Deep endoscopic access using double- and single-balloon enteroscopes and rotational endoscopy has vastly improved endoscopic therapeutic options in the small intestine. In this new era of interventional enteroscopy, significant advances have been made in the endoscopic treatment of small bowel polyps, angioectasias, and strictures. Although a decade ago small bowel polyps arising in the setting of a polyposis syndrome such as Peutz-Jeghers would have necessitated surgical resection, today endoscopic resection can typically be performed with positive clinical results. This article describes the current endoscopic management of small bowel polyps, arteriovenous malformations, strictures, and miscellaneous lesions identified within the small intestine.
Key Points
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In the era of intraoperative enteroscopy, the endoscopist has access to a plethora of new endoscopes and devices, which have significantly altered the therapeutic modalities that can be applied deep within the small intestine.
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The need for intraoperative enteroscopy or surgical resection of small bowel has been significantly decreased (and in some cases, eliminated) by the application of these technologies in clinical practice.
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This field remains in evolution and the future will undoubtedly include the design of new instruments that may help overcome many of the technical limitations associated with performing therapeutic maneuvers deep within the small intestine.
Introduction
Advances in endoscopic techniques and the availability of newer endoscopes and accessories have allowed for exciting new applications of therapeutic endoscopy within the small intestine. Many procedures that were previously the purview of surgery are now performed endoscopically. This article provides an overview of the current endoscopic management of small bowel polyps, arteriovenous malformations (AVMs), strictures, and miscellaneous lesions identified within the small intestine.
Introduction
Advances in endoscopic techniques and the availability of newer endoscopes and accessories have allowed for exciting new applications of therapeutic endoscopy within the small intestine. Many procedures that were previously the purview of surgery are now performed endoscopically. This article provides an overview of the current endoscopic management of small bowel polyps, arteriovenous malformations (AVMs), strictures, and miscellaneous lesions identified within the small intestine.
General principles of endolumenal therapy in the small bowel
The primary challenge for endoscopic interventions in the small bowel is access to the lesions, particularly past the proximal jejunum. Endoscopic interventions in the proximal duodenum are usually performed with regular or therapeutic upper endoscopes or duodenoscopes. Previously, deeper access into the small bowel was achieved with the use of a pediatric colonoscope or a push enteroscope, which could be advanced to the proximal jejunum. More distal lesions would require intraoperative enteroscopy with significant associated morbidity.
In the past decade, the introduction of single-balloon (SBE) (Olympus Corporation, Tokyo, Japan) and double-balloon enteroscopes (DBE) (Fujinon Inc, Saitama, Japan) and rotational enteroscopy (RE) (Spirus Medical Inc, Stoughton, MA, USA) has substantially improved deep access into the small bowel so that most lesions are accessible endoscopically. These devices allow for access to the small bowel either per os or per rectum. Therefore, having an estimate of the approximate location of the lesion of interest before embarking on endoscopy is critical. Today, most deep enteroscopy is directed by capsule endoscopy, although CT or MRI can also be used.
Although location and the ability to reach the lesion are critical, other factors may define whether a lesion in the small bowel can be approached endoscopically. Position and endoscope control are critical to performing therapeutic endoscopy. Optimizing these 2 factors deep within the small intestine can occasionally present a significant challenge. Another key aspect of therapeutic intervention in the small bowel is availability and selection of endoscopic accessories. Currently, most of the accessories required for endolumenal therapy of polyps, vascular lesions, and strictures (snares, thermal devices, dilation balloons, and clips) are either long enough (>230 cm) or are available in the enteroscopy length. However, the length of the enteroscope (2 m) and the limited diameter (2.8 mm) of the accessory channel combined with significant looping can make the use of these accessories difficult. Loop reduction through shortening the endoscope before attempting therapy greatly improves the ability to pass accessories through the scope channel and perform successful interventions.
Small bowel polyps
Sporadic small bowel polyps are rare and usually found incidentally on endoscopy. The prevalence of sporadic duodenal polyps is estimated to be 4.6% of all patients undergoing diagnostic endoscopy. These polyps are usually asymptomatic but can occasionally present with bleeding or abdominal pain. Ampullary adenomas are usually also discovered incidentally but can present with biliary colic or obstructive jaundice, or can be suspected on cross-sectional imaging if biliary or pancreatic ductal dilation up to the level of the ampulla is noted. Otherwise, small bowel polyps are usually encountered in the setting of polyposis syndromes, such as Peutz-Jeghers syndrome (PJS) or familial adenomatous polyposis syndrome (FAP).
PJS
PJS is an autosomal dominant genetic disorder whose gene locus has been mapped to chromosome 19p13.3, which is a serine threonine kinase gene known as LKB1 or STK11. The syndrome manifests as hamartomatous polyps in the gastrointestinal tract, mucocutaneous pigmentation, and an increased risk of gastrointestinal and other cancers. Hamartomas in PJS are primarily located within the small bowel, and clinical diagnosis of PJS is usually related to a manifestation of bowel hamartomas, such as small bowel obstruction from intussusception, abdominal pain, rectal bleeding, and polyp extrusion. In a study involving 222 patients with PJS, 49% had gastric polyps, 64% had small bowel polyps, 53% had colon polyps, and 32% had rectal polyps. In one series, the lifetime intussusception risk was approximately 70%, with a 50% intussusception risk by the age of 20 years ; 95% of the intussusceptions occurred in the small bowel, and among small bowel intussusception events, 53% occurred in the jejunum and 47% were within the ileum. The hamartomas associated with small bowel intussusception were also noted to be larger than 15 mm, with a median size of 35 mm.
