Small bowel capsule endoscopy: a systematic review.

Abstract: Wireless capsule endoscopy offers a revolutionary diagnostic tool for small bowel diseases. Since its formal introduction, it has become an integral part of the diagnostic evaluation for obscure gastrointestinal bleeding. This relatively noninvasive imaging modality offered by small bowel capsule endoscopy is appealing to both patients and providers and consequently, the desire to expand its diagnostic role continues to grow. The use of CE in the diagnosis of Crohn disease and chronic diarrhea is being further investigated, as is the potential of employing this technique as a cancer surveillance mechanism in patients with hereditary polyposis syndromes which may involve the small bowel. This review article discusses the current indications for small bowel capsule endoscopy, the results of capsule endoscopy in patients with obscure gastrointestinal bleeding and small bowel diseases, and patient outcomes following capsule endoscopy. Capsule endoscopy is compared with traditional diagnostic modalities, including small bowel series, enteroclysis, CT, and push enteroscopy. Small bowel capsule endoscopy is the procedure of choice to evaluate obscure gastrointestinal bleeding, and is superior to radiographic procedures in detecting Crohn disease of the small bowel.

Key Words: capsule endoscopy, obscure gastrointestinal bleeding, wireless endoscopy 

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The investigation of pathology located within the small intestine has always represented a diagnostic challenge. Conventional techniques of endoscopy are limited by length while radiologic examinations, such as barium studies, are insensitive. (1) The concept for small bowel capsule was developed independently by two groups. Dr. Paul Swain, a British gastroenterologist demonstrated the first live transmissions in 1996 with the broadcast of a pig's stomach. In 1997, he collaborated with Dr. Gavriel Iddan, a mechanical engineer working with the Israel Ministry of Defense. (2-4) Successful animal trials were conducted and first published in 2000. (2) Human studies followed and the use of capsule endoscopy (CE) in clinical trials was first published in 2001. (5) With the development of CE, physicians now have a minimally invasive, well-tolerated mechanism with which to visualize the entire small bowel. The purpose of this article is to review the existing literature to determine the indications for, contraindications to, and results of small bowel CE and to compare the technique to other imaging modalities for the small bowel.

Methods

We conducted an English language literature search using the MEDLINE database for the time period of January 2001 through June 2005. Our search included the key words capsule endoscopy, wireless capsule endoscopy, video capsule endoscopy, and obscure gastrointestinal bleeding. All of the pertinent publications were reviewed and the data included if relevant to the topics being reviewed in this paper.

The Capsule & Mechanism

The small bowel capsule, manufactured by Given Imaging (Yoqneam, Israel) measures 11 X 26 mm and weighs 3.7 g. (6,7) Essentially, it consists of a CMOS (complementary metal oxide silicon) camera, a lens, 4 to 6 LEDs (light emitting diodes), a radio-frequency transmitter and antenna, and 2 silver oxide batteries. (6) The camera moves through the GI tract via peristalsis and transmits 2 images per second to a data recorder located on the waist of the patient. An average of 7 to 8 hours of data is collected generating between 50,000 to 60,000 images. The images are subsequently downloaded onto a computer where it can be reviewed as a video (8-20 images/sec). Interpretation takes between 45 minutes to 2 hours. (8)

The Study

The study takes approximately eight hours and allows the patient to resume most daily activities during that time. In preparation for the examination, patients are maintained on a liquid diet for 24 hours and fast after midnight on the day before the study. A polyethylene glycol solution may be given the day before the procedure. Two hours after capsule ingestion, the patient may consume clear liquids and may eat a light meal 3 to 4 hours later. The capsule is excreted naturally, and it is recommended that patients avoid magnetic fields (such as MRI and metal detectors) until then. (9)

