Radiology Section - Wireless Capsule Endoscopy as a Diagnostic Technique in Disorders of the Small Bowel and Esophagus

IMPORTANT REMINDER

This Medical Policy has been developed through consideration of medical necessity, generally accepted standards of medical practice, and review of medical literature and government approval status.

Benefit determinations should be based in all cases on the applicable contract language. To the extent there are any conflicts between these guidelines and the contract language, the contract language will control.

The purpose of medical policy is to provide a guide to coverage. Medical Policy is not intended to dictate to providers how to practice medicine. Providers are expected to exercise their medical judgment in providing the most appropriate care.

DESCRIPTION

Wireless capsule endoscopy is performed using a miniature disposable video imaging capsule.  The capsule measures approximately 11 by 30 mm, contains video imaging, self illumination, and image transmission modules as well as a battery supply that lasts for up to eight hours. After the video capsule is swallowed, the indwelling camera takes images as peristalsis carries the capsule through the gastrointestinal tract. The average transit time from ingestion to evacuation is 24 hours. The device uses wireless radio transmission to send the images to a receiving recorder device that the patient wears around the waist. This receiving device also contains some localizing antennae sensors that can roughly gage where the image was taken over the abdomen. Images are then downloaded onto a workstation for viewing and processing.

The PillCam™ Given® Diagnostic Imaging System (previously called M2A®) device received marketing clearance from the U.S. Food and Drug Administration (FDA) on August 1, 2001, through the 510(k) process. The FDA clearance provides for the capsule's use "along with - not as a replacement for - other endoscopic and radiologic evaluations of the small bowel." The FDA clarified that the "capsule was not studied in the large intestine." On July 1, 2003, a supplemental 510(k) pre-market notification was cleared, and the labeled indications were modified by removing the "adjunctive" use qualification: "the Given® Diagnostic System is intended for visualization of the small bowel mucosa. It may be used as a tool in the detection of abnormalities of the small bowel."  In November 2004, the device received FDA clearance for the following additional labeled indication: “the Given® Diagnostic System with the PillCam™ ESO Capsule is intended for the visualization of esophageal mucosa.”  The Olympus Capsule Endoscope, (Olympus America, Inc., Allentown, PA) also received FDA 510(k) approval in September 2007 for visualization of small intestine mucosa.

In the small bowel, the capsule camera has been most frequently proposed as a technique to identify the source of obscure intestinal bleeding, defined as "recurrent or persistent iron-deficiency anemia, positive fecal occult blood test, or visible bleeding with no bleeding source found at original endoscopy." (4) Recently there has also been interest in exploring use of the capsule camera in patients with inflammatory bowel disease. Alternative diagnostic techniques include barium studies or small intestinal endoscopy.  In the esophagus, the capsule camera has been proposed as a screening technique for Barrett’s esophagus associated with gastroesophageal reflux disease (GERD). Evaluation of the esophagus requires limited transit time, and it is estimated that the test takes 20 minutes to perform. Alternative techniques include upper endoscopy.

Due to the risk of capsule retention, wireless capsule endoscopy is contraindicated in patients with suspected small bowel strictures.  According to the 2006 American Society of Gastroenterology guidelines for wireless capsule endoscopy, retention of a capsule above an intestinal stenosis may necessitate removal either endoscopically or surgically. (43) The Given® Patency Capsule (PC) is a disintegrating, time-controlled capsule developed to identify patients with strictures that may cause retention of the video capsule.  The patency system consists of a dissolvable capsule and a radio-frequency scanner.  The PC has the same size as the video capsule. It has cellophane walls that are filled with lactose (mixed with barium) and surround a radio-frequency identification tag (RFID). When retained in a fluid filled environment, the core of the patency capsule dissolves after approximately 40 hours, allowing the insoluble outer membrane to collapse and pass.  The detection of a retransmitted signal by the hand-held scanner means that the RFID is still retained in the GI tract.  The physician can determine the presence of the patency capsule in the body of the patient using the scanner.

The patency capsule device received marketing clearance from the U.S. Food and Drug Administration (FDA) on May 8, 2006, through the 510(k) process.

