Preparing for a Colonoscopy: Chemistry & Personal Observations

I’m turning 50 this year. If having lost an uncle to colon cancer and seeing an aunt suffer from it were not enough to convince me to take preventive action, last spring my students and I took a little trip to a pathology department of a local hospital. We saw polyps at the core of a cancerous growth, and a few weeks later I asked my family doctor for a colonoscopy.

In Quebec, Canada there is about a six-month waiting period for such a procedure, if you want it free and not go through a private clinic.Yesterday, was almost six months later, so on Sunday, I was put on a liquid diet. At 4 PM and 8 PM I dissolved a mixture of magnesium oxide, citric acid and sodium picosulfate(disodium (pyridin-2-ylmethylene)di-4,1-phenylene disulfate) in 250 ml of water. The reaction was exothermic, so I was advised to let it cool before drinking it. The picosulfate is a contact laxative which increases the motor activity of the intestinal tract. The first two compounds in water create aqueous ions of citrate and mamgnesium, which cause the inside of the colon to be hypertonic. This spells out osmosis as the rate of diffusion of water moving into the colon will exceed the rate of absorption. Summary: lots of peristlasis and lots of water in the colon spell out intense diarrhea one hour after ingestion of the product.

After ingesting each pouch of this concoction, I had to drink a liter of fluids including a sports drink to compensate for the loss of electrolytes. They could not be red or dark-coloured since such solutions could interfere with the colonoscopy. Since I was spending so much time on the bowl and since the Celtics had finished beating the Lakers, I had time to go through the CPS(Compendium of Pharmaceuticals and Specialties ) entry for PicoSalax and noticed that the instructions differed from the one my doctor gave me. Yesterday the specialist explained to me that his procedure was more effective. By the way, before starting the diarrhea, if you don’t have a bidet, apply zinc oxide so that you don’t rub your butt off with toilet paper.

At 10 PM I had to take a different laxative that was effective 8 hours later. Finally after a rough night’s sleep I seemed to discharge the last of my colon’s contents at about 6:30 AM. I was taken in by the orderly 15 minutes ahead of schedule, which stunned me. When I worked in Honolulu and had medical insurance with Kaiser, if they were 10 minutes late with an appointment I received a letter of apology and a free parking voucher. But in Montreal, hospitals that run hours behind schedule are as common as hockey and poutine. With the IV already inserted, the specialist gave me the option of having the colonoscopy done without sedatives, I agreed after hearing about the new equipment, seeing the high resolution monitor and being told that 50 year olds tend to have straighter colons. There were a couple of sharp pains as the tube took turns, but the procedure was far less discomforting than the toilet bowl bouts. I was happy that the previous night’s ordeal had resulted in a clean colon and happier to discover that I, like about 80% of the population at age 50,was totally free of polyps. The images were so sharp that you could see the blood vessels on the walls of the intestine and the opening to the appendix. Without having been sedated, within a half hour I walked out, inflated with air that had been pumped into me and inflated with the thought that I would not have to feel intense osmosis for another 5 years until the next appointment.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Create a website or blog at

Up ↑

%d bloggers like this: