Obscure Gastrointestinal bleeding: Investigation of the small bowel – The Last Frontier
Introduction: Obscure gastrointestinal bleeding (OGIB) is increasingly becoming a common problem in the aging population. These patients, typically, had at least one set of normal gastroscopy and colonoscopy without being able to detect a site of blood loss in the upper or lower gastrointestinal tract.
Obscure gastrointestinal bleeding (OGIB) could be either overt when patient describes intermittent melae- na or haematochezia (fresh rectal bleeding) or occult when only faecal occult blood is positive with substantial drop in Hb without any macroscopic evidence of blood loss. Typically, these patients are elderly with background valvular or ischaemic heart disease, COAD, chronic renal failure with or without anti-platelet agents or other anti-coagulants on board. These elderly patients are predisposed to bleeding from angioectatic lesions, mostly, of the small bowel.
Indications: Although there are many deserving indications for which small bowel should be investigated such as Crohn’s disease, malabsoption, chronic diarrhoea, unexplained weight loss, ischaemia etc, only OGIB attracts medicare rebate.
Which tools to use?: There are now 3 tools with variable availability and differ- ing functionality to choose from for the investigation of the small bowel e.g., capsule endoscopy (the pill camera), the push enteroscope (long small bowel endoscope) and the double balloon enteroscope (yet another endoscope with longer range). The general idea is to use the least invasive test first which is capsule en- doscopy. If the capsule demonstrates a pathology within the reach of the push enteroscope (usually the proximal 1.5 metre of the small bowel), then the push enteroscope should be used to coagulate a bleeding point/angioectasia, snare a polyp or take a biopsy. Lesions detected beyond the reach of the push enteroscope, would need to be dealt with either surgically or in some cases by angiography and embolisation of an offending blood vessel. Unfortunately, the double balloon enteroscope is only available in 3 centres in Australia .
Capsule endoscopy advantages: This is a relatively non-invasive, painless out patient procedure which requires no sedation. It views the entire 6 metres of the small bowel. Pathology is found in 60% cases. The capsule components and the patients’ attachments are shown in Figs 1 & 2 respectively.
Patient logistics: Patient fasts overnight and swallows the capsule first thing in the morning. The capsule sends video images to the patient recorder over 8 hours as it traverses the small intestine while the patient is ambulant. The video is then down loaded to a work station, burned to a disc if necessary and analyzed. Disadvantages: The capsule can not biopsy a lesion, coagulate an angioectasia or remove a polyp and is purely a diagnostic test. Image quality is poorer than standard endoscopes. Unsuspected small bowel stricture could cause obstruction. It is expensive (Schedule $1800 with a rebate of $1635). The light intensity can not be adjusted nor can the small bowel be inflated with air for better views as can be done with standard endoscopes.
Push Enteroscopy: It is a 2.2 metre long endoscope capable of examining the proximal 1.5 metre of the small bowel. Patients who have angioectasias or polyps or other lesions identified by capsule endoscopy in the proximal small bowel should have this test.
Advantages: The push enteroscope is both a therapeutic and diagnostic endoscope, within its range, capable of biopsy, polypectomy and coagulation of bleeding points or angioectasias. It has much better image quality than capsule endoscopy and small bowel can be inflated with air to get a more detailed inspection. The procedure takes approximately 30 minutes.
Disadvantages: The push enteroscope can examine the proximal 1.5 metre, on an average, of the small bowel. It is invasive and patient requires sedation. When used as a diagnostic equipment, pathology is found in 30-40% of patients.
Double Balloon Enteroscope: This equipment is now used on a trial basis in 3 centres in Australia. It can be passed halfway into the small bowel in 1-2 hours. However, the distal half of the small bowel is examined, on a different day, retrogradely from the colon. It also takes about 2 hours to examine the distal small bowel. It clearly has a longer range and the potential to examine the entire small bowel and represents a significant advance above both the push enteroscope and the capsule endoscope. It clearly also has the therapeutic capability to take biopsies, snare polyps and coagulate bleeding points. It does not attract a rebate yet although this is being currently pursued.
Summary: My recommendation is to use the capsule first up as a diagnostic test for OGIB. Then use the push enteroscope if the lesions detected by the capsule are within the proximal small bowel. We provide both capsule endoscopy and push enteroscopy service through the Southcoast Digestive Diseases Centre. I shall be watching the space closely for the availability of rebate for the double balloon enteroscope and consider its introduction to Southcoast Digestive Diseases Centre.
Bhaskar Chakravarty