Patients with PJS are also at a substantial risk for gastrointestinal and other malignancies. The risk of gastrointestinal cancer is estimated to be between 38% and 66%, with 39% occurring in the colon and rectum, 29% in the stomach, 13% in the small bowel, and 11% to 36% in the pancreas.
The objectives of screening and surveillance for polyps in PJS include the prevention of obstruction, intussusception, and cancer. Upper endoscopy and colonoscopy are used to evaluate the upper and lower gastrointestinal tract, but evaluation of the small bowel can be challenging. Video capsule endoscopy and MR enterography are the preferred modalities for screening and surveillance of small bowel polyps, although small bowel series and CT enterography are often used. The goals of endoscopic therapy are to resect polyps that are larger than 15 mm, because these pose the highest risk for intussusception.
Endoscopic polypectomy for small bowel PJS polyps can be performed using DBE, SBE, or RE ( Fig. 1 ). In a prospective series of 13 patients with PJS, Gao and colleagues described a total of 82 polyps 1 cm or larger; polyps were predominantly noted in the proximal jejunum (94%). Most patients (77%) underwent a previous partial bowel resection for small bowel polyps. In this group, a total of 29 DBE procedures were performed, and 79 of 82 polyps (96%) were resected without any major complications. After endoscopic resection and a follow-up of 356 person-months, no small bowel–related complications were seen and none of the patients required surgery. Similar results were also noted in another series of 15 patients with PJS from Japan. This series also reported that the average size of the polyps decreased with successive endoscopies.
A hybrid approach using a laparoscopy-assisted DBE with complete enteroscopy and polypectomy of all lesions greater than 0.5 cm has also been described. Many patients with PJS have had previous bowel resections, and angulation from adhesions may make enteroscopy challenging. In these instances, a combined endoscopic and surgical approach may be suitable for complete examination of the small bowel. In centers in which balloon-assisted enteroscopy is not available, intraoperative endoscopy for clearance of small bowel polyps is a reasonable approach. Surgical resection remains the mainstay for patients with PJS who present with acute obstruction, intussusception, and large polyps not amenable to endoscopic resection.
Current surveillance guidelines for PJS recommend baseline small bowel video capsule endoscopy at the age of 8 years, or earlier if the patient is symptomatic. If polyps are identified on baseline video capsule endoscopy, this procedure should be repeated every 3 years. If few or no polyps are found on initial video capsule endoscopy, small bowel screening should resume at 3-year intervals beginning at 18 years of age, or sooner if symptoms develop. MR and CT enterography and conventional small bowel contrast radiography using barium have been proposed as alternatives when video capsule endoscopy is not available or is contraindicated.
In addition to PJS, small bowel polyps are also occasionally encountered in other hamartomatous polyposis syndromes, such as juvenile polyposis syndrome and PTEN hamartoma tumor syndrome, which includes Cowden, Bannayan-Zonana, and Proteus syndromes.
FAP
The duodenum is the most common site for adenomas in FAP after the colon. Nearly 65% of FAP patients will have a duodenal adenoma at their first endoscopy (median age, 35 years), and over time virtually all patients develop a duodenal adenoma, with more than a half having an advanced adenoma. Consequently, these patients have a markedly higher risk of duodenal and periampullary adenocarcinoma, and this is the leading cause of death in these patients. Therefore, patients with FAP are recommended to have surveillance endoscopies, including a side-viewing examination of the ampulla every 1 to 2 years. Endoscopic treatment of duodenal and ampullary adenomas is a crucial aspect of the care of these patients. The management of ampullary adenomas is discussed in detail elsewhere in this issue by El Hajj and Coté.
Nonampullary Duodenal Polyps
Nonampullary duodenal polyps are usually detected incidentally at upper endoscopy, and their prevalence ranges from 1 to 3 per 1000. These polyps are also seen in the setting of polyposis syndromes, such as PJS and FAP. Most of these polyps can resected endoscopically using a technique of submucosal injection followed by snare resection. Endoloop placement may be helpful for thick pedunculated polyps. Argon plasma coagulation is commonly used to ablate the borders of the polypectomy or remaining polypoid tissue. Surgery is reserved for lesions that are not amenable to endoscopic resection or in the presence of evidence of malignancy with submucosal invasion.
In a series of 62 patients treated for nonampullary duodenal polyps over the course of 10 years from 1990 through 2000, Perez and colleagues reported that most patients (47/62, 76%) were treated endoscopically and 15 patients underwent surgery. Major morbidity was seen in 1 of 47 patients treated endoscopically compared with 5 of 15 patients treated surgically ( P = .002). Surgically treated patients expectedly had a higher median polyp diameter compared with those treated endoscopically (35 vs 8 mm, respectively; P <.01). In another series of 59 patients, the mean polyp size was 17.2 ± 1.6 mm, and complete endoscopic resection was achieved in 98% of these polyps. Polyps greater than 2 cm were more likely to recur after endoscopic resection. Another study compared endoscopic resection of giant hemicircumferential lateral-spreading tumors (mean size, 4 cm; range, 3–8 cm) with smaller duodenal adenomas (<3 cm) and reported that endoscopic resection was safe and effective even in these challenging lesions. The incidence of bleeding complications was higher in the larger tumors than in the smaller tumors (26% vs 3%; P = .01).
Collectively, these studies indicate that endoscopic resection is safe and effective for most duodenal adenomas. However, it is associated with a higher rate of complications, particularly bleeding (both early and delayed), than is typically observed with polypectomy at other sites in the gastrointestinal tract. Recurrence is common, and therefore endoscopic surveillance is routinely performed.
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