Water method for unsedated colonoscopy; interval between prep and colonoscopy predicts prep quality

In recognition of National Colorectal Cancer Awareness Month during March, GIE: Gastrointestinal Endoscopy has put out a special issue on colonoscopy for colorectal neoplasia. Studies of note regarding colonoscopy appear in both the monthly March issue and the special issue. A study appearing in the March issue from researchers in California focuses on the impact of a novel water method on scheduled unsedated colonoscopy in U.S. veterans. Researchers in Texas looked at how the time interval between the completion of the last dose of bowel preparation and the start of colonoscopy predicts the quality of the bowel preparation in a study appearing in the special issue. GIE: Gastrointestinal Endoscopy is the monthly peer-reviewed scientific journal of the American Society for Gastrointestinal Endoscopy (ASGE).

Endoscopy is a procedure that uses an endoscope - a thin, flexible tube with a light and a lens on the end to look into the esophagus, stomach, duodenum, small intestine, colon, or rectum, in order to diagnose or treat a condition. There are many types of endoscopy, including colonoscopy, sigmoidoscopy, gastroscopy, enteroscopy, and esophogogastroduodenoscopy (EGD). Colonoscopy is frequently used to screen for colorectal cancer, which most typically develops from polyps (growths in the colon).

March Issue: "Impact of a novel water method on scheduled unsedated colonoscopy in U.S. veterans"

During a colonoscopy, the colon must be distended (expanded) in order to pass the colonoscope through the full length of the colon to the cecum (the cul-de-sac lying below the terminal ileum forming the first part of the large intestine or colon ). The advancement of the scope into the cecum is termed cecal intubation and is mandatory for colonoscopy to be effective. Air is the usual medium to distend the bowel. However, air insertion can lengthen the colon (much like an accordion) and result in discomfort that may prevent cecal intubation, particularly in the unsedated patient.

The authors of this study used warm water, rather than air, to distend the colon based on their prior experience with this technique. They previously found that when water was infused into the colon instead of air during colonoscope insertion, approximately 50 percent of the colon exams could be completed without sedation. Based on this background information, researchers in California hypothesized that the novel water method would enhance cecal intubation and increase the proportion of patients willing to have another colonoscopy with no sedation.

An unsedated colonoscopy program was instituted in 2002 at the Veterans Affairs Sepulveda Ambulatory Care Center in California. From June 2005 to May 2006, the air method was used for colonoscopy. From June 2006 to October 2007 the water method was used. With the latter method, the air pump was disabled and "warm to touch" tap water in lieu of air was used. Sixty-two veterans were examined using the air method and 63 veterans were examined using the water method. The cecal intubation rate with the air method was 76 percent, while the water method was 97 percent. The proportion of patients who reported a willingness to repeat an unsedated colonoscopy was significantly higher with the water method at 90 percent compared with 69 percent for the air method.