CHICAGO – Inspection of the mucosa during colonoscope insertion does not increase adenoma detection rates at colonoscopy, according to data from a randomized trial presented at the annual Digestive Disease Week.
At least one adenoma was detected in 52% of patients who were randomly assigned to inspection during both insertion and withdrawal of the colonoscope, and in 58% of patients who were inspected only during withdrawal. The total inspection time was the same, at about 9 minutes. The two groups were labeled the "insertion group" and "withdrawal group."
The mean number of adenomas detected was 1.4 vs. 1.8 in the insertion and withdrawal groups, respectively. The groups were also similar with regard to such secondary end points as dose of propofol used for sedation (345 mg vs. 330 mg, respectively) and postprocedure pain assessed using a visual analog scale (1.2 vs. 1.1).
"Inspection during colonoscope insertion offered no additional benefit, compared with an equivalent period of inspection performed entirely during instrument withdrawal," Dr. David G. Hewett said.
Colonoscopy is typically performed with inspection only on withdrawal. This can be problematic because polyps that are visualized and not removed during instrument insertion sometimes cannot to be found during the withdrawal phase. This may be because views of the mucosa are different on insertion, because of conformational differences in colonic anatomy, such that the colon is shortened and pleated over the instrument during withdrawal, explained Dr. Hewett of Indiana University, Indianapolis, and the University of Queensland, Herston (Australia).
Dr. Douglas K. Rex
Dr. Hewett and his colleague Dr. Douglas K. Rex, distinguished professor of medicine at Indiana University and director of endoscopy at Indiana University Hospital, randomly assigned 340 patients undergoing routine screening or surveillance colonoscopy to 6 minutes of inspection during instrument withdrawal and an additional 3 minutes of inspection during either instrument insertion or withdrawal.
Inspection time (defined as time spent in active inspection of the mucosa) was measured with a stopwatch by a research assistant. The stopwatch was stopped for washing, suction, red-out, polypectomy, or biopsy. The colonoscopies were performed by two experienced endoscopists using high-definition colonoscopes (Olympus H180AL).
The 171 insertion patients and 169 withdrawal patients had similar baseline characteristics, including mean age (62.6 years vs. 63.6 years), indication (surveillance for 65% vs. 68%) and bowel preparation (excellent in 60% vs. 62%).
In all, 299 adenomas were detected in 187 patients, and the overall adenoma detection rate was 55%, Dr. Hewett said. Twelve patients had high-grade dysplasia or villous histology, and no cancers were detected.
Importantly, there were no significant differences in total procedure time or total inspection time, he said. Specifically, total procedure times were 24.2 minutes in the insertion group vs. 27.5 minutes in the withdrawal group, whereas total inspection times were 9.6 minutes vs. 9.4 minutes. As expected from the study design, mean withdrawal inspection times were 6.5 minutes in the insertion group and 9.4 minutes in the withdrawal group.
After adjustment for demographic, clinical, and procedural variables (age, sex, indication, endoscopist, and bowel preparation quality), there were no significant differences between groups in rates of adenoma detection or numbers of adenomas detected, Dr. Hewett said.
"We conclude that these results do not support a role for routine inspection during colonoscope insertion," he said.
During a discussion of the study, an attendee asked whether insertion times were equivalent, or whether the endoscopist simply "zipped" to the cecum when the 3 minutes had elapsed. This concern was echoed by session cochair Dr. Walter Coyle of the Scripps Clinic in La Jolla, Calif., who said he’s had fellows who can still be in the rectum at 3 minutes. Dr. Hewett replied that insertion times were similar between groups, and that the endoscopists were typically pretty close to the cecum in the proximal ascending colon at 3 minutes.
Another attendee asked whether the internal review board and patients were made aware of the theoretical risk of polyp perforation if polyps are removed during insertion. Dr. Hewett said they were not required to disclose this and that it is not something they’re typically worried about.
Dr. Coyle asked whether the researchers remove large (2- to 3- cm) polyps upon insertion, adding, "I tend to biopsy the site, so I can find it on the way back and take it on the way out because of that same concern, but I’m sort of old school."
Dr. Hewett replied that yes, they removed large polyps upon insertion, but could not provide specifics on how often this happened during the study.