Incomplete colonoscopy

I has just underwent a colonoscopy and the doctor tell me it was incomplete and now recommends a barium enema

Polyps can occur anywhere in the colon but are most common in the left or sigmoid colon. Some polyps tend to grow and eventually turn cancerous. Thus, colonoscopy is a useful tool to screen for polyps and remove them if possible. However, all consumers should understand that in nearly 30% of patients, colonoscopy cannot assess the whole colon. The reason for this failure may be technical (incompetent doctor) or poor bowel preparation. When the doctor is unable to visualize the entire colon, the options are to repeat the colonoscopy or undergo a barium enema. Barium enema is an imaging study whereby contrast is inserted into the rectum and picture of the colon are obtained. Barium enema unlike colonoscopy does not always visualize polyps less than 5 mm. Moreover, during a barium enema one cannot even do a biopsy or remove the polyp. Therefore, if your colonoscopy is unsuccessful, you should discuss the topic with your doctor and find out why it was unsuccessful and perhaps be referred to another doctor who is more proficient at the technique