Water Improves Patient Tolerance of Unsedated Colonoscopy

The October issue of GIE: Gastrointestinal Endoscopy features the results of two randomized controlled trials of unsedated colonoscopy comparing water infusion versus air insufflation to distend the colon.

Both studies showed that patient tolerance with the water method during unsedated colonoscopy was greater than with air insufflation and enhanced patient willingness to undergo a repeat unsedated exam; however, the cecal intubation and adenoma detection rates varied somewhat between the two studies.

Unsedated colonoscopy is common worldwide, but in the United States, conscious sedation is dominant and deep sedation is gaining support. Without sedation, the exam can cause discomfort due to the air pumped into the colon which causes the colon to stretch in order to more easily insert the colonoscope. Scheduled unsedated colonoscopy has been requested by seven percent of US patients.

In unsedated patients, discomfort during colonoscopy limits cecal intubation (colonoscope insertion reaching the cecum, which is the pouch that marks the beginning of the large intestine also known as the colon), which is essential for a complete exam. Methods for reducing discomfort have included several water-related techniques.

Improved Outcomes in Scheduled Unsedated Colonoscopy by the Water Method

Researchers at Veterans Affairs Healthcare System facilities in California developed a novel water method for scheduled unsedated colonoscopy using water infusion in lieu of air insufflation to more comfortably open the colon and insert the colonoscope. In their observational study of veterans, they showed that the novel water method enhanced cecal intubation and patient willingness to undergo a repeat scheduled unsedated colonoscopy.

In this prospective, randomized controlled trial, the researchers’ objective was to confirm these beneficial effects. From November 2007 to April 2009, eighty-two veterans underwent scheduled unsedated colonoscopy by either the air method (40 patients) or water method (42 patients). The main measurements were discomfort and procedure-related outcomes. The colonoscopies were performed by a single colonoscopist without registered nurse support.

The cecal intubation rate in the water group was 98 percent, significantly higher than that in the air group which was 78 percent. The percentage of patients reporting a willingness to repeat a scheduled unsedated colonoscopy was also significantly higher at 93 percent for the water group compared to 78 percent with the air group.

The proportion of patients with at least one adenoma (precancerous polyp) showed a trend in favor of the water group at 36 percent, versus 23 percent in the air group. This trend was present for all indications in the proximal colon and for polyp size of 10 mm or larger. The cleansing effect of the water might have contributed to the higher adenoma detection yield. The adenoma detection rates were comparable to those in sedated colonoscopy.

Patients were blinded to the study method. To determine outcome measures for discomfort, a scale of zero (no discomfort) to 10 (most severe discomfort) was verbally communicated by the patients to an unblinded assistant during the colonoscopy and to a blinded observer five to 10 minutes after colonoscopy. The researchers reported that the decrease in maximum discomfort was significant and the decrease in overall discomfort approached significance with the water method. The method, but not patient charactersitics, was a predictor of discomfort.

The study acknowledges that the results from this Veterans Affairs trial cannot be generalized to other practice settings that rely primarily on sedation. Until demonstrated otherwise, the prolonged procedure time (56 minutes) is a distinct disincentive for the incorporation of scheduled unsedated colonoscopy into a busy endoscopy unit, even if discomfort is significantly reduced by the water method.

The researchers concluded that evaluation of water method-assisted unsedated colonoscopy in diverse settings deserves to be supported.

Source: American Society for Gastrointestinal Endoscopy