In the field of gastroenterology, endoscopy refers to the insertion of a video technology based flexible instrument into either the mouth to evaluate the esophagus, stomach and duodenum (first portion of the small intestine) or insertion of this instrument through the anal canal to evaluate the colon (large intestine) and sometimes the terminal ileum (the very last portion of the small intestine. The section in between the first and the last portion of the small intestine can be examined with a pill camera. During most endoscopic procedures the patient is sedated; the patient is either in a twilight zone or he or she is truly asleep but arousable. Sedation is extremely safe as the patient’s vital signs and oxygen saturation are monitored continuously and reversal agents are immediately at hand should a patient be very sensitive to the sedatives given: Versed and/or Fentanyl. The time spent in the endoscopy center is usually 1.5 – 2 hours (30 - 40 minutes for unsedated procedures). After sedation, a patient is not allowed to drive a car that day and therefore a driver (not taxi driver) needs to pick up the patient and drive him or her home.
During a colonoscopy, which takes about 15 minutes to complete, the patient is on the left side (fetal position) and the instrument is inserted through the anal canal, rectum and all the way to the beginning of the colon, the cecum where the appendix is located and where the small intestine enters. The instrument is then withdrawn and the entire lining is carefully inspected paying attention to both raised and flat lesions or polyps; when present, these are removed by a forceps or a snare device that runs through an operating channel. The colon usually is cleared of all polyps. This is the preferred procedure for colon cancer screening as it examines the entire colon. The colonoscopy therefore is not only diagnostic but also therapeutic and preventative as precancerous lesions or polyps are being removed. Other than screening for cervical cancer by Pap smears, colonoscopy is the only procedure done in the human body that can actually prevent a cancer. Again, colon cancer is the second most common cause for cancer death in the U.S. and most western countries. A full bowel preparation is needed (see section for bowel preps).
This procedure is similar to the colonoscopy but the instrument is shorter and therefore only the lowest end of the colon and rectum are being evaluated. The procedure time is 2 – 5 minutes and the patient is usually not sedated and therefore does not need a ride. It is no longer used to screen for cancer as only a portion of the colon is being examined. However, it is still helpful in evaluating a patient’s symptom such as diarrhea and rectal bleeding. It is more commonly used in younger patients as colon cancer is less of a concern in that age group. Usually, 2 Fleet enemas are applied to clean the lowest end of the colon.
The patient is either sedated or sometimes unsedated on his or her left side and a pencil thin tube is inserted through the mouth protected by a bite block into the esophagus, stomach and duodenum. This typically takes 2 – 5 minutes to complete. The procedure is usually used to assess inflammatory changes in the esophagus (esophagitis) or in the stomach (gastritis). Frequently, biopsies are taken (which does not hurt) from the stomach to look for the bacterium H. pylori that can cause ulcers, cancer and lymphoma. A bowel preparation is not needed and the patient may have water or other clear liquids up to 2 hours before the procedure.