POLICY/CRITERIA

POSITION STATEMENT

Obscure Gastrointestinal Bleeding

This policy is based on a February 2003 BlueCross BlueShield Association Technology Evaluation Center (TEC) Assessment (2), which focused on the clinical applications of wireless capsule endoscopy in patients with obscure gastrointestinal bleeding suspected of being of small bowel origin.(3) Obscure GI bleeding is defined as “recurrent or persistent iron-deficiency anemia, positive fecal occult blood test, or visible bleeding with no bleeding source found at original endoscopy.”(4) Most lesions resulting in obscure GI blood loss are located in the small intestine. Causes of obscure bleeding in the small intestine include angiodysplasia (70%–80%), tumor (5%–10%), and other causes (10%–25%) including medication-related, infectious (tuberculosis), Crohn’s disease, Meckel’s diverticulum, Zollinger-Ellison, vasculitis, radiation enteritis, jejunal diverticula, and chronic mesenteric ischemia. (4) In patients over age 60 years, angiodysplasia is the most likely cause; while in those under the age of 50, a small bowel tumor would be the most likely cause of bleeding. (5)

Estimates of the frequency and natural history of obscure GI bleeding, either overt or occult, are not well established. (4) An estimated 3%–5% of cases of GI bleeding arise from small intestinal lesions. (5) While some cases of GI bleeding will resolve with conservative treatment, other cases will persist with recurrent episodes of overt bleeding or ongoing anemia, and these cases are considered obscure GI bleeding. GI bleeding may manifest clinically as overtly visible blood in emesis or feces or as occult bleeding, only detected by the observation of iron-deficiency anemia or fecal occult blood testing. (4) The source of GI bleeding may be identified nonsurgically using a variety of radiological or endoscopic techniques. However, a source for bleeding may remain unclear even after all conventional diagnostic tests (such as upper endoscopy, colonoscopy, oral contrast small bowel radiographic studies, tagged red blood cell scintigraphy, or angiography) have been performed.

The first comparative study involving capsule endoscopy included 20 patients with obscure digestive tract bleeding. (6) Capsule images were reported as good or excellent by the two physician reviewers, one of whom was blinded to clinical information and results of push enteroscopy. Overall, wireless capsule endoscopy found a bleeding site in 11 of 20 (55%) patients studied and provided additional information not detected by push enteroscopy in 5 of 20 (25%) cases. All lesions detected by wireless capsule endoscopy were distal to the region examined during push enteroscopy. The five additional cases diagnosed with wireless capsule endoscopy included one small bowel carcinoid that was treated with surgical resection. Two ileal lesions consistent with angiectasia were surgically resected. In one case, wireless capsule endoscopy findings of diffuse angiectasia throughout the entire small bowel ruled out the possibility of surgical resection. In yet another case, wireless capsule endoscopy excluded the presence of distal angiectasia in a patient with multiple jejunal angiectasias, and this patient responded to surgical resection of the proximal small bowel and did not require further transfusion.

The second comparative study was conducted in 32 subjects in Germany. (7) Overall, this study found that wireless capsule endoscopy identified a definite source of bleeding in 21 of 32 (66%) patients studied and provided additional information not detected by push enteroscopy in 16 of 32 (50%) cases. Additional diagnoses identified by wireless capsule endoscopy included 2 lesions related to chronic inflammatory bowel disease, 13 definite or probable angiectasias, and 1 case not fully described in the report.

No significant complications from wireless capsule endoscopy were reported in these studies.

An updated search of the MEDLINE database through July 1, 2009  identified additional studies which support the conclusions reached in the February 2003 TEC Assessment. (8-13)

Capsule Endoscopy for Small Bowel Diseases Other than Obscure GI Bleeding

The above indication for capsule endoscopy was addressed in a December 2003 TEC assessment which focused on the clinical applications of wireless endoscopy  in patients with small bowel diseases other than obscure GI bleeding.(14) This TEC assessment along with the updated BCBSA policy offered the following observations and conclusions: (1,14)

• Crohn's Disease

  A systematic review of the literature identified three studies that examined the use of wireless capsule endoscopy for initial diagnosis of Crohn’s disease.  (15-17) These studies provided consistent evidence that wireless capsule endoscopy may demonstrate Crohn’s lesions when other conventional tests have been negative.  This conclusion is further supported by literature published after completion of the December 2003 TEC Assessment.  (11, 18-20)
  
  Several small studies have explored the role of capsule endoscopy to determine the extent of Crohn’s disease in patients in whom the diagnosis was already established.(21-24) In one prospective case series of 31 patients, capsule endoscopy (CE) identified additional areas of Crohn’s disease that were not identified by enteroclysis. (21)  However, it is unclear how knowledge regarding the extent of involvement would direct patient management. A second study evaluated the effectiveness of treatment for Crohn’s disease by using wireless capsule endoscopy before and after therapy.(22) The authors reported only one of three endoscopic outcomes improved with treatment and clinical response did not seem to correlate with mucosal healing. Other studies include, small  or retrospective case series that do not permit conclusions to be reached on the clinical utility of this test for known Crohn’s disease. (23,24)  Larger, prospective  randomized trials are needed to determine the benefit of this test for known Crohn’s disease.

