A colonoscopy is a procedure in which a doctor examines your large intestine (also called your colon) to look for and remove growths that could be precancerous or cancerous. 
There are two kinds of anesthesia used during colonoscopies. If you have conscious sedation, it is usually administered by the doctor who performs your colonoscopy. If you undergo general anesthesia (also known as full or deep sedation), you can expect to be monitored by a credentialed anesthesiologist and nurse anesthetist.
During the procedure, a doctor explores the colon with a colonoscope, which is a thin, flexible tube with a video camera attached to it. This instrument helps doctors look for growths such as polyps or tumors as well as inspect for inflammation, bleeding, and ulcers.
Propofol is considered safe and effective for most patients, but some side effects need to be considered. The drug may lower blood pressure and cause slower breathing. If you have very low blood pressure or heart and/or breathing problems, your doctor may advise against using propofol for your colonoscopy.
Your doctor will give you advice on how to prepare for your colonoscopy well in advance of your procedure. You can expect to have restrictions regarding the food you can eat and liquids you can drink the day before. You will also be given instructions on how to empty your colon.
On the day of your procedure, an anesthesiologist and nurse anesthetist meet with you to review your medical history and vital signs. If they identify any potential problems, your doctor will discuss making an alternative plan such as using conscious (light) sedation instead of general anesthesia during your colonoscopy or rescheduling it for another time.
For patients in good health, whose heart and blood pressure are working normally and who are breathing well, the anesthesiologist will attach an intravenous drip to the arm. This helps to make sure that the drug flows correctly and consistently into the vein. Within a few minutes, the patient is asleep, and the doctor then begins the colonoscopy.
Most colonoscopies take between 30 minutes and an hour to complete. During the procedure, the anesthesiologist and nurse anesthetist work together to ensure that the patient’s vital signs, especially blood pressure and breathing rate, remain in a safe range.
When the procedure is over and we stop the intravenous drip, it generally takes only 10 to 15 minutes before patient is fairly wide awake again.