Background More and more people have undergone colonoscopy for colorectal cancer screening. The surveillance interval is up to the patients with low- or high-risk polyps at the first screening. According to the guideline of US Multi-Society Task Force on Colorectal Cancer, they recommend that the surveillance intervals for patients with the low-risk polyps are 5 to 10 years, and for high-risk are 3 years.

Aims We would like to investigate what is the time of follow-up interval in the patients (low- and high-risk) at present.

Methods We retrospectively study individuals who had undergone surveillance colonoscopy during 2011 through 2017 in a community hospital. Each time colonoscopic findings were divided to two groups: (1) low-risk polyps (2) high-risk polyps. No polyps or small (<10 mm) hyperplastic polyps detected were inclusive to low-risk polyps.

Results A total of 55 patients were collected. 40 patients (72.7%) were in low-risk polyps group and 15 (27.3%) were in high-risk polyps group according to their first colonoscopy result. In low-risk group, the average years of follow-up intervals are 3.68 years (SD 2.09), and 27 of 40 patients (67.5%) are less than 5 years (range 1–4 years). Positive fecal occult blood test (29.6%), bloody stool passage (22.2%) and colonic polyps’ history (25.5%) are the common reasons why these patients practiced next screening colonoscopy in advance. In high-risk group, the average years of follow-up intervals are 2.38 years (SD 1.45), and 10 of 15 patients (67.5%) are less than 3 years (range 1–2 years). Colonic polyps’ history (70%) is the most frequent reasons why the patients practiced next screening colonoscopy in advance. Another issue is for age older than 75 years old, 2 of 5 patients had high-risk polyps at first time colonoscopy, however, they all had low risk polyps at follow-up colonoscopy surveillance.

Conclusions This study reveals the discrepancy between practitioner recommendations and current guidelines for colonoscopy surveillance in the time of follow-up colonoscopy. It might be caused by frequent fecal occult blood test (biennial), bowel cleansing preparation, and continuing education for practitioners. The Ministry of Health and Welfare must conduct a broader assessment of screening schedule.