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Bowel prep oral sodium phosphate equal to fasting before capsule endoscopy for obscure GI bleeding

June 18, 2008

According to a new study from researchers in France, bowel preparation with oral sodium phosphate for capsule endoscopy in patients with obscure gastrointestinal (GI) bleeding is no better at cleansing the small bowel than the standard method of preparation, which is an eight-hour fast before the procedure. The study appears in the June issue of GIE: Gastrointestinal Endoscopy, the monthly peer-reviewed scientific journal of the American Society for Gastrointestinal Endoscopy (ASGE).

Capsule endoscopy (CE) is performed via a swallowed capsule containing a tiny video camera. The capsule, about the size of a large vitamin pill, contains a light source, batteries, a radio transmitter and an antenna. The capsule transmits the images to a recording device worn around the patient's waist. When complete, the recording is downloaded to a computer where the images are reviewed by the physician. The capsule is disposable and usually takes eight hours to move through the digestive system, after which it is passed harmlessly in a bowel movement. Capsule endoscopy does not require sedation and is painless. Capsule endoscopy can be used to diagnose hidden GI bleeding, Crohn's disease, celiac disease, and other malabsorption problems, tumors (benign and malignant), vascular malformations, medication injury, and to a lesser extent, esophageal disease. Currently, capsule endoscopy cannot be used to biopsy or treat any conditions.

Diagnostic results of CE may be reduced when visibility of the mucosa is impaired because of intestinal content or slow capsule progression. Prior to this study, there was only a limited consensus that preparations or prokinetics (drugs that promote gastrointestinal motility) probably improve the quality of small bowel cleanliness. Currently, an overnight fast only is proposed by the CE manufacturer.

"The aim of our study was to compare bowel preparation with oral sodium phosphate versus none, without prokinetic, for capsule endoscopy examination of the small bowel in obscure GI bleeding," said study lead author Marie-George Lapalus, MD, Hopital Edouard Herriot, Lyon, France. "We found that there was no difference observed for cleanliness and visibility between the group that was given oral sodium phosphate and the group that fasted. Therefore, our study concludes that oral sodium phosphate cannot be recommended for CE exploration in patients with obscure GI bleeding."

Patients and Methods

A total of 129 patients with obscure GI bleeding were enrolled in this prospective, multicenter, controlled trial study between December 2004 and February 2006. The patients (53 men and 76 women with a median age of 56.9 years), were randomized into two groups. In group A, the patients were instructed to consume only clear liquids during the evening before the procedure, followed by an eight-hour fast. In group B, patients were asked to drink 45mL of oral sodium phosphate with a glass of water the evening before and the morning of the procedure by using at least 2 L of clear liquid until midnight. Only a three-hour fast was required in group B.

After swallowing the capsule, the patients were not to drink for two hours and not eat for four hours regardless of randomization. Iron supplements and vegetal charcoal were stopped eight days before CE examination to avoid black stool residue. No added prokinetic drug was used.

Sixteen experienced investigators in eight centers, blinded to the randomization, independently evaluated the CE images. Gastric emptying time (i.e., the time from the first gastric image to the time of the first duodenal image), small bowel transit time (i.e., the time from the first duodenal image to the time of the first cecal image), and whether or not the cecum was reached were recorded for each patient. Because a universally accepted scale for grading bowel cleanliness is lacking, researchers developed their own scale, assessing preparation at five different segments: duodenum, jejunum, middle small bowel, ileum and distal ileum. Bowel cleanliness and visibility were evaluated by assessing the presence of bubbles, liquid and the rate of visibility.

Results

A total of 127 patients were analyzed (two patients were not able to swallow the capsule). The primary outcome variable, quality of the bowel prep, was not different between the two groups. Furthermore, no difference was found for gastric transit time, small bowel transit time, or likelihood of finding small bowel lesions. The authors concluded that despite some study limitations (e.g., use of a non-standardized scoring system, possibility that too few patients were enrolled), oral sodium phosphate before CE in patients with GI bleeding cannot be recommended based on their results. They acknowledge that further large studies combining preparation and prokinetics with diagnostic yield as the primary end point are still necessary.

American Society for Gastrointestinal Endoscopy