After the patient's bladder is filled with a liquid called contrast material, an X-ray machine sends beams of radiation through the abdomen and pelvis, and images are recorded on special film or a computer. These images help doctors see problems in parts of the urinary system, including the bladder, urethra (the tube connecting the bladder with the outside of the body), and the ureters (the tubes connecting the kidneys to the bladder).
A radiologist takes the X-rays using a technique called fluoroscopy. While the contrast material fills your child's bladder, and then while your child empties the bladder, the radiologist watches an onscreen X-ray video of the liquid moving through the urinary system and a series of X-ray films is recorded.
In general, X-rays are very safe. Although there is some risk to the body with any exposure to radiation, the amount used in a VCUG is small and not considered dangerous. It's important to know that Nemours radiologists use the minimum amount of radiation required to perform the study properly.
What does a VCUG show?
A VCUG can show whether the urine is moving in the right direction. Normally, urine flows from the kidneys down to the bladder through the ureters. When urine goes back up toward the kidneys, it's called vesicoureteral reflux (VUR), which a VCUG can detect. Sometimes VUR only occurs while urinating (voiding), which is why the VCUG includes taking X-ray images while the bladder is being emptied.
At times, fear, anxiety, and developmental stage of a child contribute to his or her ability to cooperate with medical procedures. Pediatric procedural sedation can be used to decrease discomfort and anxiety for your child.
Sedation is available for VCUG and a separate sedation appointment would be needed to be scheduled prior to the study.
Providing sedation means a child is given medicine to make the child more relaxed. When a child is sedated, he or she may better tolerate a medical procedure and will probably not remember it.
The sedation team aims for mild to moderate sedation, meaning that your child will be relaxed, but awake enough to answer questions and to sense a full bladder. Typical sedatives for this procedure include midazolam (Versed), given orally or as a nasal spray, or nitrous oxide (“laughing gas”) given with a mask. This procedure takes about 10 minutes for catheter placement and bladder filling, and another few minutes for the child to urinate.
A renal ultrasound is a safe and painless test that uses sound waves to make images of the kidneys, ureters, and bladder.
The kidneys are a pair of bean-shaped organs located toward the back of the abdominal cavity, just above the waist. They remove waste products from the blood and produce urine. The ureters are thin tubes that carry the urine from the kidneys to the bladder.
During the examination, an ultrasound machine sends sound waves into the kidney area and images are recorded on a computer. The black-and-white images show the internal structure of the kidneys and related organs.
Why It's Done
Doctors order renal ultrasounds when there's a concern about certain types of kidney or bladder problems. Renal ultrasound tests can show:
Usually, you don't have to do anything special to prepare for a renal ultrasound, although the doctor may ask that your child not eat or drink anything for several hours before the test. Sometimes a renal ultrasound needs a child to have a full bladder; in this case, the doctor will give specific instructions on what to do.
You should tell the technician about any medicines your child is taking before the test begins.
The renal 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 reassurance and support. 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 your child's abdomen over the kidney area. This gel helps 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 the sound waves bounce back from inside the body. The computer changes those sound waves into images to be analyzed.
Sometimes a doctor will come in at the end of the test to meet your child and take a few more pictures. The procedure usually takes less than 30 minutes.
What to Expect
The renal ultrasound test is painless. Your child may feel a slight pressure on the abdomen as the transducer is moved over it. You'll need to tell your child to lie still during the procedure so the sound waves can reach the area effectively. 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 is specially trained in reading and interpreting X-ray and ultrasound images) will interpret the ultrasound results and then give the information to the doctor. You and your doctor will go over the results. If the test results appear abnormal, your doctor may order further tests.
In an emergency, the results of an ultrasound can be available within a short period of time. Otherwise, results are 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 renal ultrasound. Unlike X-rays, radiation isn't involved with this test.
Helping Your Child
Some younger children may be afraid of the machinery used for the ultrasound test. Explaining in simple terms how the renal ultrasound test will be conducted and why it's being done can help ease your child's fears. You can tell your child that the equipment takes pictures of his or her kidneys.
Encourage your child to ask the technician questions and to try to 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 renal ultrasound, speak with your doctor. You can also talk to the technician before the exam.
Reviewed by: Rupal Christine Gupta, MD
Date reviewed: April 28, 2017