What if the flexible sigmoidoscopy shows something abnormal?

Depends on findings. Flexible sigmoidoscopy looks at lower 1/3 of colon. Better look is with colonoscopy, which looks at entirety of colon. In general, if abnormality seen on flex sig, colonoscopy is recommended.
Sigmoidoscope. Then your gastroenterologist will talk with u about the findings & plan for treatment, if any. Prepare to ask all questions u might have during that appointment. Wish u well.