Indications

Presently, CE is indicated in the diagnosis of obscure gastrointestinal bleeding. Defined as persistent or recurrent bleeding of unknown origin with negative findings on upper and lower endoscopy studies, obscure gastrointestinal bleeding represents approximately 5% of all gastrointestinal bleeding. (10,11) Of these, up to 50% can remain undiagnosed. (12) Multiple studies have examined the ability of CE to detect bleeding sources in such patients. (9-11,13-27) In the majority of these publications, CE was indeed successful and found to be superior to conventional technology used for this purpose. A recent meta-analysis comparing CE to other diagnostic modalities in patients with obscure gastrointestinal bleeding showed that the incremental yield of CE over PE and small bowel barium studies for clinically significant findings was greater than 30% with a number needed to treat (NNT) of 3. (28) The role of CE is expanding. Its value in diagnosing a variety of conditions, including malabsorption, chronic diarrhea, Crohn disease and primary small intestinal disease such as refractory celiac disease and nonsteroidal antiinflammatory drug (NSAID)-induced enteropathy, is currently under investigation. (14) The follow-up of patients with small bowel transplants has also been proposed as a future indication of CE, as well as cancer surveillance in patients with familial adenomatous polyposis (FAP), Peutz-Jeghers syndrome (PJ), and familial juvenile polyposis (FJP). (29)

Contraindications

Absolute contraindications to CE include the presence of intestinal obstruction, fistulas or strictures, as these abnormalities may impede the excretion of the capsule and can potentially cause a bowel obstruction. Patients with swallowing abnormalities are at risk for aspiration of the capsule. Patients with an esophageal stricture are at risk for impaction of the capsule in the esophagus with subsequent esophageal obstruction. According to the manufacturer, pacemakers are still listed as contraindicated; however, several abstracts have demonstrated that CE is safely performed in such patients. (13) A thorough history and physical examination is recommended before initiating the study to help identify patients at risk for complications. Radiographic imaging such as a small bowel series is recommended before CE for patients in whom the presence of adhesions or partial obstruction is suspected.

Results from CE Studies

Bleeding

The diagnostic yield for identifying the source of GI bleeding was variable in many studies and depended most consistently upon the type of bleeding. A study of 100 consecutive patients conducted by Pennazio et al (9) found that the highest yield of CE was in patients with ongoing obscure-overt GI bleeding (92.3%; 95% CI:82-100%). The results from patients with obscure-occult bleeding were somewhat lower (44.2%; 95% CI: 29-59%). Those individuals with previous obscure-overt bleeding were determined to have the lowest yield (12.9%; 95% CI:1.2-25%). Of the patients with a history of previous obscure-overt bleeding, the researchers observed that findings were indirectly proportional to the length of time since the last bleeding episode. The longer the time from last bleed, the lower the diagnostic yield. (9) This was thought to be attributable in part to mucosal healing before the procedure. The discoveries made by CE were classified into positive, suspicious and negative findings. Positive findings were reported in 47% of the study population and included angiodysplasias, aphthoid and serpiginous ulcers, active bleeding, varices, stenosis with ulcers, tumor, bleeding ileal polyps, gastric ulcers and GAVE (gastric antral vascular ectasia.) Fifteen percent of the enrolled patients had suspicious findings, such as isolated nonbleeding angiodysplasias, venous ectasias, isolated clots and erosions, and small non-bleeding polyps. Of the remaining 38%, no findings were made on CE; thus the study was read as negative. There is no current gold standard against which to verify the findings made by capsule endoscopy. Therefore, the authors of this study developed a system (centered on the verification of capsule findings through various means) by which to generate values for sensitivity, specificity, and positive and negative predictability. Using their method, the results of the study demonstrated a sensitivity of 88.9% and a specificity of 95%. The positive predictive value was 97%, and negative predictive value was 82.6%. The overall accuracy of CE findings was determined to be 91.1%. (9)

Scapa et al (19) examined thirty-five patients with a history of obscure GI bleeding. These individuals had been previously evaluated through endoscopic and radiologic means. Capsule endoscopy was determined to have a diagnostic yield of 63% in this investigation. Abnormalities such as ulcers, erosions and angiodysplasia were discovered in 29 of the 35 subjects with a definitive bleeding source described in 22 of the 29.

The use of CE early on in the evaluation of patients with obscure GI bleeding is also thought to decrease the time to diagnosis. The time from symptom onset until diagnosis has been reported to range from 1 month to 8 years (with an average of 2 years). (14) During this period, patients may undergo multiple and often invasive examinations and require multiple blood transfusions. One study reported that 40 patients (in whom CE studies were positive) had previously undergone a total of 212 investigations, including repeat endoscopies, enteroclysis, angio-CT scan, small bowel x-rays, arteriography and 99mTc scans, all of which were negative. They concluded that these additional examinations could have been avoided if CE was employed following the initial upper and lower endoscopy studies which failed to detect a source. (9)

A detailed meta-analysis of twenty trials comparing the diagnostic yield of CE versus other modalities in the setting of obscure gastrointestinal bleeding was recently published. The authors concluded that CE was superior to PE, as well as small bowel barium studies for diagnosing clinically relevant small bowel pathology. Their calculations demonstrated that in the study populations, CE had an incremental yield of [greater than or equal to]30% when compared with PE and small bowel radiography, with a NNT of 3. This was attributed to vascular and inflammatory lesions which were detected by CE but not visualized by PE or radiographic studies. (30)

Crohn Disease (CD)/Irritable Bowel Syndrome (IBD)

Fireman et al examined 17 patients with suspected CD involving the small bowel that had been previously undiscovered by conventional methods. Presenting symptoms included iron deficiency anemia (mean hemoglobin 10.5 g%) (SD 1.8) (n = 9), abdominal pain (n = 8), diarrhea (n = 7), and weight loss (n = 3). Images from the CE studies revealed ulcerations within the distal small bowel. Based on these findings, 70.6% (12/17) of the patients were diagnosed as having CD of the small bowel. Of these 12 individuals, 10 improved clinically with 5-ASA and short-term corticosteroids. (31) In a study of similar patients by Eliakim et al, (32) CE was found to have a diagnostic yield of 70%, compared with barium studies which were diagnostic in 35%.

Triester et al performed a meta-analysis of 11 trials comparing the yield of CE to that of a variety of other diagnostic modalities. Their results showed CE to have a higher diagnostic yield for nonstricturing small bowel disease than small bowel barium studies, CT enterography, PE, and colonoscopy with ileoscopy in study populations. Subanalysis of the selected studies demonstrated no statistical significance in the incremental yield between CE and other diagnostic modalities in patients suspected of having CD. However, there was a statistically significant increase in the incremental yield of CE over alternative diagnostic techniques in patients with known CD undergoing evaluation for small bowel recurrence. Consequently, the authors believed that in patients without small bowel strictures, diagnosing Crohn disease by CE should be applied to those individuals with known CD being evaluated for small bowel recurrence. Although the studies in their analysis did demonstrate a trend toward higher diagnostic yields with CE, larger studies are necessary to further delineate its role in previously undiagnosed patients presenting with symptoms suspicious for CD. (33)

Chronic Abdominal Pain/Surveillance

The use of CE to evaluate patients with chronic abdominal pain was investigated by Bardan et al (34) In this study, 20 patients with chronic abdominal pain ranging from 6 to 96 months' duration underwent CE imaging. Previous diagnostic workups performed before their enrollment in the study had been negative. Their findings revealed a normal examination in 14 of the patients and clinically insignificant findings in the remaining 6 patients. They concluded that CE was not of significant clinical value when investigating the source of obscure chronic abdominal pain.

