Hong Kong Imaging and Diagnostic Centre

Ultrasound Scan


If you have never had an ultrasound scan before, you might not know what to expect. This brief guide is designed to answer any questions you may have:

What is an ultrasound?

An ultrasound scan, or sonography scan, is an imaging test that uses high-frequency sound waves to capture live images of the internal organs of the body.

The technology for ultrasound is similar to that used by sonar and radar, and unlike some other imaging tests, it doesn’t use radiation. It is therefore the preferred method of scanning used by doctors during pregnancy.

An ultrasound allows your doctor to see organs, blood vessels, and tissues—without needing to make an incision. However, the ultrasound wave cannot show bone, air or metallic objects, and therefore has its limitations for certain types of investigations.

Ultrasound is most often used to examine:
  • The developing foetus during pregnancy
  • Breast in combination with a mammogram
  • Thyroid, salivary glands, lymph nodes, testes and other small parts
  • Doppler studies of arteries and veins
  • Abdominal organs such as liver, kidneys, pancreas, bladder, uterus and ovaries
  • Joints and soft tissues
  • Guide minimally invasive procedures such as fine needle aspirations (FNA’s) and core biopsy

What to expect?

Having an ultrasound is painless, and it is also relatively fast. The process should only take 10-45 minutes, depending on the area to be scanned.

Once you check in at reception, you will be shown to a small private changing room where you will be given a gown to change into yourself. Depending on the area being scanned, you will be asked to remove clothing from that area, and this can be placed in the secure locker provided.

How is an ultrasound done?

The individual performing the ultrasound will be either a trained sonographer (technician) or a radiologist, who will place warm gel on a probe that will be placed on the area that is being scanned. The probe is a small hand held device that is attached by a wire to the ultrasound machine. The images detected by the probe can be seen on the monitor.

The sonographer/radiologist will move the probe around in order to obtain the best images. At certain points, the technician may take ‘still’ images of specific areas and log measurements.

The Radiologist may request that a further investigation be performed such as an FNA or core biopsy. If required, this will be discussed with you in detail in advance.

After the procedure, you will be provided with a towel or tissues to clean off the gel.

What to expect afterwards

You will usually be able to go home directly after the scan. However, if you have been sedated or had a minimally invasive procedure, it’s best not to drive, drink alcohol, or sign any legal documents for 24 hours afterwards. If you have had sedation, you should ask a friend to accompany you home.

Your radiologist will examine your ultrasound examination and send the film and report to your referring doctor.