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Virtual colonoscopy is a method for screening for
colon cancer or colon polyps using a CAT scanner,
which is a special type of x-ray machine.
So virtual colonoscopy is usually performed in
the radiology department of a hospital or
outpatient imaging center.
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Well, virtual colonoscopy has several advantages,
including it's fast.
It only takes about ten minutes in the room,
the scan itself only takes a few seconds, so definitely fast.
It’s safe, it does not require sedation like conventional
colonoscopy, has a lower preparation rate.
It also has the advantage of always seeing the entire colon.
So a regular colonoscopy, sometimes a colonoscopist can't
maneuver the scope around the entire colon, but
since this is a CAT scan, we can always see the entire colon.
And also it has the advantages of we see the other organs in
the abdomen and pelvis at the same time.
So sometimes we're able to diagnose unsuspected conditions
outside of the colon.
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There have several multi-institutional trials
comparing virtual colonoscopy with conventional colonoscopy,
and they've shown that virtual colonoscopy is comparable to
a conventional colonoscopy when we're trying to detect
precancerous polyps, or cancer one centimeter or larger.
Polyps smaller than one centimeter sometimes
can be a challenge to detect on virtual colonoscopy, but
they do not have cancer.
So we're really trying to detect lesions one centimeter or
greater, and therefore it's a similar sensitivity to
conventional colonoscopy.
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Virtual colonoscopy is really designed for
average risk patients.
So the American Cancer Society recommends screening for
colon polyps and colon cancer at the age of 50,
if you're an average risk patient.
If you're a high risk patient, meaning you're having symptoms,
or you have a family history, or other conditions,
you may want to schedule a regular colonoscopy
because there's a higher chance that you will have a polyp or
cancer at that time.
So it's really designed for
average risk patients above the age of 50 for
screening, it's not meant for a patient who has symptoms.
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In order to do a virtual colonoscopy,
patient still needs to have a bowel prep.
So the day before the study, they have to have
colon cleansing agents to completely clean the colon.
Once they arrive in the radiology department,
they'll be brought into the CAT scanning room,
where they'll meet the radiologist, so
if I were there that day, you would meet me,
put a small tube in the patient's rectum, and
then we have a pump to distend the colon with carbon dioxide.
And so what happens is the colon gets distended,
then we do our CT examination, usually twice, the patient lying
on their back and on their stomach or their side.
Afterward, we remove the tube, patient gets up and
goes to the bathroom, gets dressed,
and feels back to normal.
You're in the room for about ten minutes, the entire exam,
the scanning only takes a few seconds.
And then, you feel normal and go back to work.
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During the study when we distend the colon,
the patient is uncomfortable and they basically feel gassy,
cuz that's what's happening, the colon is distended with gas.
But it shouldn't be painful, if it's painful,
you need let the radiologist know cuz it may be that you have
an obstruction there.
We use a pump to insufflate the color, or to distend the colon.
So the pump is very sensitive and if there's a blockage,
the pump will stop adding the air in, so
it's a very safe procedure in that regard.
But you'll feel uncomfortable, and you'll feel gassy, but
you should not feel pain.
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Since virtual colonoscopy is performed with a CT scanner,
it is a type of x-ray so that,
there is some radiation involved.
The amount of radiation you would get depends on many
factors, including patient size, the type of scanner, and
type of protocols used.
At Hopkins, we have the latest scanners, and
we use low dose protocols to minimize the radiation.
Everybody gets radiation every day because there's radiation in
the environment.
With the low dose protocols we use,
it should be less radiation than a person would get with
a background of radiation over a year in the environment.
So it's very low dose, and it's safe.
And also remember, virtual colonoscopy is designed for
patients over the age of 50, so we're not doing these in
young children or premenopausal patients.
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When you make your appointment for a virtual colonoscopy,
you'll speak with one of our coordinators, and
they will explain to you the prep that you need to do before
you come for your test.
We actually mail out a small kit to you with the instructions and
everything you need, including a prescription for
a bowel cleansing agent.
So at home, the day before, you'll take these bowel
cleansing agents to make sure your colon is clean.
When you arrive and are taken into the CAT scanning room,
you'll meet a radiologists who will place a small flexible tube
in your rectum and distend the colon with carbon dioxide,
which is a gas that helps us see inside the colon.
Then you'll have your CAT scan, with you lying on your back and
on your stomach, or your side if it's more comfortable.
It will only take a few minutes for your exam.
Then you'll get up, you'll get dressed, and
you'll feel back to normal.
What happens then is the images that we took are transferred to
a workstation and a radiologist, who's specialized in virtual
colonoscopy, will interpret the images using special software
that lets us travel through the colon.
So it's 3D software that lets us see inside the colon.
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Virtual colonoscopy has some risk in limitation.
The risk include, there is a small dose of radiation,
which we've discussed before.
Besides that risk, there is a small risk of perforation.
And a perforation means, a small tear in the colon that can occur
when we distend the colon.
The chance of perforating the colon is very,
very small in a virtual colonoscopy,
especially compared to conventional colonoscopy.
And we use a special pump to distend the colon,
which will shut off if we add too much air.
So it's a very small theoretical risk.
The other limitation of virtual colonoscopy is,
it's a virtual camera.
We're not actually inside the colon, so
if we find a polyp, we can't remove it.
So if we would find a polyp one centimeter or greater,
we're gonna send you to a regular colonoscopy to have
the polyp removed.
But you have to remember, most patients who are healthy
over the age of 50, won't have a polyp of that size.
So really, it's unlikely we're gonna find something significant
that would require a conventional colonoscopy.
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Virtual colonoscopy is safe, and it is approved by
the American Cancer Society as a potential screening study for
average risk patients above the age of 50.
It's also very safe because there's no sedation required.
So, conventional colonoscopy requires that the patient be
sedated, which means they have IV medication and
they need monitoring before and after the study.
So it's very safe, especially for older patients with heart
and lung disease, who would have a higher risk of being sedated.
So it's safe, small risk of perforation, no sedation,
fast study, and low dose radiation.
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Virtual colonoscopy is less expensive than regular
colonoscopy, because it doesn't require sedation.
With a regular colonoscopy,
you're gonna be getting IV medication, and
you're gonna need monitoring before and after.
And that tends to be expensive,
especially if an anesthesiologist is involved.
Also with a regular colonoscopy, you wouldn't be able to drive
home or go to work because of the sedation.
With virtual colonoscopy, you totally eliminate the need for
sedation, and you don't need somebody to drive you home.
After a few minutes, you'll feel back to normal.
Whether or not your insurance covers it,
depends on what state you live in.
You'll have to check.
In some states, the insurance will cover it for screening.
In some states,
they will only cover it if you've had a failed colonoscopy
or can't have a regular colonoscopy,
maybe you have a bleeding disorder or
you're on certain medications.
So there's a website called VC, Virtual Colonoscopy,
vcreimbursement.com, and you can check there to see if your
insurers, in your state, will pay for virtual colonoscopy.
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