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Dr Timothy Cain
Date last modified: April 28, 2015
A paediatric renal ultrasound is an examination of the kidneys and bladder with an ultrasound machine, which uses sound waves to form images of different organs within your child's body. The sound waves cannot be heard by the human ear and cannot be felt by the child having the ultrasound study.
Renal ultrasound studies are most commonly performed to investigate the causes of urinary tract infections (infections affecting the urine or the organs that form and discharge the urine). They are sometimes performed in very young children so that doctors can keep track of changes in a baby's development identified on scans that were performed while the child was still in the mother's uterus (womb).
Ultrasound examinations are particularly useful in examining the liver and kidneys, but can provide very useful information about other organs which may be seen during the examination.
Your child needs to take clear liquids without bubbles to fill the bladder and allow the bladder to be seen properly on the renal ultrasound images. Water is the best liquid to drink in preparation for a renal ultrasound, but clear juices (such as apple or blackcurrant) or cordials are also suitable.
Food and air in the stomach and intestines makes a renal ultrasound study difficult to perform and interpret so it is also important that your child does not eat food before the ultrasound study. Soft drinks and fizzy or sparkling drinks also fill the stomach and intestines with gas so these should also not be taken. The length of time your child will need to go without food will depend on their age. Very young children will only be asked to fast for as little as 3 hours but older children will be asked to fast for up to 10 hours. This can be difficult for some children and parents. It is often best to make the ultrasound appointment early in the day so your child is awake for as little time as possible without being able to eat.
If your child takes medications with clear liquids, these can be taken as normal before the ultrasound scan. If your child needs to take medication with food, you will need to discuss with your doctor the timing of the medication and ultrasound study.
Your child should wear clothes that allow the abdomen (stomach area) to be exposed easily from the lower chest to the skin crease where the legs "join" the pelvis and lower abdomen.
A transducer (a small, smooth, hand held device), which converts electrical energy from the ultrasound machine computer to sound waves, is placed on the abdomen and moved gently back and forth over the skin to show different parts of the body.
A clear gel is used to make the transducer contact closely with the skin and allow it to slide smoothly across skin of the abdomen. The sound waves which are bounced back from the body to the transducer are converted back to electrical energy, which is then analysed by the ultrasound machine computer to make an image or picture which can be seen on the video screen of the ultrasound machine.
Your child will lie down on an ultrasound bed, usually on his or her back for the examination. Sometimes, the sonographer (the person performing the ultrasound scan) will roll your child into different positions or ask your child to roll into different positions, depending on your child’s age. Older children will sometimes be asked to take a deep breath or hold his or her breath for a short time to get as clear a picture as possible on the ultrasound screen.
The study usually begins with images of the bladder while it is full, followed by images of the kidneys. If the bladder is not filled enough, your child may be asked to drink more water before the study can be completed.
The ultrasound waves used for diagnostic ultrasound examinations cannot be felt by humans and do not cause any harm.
The gel used in the study washes off in water and should not mark or stain clothing. It may dry as a white powder on your child's skin.
Your child will not feel any different before, during or after the test, and can return to school, kindergarten, or child care after the study provided there is no medical reason not to do so.
The time taken for the ultrasound varies with the age and level of cooperation of the child and the reason for the scan. However, it would usually take about 15-20 minutes if the child is cooperative. It can take considerably longer if the bladder is not filled before the examination commences and the sonographer has to wait for bladder filling to occur.
A paediatric renal ultrasound study is a safe procedure which causes no harm. If there is a lot of gas in the abdomen or the patient is unable to hold still, some organs or areas inside the body may not be seen properly and the examination may not give all the information your doctor was expecting to receive. For example, the ultrasound examination may not show the cause of the child's symptoms and further investigation(s) may be necessary.
An ultrasound study is ideally suited to babies and children as there are no potentially harmful X-rays and the ultrasound examination can be performed without the child having to be sedated, hold still, or alter their breathing (although sometimes older children may be asked to take a deep breath or hold their breath for a short time).
Ultrasound studies have no side effects and can usually show the kidneys and bladder very easily and clearly.
Ultrasound examinations are performed by a radiographer (also known as a medical imaging technologist - MIT) or doctor who has undertaken special training in ultrasound. The radiographer is often called a "sonographer" and a doctor who performs the ultrasound examination is sometimes referred to as a "sonologist".
The images are usually obtained by the sonographer under the supervision of a radiologist or other medical specialist. Obstetricians and cardiologists are two other medical specialists who use ultrasound routinely in their medical practice. A radiologist is a specialist doctor trained to interpret medical images and provide a report to your doctor. Sometimes the radiologist will also examine your child or watch some of the images being taken.
Any doctor is allowed to use an ultrasound machine to assist in the investigation of clinical problems, but their use of an ultrasound machine will probably be limited to their special areas of interest.
Ultrasound examinations are usually performed in a public or private hospital or private radiology practice. Some ultrasound examinations are undertaken in a hospital ward, operating theatre or theatre recovery ward as modern ultrasound equipment is able to be moved to the patient if necessary. Some doctors have their own ultrasound machine in their consulting rooms and may use it as a part of their examination of a patient.
The time it takes your child's doctor to receive a written report on the test or procedure will vary depending on:
Please feel free to ask the private practice, clinic, or hospital when the written report will be provided to your child's doctor.
It is important that you discuss the results with your child's doctor, either in person or on the telephone, so that they can explain what the results mean for you and your child.