Radionuclide Cystogram (RNC): What you and your child can expect
When your child is scheduled for a radiology test, both you and your child may have questions about it. We encourage parents to read this information, then talk about the test with your child.
What is a radionuclide cystogram?
This test, called an RNC, helps determine how the lower urinary tract is working. The lower urinary tract includes the bladder (where urine is stored) and the urethra (the tube from the bladder to the opening where urine is voided).
See our Patient / Family Education sheets for a detailed handout of specific Renogram exams.
- Radionuclide Cystogram (PDF)
How is the test performed?
A technologist will take you and your child into an exam room. You will see a large table and camera attached to a computer.
The nuclear medicine technologist will ask your child to put on a hospital gown and lie on the table. Girls will be asked to pull their legs up into a "frog" or "butterfly" position. Boys may keep their legs straight. A technologist will wash and dry the area between your child's legs, to make sure it is very clean. It may feel uncomfortable to your child as the technologist touches between his legs, but this part of the test is over quickly.
The technologist will then insert a small soft, flexible tube, called a catheter, into your child's bladder. The size of the catheter is small enough to fit inside a juice box straw. A radioisotope liquid, a liquid that makes it possible to view the bladder, will flow from a bottle through the catheter. Your child will not feel any side effects of the radioisotope. It loses its radioactivity within hours.
When the bladder is filling, your child will feel the urge to urinate. The technologist will ask your child to say when she feels she can't hold any more water. Then your child can either urinate on the table into a diaper or sit on a potty chair. Pictures will be taken while she is urinating. It is important for your child to remain still while the pictures are being taken.
The technologist will check the pictures to make sure they are complete before you leave the hospital.
How do I tell my child about this test?
Because you know your child best, explain this test to your child in a way that he will understand before you come to Children's. The staff also will explain the procedure to you and your child before and during the test.
Will it hurt?
For many children, the most important thing to know is whether or not this test will hurt. Assure your child that although there may be some discomfort, it will only last a few minutes. Remind your child that this test is being done to help the doctor find out how her body is working inside. By talking about the test with your child, you may help her be more comfortable during the test, which will make the procedure easier for your child and you.
Does my child have to do anything different before the test?
Usually you can maintain your child's routine eating, sleeping, and medicine schedules before the test. This test usually takes about 30 minutes.
There may also be different instructions if your child will have more tests, such as an IVP or an ultrasound. Your child's doctor or a nuclear medicine technologist will tell you if your child needs any special preparations.
Children under 18 years old must be accompanied by a parent or legal guardian.
What can my child expect after the test?
The next few times your child urinates, she may be a little sore and the urine may have a pink look to it. This is from the catheter that was placed in her bladder. Assure her that the discomfort will go away, and encourage her to drink plenty of fluids. Sometimes a warm bath (plain water, no bubbles) can provide comfort. Your child may resume normal activity and diet.
General radiology requirements
- Pregnant mothers: Women who are pregnant can't be in the exam room. They must have a family member or friend over the age of 18 accompany their child into the examination room during the exam (with the exception of the ultrasound and nuclear medicine rooms).
- Family or friends under the age of 18 years old: If you are not the patient and under the age of 18 years old you will not be allowed to remain in the radiology exam room during the exam.
- Siblings: Siblings are not allowed in the radiology room while the exam is being performed (with the exception of the ultrasound rooms). Please make arrangements to have an adult accompany them in the waiting room.
- Attire: Children wearing clothing with snaps or buttons will need to change into hospital attire. Any item such as jewelry, undergarments with metal, or EKG patches in affected area will be removed prior to the exam.