Diagnostic ultrasound, also called sonography or diagnostic medical sonography, is an imaging method that utilises sound waves to produce images of structures inside our body.
Ultrasound is relatively affordable, non-invasive and does not bring much discomfort to patients in general.
The image below is a picture of a foetus taken by ultrasound.
How does it work?
As shown in the photo below, a diagnostic ultrasound involves the use of a transducer, which is placed on top of the organ of interest and transmits high-frequency sound waves to produce a sonogram – real-time images of the internal organ and blood flow which are projected onto a monitor. Prior to the procedure, a layer of gel is applied onto the surface of the body at the area to be studied. This keeps air pockets from forming between the transducer and the skin, which can block the sound waves from getting into our bodies.
Some ultrasound scans (abdominal ultrasound) would require the patient to come fast, in order to obtain clear images of the gastrointestinal system.
The sound waves produced by the transducer bounce back upon contacting the tissues of different densities along the path. These reflected signals are combined by computer and form the eventual 2D sonogram. The procedure is usually carried out by a certified radiographer, and the results are interpreted by a radiologist, who is a trained doctor specialising in radiology.
What does it do?
Ultrasound can help doctors diagnose various conditions, such as:
- Carotid artery plaque
- Enlarged heart
- Breast tumour
- Common liver conditions: fibrosis, abscess, tumour
- Common kidney conditions: obstruction, abscess, infection
- Gallstones
- Spleen enlargement
- Pregnancy
- Prostate abnormalities
Other than diagnostic purposes, it is also commonly applied in clinical settings to:
- Help visualize veins during intravenous injection
- Help visualize nerves during a nerve block
- Measure the volume of urine in the bladder
Are there any risks involved?
Ultrasound is one of the safest diagnostic procedures. It is even less invasive than a blood test, which entails the penetration of the skin and blood vessels. Unlike other medical imaging techniques, such as X-ray and CT, there is no radiation exposure or harm to body cells in any way.
What are the pros and cons?
So far, we have mentioned quite a few advantages of using ultrasound: cheap, non-invasive, and safe for patients with a wide range of diagnostic capabilities. Compared to other imaging tests, ultrasound is more widely available in community clinics as well.
However, ultrasound has limitations e.g. it is unable to provide detailed images of lungs, bones, or brain. Those organs require either X-ray, Computed Tomography (CT), or Magnetic Resonance Imaging (MRI) scans to aid in the diagnosis of conditions.
