A journey inside our gastrointestinal tract: the pillcam

My name’s Dr. Jo Brooks. I’m one of the gastroenterology team at the Norfolk and Norwich Hospital. And today, I’m going to be talking you through wireless capsule endoscopy and taking a journey through Professor Carding’s gastrointestinal tract using the capsule that he swallowed. So what, actually, is a wireless capsule endoscopy? You may have heard of it as the PillCam. What it is is a very, very small camera that you can swallow. It’s the size of a pill. And it takes pictures of your insides, specifically your gut, and transmits them to a little recorder that you wear as a belt. It can do this for eight hours, and it goes all the way from swallowing it to when you pass it.

It’s only used the once, so you don’t have to worry about recycling. We, as gastroenterologists, use it to have a good look at the small bowel. Now, the small bowel is the part of the bowel that goes from your stomach and joins it to your large bowel. And I’ll be talking a little bit more about that when we actually see Professor Carding’s small bowel. We use it to diagnose problems with bleeding in the small bowel or a disease called Crohn’s disease, which is an inflammation of the bowel, which causes ulceration and narrowing that we can’t see in very many other ways. And the PillCam is very useful for diagnosing it.

When Professor Carding swallowed the capsule, it went down his oesophagus. As with anything, when we swallow it, it passes through the oesophagus fairly rapidly. So we actually only have one individual picture of Professor Carding’s oesophagus before it passed on into his stomach.

So here we are in Professor Carding’s stomach. You can see all the big folds. And you can see how much the PillCam is actually moving around. It’s tumbling around in the stomach. The PillCam itself does have two cameras, a front and a back. We are just getting images from one of them. It’s also got light sources so that we can see what we’re looking at. The function of the stomach is actually to cause this tumbling, to cause all of the food that we’re swallowing to be mashed around and broken down and start the mechanical breaking down of the stomach.

You can also see some fluid there, and that is actually gastric acid that is helping to break down your food and killing any bacteria that are around. It very quickly passes on into the first part of your small bowel called your duodenum. And this is what we can see here. The duodenum is a very, very long tube– the first part of the small bowel. And you can actually see, if you look very closely– you can see the little fronds called villi, which increase the surface area of our small bowel to allow the food to be absorbed in its individual components. Now, those of you who are watching closely will have noted that there was a smoky-like appearance.

That’s actually your fluids, your gastric acid, coming through. But that’s also fluid that the body produces, called enzymes, to help break down our food into its individual components– proteins, fats, and carbohydrates– to allow the small bowel to actually start absorbing it. Now, these villi are very, very important to us. They increase the surface area of the small bowel to such an extent that if you were to take someone’s small bowel out, flatten it all out and flatten out all the villi, the surface area would be that of a football field.

Obviously, we can’t all fit the size of a football field into our tummies, so having these little villi there to increase the surface area to absorb all of our nutrients is very important.

So here, we see the entry point for all of the enzymic fluids that our body produces into the small bowel. When we think about eating or actually have food in our stomach, our body produces lots and lots of these fluids to allow us to break everything down. We don’t want it there in our small bowel all the time because then it would start breaking down things that we don’t want it to break down.

But once food is actually there, these enzymes are released through this little nodule head, called the ampulla of Vater, into the small bowel directly into the food to help break it down into its individual components and allow us to absorb all the nutrients that we need to from our food.

Here, we see a very good close-up of the lining of the small bowel. And you can also see that yellowish colour, which is actually bile. That’s the fluid that contains all the enzymes that helps us break everything down. The villi, as I’ve explained before, increase the surface area of the small bowel. And we have approximately 7 metres of small bowel all tucked up into the centre of our abdomen. And we need that length to allow us to absorb all of the nutrients, the salts, the vitamins, the fluid that our body requires for its everyday energy.

You can see that there’s a lot of movement with the PillCam. Some of that is actually because when you take the PillCam, you don’t have to remain static. You don’t have to remain stood up or sat still or lying down for any length of time. You can continue your everyday life. You can take the PillCam in the morning and go shopping– then come back and give the little recorder back to us after eight hours. But also, your bowel is not staying still all the time. Your bowel is constantly in motion. It’s constantly pushing through the food and the food bolus that you’ve just eaten. It’s like a wave-type motion called peristalsis.

And that not only allows the maximum amount of content to come up against the large surface area of the bowel, but it also means that waste can be excreted within a timely manner. It has to be said that the food that we eat generally takes about 30 seconds to get through your oesophagus, about two hours to get through the stomach. It then takes a considerably longer time to get through the length of the small bowel. And then the large bowel, our last exit point, so to speak, for the food bolus that you’ve eaten, can take several hours to even days to empty depending on how often you have your bowels open.

I think you’ll agree. This is an incredibly beautiful sight with all the little fronds standing up in the fluid.

Here, we’ve passed from the small bowel across into the large bowel. Now, you’ll notice that the picture is not quite so clear. The PillCam is tumbling. The large bowel is a large, saggy– for want of a better phrase– tube that, actually, is a lot wider than the small bowel. And that allows the PillCam to tumble within it. So the pictures we get are a little bit more jerky. They’re not quite so clear. We know it’s the large bowel for a few reasons. One, we’ve lost all those villi, those frond-like projections. You can’t see them on the edge. The lining of the bowel looks very healthy. It looks pink. It looks shiny.

But we’re beginning to see blood vessels within the lining, so that tells us we’re in the large bowel. The other, possibly more pertinent, point is you’re seeing residue. So all of this is residue, and it’s quite fluidic at the moment. The function of the large bowel is to remove water, not really to absorb nutrients anymore. So by the time that this actually passes a bit further down, it will become more solidified into the stool that we would normally recognise as passing. You can see all the way down the large bowel. It’s a very, very large, vacuous tube.

People often ask me, why can I not have a PillCam instead of having slightly more invasive tests, such as camera tests down the mouth into the stomach or up the back passage, to have a look around the large bowel? And this shows you one of the reasons why. The PillCam is quite small. If it’s tumbling, we don’t get a good, prolonged picture of all of the bowel all of the time whereas in the small bowel, which is narrower, and the PillCam gets peristalsed along nicely, you get to see more of it. You get a clearer picture.

And if we’re doing this test to try and diagnose, for example, if someone was losing blood, we would like to see as much as we possibly can. PillCams are an amazing technology, but at the moment, they are just used for diagnosis. They are there to tell us what is there. At the moment, we don’t have the availability to be able to reverse back, for example, and say, oh, I’d like to have a closer look at that area, nor can we take tiny, little samples, if we need to, or give treatment, which we can do in the other ways that we currently look at the top of the gastrointestinal tract and the bottom. Future developments, though, are very, very exciting.

There is coming to the fore little PillCams that we can move backwards and forwards using magnets. There is also the availability to start taking little samples, if we need to, to help with a diagnosis. Or even, if we find an area that’s bleeding, to stop the bleeding using heat treatment. It’s still a long way off, though, and it’s still science fiction. But it will soon, potentially, be science fact.