Limitations and Adverse Events Associated with Capsule Endoscopy

Limitations of CE that have been encountered include the quality of visualization provided by the capsule. For instance, some studies have reported that the duodenum is not effectively visualized. (21,22) Mylonaki et al (17) opined that the quality of images obtained from push enteroscopy were superior to that of CE. This was thought to be due in part to several factors, including the light intensity which can be manipulated during PE in response to the changing requirements, but is fixed in CE. Likewise, the lesions that are discovered are unable to be washed by the capsule or examined repeatedly. Other criticisms of CE focus on its inability to obtain biopsies or deliver therapeutic intervention. (20)

The major adverse event associated with CE is the potential for intestinal obstruction caused by capsule retention resulting from a stricture, stenosis, diverticula or fistulas. Patients who do experience capsule impaction, a documented incidence of 1%, are generally asymptomatic. (8) Capsule retention can also be diagnostic by revealing the underlying pathology that prevented its passage. It is currently recommended that a barium study be performed before capsule endoscopy in patients with symptoms suggestive of partial obstruction. Other proposals to minimize capsule retention include the administration of a patency test capsule that can degrade in 2 to 3 days if retention occurs. (35) Additional complications that have been encountered include lodging in a Meckel diverticulum and aspiration, both of which are rare. Overall, patient tolerance is very good, especially when compared with the other current available modalities.

Capsule Endoscopy versus Push Enteroscopy (PE)

Ell et al performed a study comparing CE to PE on 32 patients with a history of GI bleeding. The patients had been previously examined by a variety of imaging techniques, which failed to identify the source of pathology. The results of their investigation revealed that PE detected a definitive source of bleeding in 28% compared with 66% by CE. The most common etiologies encountered were IBD, angiodysplasia and tumors. (16)

The use of CE and PE were also compared in a group of 50 patients with a history of chronic GI bleeding and negative workups in the past. The results of this study were similar to those of Ell et al in that CE was found to be superior in diagnosing a source of bleeding located within the small intestine (68% versus 32% P < 0.05). The total diagnostic yield, which took into account pathology both within and outside of the small intestine, also demonstrated the superiority of CE over PE (76% (38/50) versus 38% (19/50); P < 0.05). (17)

In comparing the two techniques, it is pertinent to evaluate the advantages and disadvantages of using one modality over the other. Push enteroscopy provides excellent visualization of the mucosal surface, which often contains abnormalities of interest that are too subtle to be detected by radiography. Similarly, CE allows viewing of the mucosal wall but accomplishes this through a less invasive process when compared with PE. It is consequently a more desirable/preferable examination for patients. The overall time to perform PE ranges from 15-45 minutes. In addition, patient sedation is required, as well as recovery time to relieve the effects of the sedation. Small bowel capsule endoscopy does not involve patient sedation, and therefore no recovery time is needed. With regards to length of the small intestine able to be investigated, PE can visualize approximately 80-120 cm beyond the ligament of Treitz, while CE has the potential to examine the entire small bowel. (10,20) It is, however, important to note that failure of CE to reach the cecum during the eight hours of recording has been reported in approximately 15% of patients undergoing the study. (20) Despite this statistic, multiple studies have reported CE to be more sensitive than PE in detecting causes of obscure GI bleeding. (See the Table) (16) A limitation of CE is the inability to obtain biopsies and provide therapeutic intervention, a capability possessed by PE. Potential complications of PE include intestinal perforation and acute pancreatitis, as well as the rare occurrence of bleeding and infection. (2) Many authors have described the two examinations as being complimentary to one another and suggest that CE be the initial diagnostic procedure to better select patients likely to benefit from the therapeutic capability offered by PE studies (ie, those patients with lesions identified in the proximal small bowel).

CE versus Barium Studies/Enteroclysis:

The diagnosis of bleeding by capsule endoscopy has also been compared with that of barium imaging. A study by Costamagna et al examined the use of CE in a total of 20 patients with a variety of small bowel diseases, including GI bleeding, IBD, suspected sarcoma recurrence, FAP, chronic diarrhea and small bowel polyps. Several procedures, including PE, gastroscopy, colonoscopy, angiography, intraoperative enteroscopy and radionuclide scanning, had been performed before the study. The diagnostic yield of CE in their investigation was 45% (9/17), while that of barium follow-through was only 20% (4/17). The most common sources of bleeding detected were angiodysplasias followed by suspected IBD and polyps. (36)

