A bladder ultrasound is a safe and painless test that uses sound waves to make
images of the bladder before and after urination (peeing).
During the examination, an ultrasound machine sends sound waves into the bladder
area and images are recorded on a computer. The black-and-white images show the internal
structure of the bladder, as well as the amount of urine inside.
Why It's Done
Doctors order bladder ultrasounds when there's a concern about bladder problems,
such as difficulty urinating or daytime wetting.
A bladder ultrasound can show how much urine the bladder holds when it's full and
whether someone completely empties the bladder when urinating. It can also demonstrate
any obvious abnormalities of the bladder, the size of the bladder, the thickness of
the bladder walls, and the presence of blockages or stones (lumps of built-up minerals).
A bladder ultrasound is often done along with an ultrasound of the kidneys.
Usually, you don't have to do anything special to prepare for a bladder ultrasound,
although the doctor may ask that your child drink lots of fluids before the exam so
that he or she arrives with a full bladder. You should tell the technician about any
medications your child is taking before the test begins.
The bladder ultrasound will be done in the radiology department of a hospital or
in a radiology center. Parents are usually able to accompany their child to provide
Your child will be asked to change into a cloth gown and lie on a table. The room
is usually dark so the images can be seen clearly on the computer screen. A technician
(sonographer) trained in ultrasound imaging will spread a clear, warm gel on the lower
abdomen over the pelvic area, which will help with the transmission of the sound waves.
The technician will then move a small wand (transducer) over the gel. The transducer
emits high-frequency sound waves and a computer measures how they bounce back from
the body. The computer changes those sound waves into images to be analyzed.
After the first image with a full bladder is taken, your child will be asked to
empty the bladder and more images will be recorded. Sometimes a doctor will come in
at the end of the test to meet your child and take a few more ultrasound pictures.
The procedure usually takes less than 30 minutes.
What to Expect
The bladder ultrasound is painless. Your child may feel a slight pressure as the
transducer is moved over the abdomen. Ask your child to lie still during the procedure
so the sound waves can produce the proper images. The technician may ask your child
to lie in different positions or hold his or her breath briefly.
Babies might cry in the ultrasound room, especially if they're restrained, but
this won't interfere with the procedure.
Getting the Results
A radiologist (a doctor who's specially trained in reading and interpreting X-ray,
ultrasound, and other imaging studies) will interpret the ultrasound results and then
give the information to your doctor, who will discuss them with you. If the test results
appear abnormal, your doctor may order further tests.
In an emergency, the results of an ultrasound can be available quickly. Otherwise,
they're usually ready in 1-2 days. In most cases, results can't be given directly
to the patient or family at the time of the test.
No risks are associated with a bladder ultrasound. Unlike X-rays, radiation isn't
involved with this test.
Helping Your Child
Some younger kids may be afraid of the machinery used for the ultrasound. Explaining
in simple terms how the bladder ultrasound will be conducted and why it's being done
can help ease any fear. You can tell your child that the equipment takes pictures
of the bladder.
Encourage your child to ask the technician questions and to try and relax during
the procedure, as tense muscles can make it more difficult to get accurate results.
If You Have Questions
If you have questions about the bladder ultrasound, speak with your doctor. You
can also talk to the technician before the exam.