A soothing salve such as petroleum jelly applied after cleaning the anus will reduce discomfort. The patient may be asked not to take aspirin or similar products such as salicylate, ibuprofen, etc. for up to ten days before the procedure to avoid the risk of bleeding if a polypectomy is performed during the procedure. A blood test may be performed before the procedure. Investigation
During the procedure the patient is often given sedation intravenously, employing agents such as fentanyl or midazolam. Although meperidine (Demerol) may be used as an alternative to fentanyl, the concern of seizures has relegated this agent to second choice for sedation behind the combination of fentanyl and midazolam. The average person will receive a combination of these two drugs, usually between 25 and 100 µg IV fentanyl and 1–4 mg IV midazolam. Sedation practices vary between practitioners and nations; in some clinics in Norway, sedation is rarely administered.Some endoscopists are experimenting with, or routinely use, alternative or additional methods such as nitrous oxide and propofol, which have advantages and disadvantages relating to recovery time (particularly the duration of amnesia after the procedure is complete), patient experience, and the degree of supervision needed for safe administration. This sedation is called "twilight anesthesia". For some patients it is not fully effective, so they are indeed awake for the procedure and can watch the inside of their colon on the color monitor. Substituting propofol for midazolam, which gives the patient quicker recovery, is gaining wider use, but requires closer monitoring of respiration.
In order to inspect this surface thoroughly, the physician blows it up like a balloon, using air from a compressor or carbon dioxide from a gas bottle (CO2 is absorbed into the bloodstream through the mucosal lining of the colon much faster than air and then exhaled through the lungs which is associated with less post procedural pain), in order to get the creases out. The stomach, intestines, and colon have a so-called "second brain" wrapped around them, which autonomously runs the chemical factory of digestion. It uses complex hormone signals and nerve signals to communicate with the brain and the rest of the body. Normally a colons job is to digest food and regulate the intestinal flora. The harmful bacteria in rancid food, for example, creates gas. The colon has distension sensors that can tell when there is unexpected gas pushing the colon walls out—thus the "second brain" tells the person that he or she is having intestinal difficulties by way of the sensation of nausea. Doctors typically recommend either total anesthesia or a partial twilight sedative to either preclude or to lessen the patients awareness of pain or discomfort, or just the unusual sensations of the procedure. Once the colon has been inflated, the doctor inspects it with the scope as it is slowly pulled backward. If any polyps are found they are then cut out for later biopsy. Some doctors prefer to work with totally anesthetized patients inasmuch as the lack of any perceived pain or discomfort allows for a leisurely examination.