Ultrasound is high frequency sound wave, too high for human ear to hear. It can pass through the skin and tissues without being felt or heard. Ultrasound examinations use these high frequency sound waves to produce images of tissues in the body parts such as liver, gallbladder, pancreas, kidney, uterus, ovary, breast, etc. It helps diagnose diseases like cirrhosis, gallstones, pancreatitis, kidney stones, tumours, vascular diseases, etc.
Ultrasound examination of pregnant mother can help doctor to assess the condition of the baby inside the womb. Under normal clinical practice ultrasound examination is painless and harmless to human body.
Preparation before the procedure
- Fasting is required 4-6 hours before ultrasound examination of the upper abdominal (such as liver and gallbladder). For lower abdominal examinations (such as kidney and female reproductive organs), patient may be required to drink several glasses of water beforehand so that the bladder is full during ultrasonography. Examination of other body parts (such as breast, thyroid) does not require any preparation.
- Wear loose and comfortable clothing.
- Patient may be asked to change into an examination gown. Patient will need to uncover the skin over the area to be examined.
- Patient will lie on a padded couch, and may be required to lie on the sides or other position.
- Ultrasound waves do not travel well through air and bone, and the gel is used to prevent air from interfering with the ultrasound waves. The radiological staff will apply gel to patient’s skin over the area to be studied. A hand-held transducer will be moved over the gel on patient’s skin.
- Patient may be asked to lie still, and perhaps to hold breath, so that clear ultrasound images can be obtained.
- Multiple ultrasound images will be taken during examination for record.
- An ultrasound examination takes 20 to 30 minutes to complete and may take longer for difficult examination.
- When the examination is over, clean the gel from your skin and you may leave.
After the procedure
Patient may go back to regular diet and activities after this examination. The radiologist will report the findings to your doctor.
For further information please contact your doctor.
For details, please refer to the following Common Cancers in Hong Kong webpages: