Indeed, colonoscopy is commonly performed for 2 main purposes:
1. Diagnosis of a symptoms like PR bleeding (rectal bleeding) or Screening for colorectal cancer.
2. In the hospital setting, it serves another purpose for the treatment of patients with colorectal conditions like bleeding or even obstruction.
In terms of screening, there are standard guidelines to guide the necessity of it.
An example of this would be https://fascrs.org/healthcare-providers/education/clinical-practice-guidelines/colorectal-cancer-screening-and-surveillance-recom. This is based in United States.
Do check with any doctor/nurse or if you know anyone whom is a locally trained healthcare professional, there is no harm in having a casual conversation about this.
