Computed Tomography Enterography (CTE) Versus Capsule Endoscopy for Overt, Obscure Gastrointestinal (GI) Bleeding

• Contribution of diagnostic test to clinical management [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  We will assess whether either CT or CTE changes managemet based on findings
• Overall cost of evaluation [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  We will assess the cost of each test and cost based on findings
• Adverse events [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  We will measure any and all adverse outcomes based on CT or CTE for the month following whichever study is performed last.

• Contribution of diagnostic test to clinical management [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  We will assess whether either CT or CTE changes managemet based on findings
• Overall cost of evaluation [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  We will assess the cost of each test and cost based on findigs
• Adverse events [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  We will measure any and all adverse outcomes based on CT or CTE for the month following whichever study is performed last.

Up to 5% of patients with recurrent gastrointestinal (GI) bleeding remain undiagnosed by upper endoscopy and colonoscopy, the presumed source of bleeding in these patients being the small intestine. These patients fall under the category of "obscure gastrointestinal bleeding," and frequently require an extensive diagnostic work-up.

Although capsule endoscopy (CE) has a high yield for findings, there are several limitations to its utility in the care of patients with obscure GI bleeding. For these reasons, most patients who present with obscure or occult gastrointestinal bleeding typically undergo various radiologic imaging studies, including enteroclysis, small bowel series, CT scan, angiography, and radionuclide scan. Recently, many centers (including the Brigham and Women's Hospital) have begun using CT enterography (CTE) for evaluation of suspected small bowel pathology. CT enterography combines the improved spatial and temporal resolution of multidetector row CT with large volumes of an orally administered neutral enteric contrast material to permit visualization of the small bowel wall and lumen. This modality has been shown to have considerable advantages over barium small bowel studies by allowing detection of subtle findings such as mucosal hyper-enhancement or mild wall thickening, and is better tolerated by patients than CT enteroclysis.

At the Brigham and Women's Hospital, CTE has recently replaced standard abdominal CT when small bowel pathology is suspected. While CT enterography and capsule endoscopy have been directly compared in the evaluation of non-stricturing Crohn's Disease, they had not been directly compared in the evaluation of obscure GI bleeding until recently (see "Pilot Data" below). The current diagnostic algorithm for obscure gastrointestinal bleeding based on the American Gastroenterology Association technical review was published in 2007 and does not include either capsule endoscopy or CT enterography. The videocapsule was approved by the FDA in 2001 and CT enterography technique has been developed over the last 5 years. Both of these tests are currently being used as part of standard of care to evaluate obscure gastrointestinal bleeding in centers where either or both technologies are available, including the Brigham and Women's Hospital. In addition, patients are also currently being referred from area hospitals without the capacity for this type of testing to the Brigham and Women's Hospital for either or both tests for the evaluation of obscure GI bleeding.

Obscure gastrointestinal bleeding (OGIB) refers to bleeding undiagnosed by upper endoscopy and colonoscopy. In 40-70% of cases of OGIB, a bleeding lesion is localizable to the small bowel. In OGIB, capsule endoscopy (CE) has a diagnostic yield of 40-80%, and has demonstrated diagnostic superiority to push enteroscopy, barium studies, angiography, CT angiography, and routine abdominal CT scan. When CE is non-diagnostic, however, the subsequent diagnostic algorithm is not well-defined. There is currently no established role for cross-sectional imaging for this indication. CT enterography (CTE) combines the spatial and temporal resolution of CT with an orally administered neutral enteric contrast material that permits detailed visualization of the small bowel. Unlike other imaging modalities such as nuclear medicine techniques and catheter angiography, CT is less labor-intensive, more readily available, and provides precise anatomic localization. A novel OGIB-protocol available at Brigham and Women's Hospital for CTE utilizes a dual-phase, dual energy technique that obtains images at two time points to better identify active bleeding in the mesentery. We, the investigators, plan to prospectively study an algorithm that employs CTE and compare to capsule endoscopy to investigate the effectiveness of both modalities and to evaluate the potential role of CTE in OGIB.

The goal of our study is to determine observationally the contribution of both CE and the new protocol for CTE to the evaluation and management of overt obscure GI bleeding and accordingly revise the clinical algorithm.

We hypothesize that CTE will be as or more effective than CE at identifying culprit lesions in overt, obscure gastrointestinal bleeding.

• Device: Capsule Endoscopy
  Prior to the test, patients will be on a clear liquid diet for 24 hours and will have undergone an overnight fast. If a clear liquid diet is not possible, some patients may undergo a bowel preparation the day before the procedure. On the morning of the test, patients will swallow a video capsule with water. Clear liquids will be permitted after 2 hours, and a light meal permitted 4 hours after swallowing the capsule, if appropriate. No medications will be allowed 2 hours before the procedure and drugs that can delay gastric emptying will be avoided until the study is complete. At 8 hours after ingestion, the sensor array and recorder/battery belt pack will be disconnected and the data will be downloaded onto a computer equipped with software for image viewing. Images are sent through 8 skin electrodes to the recorder, stored and viewed on a RAPID workstation. At the end of the recording, the video is transferred to a computer for analysis.
• Radiation: CT Enterography
  CT enterography at the Brigham and Women's hospital is performed by using intravenous iodinated contrast material (Ultravist 300) and a neutral oral-enteric contrast material containing methylcellulose (Volumen). During scanning, 150 mL of nonionic intravenous contrast medium will be administered at a rate of 3mL/sec and the imaging conducted 40 and 70 seconds after the administration of the intravenous contrast medium. All imaging will be performed on a Dual-Energy multi-detector row CT scanner, Somatom Definition (Siemens Healthcare, Forcheim, Germany). Two independent X-ray tube/detector system will be used for image acquisition. One tube operates at 140 kV and the other at 80 kV . Slice collimation will be 0.6 mm and images reconstructed at 3 mm thickness with 3 mm reconstruction intervals. Coronal and sagittal images will be reconstructed at 3 mm thickness with 3 mm increments. Images will be reviewed by a radiologist experienced in the interpretation of CT enterography.

Inclusion Criteria:

• Patients presenting with signs and symptoms of "overt, obscure GI bleeding" including hematemesis, melena, and hematochezia within the past 14 days with negative endoscopic evaluation (including upper endoscopy for hematemesis, and both upper and lower endoscopy for hematochezia) despite clinical evidence of GI bleeding.

Exclusion Criteria:

• Known renal insufficiency (or blood Creat >1.5 or estimated glomerular filtration rate [eGFR]<60)
• Allergy to iodinated intravenous (IV) contrast media
• Swallowing difficulties
• Known small bowel strictures
• Suspected bowel obstruction
• Under the age of 18
• Unable to give consent
• Currently pregnant