Colonic work-up after incomplete colonoscopy: significant new findings during follow-up.

BACKGROUND AND STUDY AIMS Cecal intubation is not achieved in 2 - 23 % of colonoscopies. The efforts made by physicians to visualize the remaining colon and the number of missed significant lesions are unknown. This study evaluates 1) the reasons for incomplete colonoscopy, 2) the rates of complete colonic evaluation after incomplete colonoscopy, and 3) the number of (pre-) malignant lesions missed by incomplete colonoscopy. PATIENTS AND METHODS In this population-based cohort study index colonoscopies were performed between September and December 2005. Prospectively collected data from consecutive patients with an incomplete colonoscopy were analyzed. For up to 18 months after the index colonoscopy, any further examinations performed in these patients were identified retrospectively. These secondary examinations included: repeat colonoscopy, computed tomography (CT) colonography, barium enema, abdominal CT scan, and surgery involving the colorectum. RESULTS Of 5278 colonoscopies, 511 were incomplete (9.7 %). The most frequent causes of incomplete colonoscopy were looping of the scope (20.4 %), patient discomfort (15.3 %), and obstructing tumor (13.9 %). Secondary examination was performed in 278 patients (54.4 %) after incomplete colonoscopy. Patients undergoing surveillance after colorectal cancer (CRC) (78.9 %) and those with anemia (73.1 %) most frequently received a secondary examination. Incomplete colonoscopies due to stenosis (78.9 %), severe inflammation (77.8 %) or an obstructing tumor (74.6 %) were most frequently followed by a secondary examination. In all of the follow-up examinations, CRC was diagnosed in 18 patients (3.5 %) and advanced adenoma in four patients (0.8 %). CONCLUSIONS In 4.3 % of the patients, advanced neoplasia was missed by incomplete colonoscopy. Our data therefore suggest that additional imaging is obligatory to visualize the remaining colon adequately.