Colonography – What Exactly Is It?

Since I shared my colonoscopy experience with you, I thought I should share my colonography experience, too. CT colonography (CTC) is a way to detect problems in the large bowel (colon).

What Is A CT Colonography?

Ready for a colonography
Ready for the CTC – no sexy shorts this time

CTC is a specialised type of scan that uses x-rays to produce an image. It helps to diagnose bowel cancer when it is still at an early stage.

I was offered the CTC because, as regular readers know, my colonoscopy was not a success. I have bendy bowels and they could not get the camera around them and see the whole length of my large bowel. The nurse who did my colonography today told me that this is quite common.

Some people might be offered a CTC scan if colonoscopy is not suitable for them for other reasons. I’m not sure what the other reasons might be as none of the information I read on the procedure expanded on it.

Preparing for CTC

The preparation for the colonography is similar to preparing for a colonoscopy. They both involve drinking disgusting drinks, regular visits to the toilet and a burning bum.

This is because the bowel has to be completely empty so they can get a clear image. Otherwise, they might have to repeat the procedure. I have no wish to go through it again for a while, so I followed the instructions to the tee.

I stopped taking my multivitamin seven days before the procedure. The multivitamin includes iron, which makes everything inside the bowel black and difficult to see everything properly.

The instructions tell you to have a low-residue diet for two days before the scan. They give you a list of foods that you can and can’t have. Sadly, you cannot have anything high in fibre, so all fruit and vegetables are off the menu.

And then, the day before, it’s time for the emptying process to begin.

On route to my colonography

The Day Before The Colonography

The instructions said to have a substantial breakfast at 7am on the day before the procedure using the foods on the ‘allowed’ list. I had an omelette with cheese which was a lot more than I would usually have that early in the morning.

As a result, I needed a poo when I don’t usually have one. I did half a day at school as the full on prep didn’t start until the afternoon… Suddenly I felt the need to go to the toilet. Urgently.

Luckily it was only a few minutes until break and I ushered the kids out before rushing to the toilet.

Note to self: don’t have egg and cheese omelette on school mornings!

At 2pm, safely at home for the prep to begin, I had to take ten Senna tablets and drink a cup of Microcat. The Senna tablets help to empty the bowels, and the Microcat outlines the bowel in the scan. The tablets were no problem; they were quite small and easy to swallow. Microcat was disgusting. The taste reminded me of something, but I can’t think of what. Possibly some medicine I had to take as a child.

Then at 4pm, I had a sachet of Citramag dissolved in about 150ml water. Citramag works to empty the bowels together with the tablets. Once again, the drink is disgusting. Sickly sweet and lemony. After that, I had another cup of Microcat.

I repeated the last step again at 6pm. The drinks were horrible but at least there was less to drink than when I had to have Moviprep before the colonoscopy.

I spent most of the evening running to the toilet, but it all calmed down by bedtime so at least I could get a decent night’s sleep.

Scan Day

The foggy scene on route to the CTC scan

My scan was at 8:30 in the morning.

When I got to the Royal Marsden, a nurse first inserted a cannula so they can give me a contrast (a special dye) which improves the quality of the images.

I then went through the procedure with another nurse and the risks. The risks include a dry mouth caused by a muscle relaxant, bloating and bowel discomfort and bowel perforation. The last one is a tear in the bowel wall, but the risk of this is very small, about one in 3000.

Then it was time to take off my clothes, put on the gown and get on the bed.

They gave me an injection of Buscopan to relax the muscles and help with stomach cramps first. Then I had to lie on my side while the nurse inserted a small tube in the anus, only a few centimetres deep. No pain or discomfort so far.

The nurse used the tube to pump CO2 into the bowel. They use CO2 as any gas that doesn’t come out the way it went in, will get absorbed into the blood vessels and get out of your body through regular breathing.

As more gas went in, I got more uncomfortable. I felt like I needed to go to the toilet, but couldn’t. When the bowels were full enough, I got on my stomach and they took the first set of images. For the second set, I had to turn onto my back.

That’s when I felt the most discomfort. I wouldn’t go as far as calling it pain. The nurse explained it’s because when you are on your stomach the gas is pressed in place, but when you turn, the gas can move, too. It felt like bad period cramps, but that didn’t last long. The rest of the time all I felt was mild discomfort.

The procedure itself took about 20 minutes.

It is common to feel bloated or discomfort in the bowel for a few days after the scan. I didn’t feel too much discomfort, but it took the rest of the day for my stomach to get back to more normal.

At the time I’m writing this (Saturday morning), my poo has returned to normal consistency (woohoo, I bet you all wanted to know that) and my stomach feels normal. I think that the discomfort continues longer if you have excess gas lingering in your bowels. Maybe I got most of the gas out yesterday. I also think that doing some yoga helped to expel some gas. Let’s just say that I was definitely glad I did the yoga in the privacy of my own home.

Colonography Vs Colonoscopy

You cannot eat fruit or vegetables before a colonography
Post scan treat

I definitely prefer having a colonography. It is less uncomfortable, especially with bendy bowels, and over quicker. It’s also less invasive, as all it requires is the small tube for getting the gas in. Colonography doesn’t require sedation whereas colonoscopy usually does.

The benefit of a colonoscopy is that the doctor can remove any polyps or remove tissue for testing during the procedure. However, colonoscopy only allows the doctors to see inside the bowel. A CTC scan gives the doctor information not only about the colon but the other structures inside the abdomen, too.

Preparation wise there is not much difference. Both were unpleasant. The only upside to colonography prep was that there was less to drink.

One big difference is the time it takes to get the results. With colonoscopy, the doctor can tell you straight away if everything appears normal. With the colonography, I have to wait 15 days to get the results.

So, keep me in your thoughts and prayers that everything is normal.


You can get more information on CTC from the NHS.

Thank you for being here and reading the post. 

Until next time!

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