Ultrasound Scans Explained: Uses, Preparation and Results

How ultrasound creates images

Ultrasound uses high-frequency sound waves sent into the body by a handheld probe. The waves echo back from tissues and are processed into real-time images. Because ultrasound does not use ionising radiation, it is widely used for many examinations, including abdominal organs, the pelvis, thyroid, tendons, muscles, soft-tissue lumps and selected blood vessels.

Ultrasound is not suitable for every body part or clinical question. Sound waves do not travel well through air or bone, and image quality can be affected by the area being examined, body habitus, movement and other factors. The person arranging the scan should match the examination to the clinical question. In some cases, MRI, CT, X-ray or a different test provides more useful information.

Common types of ultrasound

An abdominal ultrasound may examine organs such as the liver, gallbladder, kidneys, pancreas and spleen. A pelvic ultrasound looks at structures in the pelvis and may be performed over the lower abdomen or, when appropriate and with explanation and consent, using an internal probe. Musculoskeletal ultrasound can assess selected tendons, muscles, joints and superficial lumps, while Doppler techniques can assess blood flow in certain vessels.

An echocardiogram is a specialised ultrasound examination of the heart. It helps assess heart chambers, valves and pumping function, but it is different from an ECG, which records electrical activity. Each type of ultrasound has its own purpose and preparation requirements. When booking, check that the requested body area and examination type match the reason for the investigation.

Preparation: fasting, water and medicines

Preparation varies considerably. Some abdominal ultrasound appointments require fasting for a specified period so the gallbladder and other structures can be assessed clearly. A pelvic ultrasound may require a full bladder, while many other ultrasound examinations need little or no preparation. Do not assume that fasting is required for every ultrasound, and do not fast longer than instructed.

If you have not received preparation instructions, contact the provider before the appointment. This is especially important if you have diabetes, take medication with food, are pregnant or have another condition affected by eating or drinking. Ask whether you should take your usual medicines and whether you need to bring a referral, previous scan reports or other information.

What to expect during the examination

You may be asked to change into a gown or move clothing away from the area being examined. The sonographer applies gel to the skin and moves the probe across it, sometimes pressing gently to obtain clearer images. You may be asked to change position, take a breath in or out, or hold still for short periods. Most external ultrasound examinations are painless, although pressure can be uncomfortable if the area is already tender.

The length of the appointment depends on the examination and the images needed. The person performing the scan may not be able to give a complete explanation of the findings straight away because the images need to be reviewed and reported. If you are worried about discomfort, privacy or an internal examination, ask questions before the procedure begins; the team should explain what will happen and obtain appropriate consent.

Benefits and limitations

Ultrasound can provide real-time images, does not use ionising radiation and can be very helpful for specific clinical questions. It can also guide some procedures. However, it cannot see every structure equally well and may not detect all conditions. A normal ultrasound does not automatically rule out a problem if symptoms persist or if the suspected condition is not well assessed by ultrasound.

Sometimes the scan identifies an unexpected finding or does not provide a definite answer. your doctor may recommend follow-up imaging, blood tests or a different assessment. This does not necessarily mean the scan was unsuccessful; each test has limits and provides one part of the clinical picture. The next step should be based on the report and the reason the scan was requested.

Reports, costs and what happens next

After the examination, the images are reviewed and a report is prepared. The report may describe normal appearances, a finding that could explain symptoms, an incidental finding or a recommendation for further assessment. Ask how and when you will receive the report and who can explain it in the context of your health.

PrivateScans includes the pre-scan GP consultation, referral where clinically appropriate, the scan, consultant radiologist's report, digital access to your images and report, post-scan GP consultation and Patient Care Team support in the scan price. The initial consultation costs £25 and is deducted from the total scan cost if you proceed. Appointments are available within 1–3 days and results are returned within 3 days of the scan.

Doppler, abdominal and pelvic ultrasound: what differs

Some ultrasound examinations use Doppler techniques to assess the direction and pattern of blood flow in selected vessels. Others focus on organs, soft tissues or fluid-filled structures. An abdominal ultrasound may require fasting, while a pelvic ultrasound may require a full bladder; musculoskeletal examinations often need little preparation. Instructions vary because the structures being assessed and the way they are visualised are different.

An internal pelvic ultrasound, when appropriate, uses a probe inserted into the vagina to obtain closer images of pelvic organs. The sonographer should explain the examination, answer questions and obtain consent before proceeding. You can ask about alternatives, privacy and what to expect before deciding. If an internal examination is not suitable or you do not wish to proceed, tell the clinical team so they can discuss the available options.

Ultrasound is useful for many questions, but it has limitations. Air and bone can block sound waves, and not all conditions produce a visible change. If symptoms continue after a normal scan, discuss the result with our doctor; a different test or further assessment may still be appropriate.