DRCG (Direct-radionuclide cysto-ureterography) scan

Direct Radionuclide Cystoureterography (DRCG), also referred to as DRC scan or DRCUG scan, is a specialized nuclear medicine imaging procedure used to detect vesicoureteral reflux (VUR)—a condition in which urine flows backward from the bladder into the ureters and sometimes up to the kidneys. This condition is especially common in infants and children and is a major cause of recurrent urinary tract infections (UTIs) and kidney damage in the pediatric population. The DRCG scan is a sensitive, accurate, and low-radiation test that provides real-time functional imaging of the bladder and ureters during urination. It is considered one of the best tools for monitoring reflux and evaluating the effectiveness of medical or surgical treatment.

What is Vesicoureteral Reflux (VUR)?

Vesicoureteral reflux (VUR) is a urological disorder where urine travels in the wrong direction—from the bladder up toward one or both ureters and sometimes into the kidneys. Normally, the urine should flow only one way—from the kidneys to the bladder—but in VUR, the valve mechanism fails, allowing reverse flow. Over time, this abnormal flow of urine can lead to kidney infections, renal scarring, hydronephrosis, and even permanent kidney damage if left undiagnosed and untreated. Diagnosing VUR early is critical, especially in children, to preserve long-term kidney function.

What is a DRCG Scan?

Direct Radionuclide Cystoureterography (DRCG) is a dynamic imaging study that evaluates the presence and severity of urinary reflux. It involves instilling a radiotracer-labeled fluid directly into the bladder via a catheter and capturing images with a gamma camera as the bladder fills and the patient voids (urinates).

This test offers high sensitivity in detecting even low-grade reflux episodes that may not be visible with conventional radiologic studies, such as voiding cystourethrography (VCUG). Importantly, the DRCG scan uses significantly lower radiation, making it ideal for repeated follow-up assessments, especially in children.

Why is a DRC Scan Performed?

The main objective of the DRCG scan is to diagnose or monitor VUR in patients with urinary tract symptoms, especially in the pediatric group. It also plays a pivotal role in guiding treatment decisions and assessing the success of anti-reflux surgery or medical management.

Common Indications for DRCG Scan:

• Evaluation of vesicoureteral reflux (VUR)
• Recurrent urinary tract infections (UTIs) in infants or children
• Follow-up after reflux treatment (surgical or non-surgical)
• Postnatal assessment in children with antenatally detected hydronephrosis
• Screening of siblings or children of patients with known VUR
• Unexplained kidney scarring or abnormal ultrasound findings
• Evaluation of bladder dysfunction associated with reflux

How is the DRCG Scan Performed?

The DRC scan is generally performed in a nuclear medicine department under the supervision of a nuclear medicine physician and trained technologists. The scan is non-invasive except for the catheter insertion, which may cause minor discomfort.

Step-by-Step Procedure:

1. Patient Preparation
   • No fasting is needed
   • The procedure is explained in detail to the parent/patient
   • Written consent is taken, especially in pediatric cases
   • In younger children, mild sedation may be considered if required
2. Catheterization and Radiotracer Instillation
   • A soft urinary catheter is gently inserted into the bladder
   • The bladder is filled slowly with a sterile solution containing a small amount of radioactive tracer (commonly 99mTc-DTPA or 99mTc-sulfur colloid)
3. Image Acquisition
   • Dynamic imaging is performed with a gamma camera while the bladder is filling
   • The camera continues to record during voiding (urination) to assess for reflux
   • The process takes around 30 to 60 minutes, depending on the bladder filling and cooperation
4. Post-Test Care
   • The catheter is removed after the test
   • The patient is observed for any discomfort or urinary complaints
   • Normal activities can be resumed immediately afterward

What Does the DRCG Scan Show?

The DRC scan provides detailed functional images that help in detecting:

• Presence or absence of VUR
• Laterality (unilateral or bilateral reflux)
• Grade of reflux (though not numerically graded like in VCUG, severity can be inferred)
• Bladder dynamics during filling and voiding
• Early or delayed reflux during different phases of the scan
• Changes in reflux pattern after treatment

Who Should Avoid the Test?

While the DRCG scan is very safe, some conditions may warrant caution:

• Patients with active urinary tract infections should be treated first
• Children with severe urethral strictures or obstructions
• Patients with known allergic reactions to radiotracers (very rare)
• Pregnant women should avoid this test

Benefits of the DRC Scan

• High sensitivity in detecting low-volume reflux
• Minimal radiation, ideal for children and follow-up
• Provides real-time assessment of bladder and ureter function
• Safe, well-tolerated, and simple to perform
• Allows monitoring of treatment outcomes
• Suitable for large-scale pediatric screening in at-risk families

Conclusion

Direct Radionuclide Cystoureterography (DRCG scan) is a safe, sensitive, and low-radiation diagnostic procedure that plays an essential role in identifying vesicoureteral reflux (VUR). It offers superior sensitivity in detecting even subtle reflux episodes and is considered the test of choice for follow-up evaluations in children with recurrent UTIs or previously diagnosed VUR. By using functional imaging of urine flow during bladder filling and voiding, DRCG scans help clinicians make informed decisions regarding medical therapy, surgical interventions, and long-term monitoring. Its non-invasive nature, quick execution, and reliability make it a valuable tool in both pediatric and adult urological diagnostics.