Radionuclide Cystogram (RNC)

Radionuclide cystograms (RNCs) are tests that employ nuclear medicine to study pathologies like vesicoureteral reflux (VUR). This is a medical condition where, instead of flowing in a one-way direction from the kidneys to the ureters, bladder and urethra, urine flows backward. This can result in serious complications, such as renal scarring and failure.

The radiopharmaceutical technetium-99m is used for RNC diagnostics and is injected into the bladder via the urethra while gamma cameras are used to take pictures of the bladder as it fills and empties. The RNC testing is similar to a voiding cystourethrogram (VCUG), but as opposed to the RNC, the VCUG uses a contrast dye instead of a radiopharmaceutical and provides more anatomical detail.  

What to Expect

The entire procedure may last up to half an hour and is more or less painless, but children may understandably be scared. Thus, it is advisable that a guardian is present to give a sense of security and assurance to the child that he or she will be ok. Any allergies to medications or X-ray contrast material must be communicated to the physician, and all jewelry or accessories that might affect the quality of the images must be removed from the body. Prior to the test, unless otherwise indicated by the attending physician, no special preparations are required, which means that patients may drink or eat as usual.

At the onset of the procedure, the patient is placed on an imaging table and a catheter is inserted into the urethra under sterile conditions and lubed with some local anesthetic to numb the lining of the urethra. Via this catheter, saline combined with radiopharmaceutical is infused into the bladder, which will be filled to its capacity. Imaging is already started during this process and once the bladder is full, the catheter is removed and the patient is asked to urinate into a container placed nearby. Imagining will continue during this process, until the bladder is empty.

After the procedure is done, the radiologist will analyze all of the acquired images before making a report and sending that report to the attending physician. If normal, the bladder and urethra will show typical function and size. Neurogenic bladder, reflux nephropathy, ureterocele (i.e. the ballooning of the distal ureter to form a pouch as it opens into the bladder) and diverticula, are just some of the pathologies that may be identified with an RNC. Patients are managed accordingly.

Risks and Complications

There are small risks involved in terms of radiation exposure from the radioisotopes used in RNCs, but the radiation is mild and leaves the body within a short period of time. Following the procedure, a patient may experience some perineal discomfort and painful urination, which are both transient and disappear within a few hours. Urinary tract infections are also possible and this is the reason why sterile conditions during catheterization are the rule and not the exception. Bladder perforation is another complication that may occur, but it is fortunately rare.

References

• http://www.childrenshospital.org/conditions-and-treatments/treatments/radionuclide-cystogram
• https://medlineplus.gov/ency/article/003832.htm
• http://urology.ucsf.edu/sites/urology.ucsf.edu/files/uploaded-files/basic-page/Voiding%20Cystourethrogram_Procedure.pdf