Colonoscopy enables your doctor to examine the lining of your colon (large intestine) for abnormalities by inserting a flexible tube as thick as your finger into your anus and slowly advancing it into the rectum and colon.
Upper endoscopy lets your doctor examine the lining of the upper part of your gastrointestinal tract, which includes the esophagus, stomach and duodenum (first portion of the small intestine).
Flexible sigmoidoscopy lets your doctor examine the lining of the rectum and a portion of the colon by inserting a flexible tube about the thickness of your finger into the anus and slowly advancing it into the rectum and lower part of the colon.
Anesthesia is a treatment that involves using medicine to prevent pain during a medical procedure. It is used for many types of procedures from small ones, like dental work, to major ones, like open heart surgery.