Twenty-two patients with presumed small-bowel pathology (obscure gastrointestinal bleeding (n = 8), Crohn disease (n = 8), unexplained diarrhea (n = 5), and suspected carcinoid tumor) underwent investigation with CT enteroclysis and capsule endoscopy in a study by Voderholzer et al. (26) Their results revealed a diagnostic yield for CE of 50% (4/8) in patients with obscure bleeding versus 12.5% (1/8) by CT enteroclysis. Other studies have shown the yield of enteroclysis in patients with obscure GI bleeding to be between 10 and 20%. (12)

Patients with suspected Crohn disease have historically been evaluated through radiologic techniques including SBFT or enteroclysis; however, the sensitivity of these methods has varied, ranging from very low to very high values. (3,31,32,37) Several recent studies sought to compare the use of capsule endoscopy to barium studies in diagnosing Crohn disease. Eliakim et al looked at 20 patients with a history of recurrent abdominal pain, weight loss, or chronic diarrhea. Each one underwent evaluation by barium studies followed by CE and CT enteroclysis. The diagnostic yield of CE was determined to be 70% and that of the radiologic procedures 37%. Furthermore, CE detected all of the lesions located by SBFT and CT enteroclysis and detected additional lesions in 47% of the cases. (32) In another study by Eliakim et al (38) looking at a similar cohort of patients (n = 35), the diagnostic yield of capsule endoscopy was reported to be 77%, while that of barium and CT studies were 23% and 20%, respectively (P < 0.05). In a recent prospective study of 31 patients documented to have terminal ileal involvement with Crohn disease on colonoscopy, which included retrograde ileoscopy, the diagnostic yield of CE was significantly superior to enteroclysis (89% versus 37%, P < 0.001). (28)

A disadvantage in using radiologic examinations such as barium SBFT and enteroclysis is the exposure of the patient to radiation. (39) In addition, indirect studies such as these do not permit close examination of the mucosa and therefore have a low sensitivity for flat, small, infiltrative, or inflammatory lesions. This, in addition to their poor diagnostic sensitivity during the early stages of a disease process, (31) could account for some of the low diagnostic yields (5-8%) associated with SBFT and enteroclysis in patients with small intestinal bleeding. (11,40) Although the sensitivity of enteroclysis has been reported to be superior to that of SBFT, (12) the procedure is relatively invasive and may require patient sedation.

Using radiologic imaging as a mechanism to evaluate patients with suspected risk factors for capsule retention has been proposed. The theory behind this is to help identify strictures or other anatomic derangements that would impede the capsule's course. The problem with this role for SBFT is that a negative study does not completely exclude the presence of structural defects. (9) A novel method now being evaluated is the use of a patency capsule, which, in the event that it cannot be naturally excreted, will begin to dissolve and therefore avoid the need for invasive removal of the capsule. (41) Others think that the retention of the capsule in patients with CD should be seen as potentially diagnostic in and of itself as it most likely represents stricture/stenosis associated with the patient's disease. (42)

The Patency Capsule

A patency capsule designed to evaluate the presence of obstructing strictures and adhesions in the GI tract has also been developed. This device stays intact in the gastrointestinal system for approximately 30 hours post ingestion and then begins to disintegrate. It contains a small radiofrequency tag that can be detected by a scanner. Patency is confirmed in one of two ways: if the capsule is excreted within 30 hours of ingestion (as confirmed by the scanner/x-ray) or if it is excreted with the body of the capsule structurally intact any time after ingestion. One recent study examined the utility and safety of the patency capsule in 32 patients with a history of Crohn disease, previous intestinal surgery, previous obstruction or a combination of those entities. The investigators determined that subjecting high risk patients to the patency study was useful in identifying those individuals who may safely undergo capsule endoscopy without risk of capsule retention. (43)

