What is Ultrasound?

Ultrasound (US) imaging, also called ultrasound scanning or sonography, is a method of “seeing” inside the human body through the use of high-frequency sound waves. The sound waves are recorded and displayed as a real-time visual image. No ionizing radiation is involved in ultrasound scanning.

In most ultrasound examinations, a transducer, a lightweight device which produces sound waves, is placed on the patient’s skin. There are also special transducers which can be put into the vagina or rectum to image these areas of the body.

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What are the common uses of Ultrasound scanning?
  • Abdominal organs e.g, liver, gallblader, spleen, pancreas, kidneys, bladder.
  • Pelvic organs e.g., prostate, uterus and ovaries.
  • During pregnancy to monitor the development of the embryo or fetus.
  • Superficial organs e.g., breast, thyroid, joints(shoulder, ankle).
  • Heart
  • Blood Flow. Doppler ultrasound is a special technique used to examine blood flow. Doppler images can help to see and evaluate blockages to blood flow, such as clots, and build-up of plaque inside the vessels.
  • Biopsy. It can also be used to guide procedures such as needle biopsies, in which a needle is used to sample cells from an organ for laboratory testing.

How should I prepare for the procedure?
  • You should wear comfortable, loose-fitting clothes.
  • For Gallblader examination, a fasting period of 4-6 hours is required to visualize your gallblader, otherwise no fasting is required.
  • For pelvic ultrasound, you may be asked to drink up to six glasses of water prior to your exam and avoid urinating, so your bladder is full when the scan begins.

How is the procedure performed?
  • You will lie on your back on an examination table
  • A clear gel is applied to your body in the area to be examined, to help the transducer make secure contact with the skin. The sound waves produced by the transducer cannot penetrate air, so the gel helps eliminate air pockets between the transducer and the skin. The gel is water soluble, safe and harmless and can easily be wiped off after the scan with a paper tower.
  • The radiographer presses the transducer firmly against the skin and sweeps it back and forth to image the area of interest.
  • Transvaginal and transrectal ultrasound involves the insertion, lubricated with a small amount of gel and then inserted in the vagina or rectum. The images are obtained from different orientations to get the best views of the uterus and ovaries or the best view of the prostate gland.
  • For pelvic ultrasound, it may be done transabdominal or transvaginal to see the uterus and ovaries. Similarly for prostate gland it may be done transabdominal or transrectal.
  • When the examination is complete, the gel can be easily cleaned with the use of tissue and you may be asked to dress and wait while the ultrasound images are reviewed.

What will I experience during the procedure?
  • Ultrasound imaging is painless, fast and easy. The radiographer will spread some gel on your skin and then press the transducer firmly against your back, moving it ultil the desired images are captured. There may be varying degrees of discomfort from pressue as the radiographer guides the transducer over your abdomen, especially if you are required to have a full bladder.
  • There is no pain.
  • The examination usually takes about 30 minutes. If blood flow visualization is required, this may take 60 minutes.

When can I expect results?

The radiologist will review the images and the report will be sent to your doctor who will then discuss the scan results with you.

What are the benefits versus risks

  • Ultrasound scanning is non-invasive(no needles or injections in most cases) and is usually painless.
  • Ultrasound is widely available and easy to use.
  • Ultrasound imaging uses no ionizing radiation and is the preferred image modality for diagnosis and monitoring of pregnant women and their unborn infants.
  • Ultrasound provides real-time imaging, making it a good tool for guiding minimally invasive procedures such as needle biopsies.
  • Ultrasound images can visualize structures, movement and live function in the body's organs and blood vessels.

  • For standard diagnostic ultrasound there are no known harmful effects on humans.


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 
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,
Mount Elizabeth Novena Hospital
38 Irrawaddy Road, #01-03/04, #01-13 
Singapore 329563
Tel: (65) 6388 4333
Fax: (65) 6266 3085

Radiologic Clinic,
The Arcade
11 Collyer Quay
#18-02 The Arcade
Singapore 049317
Tel: (65) 6507 9750
Fax: (65) 6224 0861

Radiologic Clinic,
Jurong East
130 Jurong Gateway Road
Singapore 600130
Tel: (65) 6569 0300
Fax: (65) 6569 7593

Radiologic Clinic,
Health Promotion Board
3 Second Hospital Avenue
Singapore 168937
Tel: (65) 6533 2721
Fax: (65) 6533 0125

For more information, please visit our FAQ (Frequently Asked Questions) page.