunction with the anesthesia team based on the procedure and the patient’s comorbidities. For antegrade procedures, we typically perform the procedure under general anesthesia with endotracheal intubation, but monitored anesthesia care could be considered. For retrograde procedures, we typically utilize monitored anesthesia care.
8. Position the patient in the left lateral decubitus position, as in standard upper endoscopy. Place a bite guard to protect the scope and patient’s teeth for antegrade procedures.
9. The appropriate overtube should be back-loaded on the endoscope prior to insertion. The balloon should be installed and tested prior to insertion.
10. A trained assistant familiar with the deep enteroscopy technique is necessary.
11. Appropriate consent, protective radiation gowns, and shields should be available if fluoroscopy is used. Fluoroscopy for deep enteroscopy is rarely necessary.
SINGLE-BALLOON ENTEROSCOPY PROCEDURE
1. Antegrade SBE insertion: Gently flex the patient’s head anteriorly prior to insertion of the enteroscope. The enteroscope is passed over the patient’s tongue and across the epiglottis to the cricopharyngeus muscle. The upper esophageal sphincter is traversed, and the esophagus and stomach are closely examined.
2. After excluding esophageal varices, the overtube is advanced. If there is concern that the overtube cannot safely be advanced, either due to varices or mechanical stenosis, then the scope can be withdrawn, the overtube removed, and the scope reinserted without an overtube to address the source of obstruction.
3. A careful diagnostic examination of the esophagus and stomach, including a retroflexed view of the cardia and fundus, should be performed prior to advancing the enteroscope into the small bowel. Assess for the presence of varices, Cameron erosions/ulcers, and gastric antral vascular ectasia (GAVE). These can be overlooked but may explain iron-deficiency anemia or melena. “Scope trauma,” or superficial mucosal injury, occurs frequently with device-assisted enteroscopy technique than with standard upper endoscopy or push enteroscopy.
4. The enteroscope should be shortened or straightened prior to entering the small bowel. This occurs by suctioning air from the stomach while gently withdrawing the enteroscope.
5. Small bowel insertion: The endoscope and overtube are advanced in a technique similar to push enteroscopy (see separate chapter) into the proximal jejunum. Prior to inflation of the balloon, it is important to ensure that the ampulla has been traversed to minimize potential balloon trauma in this region, thus mitigating the risk of pancreatitis.
6. Balloon basics: As there is only one balloon in SBE (present on the overtube), knowledge of balloon status (inflated/deflated) is simplified, and the mechanics are less complicated compared to DBE. However, the absence of a second balloon may lead to difficulty with enteroscope advancement and reduction.
7. Insertion technique: Once in the small intestine, the enteroscope is advanced to the point of maximal insertion. Anchoring is achieved by deflection of the endoscope tip toward the wall (in a hooking technique) and/or with use of continuous suction, as the overtube is advanced. Once both are maximally inserted, the overtube balloon is inflated, and the overtube and enteroscope are withdrawn together, while keeping the endoscope tip deflected in angled fashion to maintain positioning. This withdrawal aims to pleat the small bowel over the overtube. The scope is then advanced with the overtube balloon inflated, and the process is repeated as a cycle until the point of maximal insertion is reached.
8. Inspection of the mucosa should be done during intubation as well as during withdrawal of the endoscope. Frequent small bowel contractions may make visualization difficult. Intravenous (IV) glucagon (0.5 to 1 mg) may be given to reduce small bowel motility and improve mucosal examination. Care should be taken to look behind folds for small bowel pathology.
9. A working channel is present for diagnostic biopsies and therapeutic hemostasis. Cautery should be performed at lower energy settings because of the thinner wall of the small intestine. APC can be used for noncontact thermal treatment of small bowel angioectasias.
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