Ultrasound scan

An ultrasound scan (also called a sonogram) uses high-frequency sound waves to create pictures of the inside of the body.

The sound waves bounce off the different tissues that make up your body and these echoes are detected by the ultrasound probe. This information is sent to a computer that turns them into moving images in real-time. You can’t hear the sound waves produced — the term ultrasound refers to sound waves that are beyond the human hearing range.

The unit of measurement for sound waves — their frequency — is Hertz. Ultrasound scans that are used to diagnose conditions are usually performed at 2-18 Hertz. Higher frequencies produce better quality images but they are also absorbed by your skin and other tissues. This means high-frequency sound waves can’t create images of tissues deep inside your body. Lower frequencies pass further into your body and therefore can create images of tissues deep inside your body, but the images are of poorer quality.

Your ultrasound scan will usually be carried out by a radiologist or a sonographer (a person trained in ultrasound scanning) who will also analyse the results of your scan.

An ultrasound scan can:

• Diagnose bone, joint, muscle or tendon problems eg carpal tunnel syndrome, frozen shoulder, Morton's neuroma and tennis elbow
• Examine internal organs and tissues (eg the appendix, bladder, gallbladder, kidneys, liver, lymph nodes, ovaries, pancreas, testes and thyroid gland) to diagnose a condition — an ultrasound scan can determine whether an abnormal lump is a solid tumour or fluid-filled cyst and can also detect kidney or gallbladder stones
• Guide doctors during certain procedures eg a needle biopsy, where a needle is inserted to collect a tissue sample, or an injection to treat frozen shoulder
• Check the flow of fluids through your body eg blood flow problems, such as deep vein thrombosis or aneurysms — this uses either a Doppler or duplex ultrasound scan
• Detect heart abnormalities eg heart valve defects or examine the size, function and pressures in your heart and heart valves — this uses an echocardiogram

Your doctor may recommend an ultrasound scan if you have or they suspect you have:

• An abnormal growth or lump
• Damaged ligaments, tendons or soft tissues
• Liver and kidney problems
• Bleeding or fluid in your muscles or joints
• A heart problem

Your healthcare team will tell you how to prepare for your ultrasound scan — what you need to do will vary depending on the part of your body being scanned.

If you are having a pelvic ultrasound scan you may be asked to drink water and not urinate until after your scan.

If you are having an ultrasound scan of your digestive system, liver or gallbladder, you may be asked to:

• Avoid drinking or eating for a few hours before your scan
• Eat a low-fibre diet for several days leading up to your scan
• This is to help reduce the amount of gas in your gut

Depending on the part of your body being scanned, you may be asked to change into a hospital gown. For some ultrasound scans, you may be injected with a contrast agent ie a special dye to improve how well certain tissues appear on the ultrasound images.

The ultrasound transducer (also called a probe) is a handheld device that is placed on the surface of your body, on the area that needs to be scanned, or in some cases, is inserted into your body.

In a hospital, a radiologist will usually conduct your scan but in some cases, your consultant will. You may have an ultrasound scan at a clinic or GP practice, where it may be a doctor, midwife or nurse who performs your ultrasound scan — they will have completed special training to do this.

During your scan, you will lie down on an examination bed and the transducer will be placed over the part of your body to be examined.

The high-frequency sound waves produced in an ultrasound scan bounce off internal structures in your body. These create echoes that are detected by the transducer on your skin and turned into a moving image on a monitor. The transducer will be moved around to capture images in real-time from different angles. The images can show both structure and movement.

External ultrasound scan

External ultrasound scans are often used to examine organs in your abdomen (eg kidneys and liver) and pelvis, as well as more superficial tissues such as your muscles and joints. However, they are also used to examine your heart.

A small, handheld transducer is placed on your skin, with a lubricating gel, and is moved over the part of your body being scanned. The lubricating gel ensures smooth movement and continuous contact between the transducer and your skin. The gel may feel cold.

