Walter LC, deGarmo P, Covinsky KE. Association of older age and female sex with inadequate reach of screening flexible sigmoidoscopy. Am J Med 2004; 116:174-178.

While most clinical guidelines promote the screening of asymptomatic people older than 50 with a flexible sigmoidoscope every five years to detect colorectal cancer, a study supported by the Agency for Healthcare Research and Quality in Washington, DC, shows that using a 60-cm flexible scope may not be the best tool for women and older people.

Researchers measured the maximum depth of insertion of the sigmoidoscope among 15,406 asymptomatic people who underwent the screening procedure between April 1997 and October 2001 at 71 sites in 27 states. A depth of 50 cm was defined as adequate to view the colon and less than 50 cm as inadequate.

Overall, 18% of patients had an inadequate exam. As men increased in age, so did the rate of inadequate exams, with 10% of men ages 50 to 59 receiving inadequate exams, and 22% of men 80 and older receiving inadequate exams. Inadequate exams were more prevalent in women of all ages, with 19% of women ages 50 to 59 receiving inadequate exams and 32% of women older than 80 receiving inadequate exams.

The reasons for the inadequate exams were women’s longer colons in a smaller abdominal cavity, which means more twists and turns that make it difficult to pass the scope, and poor bowel preparation and coexisting problems such as previous abdominal surgeries for older patients.