Constipation is a common problem and systematic review data suggests this is not an accurate symptom in diagnosing organic disease. If the patient is also under the age of 50 and does not have a family history of colon cancer and there are no alarm features such as anemia or weight loss, then the risk of colorectal cancer is very low and the risks of colonoscopy usually outweigh the benefits in these patients.
Sources:
Ford AC, et al. Diagnostic utility of alarm features for colorectal cancer: systematic review and meta-analysis. Gut. 2008 Nov;57(11):1545-53. PMID: 18676420.
Related Resources:
Patient Pamphlet: Colonoscopy: When you need it – and when you don’t