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What is an ultrasound scan (USS)?

Ultrasound scans use sound waves to build up a picture of the inside of the body. They are painless. You usually have this test in the hospital X-ray department. A trained professional who specialises in ultrasound scanning is called a sonographer.

The ultrasound scanner has a microphone which gives off sound waves. The doctor (radiologist) or sonographer moves the microphone over the area of your body being scanned. The sound waves bounce off the organs inside your body, and the microphone picks them up again. It is linked to a computer which turns the sound waves into a picture.

Having an USS

Whether you need to do anything to prepare for the scan depends on the part of your body being scanned. Your appointment letter will give you instructions about what you need to do.

You lie on a couch next to the ultrasound machine. The doctor or sonographer spreads a clear gel onto your skin over the scanning area. They press the microphone against your skin and move it back and forth over that area. The scans take from 5 minutes to about half an hour.

Doctors can also use a probe to do an ultrasound of the inside of the body, for example to examine your prostate gland or vagina. These tests can be uncomfortable but shouldn’t be painful.

An endoscopic ultrasound scan is a type of ultrasound that can examine your digestive system, including the food pipe (oesophagus), stomach and part of the small bowel (duodenum). This test combines an endoscopy and an ultrasound.

Results

If you have the test as an emergency you may get the results the same day. If the test is a routine one and you haven’t heard from the hospital after a couple of weeks, contact your doctor's secretary or GP.

 

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How an ultrasound scan works

Ultrasound scans use high frequency sound waves to build up a picture of the inside of the body. They are completely painless. These scans are usually done in the hospital X-ray department.

The ultrasound scanner has a microphone which gives off sound waves. The microphone is passed over your body. The sound waves bounce off the organs inside your body, and are picked up again by the microphone. The microphone is linked to a computer. This turns the reflected sound waves into a picture.

 

What will happen

A photograph of someone having an ultrasound scan

Once you have checked in with the receptionist, you will be asked to take a seat in the waiting room until the doctor (radiologist) or sonographer calls you. A sonographer is a trained professional who specialises in ultrasound scanning.

When you are called, you may be shown to a cubicle and asked to take off your outer clothing down to your underwear and put on a hospital gown. Whether you have to undress or not will depend on the part of your body to be scanned.

You will go into the scanning room and lie on the couch next to the ultrasound machine. You may be able to sit up depending on which part of your body is being scanned. A clear gel will be spread onto your skin over the scanning site. This helps to transmit the sound waves to the microphone.

Ultrasound scans

The doctor or sonographer presses the microphone against your skin and moves it back and forth over the part of your body being scanned. You may feel pressure but it does not usually feel uncomfortable. The scan appears on the screen, which will be next to you. If you would like to see it, just ask. But ultrasound scans are quite difficult to read and you may not be able to see very much.

Ultrasounds take from 5 minutes to about half an hour, depending on the scan. At the end of the scan, the doctor or sonographer will wipe the gel from your skin and help you down from the couch. You will be able to go home once the scan is over. Ultrasound scans are very safe, and there are no known risks.

 

Preparation for the scan

Generally there is no preparation for ultrasound scans. But for particular scans, you may be asked not to eat or drink for about 6 hours beforehand. If you are having your womb scanned, you may be asked to come to the appointment with a full bladder. This is because the full bladder pushes the womb up so it is in a position that is easier to scan. You may need a full bladder for a bladder scan too. There will be a toilet close by, so you will be able to empty your bladder as soon as the scan is over. Your appointment letter will give you instructions about what you need to do before your scan.

 

Types of internal ultrasound scan

Sometimes, doctors need to put the ultrasound microphone inside your body to get a clearer picture. Most often this is done for a scan of your prostate or vagina. You may also have internal ultrasound to examine your food pipe (oesophagus), stomach or gallbladder. This is called an endoscopic ultrasound.

 

Rectal ultrasound

If you are having your prostate gland examined, you have a rectal ultrasound. This is called a transrectal ultrasound or TRUS. You will need to make sure you have had a bowel movement beforehand so your rectum is empty when you come for your appointment. A small ultrasound microphone or probe is put into your back passage to get a clearer picture of the prostate. This is uncomfortable, but shouldn't hurt. This type of scan does not take long.

 

Vaginal ultrasound

This is sometimes used to look at the ovaries, womb and surrounding structures. It is called transvaginal ultrasound or TVS. The doctor or sonographer will ask you to lie on your back with your knees bent and legs apart (as if you were having a cervical screening test or an internal examination). They will keep you covered with a sheet. If this position is difficult for you, you may be able to lie on your side with your knees drawn up to your chest. The doctor puts a small ultrasound microphone or probe into your vagina so that the ovaries and womb can be seen on the scan. This may be uncomfortable, but shouldn't hurt. This type of scan does not take long.

 

Endoscopic ultrasound

This is a combination of having an endoscopy and an ultrasound. An endoscope is a long flexible tube with a light and camera attached. Doctors usually use it to look at the inside of your digestive system. The endoscope can also have an ultrasound probe at the tip. This gives doctors more detailed information. 

Doctors use endoscopic ultrasound to look at the wall of the oesophagus, stomach, and part of the small bowel (duodenum), or the gallbladder and bile ducts. This test can also look at the lymph nodes in your chest and abdomen.

We have more information about having an endoscopy.

 

The results

It can take time for test results to come through. How long will depend on why you are having the scan. Usually, the scan is examined by a specialist in radiography and a report typed up. The report is then sent to your specialist, who gives the results to you. If your GP has sent you for the test, the results will be sent to the surgery.

Understandably, waiting for results can make you anxious. It usually takes a couple of weeks. If your doctor needs the results urgently, they will make a note of this on the scan request form and the results will be ready sooner. Try to remember to ask your doctor how long you should expect to wait for the results when you are first asked to go for the test. If it is not an emergency, and you have not heard a couple of weeks after your test, ring your doctor's secretary or GP to check if they are back.

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Updated: 13 May 2015