How to prepare for CT Scan?

Avoid any caffeinated drinks (coffee, tea, energy drinks, or caffeinated sodas) on the day before or the day of your exam.


Do not use Viagra or any similar medication on the day before or the day of the exam. It is not compatible with the medications you will receive during the procedure (ask your doctor if you have questions). On the day of your scan, do not eat for four hours prior to your scheduled appointment. You may drink water.


If you are diabetic, ask your doctor how to adjust your medications on the day of your test. If you think your blood sugar is low, tell the technologist immediately.


Tell your radiologist and your doctor if you are:

  • Pregnant
  • Asthmatic
  • Allergic to iodine and/or shellfish or any medications
  • Undergoing radiation therapy
  • Over 60 years old or have a history of kidney problems (you may be required to have a blood test to evaluate your kidney function prior to receiving any contrast agent)

What to expect?

Upon Arrival

  1. After registration, you will be directed to the CT scan area where a nurse will attend to you.
  2. You will change into a special gown.
  3. A nurse will insert an IV line into a vein in your arm for the administration of contrast (dye) during your procedure.
  4. You may be required to take a tablet to help slow the heart rate down before the scan. This will mean waiting a little longer for the medication to take effect.
  5. Your heart rate will be monitored during this period of time before proceeding with the scan.

In The Scan Room

  1. You will lie on the scanner couch and you will be asked to raise your arms over your head for the duration of the exam
  2. Sticky electrode patches will be attached to your chest to monitor your heart’s electrical signal during the scan. Men may expect to have their chest partially shaved to help the electrodes stick
  3. A tablet of Nitroglycerin (GTN) will be placed under your tongue to help open up and enlarge your coronary arteries for better image quality
  4. A calcium score scan for risk assessment is often performed first unless there is already a known history of coronary disease or you have already had such a scan within the last 5 years
  5. During the scan, you will feel the table move in and out of the donut-shaped scanner. You will be asked to hold your breath several times during the scan, usually no more than 6 seconds each time
  6. You will receive a contrast injection through your IV during the scan and this may produce a warm sensation as the contrast circulates through your body. You might experience a metallic taste in your mouth as well. These sensations will not last more than a few seconds
  7. Once the radiologist is sure that all the information is acquired, the electrodes will be detached and you may leave the scan room
  8. After a short period of observation, the IV line will be removed and you may leave the department.


The actual scan itself takes only a few seconds, but the preparation for the scan may take from 15 minutes to an hour on average (if medication is given to slow down your heart rate).

After The Procedure

  1. You may continue all normal activities and eat as usual after the test
  2. You are advised to drink more water to help flush out the contrast more quickly
  3. Some people might experience headaches after taking GTN. This usually resolves spontaneously or can be treated with paracetamol
  4. Your doctor will discuss the results of your test with you.


Please ask your doctor if you have any questions about the CT Scan.


Incorporated in 2005, Singapore Medical Group (SMG) is a healthcare organisation with a network of private specialist providers across four established pillars - Aesthetics, Diagnostic Imaging & Screening, Oncology and Women's and Children's Health. Within Singapore, SMG has more than 40 clinics strategically located in central Singapore and heartland estates. Beyond Singapore, SMG also has an established presence in Indonesia, Vietnam and Australia. Learn about our privacy policy here.

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