Objectives: Patients with extensive, longstanding chronic ulcerative or Crohn's colitis face greater risks of developing colorectal cancer. Current standard surveillance relies on detecting dysplasia using random sampling at colonoscopy but may fail to detect dysplasia in many patients. Dye spraying techniques have been reported to aid in detecting otherwise subtle mucosal abnormalities in the setting of colitis. We prospectively compared dye-spray technique using methylene blue to standard colonoscopic surveillance in detecting dysplasia.
Methods: One hundred fifteen patients were referred to the Chromoendoscopy Study Group and prospectively screened for the study. One hundred two (64 M, 38 F) (79 UC 23 CC) patients meeting the inclusion criteria were enrolled. Following a standard bowel preparation, each patient was examined using standard office endoscopic equipment by three methods: (a) standard surveillance colonoscopy with four random biopsies every 10 cm (for a total of at least 32 samples); (b) a targeted biopsy protocol; and finally (c) methylene blue (0.01%) dye spray was segmentally applied throughout the colon and any pit-pattern abnormality or lesion rendered visible by the dye spray was targeted and biopsied. Each patient had a single examination, which included two passes of the colonoscope. Specimens were reviewed in a blinded fashion by a single gastrointestinal pathologist. The three methods were then compared with each patient serving as his or her own control.
Results: Targeted biopsies with dye spray revealed significantly more dysplasia (16 patients with low grade and 1 patient with high grade) than random biopsies (3 patients with low-grade dysplasia) (P= 0.001) and more than targeted nondye spray (8 patients with low-grade and 1 patient with high-grade dysplasia) (P= 0.057). Targeted biopsies with and without dye spray detected dysplasia in 20 patients compared with 3 using Method (a) (P= 0.0002, two-tailed exact McNemar's Test). There were no adverse events.
Conclusions: Colonoscopic surveillance of chronic colitis patients using methylene blue dye-spray targeted biopsies results in improved dysplasia yield compared to conventional random and targeted biopsy methods. Accordingly, this technique warrants incorporation into clinical practice in this setting and consideration as a standard of care for these patients. The value of multiple random biopsies as a surveillance technique should be revisited.