Common Diagnostic Studies

CHOC Urology Center uses a number of tests to accurately diagnose patients. If you have further questions regarding the ultrasounds, X-rays or other radiological studies, please call our radiology specialists at 714-744-8775. Once the test has been completed at CHOC or St. Joseph’s, the child’s caregiver will be notified with the results within two weeks. If you have not heard from the Urology Center with the test results within two weeks, please call the center at 714-509-3919. If the study was done at a different facility, please contact the Urology Center upon its completion so our staff may obtain the results.

Scrotal Ultrasound

Most parents are familiar with ultrasounds from pregnancy. Ultrasounds are noninvasive tests that produce sound waves that transmit a picture onto a screen. Scrotal ultrasounds are used to further investigate the testicles.

Renal/Bladder Ultrasound

Most parents are familiar with ultrasounds from pregnancy. Ultrasounds are noninvasive tests that produce sound waves that transmit a picture onto a screen. With a renal ultrasound, a transducer (the wand) is passed over the kidney and allows us to determine the size and shape of the kidney, and to detect a mass, kidney stone, cyst or other obstruction or abnormalities.

Voiding Cystourethrogram (VCUG)

A VCUG is a specific X-ray that examines the urinary tract and allows specialists to see a direct image of the bladder and a refluxing ureter if present. A catheter (hollow tube) is placed in the urethra, and the bladder is filled with a liquid dye. X-ray images are taken as the bladder fills and empties. The images show if there is a reverse flow of urine into the ureters and/or kidneys. The images also show the size and shape of the bladder and the urethra. VCUGs are a common procedure, but because some children and parents find the catheter to be unpleasant, a numbing gel may be used to ease any discomfort. Speaking with the child before the procedure about what they should expect to experience can help ease anxiety. The more relaxed the child is during the procedure, the less discomfort they will feel.

Flow Rate and Post Void Residual

A flow rate is often completed at a child’s visit who has incontinence, urinary urgency or frequency, UTIs, hypospadiasis, vesicoureteral reflux or meatal stenosis. The child will be asked to drink water before the procedure so that they are comfortably full of urine. The child will then urinate in a special toilet that has a small cup at the base to collect the urine. This cup sits on a small scale (like a kitchen scale) which is connected to a computer. The computer is able to analyze information about the urination stream for the providers. This test is not invasive and the patient will be voiding as they do regularly. A postvoid residual (PVR) measurement may be performed to determine if the patient is able to empty the bladder. This is commonly done directly following a flow rate. After a patient urinates, a small scan of the bladder, using ultrasound, will be completed. This allows the providers to see how much urine was left in the bladder after the child voided. This test is not invasive.

KUB X-ray

A kidney, ureter, and bladder (KUB) X-ray may be performed to assess the abdominal area for causes of abdominal pain, or to assess the organs and structures of the urinary and/or gastrointestinal (GI) system. A KUB X-ray may be a diagnostic procedure used to assess the urinary system or intestines. X-rays use invisible electromagnetic energy beams used to produce images of internal tissues, bones, and organs on film. X-rays are made by using external radiation to produce images of the body, its organs, and other internal structures for diagnostic purposes. X-rays pass through body tissues onto specially treated plates (similar to camera film) and a “negative” type picture is made (the more solid a structure is, the whiter it appears on the film). Learn more about KUB X-rays.


MRI is a diagnostic procedure that uses a combination of a large magnet, radio frequencies and a computer to produce detailed images of organs and structures within the body. Learn more about MRI.

Video Urodynamics (VUDS) and Urodynamics (UDS)

Urodynamic testing is performed to measure the pressure inside the bladder when it is empty, filling and voiding. Two thin catheters are used in this test. One catheter is inserted through the patient’s urethra and into the bladder. The other catheter is placed into the patient’s rectum and the bladder is then filled with water. The pressure inside the bladder, rectum and abdomen is monitored. This test allows the healthcare provider to measure the pressures, muscle contraction and capacity of the bladder. During a video urodynamic test, a VCUG is done during the urodynamic procedure to visualize the urethra, bladder and ureters.

DMSA Renal Scan

This is a nuclear medicine test completed to provide images of the kidneys that will help to identify if there are areas of damage to the kidney. There are no dietary or activity restrictions before or after the test. This test may take several hours and our team recommends bringing toys and books from home for the child. Learn more about the DMSA renal scan.

Mag 3 Lasix Renal Scan

A Mag 3 Lasix renal scan is a nuclear medicine test that provides images of the kidneys to look for kidney function, size, shape, position and blockage of urinary flow. There are no dietary or activity restrictions before or after the test. Because this test can take up to two hours, please bring books and toys from home for the child. Learn more about Mag 3 Lasix renal scan.


Biofeedback is completed by a specialized nurse who teaches patients how to use their pelvic floor muscles correctly. A child will use their pelvic floor muscles to play computer games to help increase their control of these muscles. Biofeedback is non-invasive but does require the placement of stickers with sensors onto their skin around the pelvic area.

Urine Dip

A urine dip is completed in the office with a sterile sample of the child’s urine. If the child is toilet trained the sample will be taken in a small sterile cup while your child urinates regularly in the restroom. If the child is not yet toilet trained a catheter or a small bag placed over the genitals is used to collect the urine. This urine is then examined in the office to look for the particular abnormalities such as blood or proteins.

Microscopic Urine Analysis

Using the same technique to collect urine from the child as in a urine dip, the urine sample is then sent to an outside laboratory for more in-depth examination. A microscope is used to look at the urine to identify if there are particular abnormalities. This test is performed if a urinary tract infection is suspected.

Urine Culture

If a urine specimen shows bacteria, a urine culture is often completed. The bacteria is then grown in a laboratory for 24 hours to determine what type of bacteria and what medications will treat the bacteria most effectively.

24-Hour Urine Collection

A 24-hour urine collection is often completed in children with a history of renal or bladder stones. Urine is collected in a designated container for a full 24-hour period. When collecting urine for the 24-hour period, the child’s first urination for the day is not included. The urine is then collected for the remainder of that day and night and the first urination the next morning is included. This collection is then sent out to a laboratory that analyzes the urine to help determine what may be causing the body to produce stones.

Creatinine level

A creatinine level is requested in some children with concerns of renal disease. This is a standard blood test completed at an outside laboratory. Creatinine is filtered out of the blood by the kidneys. If a kidney is filtering poorly, the creatinine levels in the blood will rise.