Straight to flexible sigmoidoscopy: rationalization of 2-week wait referrals in suspected colorectal cancer

The 2-week wait pathway was designed to decrease the time from presentation to primary care of patients with 'red flag' symptoms of suspected cancer for review by a specialist for the diagnosis or exclusion of cancer. In our tertiary referral centre we have found that 968 colonoscopies per year are required to satisfy the demand for the 2-week wait, leading to limited colonoscopy availability for other services. We sought to determine the yield of colorectal cancer found at colonoscopy referred via the 2-week wait and referenced to the original red flag symptoms. This was in order to select the most efficacious alternative primary investigation based upon presenting symptoms.

Electronic records were retrospectively analysed. All patients who went through the 2-week wait for suspicion of colorectal cancer in 2013 and were found to have colorectal cancer on colonoscopy were included. Patients not undergoing colonoscopy as the first investigation were excluded. The splenic flexure was deemed to be within the range of a flexible sigmoidoscope.

In all, 2950 referrals were made. 968 colonoscopies were performed as the primary investigation of which 35 were found to have colorectal cancer. No patients referred with rectal bleeding and another symptom had a tumour more proximal to the range of flexible sigmoidoscopy. 80% of tumours proximal to the splenic flexure were suitable for CT diagnosis alone.

Our data support the use of flexible sigmoidoscopy alone as an initial investigation for patients presenting with rectal bleeding with or without additional colorectal symptoms. Patients with anaemia (without bleeding) or change in bowel habit (without bleeding) may be investigated with CT colonography alone; colonoscopy may then be used selectively prior to surgery.