An investigation of 22 patients examined whether successful passage of the patency capsule reliably confirmed small bowel patency in those with radiological evidence of potential obstruction/stricture. Their findings demonstrated that painless excretion of a patency capsule without disintegration did indicate that patients could safely undergo CE with minimal risk of retention. Furthermore, the authors stipulated that radiographic studies were not necessary before CE in those patients with no symptoms of obstruction. They also felt that pain associated with passage, or disintegration of the capsule during passage, correlated with clinically relevant small-bowel pathology and indicated that patients would likely have capsule retention. (44)

A second study conducted by Spada et al (45) concluded that the patency capsule can prove functional patency even in those patients suspected of having strictures as evidenced by radiological findings. Delvaux et al (46) arrived at a different conclusion after studying 22 patients with suspected intestinal stenosis. In their study, the patency capsule did not detect stenoses that had not already been diagnosed by CT or SBFT. They recommended that CT studies be performed before CE in patients with a history of Crohn disease but reiterated that a thorough medical history is still the best indicator of suspected intestinal stenosis. At this time, the preponderance of evidence indicates the patency capsule is useful in detecting stenosis and determining the risks of capsule retention. The patency capsule was recently (May 2006) approved by the FDA for use in the United States.

Outcomes

Modification of therapeutic strategy. Multiple studies have demonstrated CE to have a higher diagnostic yield for the detection of obscure GI bleeding than conventional diagnostic modalities. More importantly, however, is the extent to which patient management is impacted by the results of capsule endoscopy studies. In the Pennazio study, CE findings in patients with ongoing overt bleeding were verified in 91% (21 of 23) by various means including PE and surgery. All of these individuals were treated with medical, surgical or endoscopic intervention and complete resolution of bleeding was achieved in 20 (86.9%). (9) In those with a previous history of obscure-overt bleeding, 16 of 29 patients underwent further examination, which confirmed the CE findings in 11 patients. Resolution of the bleeding was accomplished in 12 individuals (41%). In patients with obscure-occult bleeding, 25 of the 39 underwent further examination, which confirmed the findings of the CE study in 20 of the individuals. Of this group, complete resolution of bleeding was observed in 27 (69.2%) patients. Results demonstrated that complete resolution of bleeding was better achieved in those patients with ongoing obscure-overt bleeding and obscure-occult bleeding than in patients with previous obscure bleeding.

Mow et al performed capsule endoscopy on a group of 50 patients with known or suspected inflammatory bowel disease. The intent of their investigation was to determine the clinical benefit of employing CE in such patients. Their results detected pathology consistent with Crohn disease in 40% of patients. The diagnosis of 5 of the 20 patients with a history of ulcerative colitis (UC) was changed to Crohn following evaluation with CE. They concluded that of the patients with diagnostic findings, 85% experienced clinical improvement with therapeutic intervention guided by CE results. (47) In an abstract by Chong et al, (48) findings made by CE changed the management in 70% of patients who were investigated for Crohn disease of the small bowel. In another study by Chong et al (25) published in abstract form, 49 patients with a history of overt or occult GI bleeding were examined using CE. The outcomes of this study demonstrated a diagnostic yield of 65% for CE and, furthermore, changed the diagnosis of 22 of the 49 patients. The management of 29 of the 49 patients was influenced by the findings made using CE with definitive treatment (surgical or endoscopic) leading to the resolution of gastrointestinal bleeding in 22% (11/49) of the patients examined.

Although CE has improved the diagnosis of obscure GI bleeding, the therapeutic impact of CE remains less established. Additional studies with longer follow-up periods are necessary to generate results by which to better evaluate the effects of CE on patient management and outcomes. Currently, CE can be beneficial as it may offer an explanation of clinical symptoms or reasons for therapeutic failure in a number of patients with obscure gastrointestinal bleeding or suspected Crohn disease. Moreover, negative CE studies may also prevent a battery of further and possibly more invasive tests from being performed.

