Ultrasound, also called sonography, is a non-invasive imaging test that uses high-frequency sound waves to produce real-time images of structures inside the body. It does not use ionising radiation.
Ultrasound can examine organs, soft tissues, blood vessels and superficial lymph nodes. In cancer care, it may help detect and characterise abnormalities, guide biopsies and treatments, assess blood flow and monitor selected findings.
Its usefulness depends on the organ and location being examined. Air, bone and deep tissues can limit image quality, so CT, MRI, mammography, PET-CT, endoscopy or another test may also be required.
Role in Cancer Care
What to Expect
Before the Test
Preparation depends on the body area being examined. Some ultrasound examinations require no special preparation, while others may require fasting or a full bladder.
Before the scan, inform the care team if you:
Are pregnant or may be pregnant
Have pain or tenderness in the area being examined
Have undergone recent surgery, biopsy or treatment
Have dressings, wounds, tubes or drains near the area
Take blood-thinning medicines, particularly if a biopsy or procedure is planned
Have previously reacted to an ultrasound contrast agent
Have relevant previous imaging or reports
For an abdominal ultrasound, you may be asked not to eat or drink for several hours to reduce bowel gas and improve visualisation. For some pelvic examinations, you may need to drink water and avoid emptying your bladder beforehand.
Ultrasound guidance for a biopsy or treatment requires separate preparation. This may include blood tests, temporary adjustment of certain medicines and instructions about eating or drinking. Do not stop any medicine unless specifically instructed.
During the TestÂ
You will usually lie on an examination table with the area being examined exposed. The sonographer or radiologist will apply a water-based gel to the skin and move the transducer over the area.
Gentle pressure may be applied to obtain clear images. You may be asked to change position, hold your breath briefly or remain still. The examination is generally painless, although pressure over a tender area may cause temporary discomfort.
Some pelvic, prostate or other examinations may require an internal transducer to obtain clearer images. The procedure and the reason for it will be explained beforehand, and consent will be obtained.
If contrast-enhanced ultrasound is required, a cannula will be inserted into a vein and a small amount of microbubble contrast will be administered. If ultrasound is guiding a biopsy or treatment, local anesthesia and sterile preparation may also be required.
A routine diagnostic ultrasound commonly takes approximately 15 to 45 minutes. Specialised, contrast-enhanced or image-guided procedures may take longer.
After the Test
After a routine external ultrasound, the gel is wiped away and you can generally return to normal activities immediately. No recovery period is required.
If an internal examination, contrast injection, biopsy or treatment was performed, you will receive specific aftercare instructions. Observation may be required after some procedures.
A radiologist will interpret the images and prepare a report for the doctor who requested the examination. Further imaging or biopsy may be advised if an abnormality cannot be fully characterised by ultrasound.
Potential Benefits
- No ionising radiation: Ultrasound uses sound waves rather than X-rays.
- Real-time assessment: Structures, movement and blood flow can be observed during the examination.
- Soft-tissue imaging: It can evaluate many organs, superficial masses and lymph nodes.
- Solid and fluid differentiation: Ultrasound can often distinguish a solid mass from a cyst or fluid collection.
- Blood-flow assessment: Doppler techniques can assess blood vessels and vascularity within or around an abnormality.
- Procedure guidance: Ultrasound can guide biopsies, drainage and selected minimally invasive treatments.
- Repeatable imaging: It can be repeated when clinically necessary without cumulative radiation exposure.
- Accessible examination: Ultrasound equipment is widely available and may be brought to the bedside when required.