• GI Polyposis Syndromes

  Mata and colleagues studied the role of capsule endoscopy in 24 patients with hereditary GI polyposis syndromes, including familial adenomatosus polyposis (n=20) or Peutz-Jeghers syndrome (n=4). (25) Compared to barium studies with small bowel follow through and enteroclysis, capsule endoscopy identified four additional patients with small bowel polyps, which were subsequently removed with endoscopic polypectomy.  While this is certainly a small study, it does demonstrate that capsule endoscopy can identify additional lesions, leading to a change in management of these patients who are at an increased risk of GI malignancy.  Therefore, surveillance of patients with hereditary GI polyposis using the wireless capsule procedure may result in improved health outcomes for this high risk patient population.

• Suspected Small-Bowel Neoplasm, Celiac Sprue disease, or Other Small Bowel Diseases

  Since publication of the TEC Assessment, an updated search of the MEDLINE database through July 1, 2009 identified several small studies investigating the use of capsule endoscopy to diagnose other small bowel diseases.(26-28) For example, Culliford and colleagues reported on 47 patients in which capsule endoscopy was used to evaluate complicated celiac disease. (26)  Findings were consistent with celiac disease in 87%.  In addition, unexpected findings were reported in 60%, including ulceration (n = 21), cancer (n =1), polyps (n =1), stricture (n =1), submucosal mass (n =1), ulcerated nodular mucosa (n =2), and intussusception (n =1).  The authors concluded that capsule endoscopy has a high yield in complicated celiac disease, by identifying mucosal abnormalities and by excluding adenocarcinoma.  The impact on patient management is unclear.  The authors report that management included discontinuation of nonsteroidal anti-inflammatory drugs (NSAIDS) as well as initiation of therapy with 5-aminosalicyclic acid containing drugs and Pepto-Bismol.  However, these treatment strategies might have been initiated empirically.  Results of this and other studies, while promising, are insufficient to reach firm scientific conclusions concerning the impact of capsule endoscopy on patients with celiac disease.

  Evidence was not of sufficient quantity or quality to determine the relative diagnostic performance of wireless capsule endoscopy as compared to alternative conventional diagnostic tests or to permit conclusions concerning the effect of using wireless capsule endoscopy on health outcomes of patients with small-bowel neoplasms, or other small bowel diseases.

Capsule Endoscopy of the Esophagus

Direct imaging of the small bowel with an endoscope is limited, and thus capsule endoscopy of the small bowel occupies a unique niche. In contrast, esophageal endoscopy, which also offers the opportunity for biopsy, is a routinely performed procedure. Therefore, assessment of capsule endoscopy of the esophagus requires comparison of its diagnostic performance with the gold standard of conventional endoscopy.

One proposed indication for the capsule camera is detection of Barrett’s esophagus, considered a premalignant condition associated with gastroesophageal reflux disease (GERD). Conventional endoscopy is often recommended in patients with longstanding symptoms of GERD or in patients requiring pharmacologic therapy to control GERD symptoms in order to rule out Barrett’s esophagus. This is a high volume indication for conventional endoscopy, given the high prevalence of GERD. Capsule endoscopy offers a potential alternative to endoscopy; those patients with a negative study could potentially forego conventional endoscopy. In this setting, the negative predictive value of capsule endoscopy is the key diagnostic parameter. Patients who are found to have suggestive findings of Barrett’s esophagus will require a confirmatory conventional endoscopy with biopsy.

There is limited published literature regarding the diagnostic performance of esophageal capsule endoscopy. Eliakim and colleagues reported on an initial case series of 17 patients with suspected esophageal disorders. (29) The negative predictive value for any esophageal disorder was 100%. Two additional small feasibility studies involved modifying the capsule by attaching strings that allowed the operator to move the capsule up and down the esophagus, thus increasing transit time and providing more esophageal images for evaluation. (30,31) Further investigation of this modification is needed, and the authors note that comparative studies to evaluate sensitivity, specificity, and positive and negative predictive values are underway.

In 2005, Eliakim evaluated 106 patients (93 with GERD and 13 with Barrett esophagus) with wireless endoscopy followed by standard endoscopy as the gold standard. (32) A blinded adjudication committee reviewed all discrepant findings. The authors reported a sensitivity of 92% (61 of 66) and specificity of 95%. Lin and colleagues reported results of a prospective blinded (without adjudication) study of capsule endoscopy compared to conventional endoscopy for Barrett’s esophagus in 66 screening and 24 surveillance patients. (33) This study reported a sensitivity of 67% (14 of 21) and specificity of 84%. Given the differences in the findings of these studies and the moderate sensitivity in the second study, additional studies of this technique, perhaps with further modifications to better visualize the esophagus, are needed.

Eisen reported on a pilot study of 32 patients with cirrhosis who were undergoing screening or surveillance for esophageal varices who had a wireless endoscopy study followed by a standard endoscopy within 48 hours. (34) Capsule videos were assessed by an investigator who was blinded to the patient’s medical history and endoscopy findings. A total of 23 of the 32 enrolled patients were found to have esophageal varices in both studies. In one patient wireless endoscopy detected small varices that were not seen at endoscopy. The overall concordance was 96.9 % for the diagnosis of esophageal varices.   Subsequent case series have shown WCE may be useful for the evaluation of esophageal diseases however these studies report  issues with  interoperator agreement, unpredictable esophageal transit times, poor image quality, and significant failure rates with up to 6% of patients unable to swallow the capsule. (35-37)  Larger, randomized studies using general screening populations are needed to evaluate the effectiveness of WCE for the presence esophageal diseases.

In sum, available studies are inadequate to permit scientific conclusions regarding the clinical role of esophageal capsule endoscopy.

Given® Patency Capsule System for Patients at High Risk of Wireless Capsule Retention

An updated Medline search through July 1, 2009 found several small case studies reporting mixed results regarding the use of the Given® patency capsule (PC) prior to doing a wireless capsule endoscopy(WCE).( 38-43)  Signorelli and colleagues performed a feasibility study on 32 patients who were considered to be at high risk for capsule retention. (38) Of the 32 patients given the patency capsule, 26 were deemed eligible for WCE and one of these refused the WCE procedure.  Ineligible for WCE were six patients who had delayed capsule with or without abdominal pain.  Of the 25 patients who went on to receive the WCE, none developed capsule retention, symptoms of bowel obstruction, or complaints of abdominal pain.  The diagnostic yield for WCE was 52% overall.  The authors conclude “The Given capsule is an effective method for the assessment of small bowel patency before CE. However, the real incidence of complications such as the development of severe abdominal pain and small bowel obstruction needs to be ascertained before the patency test can be recommended as the standard method to evaluate patients at risk of developing capsule retention.”  Spada and colleagues reported positive results from a prospective case series of 34 patients with small-bowel stricture who received the patency capsule. (39) Six patients experienced abdominal pain and delayed transit but no long-term adverse events were reported.  Delvaux and colleagues examined 22 patients with diagnosed or suspected Crohn’s disease. (40) Wireless endoscopy was not performed in six patients, five of whom experienced delayed transit of the PC. The PC induced a symptomatic intestinal occlusion in three of these five patients.  The occlusion resolved spontaneously in one and required emergency surgery in two patients.  One patient refused the WCE after experiencing abdominal symptoms with the passage of the PC.  Wireless capsule endoscopy was successfully performed on sixteen of 22 patients. There was no report of complications occurring with those receiving the WCE procedure.  The overall diagnostic yield of WCE in this set of patients was 93.8%.  The authors conclude that “the current technical development of the patency capsule limits its use in clinical practice, as it did not detect stenoses undiagnosed by CT or SBFT and the start of dissolution at 40 hours after ingestion is too slow to prevent episodes of intestinal occlusion.”  Another case series by Boivin and colleagues examined 22 patients with suspected obstructive small-bowel disease and/or radiological evidence of small-bowel strictures. (41) Thirteen of the 22 patients passed an intact capsule without complaints; the subsequent video capsule examination was uneventful in all.  In nine patients, either intact passage was painful or the capsule disintegrated.  In one of these nine patients, impaction of an intact capsule led to an ileus and emergency surgery.

In sum, these studies with variable outcomes indicate the need for larger trials to establish the technical feasibility, reproducibility, and precision of the patency capsule.