Internal ultrasound scan

Internal ultrasound scans allow your doctor to get clearer images of your internal organs, such as the prostate, ovaries and womb.

During a transvaginal ultrasound scan, you will be asked to lie down on your back or on your side with your knees bent upwards. A small transducer will then be passed into your vagina.

During a rectal ultrasound scan, you will be asked to lie down on your back or on your side with your knees pulled up to your chest. A small transducer will then be passed into your rectum.

You may feel some discomfort as the transducer is passed into your body. However, the procedure is not usually painful and doesn't take long.

Doppler ultrasound for circulatory problems

A traditional ultrasound scan detects sound waves as they bounce off your tissues while a Doppler ultrasound scan detects sound waves bouncing off moving objects (eg blood cells) to measure their speed and how they flow through your body. This is possible because sound waves bouncing off moving objects do so at a slightly different frequency than sound waves bouncing off stationary objects. These sound waves can't be heard so they are amplified to allow your sonographer or doctor to hear them.

In the case of an ultrasound to check blood flow, your radiologist or doctor can hear the flow of blood through your blood vessels and determine whether it is abnormal. In a colour Doppler ultrasound scan, the sound waves are converted to colour images on a monitor so your sonographer or doctor can see the blood flow through your veins or arteries.

There are different types of Doppler ultrasound scans, including an echocardiogram (ECG). An ECG can capture images of your heart and blood vessels to measure blood flow and the movement of your heart muscle.

Duplex ultrasound

A Duplex ultrasound scan combines a traditional ultrasound scan with a Doppler ultrasound scan. This allows images of moving objects (usually displayed in colour) and the surrounding tissue (usually displayed in grey) to be captured at the same time.

Duplex ultrasound scans are usually used to check blood flow through different veins and arteries. You may have a duplex ultrasound scan to check if you have:

• A blood clot
• An abdominal aortic aneurysm (AAA) — a widening of the main artery in your abdomen; there is a national screening programme for men aged 65 or over, which is performed using Duplex ultrasound scans
• Arterial occlusion — blockage to an artery
• Carotid occlusive disease — blockage to the arteries in your neck
• Problems with the blood vessels supplying your kidneys
• Venous insufficiency — veins that are not able to effectively send blood back to your heart
• A duplex ultrasound scan can also be used to check for varicose veins

An ultrasound scan usually takes 15-45 minutes. There are no after-effects of a standard ultrasound scan so you can leave the same day and return to your normal activities.

Spire hospitals have an agreement with radiologists that reports should be completed within five working days - this is regardless of the body part that has been scanned. However, there are occasions when a specialist radiologist opinion is needed and in these cases it can take a little bit longer.

Results are always returned to your referrer - this can be your NHS GP, private consultant or private GP, or an organisation (such as the MoD).

Spire hospitals have an agreement with radiologists that reports should be completed within five working days - this is regardless of the body part that has been scanned. However, there are occasions when a specialist radiologist opinion is needed and in these cases it can take a little bit longer.

Results are always returned to your referrer - this can be your NHS GP, private consultant or private GP, or an organisation (such as the MoD).

You should arrange a follow up appointment with your referrer to receive the results of imaging examinations.

The results of imaging examinations often only form a part of the investigations and treatments requested or carried out by consultants, so should not be read in isolation. Your referrer will have a holistic view of your medical history, so can advise on the outcome of a radiology report alongside all other tests results and previous or current medical conditions.

An ultrasound scan is generally a safe procedure with no known side effects. An ultrasound scan doesn't expose you to radiation unlike X-rays and CT scans, 

If you’re having an internal ultrasound and have an allergy to latex, it’s important to let your doctor know so they can use a latex-free cover on the ultrasound transducer that will be inserted into your body.

At Spire Healthcare, we’re careful to weigh up the benefits and risks of any ­­­­procedure and discuss it with you if you have any concerns.