Objective To perform a comprehensive audit of all colonoscopy undertaken in the UK over a 2-week period.

Design Multi-centre survey. All adult (≥16 years of age) colonoscopies that took place in participating National Health Service hospitals between 28 February 2011 and 11 March 2011 were included.

Results Data on 20 085 colonoscopies and 2681 colonoscopists were collected from 302 units. A validation exercise indicated that data were collected on over 94% of all procedures performed nationally. The unadjusted caecal intubation rate (CIR) was 92.3%. When adjusted for impassable strictures and poor bowel preparation the CIR was 95.8%. The polyp detection rate was 32.1%. The polyp detection rate for larger polyps (≥10mm diameter) was 11.7%. 92.3% of resected polyps were retrieved. 90.2% of procedures achieved acceptable levels of patient comfort. A total of eight perforations and 52 significant haemorrhages were reported. Eight patients underwent surgery as a consequence of a complication.

Conclusions This is the first national audit of colonoscopy that has successfully captured the majority of adult colonoscopies performed across an entire nation during a defined time period. The data confirm that there has been a significant improvement in the performance of colonoscopy in the UK since the last study reported seven years ago (CIR 76.9%) and that performance is above the required national standards.