REFERENCES

1. BlueCross BlueShield Association Medical Policy Reference Manual, Policy No. 6.01.33
2. BlueCross and BlueShield Association Technology Evaluation Center (TEC)  Assessment: Wireless Capsule Endoscopy, 2003; Vol. 17, Tab 21
3. Van Gossum A. Obscure digestive bleeding. Best Pract Res Clin Gastroenterol 2001;15(1):155-74
4. Zuckerman GR, Prakash C, Askin MP et al. American Gastroenterological Association Practice Guidelines. AGA technical review on the evaluation and management of occult and obscure gastrointestinal bleeding. Gastroenterology 2000;118(1):201-21
5. Lewis BS. Small intestinal bleeding. Gastroenterol Clin North Am 2000;29(1):67-95
6. Lewis BS, Swain P. Capsule endoscopy in the evaluation of patients with suspected small intestinal bleeding: results of a pilot study. Gastrointest Endosc 2002;56(3):349-53
7. Ell C, Remke S, May A et al. The first prospective controlled trial comparing wireless capsule endoscopy with push enteroscopy in chronic gastrointestinal bleeding. Endoscopy 2002;34(9):685-9
8. Mata A, Bordas JM, Feu F et al.  Wireless capsule endoscopy in patients with obscure gastrointestinal bleeding: a comparative study with push enteroscopy.  Aliment Pharmacol Ther 2004;20(2):189-94
9. Magnano A, Privitera A, Calogero G et al.  The role of capsule endoscopy in the work-up of obscure gastrointestinal bleeding.  Eur J Gastroenterol Hepatol 2004;16(4):403-6
10. Hartmann D, Schmidt H, Bolz G et al.  A prospective two-center study comparing wireless capsule endoscopy with intraoperative enteroscopy in patients with obscure GI bleeding.  Gastrointest Endosc 2005;61(7):826-32
11. Guilhon de Araujo Sant’Anna AM, Dubois J, Miron MC, Seidman EG.  Wireless capsule endoscopy for obscure small-bowel disorders: final results of the first pediatric controlled trial.  Clin Gastroenterol Hepatol 2005;3(3):264-70
12. Kalantzis N, Papanikolaou IS, Giannakoulopoulou E et al.  Capsule endoscopy; the cumulative experience from its use in193 patients with suspected small bowel disease.  Hepatogastroenterology 2005;52(62):414-9
13. Ersoy O, Harmanci O, Aydinli M et al. Capability of capsule endoscopy in detecting small bowel ulcers. Dig Dis Sci 2009;54(1):136-4
14. BlueCross and BlueShield Association Technology Evaluation Center  (TEC) Assessment: Wireless Capsule Endoscopy for Small-Bowel Diseases Other Than Obscure GI Bleeding,  2003; Vol. 18, Tab 18
15. Eliakim R, Fisher D, Suissa A et al. Wireless capsule video endoscopy is a superior diagnostic tool in comparison to barium follow through and computerized tomography in patients with suspected Crohn’s disease. Eur J Gastroenterol Hepatol 2003;15:363-67
16. Fireman Z, Mahajna E, Broide E et al. Diagnosing small bowel Crohn’s disease with wireless capsule endoscopy. Gut 2003;52:390-92
17. Herrerias JM, Caunedo A, Rodriquez-Tellez M et al. Capsule endoscopy in patients with suspected Crohn’s disease and negative endoscopy. Endoscopy 2003;35:564-68
18. Ge ZZ, Hu YB, Xiao SD.  Capsule endoscopy in diagnosis of small bowel Crohn's disease.  World J Gastroenterol 2004;10(9):1349-52
19. Mow WS, Lo SK, Targan SR.  Initial experience with wireless capsule enteroscopy in the diagnosis and management of inflammatory bowel disease.  Clin Gastroenterol Hepatol 2004;2(1):31-40
20. Voderholzer WA, Beinhoelzl J, Rogalla P et al.  Small bowel involvement in Crohn's disease: a prospective comparison of wireless capsule endoscopy and computed tomography enteroclysis.  Gut 2005;54(3):369-73
21. Marmo R, Rotondano G, Piscopo R et al.  Capsule endoscopy versus enteroclysis in the detection of small-bowel involvement in Crohn’s disease:  a prospective trial. Clin Gastroenterol Hepatol 2005;3(8):772-76
22. Efthymiou A, Viazis N, Mantzaris G et al  Does clinical response correlate with mucosal healing in patients with Crohn's disease of the small bowel? A prospective, case-series study using wireless capsule endoscopy. Inflamm Bowel Dis 2008;14(11):1542-7
23. Park CH, Kim Jo, Choi MG et al. Utility of capsule endoscopy for the classification of Crohn’s disease: a multicentner study in Korea. Dig Dis Sci 2007;52(6):1405-9
