What is Contrast Media?

Your radiology examination may require the injection of a contrast agent.

The contrast agent is usually administered by injection into a vein through a fine needle or cannula (plastic tube). This allows your organs to be seen more clearly and will assist your doctor with your medical management.

The contrast agent is processed by the kidneys and leaves the body in your urine. For people with completely normal kidney function, the contrast is easily handled.

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General risk

The contrast agent administration is normally quite safe. However, any injection carries a slight risk of harm including injury to a nerve, artery or vein; infection; or reaction to the material being injected.

Injury to a blood vessel will result in the escape of its contents to the surrounding tissue (extravasation). This risk is estimated to be about 0.04% to 1.3%.

The other side effects / complications with injection of the contrast agent may include:

  • Occasionally, mild allergic reactions such as flushes, sneezing, hives, vomiting and dizziness. Mild nausea, which should pass within a few minutes.
  • For iodine-based contrast inject you may experience a metallic taste in the mouth, funny smell and /or hot flush in the body or pelvic region and behind the throat.
  • Rarely, more severe allergic reactions such as asthma, shock and convulsions. Emergency equipment is on hand for these rare events.
  • Death in extremely rare cases - about 1 in 250,000 to 400,000 injections (0.0004%).
  • Although less than 1% of administered dose is excreted into breast milk, patients who are breast feeding are recommended to abstain from breast feeding for 24 hours post injection and to discard breast milk after the contrast injection.

How is the procedure performed?

You may be requested to change into an x-ray gown to avoid metallic items, buttons and zippers. You will also be asked to remove jewellery, eyeglasses, and any metal objects that could obscure the image.

Once you are positioned in the required pose with the x-ray plate, you may be asked to take a deep breath and hold it or just to hold your breath and keep still. The radiographer will go to another small room or cubicle and activate the x-ray equipment which will send a beam of x-rays to the positioned area. You need to keep still as any movement will lead to an unsharp picture and an accurate diagnosis cannot be made.

When the x-rays are completed you will be asked to wait until the radiographer and radiologist examine the images to determine if more are needed.

What will I experience during the procedure?

This is a painless procedure. The only discomfort results from the coldness of the x-ray plate. Sometimes to get a clear image of an injury, you may be asked to hold onto an uncomfortable position for a short time. Any movement could blur the image and make it necessary to repeat the procedure to get a useful, clear picture.

When can I expect results?

The radiologist (specialist doctor) will review the image and the report will be sent to your doctor who will then discuss the scan results with you. If requested by your doctor, the films may be handed directly to you to return to your doctor.

What are the Benefits and Risks?

  • X-ray imaging is useful to diagnose bone and joint injury and disease, such as fractures, infections, arthritis and cancer.
  • Because x-ray imaging is fast and easy, it is particularly useful in emergency diagnosis and treatment.
  • X-ray equipment is relatively inexpensive and widely available in physician offices, ambulatory care centers, nursing homes and other locations, making it convenient for both patients and physicians.

  • Exposure to x-radiation. During a single x-ray exposure, a patient is exposed to about 0.06-2mSv of radiation dose. To put this into perspective, we are all exposed to approximately 3mSv of radiation dose each year from sources like the ultraviolet rays of the sun and small traces of radioactive isotopes, such as uranium found in soil.
  • Women should always inform their doctor or x-ray technologist if there is any possibility that they are pregnant.


Radiology Department,
Gleneagles Hospital

6A Napier Road
Singapore 258500
Tel: (65) 6470 5730
Fax: (65) 6470 5749

Radiology Department,
Mount Elizabeth Hospital

3 Mount Elizabeth, Level 2
Singapore 228510
Tel: (65) 6731 2100
Fax: (65) 6732 3368

Radiology Department,
Mount Elizabeth Novena Hospital

38 Irrawady Road, Level 2
Singapore 329563
Tel: (65) 6933 1188
Fax: (65) 6933 0526

Radiology Department,
Parkway East Hospital
321 Joo Chiat Place
Singapore 427990
Tel: (65) 6340 8714
Fax: (65) 6340 8670

Radiologic Clinic,
Mount Elizabeth Medical Centre
3 Mount Elizabeth #01-01/02
Mount Elizabeth Medical Centre
Singapore 228510
Tel: (65) 6731 2727
Fax: (65) 6235 5279

Radiologic Clinic,
Breast Imaging Centre
290 Orchard Road
#07-04/05/06 Paragon
Singapore 238859
Tel: (65) 6732 1166
Fax: (65) 6732 5933

Radiologic Clinic,

6A Napier Road #02-25/26 
Gleneagles Hospital
Singapore 258500
Tel: (65) 6476 1151
Fax: (65) 6471 1151
Radiologic Clinic,
Novena Medical Center
10 Sinaran Drive #08-02/03/04 
Novena Medical Center
Singapore 307506
Tel: (65) 6397 6686
Fax: (65) 6397 6696
For more information, please visit our FAQ (Frequently Asked Questions) page.