Examines internal organs and blood flow to diagnose or monitor conditions.
You can arrange to have an ultrasound scan at a Spire Healthcare hospital near you. We provide fast access to an extensive range of diagnostic tests and scans in our high-quality facilities.
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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 sonographer (a person trained in ultrasound scanning). The results of your scan will be analysed by a doctor in the relevant area of expertise eg a radiologist, cardiologist or another specialist.
An ultrasound scan can:
Your doctor may recommend an ultrasound scan if you have or they suspect you have:
If you are pregnant, you will also have ultrasound scans to monitor and assess the health of your unborn baby.
Almost all Spire Healthcare hospitals offer private ultrasound scanning. Our fast diagnostics mean you don’t have to wait long for your results.
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 or are pregnant and are having an ultrasound scan of your unborn baby, 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:
If you are having an internal ultrasound scan ie an ultrasound scan that involves inserting a small probe into your back passage or vagina, you may be given an enema beforehand to empty your bowels. This type of scan is often used to examine the ovaries, prostate, womb or vagina.
Depending on the part of your body being scanned, you may be asked to change into a hospital gown. If you are feeling very anxious, you may be given a sedative intravenously ie through a small tube placed into a vein in the back of your hand or arm. 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 wand) 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.
Types of transducer include:
In a hospital, a sonographer or 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.
If you are having an external ultrasound scan, a lubricating gel will be applied to your skin to help the transducer move smoothly.
If you are having an internal or transvaginal ultrasound scan, a small ultrasound transducer will be passed into your vagina or rectum.
If you are having an endoscopic scan, the transducer will be passed into your mouth and down your throat to examine your oesophagus or stomach.
External ultrasound scan
External ultrasound scans are often used to examine your heart or if you are pregnant, to examine your unborn baby. However, they are also used to examine other organs in your abdomen (eg kidneys and liver) and pelvis, as well as more superficial tissues such as your muscles and joints.
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, slightly wider than a finger, 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.
Endoscopic ultrasound scan
An endoscopic ultrasound scan involves passing a thin telescope-like tube (an endoscope) with a light and a small transducer on the end through your mouth and down your throat to examine your oesophagus or stomach.
Before your scan, you will be given a sedative to help you relax and a local anaesthetic, applied as a spray, to numb your throat. You may be given a mouth guard to hold your mouth open and prevent you from biting the endoscope.
During your scan, you will be asked to lie on your side as the endoscope is passed inside you. This may feel uncomfortable and you may feel as if you want to vomit.
Doppler ultrasound for circulatory problems
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.
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 sonographer or doctor can hear the flow of blood through your blood vessels and determine whether it is abnormal. This is routinely done during an ultrasound scan to monitor the development of an unborn baby where blood flow through the baby's heart is checked.
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.
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:
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.
However, if you have a sedative (eg for an endoscopic ultrasound scan) you will be advised to stay in hospital for a few hours until you feel fully awake and alert. You will not be able to drive, drink alcohol or operate heavy machinery for 24 hours after having a sedative. It is also advised that you have someone pick you up from hospital and stay with you for the next 24 hours.
Your doctor may be able to explain your results during your scan appointment. However, sometimes the images will need to be analysed, so you’ll need to come back for another consultation or a report will be sent to the doctor who requested the scan.
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.
After an endoscopic ultrasound, you may feel some temporary discomfort such as a sore throat or bloating. There’s also a small risk of internal bleeding.
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.
What is the disadvantage of ultrasound?
The sound waves used in an ultrasound scan don’t penetrate well through bone, air or gas (eg gas in your bowels), which reduces the image quality. Being obese can also reduce the image quality. MRI and CT scans produce more detailed, clearer images.
What does a liver ultrasound scan show?
A liver ultrasound scan can help diagnose a range of conditions affecting the liver, such as liver cancer, liver cirrhosis and non-alcoholic fatty liver disease (NAFLD).
Do you need to shave before an ultrasound scan?
No, you do not need to shave before an ultrasound scan.
How accurate are ultrasound growth scans?
Ultrasound growth scans are fairly accurate in assessing the growth of your baby. However, estimating their weight from these measurements is less reliable.
How accurate is an ultrasound scan for dating a pregnancy?
An ultrasound scan during the first or second trimester is the most accurate way to date a pregnancy. It is harder to date a pregnancy if the first ultrasound scan is carried out further along the pregnancy.
Which is more accurate, an ultrasound or MRI scan?
An MRI scan provides more detailed images of the inside of your body when compared to an ultrasound scan. However, MRI scans take longer, are more expensive and require lying down in an MRI machine, which some people find claustrophobic.
Why have an ultrasound after a CT scan?
An ultrasound scan and a CT scan are both effective tools for imaging the inside of your body. However, they produce different types of images, which can reveal different things about your body. Your doctor may therefore refer you for an ultrasound scan after a CT scan if the necessary information wasn’t apparent on your CT scan.
How soon can an ultrasound scan detect pregnancy?
The earliest point at which an ultrasound scan can detect a pregnancy is around six to seven weeks after conception, which is usually when the foetal heartbeat can be detected.
What is the POD in an ultrasound scan?
POD refers to the Pouch of Douglas in women, also known as the recto-uterine pouch, which sits between the womb and the rectum (back passage). Fluid naturally collects here. If you have endometriosis an ultrasound scan may reveal that it has spread to the POD.
What happens if you eat before an ultrasound scan?
For most ultrasound scans, you can eat, drink and take your medications as usual. However, if you are having an ultrasound scan of your digestive system, liver or gallbladder, you may be asked not to eat for several hours beforehand. This is because eating will increase the amount of gas in your gut, which can reduce the quality of images produced during your ultrasound scan.
Can you see inflammation on an ultrasound scan?
Yes, an ultrasound scan can detect inflammation eg inflammation of your joints or gut.
Why is watery jelly used in ultrasound scans?
If you are having an external ultrasound scan, a watery jelly (a lubricating gel) will be placed on the part of your body to be scanned. This helps the ultrasound transducer (a handheld probe) remain in contact with your body as it is moved across it — this is necessary to ensure the sound waves effectively pass into your body and are detected as they bounce back.
The treatment described on this page may be adapted to meet your individual needs, so it's important to follow your healthcare professional's advice and raise any questions that you may have with them.