24. Lorenzo-Zúñiga V, de Vega VM, Domènech E et.al Impact of Capsule Endoscopy Findings in the Management of Crohn’s Disease. Dig Dis Sci 2009 Mar 3. [Epub ahead of print]
25. Mata A, Llach J, Castells A et al.  A prospective trial comparing wireless capsule endoscopy and barium contrast series for small-bowel surveillance in hereditary GI polyposis syndromes. Gastrointest Endosc 2005;61(6):721-5
26. Culliford A, Daly J, Diamond B  et al.  The value of wireless capsule endoscopy in patients with complicated celiac disease.  Gastrointest Endosc 2005;62(1):55-61
27. Rondonotti E, Spada C, Cave D et al. Video capsule enteroscopy in the diagnosis of celiac disease: a multicenter study. Am J Gastroenterol 2007;102(8):1624-31
28. Neumann S, Schoppmeyer K, Lange T et al. Wireless capsule endoscopy for diagnosis of acute intestinal graft-versus-host disease.  Gastrointest Endosc 2007;65(3):403-9
29. Eliakim R, Yassin K, Shlomi I et al. A novel diagnostic tool for detecting oesophageal pathology: the Pillcam oesophageal video capsule. Aliment Pharmacol Ther 2004;20(10):1083-9
30. Ramirez FC, Hakim S, Tharalson EM et al.  Feasibility and safety of string wireless capsule endoscopy in the diagnosis of esophageal varices. Am J Gastroenterol 2005;100(5):1065-71
31. Ramirez FC, Shaukat MS, Young MA  et al.  Feasibility and safety of string, wireless capsule endoscopy in the diagnosis of Barrett's esophagus. Gastrointest Endosc 2005;61(6):741-6
32. Eliakim R, Sharma VK, Yassin K et al. A prospective study of the diagnostic accuracy of PillCam ESO esophageal capsule endoscopy versus conventional upper endoscopy in patients with chronic gastroesophageal reflux disease. J Clin Gastroenterol 2005; 39(7):572-8
33. Lin OS, Schembre DB, Mergener K et al. Blinded comparison of esophageal capsule endoscopy versus conventional endoscopy for a diagnosis of Barrett's esophagus in patients with chronic gastroesophageal reflux. Gastrointest Endosc 2007; 65(4):577-8
34. Eisen GM, Eliakim R, Zaman A et al. The accuracy of PillCam ESO capsule endoscopy versus conventional upper endoscopy for the diagnosis of esophageal varices: a prospective three-center pilot study. Endoscopy 2006; 38(1):31-5
35. Lapalus MG, Ben Soussan E, Gaudric M et al. Esophageal capsule endoscopy vs. EGD for the evaluation of portal hypertension: a French prospective multicenter comparative study. Am J Gastroenterol 2009;104(5):1112-8
36. Delvaux M, Papanikolaou IS, Fassler I et al. Esophageal capsule endoscopy in patients with suspected esophageal disease: double blinded comparison with esophagogastroduodenoscopy and assessment of interobserver variability. Endoscopy 2008;40(1):16-22
37. Frenette CT, Kuldau JG, Hillebrand DJ et al. Comparison of esophageal capsule endoscopy and esophagogastroduodenoscopy for diagnosis of esophageal varices. World J Gastroenterol 2008;14(28):4480-5
38. Signorelli C, Rondonotti E., Villa F.  et al.  Use of the Given® Patency System for the screening of patients at high risk for capsule retention Dig Liver Dis 2006;38(5):326-30
39. Spada C. Spera G, Riccioni M et al.  A novel diagnostic tool for detecting functional patency of the small bowel :  the Given patency capsule. Endoscopy 2005;37(9)793-800
40. Delvaux M, Soussan EB, Laurent V et al.  Clinical Evaluation of the use of the M2A patency capsule system before a capsule endoscopy procedure, in patients with known or suspected intestinal stenosis Endoscopy 2005;37(9):852-6
41. Boivin ML, Lochs H, Voderholzer WA  Does passage of a patency capsule indicate small-bowel patency?  A prospective clinical trial? Endoscopy 2005;37(9):808-15
42. Spada C, Shah SK, Riccioni ME et al. Video capsule endoscopy in patients with known or suspected small bowel stricture previously tested with the dissolving patency capsule. J Clin Gastroenterol. 2007 Jul;41(6):576-82
43. ASGE Technology Status Evaluation Report: Wireless Capsule Endoscopy 2006; 63(4): 539-545

CROSS REFERENCES

None

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