Discussion

Capsule endoscopy has its highest diagnostic yield in patients with ongoing bleeding or those with a continued positive fecal occult blood test and iron-deficiency anemia. (9) Based on the current studies, CE should be performed early on in the workup for patients with obscure GI bleeding following a negative upper and lower endoscopy. CE should also be considered before PE in cases of obscure gastrointestinal bleeding with suspected small intestine involvement. PE should be reserved for those patients with a negative CE and a continued suspicion of proximal small bowel pathology, for those in whom CE findings dictate the need for biopsy or therapeutic intervention who have lesions in the proximal small bowel, and those with a contraindication to CE. Employing CE before PE studies may help to decrease the time between diagnosis and intervention in the treatment of patients with obscure GI bleeding and avoid unnecessary PE. This sequencing of diagnostic tests also helps decrease costs associated with extensive workups.

Capsule retention with the potential for bowel obstruction is the most common complication of capsule endoscopy. Small bowel series or CT enteroclysis is recommended to determine if a stenosis is present before capsule endoscopy in patients suspected of having small bowel Crohn disease, and in those with symptoms suggesting partial obstruction. The patency capsule, however, may be a better alternative to assess for stenoses when it becomes readily available.

CE is a valuable development in the ongoing effort to effectively examine the small bowel. Compared with current technology, it is a relatively simple and well-tolerated procedure. CE has proven to be superior to conventional techniques in the detection of obscure GI bleeding; however, its role in other small bowel diseases such as Crohn disease is less well defined. The impact made by CE on therapeutic management and outcome of patients with small bowel bleeding must also be further explored before its cost-effectiveness can be analyzed.

Since its inception, CE has continued to evolve. With advances in technology allowing improved imaging and possible therapeutic intervention, we believe that the indications and application for use in patients with suspected small bowel disease will greatly expand.

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44. Boivin ML, Lochs H, Voderholzer WA. Does passage of a patency capsule indicate small-bowel patency? A prospective clinical trial? Endoscopy 2005;37:808-815.

45. 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;37:793-800.

46. Delvaux M, Ben Soussan E, 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;37:801-807.

47. Mow WS, Lo SK, Targan SR, et al. Initial experience with wireless capsule enteroscopy in the diagnosis and management of inflammatory bowel disease. Clin Gastroenterol Hepatol 2004;2:31-40.

48. Chong A, Taylor A, Miller A, et al. Comparison of CE with PE and small bowel barium studies in the detection of Crohn's disease of the small bowel. J Gastroenterol Hepatol 2003;18(Supp):B51

Sumeeta Mazzarolo, MD, and Patrick Brady, MD

From the Department of Internal Medicine, Division of Digestive Diseases and Nutrition, University of South Florida College of Medicine, Tampa, FL.

Reprint requests to Dr. Patrick Brady, Division of Digestive Diseases and Nutrition, MDC 82, 12901 Bruce B. Downs Boulevard, Tampa, FL 33612. Email: [e-mail]

Accepted September 21, 2006.

RELATED ARTICLE: Key Points

* The use of capsule endoscopy (CE) is indicated in the diagnosis of obscure gastrointestinal bleeding.

* Multiple studies have demonstrated CE to have a higher diagnostic yield for the detection of obscure GI bleeding than conventional diagnostic modalities including enteroscopy and barium studies. The highest diagnostic yield of CE is in patients with ongoing bleeding or those with a continued positive fecal occult blood test and iron-deficiency anemia.

* Contraindications to CE include the presence of intestinal obstruction, fistulas or strictures that may impede the excretion of the capsule and can potentially cause a bowel obstruction.

* CE should be performed early on in the workup for patients with obscure GI bleeding following a negative upper and lower endoscopy.

Table. Comparison between the diagnostic yields of capsule endoscopy and
push enteroscopy in studies of patients with obscure GI bleeding

                                  Diagnostic yield
                        Capsule endoscopy  Push enteroscopy
Author                  (%)                (%)

Ell (16) (n = 32)       66                 28
Mata (18) (n = 42)      74                 19
Mylonaki (17) (n = 50)  68                 32
Saurin (22) (n = 58)    69                 38
Hartmann (34) (n = 33)  76                 21
Brown (23) (n = 32)     66                 28
Pennazio (9) (n = 100)  59                 29