Why do I need this test?
A Tauroselcholic [75selenium] acid known as a SeHCAT (pronounced “see cat”) test is used to diagnose bile acid (sometimes called bile salt) malabsorption. Bile acids are produced in your liver and are passed into your small intestine after you have eaten a meal. Most of the bile acids should be reabsorbed at the end of your small intestine and returned to your liver. If you don’t reabsorb bile acids properly and they enter your bowel it can cause diarrhoea.
How is the test performed?
There are two parts to a SeHCAT test, day zero and day seven. On day zero you are given a SeHCAT capsule and we will perform a scan one hour later to see how much of the capsule is in your body. Seven days later we will perform a second scan to see how much of the capsule is still in your body.
Is there anything I should tell the staff before the scan?
Yes. If you are pregnant or think you may be pregnant, please inform us. We also need to know if you are breastfeeding as you will need to stop breastfeeding for several hours following the scan.
Day zero
Preparation
You can eat and drink as normal before your appointment.
If you take medication called colesevelam, colestyramine or colestipol you must not take it the day before or day of your appointment. You will not be able to take it again until after the test is completed on day seven as it will give a false result. You can take all your other medication as normal.
What happens during the test?
SeHCAT is given to you as a small capsule which is swallowed. The capsule contains a very small amount of a radioactive tracer. The capsule is the same size as a regular tablet and you should have no trouble swallowing it. We will give you a drink of water with it. If you think you may not be able to swallow the capsule, please contact us at least 3 days before your appointment.
You will be asked to return to the department one hour later. An appointment time will be given to you when you are given the capsule.
When you return we will perform a scan using a gamma camera to see how much of the SeHCAT capsule is in your body. You will need to lie under the camera on your back for five minutes and then on your front for five minutes. If you think you will struggle to lay flat on either your front or back please contact us. You will not be fully enclosed and a member of staff will be in the room with you at all times. You do not need to undress for the scan.
You will then be given an appointment to return seven days later. For example, if your day zero appointment is on a Monday you will need to return the following Monday, if your day zero appointment is on Tuesday you will need to return the following Tuesday, etc.
Will I get the results after the scan?
The medical physics staff will not be able to give you any results after the scan. Your test is not complete until you have had your day seven scan.
Day seven
Preparation
There is no preparation before your day seven scan. You may eat and drink as normal and take all your medication as normal (except for colesevelem, colestyramine or colestipol)
What happens during the test?
You do not take another SeHCAT capsule today, you are only returning to have a repeat scan. The repeat scan is to see how much of the capsule is still in your body. The scan is exactly the same as the one you had on day zero.
Will I get the results after the scan?
The medical physics staff will not be able to give you any results after the scan. The scan is reported by a medical physicist who will return the results to your consultant. Your consultant is responsible for informing you of the results.
General Questions
How will you feel during the test?
The SeHCAT capsule will not make you feel any different. If we have asked you to stop taking colesevelem, colestyramine or colestipol you may find that your diarrhoea becomes worse throughout the test. This should stop when you restart taking your medication after your day seven appointment.
How long does the test take?
You should be with us for no longer than ten minutes when you are given the SeHCAT capsule. We ask that you allow twenty minutes for the scans on both day zero and day seven.
Do I have to stay in the hospital after having the SeHCAT capsule?
No. There are no restrictions after you have swallowed the capsule so you can leave the hospital if you wish but you must return for your scans on both day zero and day seven.
Do I need to bring anyone with me?
No, but you can bring someone with you if you wish. They can also stay with you during the whole procedure.
Can I drive?
Yes, this test will have no impact on your ability to drive.
Can I go back to work?
Yes. There are no restrictions with this test so you can go back to work if you wish.
I also have a colonoscopy appointment booked. Can I have both tests done on the same day?
No. The colonoscopy must be done either before you attend for day zero or after the SeHCAT test is completed on day seven. If your colonoscopy is booked between your day zero and day seven appointments, we recommend that you rearrange your SeHCAT appointment.
What if I can’t attend on day seven?
It is very important that you attend for your day seven scan. Without your day seven scan we will not be able to get any results for the test. If you know before you attend on day zero that you won’t be able to attend on day seven please contact us as we will need to rearrange your appointment.
If, after you have already had the SeHCAT capsule, you find you cannot attend for your day seven appointment you MUST contact us as soon as possible so we can try to make alternative arrangements. It may be possible to perform the scan on a different day however it is important that you are aware that the results of your test may not be accurate and the whole test my need to be repeated. It is also important that you are aware that it will not always be possible for us to perform your scan on a different day.
Is the test safe?
You will be given a radioactive substance for this procedure. The risks involved are low and a licensed doctor has judged that the benefits of doing the test outweigh the risks; if you wish to know more please visit the IAEA website; if you still have questions regarding radiation risk please get in touch with us.
Contact numbers for further advice
Specialist Radiographer/Clinical Technologists
Medical Physics
Tel: (0191) 445 2710
Monday to Friday 8:30am to 4:30pm
Physicist/Head of Medical Physics
Tel: (0191) 445 5516 or (0191) 445 2476
Monday to Friday 9am to 5pm