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.
Creatinine is a waste product that the muscles produce at a steady rate as part of normal daily activity. The bloodstream carries creatinine to the kidneys, which filter it out of the blood, then creatinine passes out of the body in the urine (pee).
A urine creatinine test measures the amount of creatinine in the urine. It can be done on its own or with other tests that determine the amounts of other substances in the urine.
Why It's Done
Healthy kidneys filter the blood to rid it of waste products that the body can't use. Low levels of creatinine in the urine may point to a kidney disease, certain muscular and neuromuscular disorders, or a blockage in the urinary tract. If test results are abnormal, other tests will be done to make a specific diagnosis.
A creatinine clearance test measures how much creatinine is passed in the urine over several hours. A blood test to measure the creatinine level in the blood is also usually done. This gives doctors information about how well the kidneys are functioning.
A doctor may order a urine creatinine test in combination with other urine tests even when no kidney problem is suspected. Because creatinine is filtered out at a fairly steady rate, doctors compare the creatinine level with levels of other substances to see if they're excreted at a normal rate.
Your child might need to temporarily stop taking certain drugs that affect the urine's creatinine levels and might be asked to not eat large quantities of meat in the day or two before the test.
For a creatinine clearance test, you'll need to collect all the urine your child passes usually over 24 hours. If you are doing this at home, this usually involves first getting a special container from the lab in which to collect the urine, plus specific instructions.
If your child isn't potty trained and can't urinate into a cup, urine collection bags with adhesive tape on one end might instead be used to collect the samples. Your baby's genital area will need to be cleaned, and then the bag is placed around the urinary opening and secured with the attached tape. A diaper can be placed over the bag. The bag will need to be changed frequently to collect all of the urine, and each bag will need to be emptied into the special container.
Another option is the use of a catheter (a narrow, soft tube), which can be inserted into the bladder and left there for 24 hours to obtain urine.
If you collect the specimen at home, follow any storage and transportation instructions the lab gives you.
What to Expect
Because the test involves normal urination, there shouldn't be any discomfort as long as your child can provide a urine specimen.
Getting the Results
In general, the results of the urine creatinine test are available within a day or two. Your doctor will go over the results with you and explain what they mean. If abnormalities are found, further tests may be needed.
No risks are associated with taking a urine creatinine test.
Infants may occasionally have skin irritation from the adhesive tape on the collection bag. If a catheter is used to get the urine, it may cause temporary discomfort. If you have any questions or concerns about this procedure, talk to your doctor.
Helping Your Child
Explaining how the test will be conducted and why it's being done can help ease any fear. Make sure your child understands that there should be no foreign matter, such as toilet paper or hair, in the sample. And all the urine should be collected for the test to be accurate.
If You Have Questions
If you have questions about the urine creatinine test, speak with your doctor.
Reviewed by: Yamini Durani, MD
Date reviewed: April 28, 2017