RGU Test for Urethral Stricture
RGU (retrograde urethrogram, also called retrograde urethrography or RUG) is an X-ray test that outlines the male urethra with contrast dye. It is one of the key tests for urethral stricture because it shows where the narrowing is and gives an estimate of its length. The test is especially useful before reconstructive surgery. It does not usually require general anaesthesia. Mild discomfort is common, and a very tight or nearly obliterated stricture may need RGU combined with MCU/VCUG to show the urethra on both sides of the narrowing.
What is an RGU test?
During RGU, contrast is gently introduced into the urethral opening while X-ray images are taken. The dye travels backward through the urethra and outlines the lumen. A stricture appears as a narrowed segment or a point where contrast cannot pass freely.
Why is RGU done for urethral stricture?
- To confirm the presence of a urethral narrowing.
- To identify whether the stricture is meatal, penile, bulbar or more proximal.
- To estimate stricture length before urethroplasty.
- To identify false passages, diverticula or other associated abnormalities.
- To assess a recurrent stricture after previous VIU or urethroplasty.
- To help plan pelvic fracture urethral reconstruction when combined with MCU/VCUG.
How should you prepare?
Most patients do not need fasting or anaesthesia for a routine RGU. Tell the team if you have fever, active UTI symptoms, a known contrast allergy or are taking medicines that may affect a planned procedure. If the test is being combined with another study, follow the specific instructions given by the radiology/urology unit.
How is the test performed?
You lie on the X-ray table, usually with the pelvis positioned slightly obliquely so the urethra can be seen clearly. The urethral opening is cleaned. A small device or catheter tip is used at the meatus to seal the opening, and contrast is injected gently while fluoroscopic or still X-ray images are taken. The test usually takes only a short time.
Does RGU hurt?
Most patients describe brief pressure or burning rather than severe pain. Discomfort can be greater when the meatus is very narrow or the urethra is inflamed. Forceful injection should be avoided. Modern urethrographic clamp devices can reduce discomfort compared with some catheter-based techniques.
What does the RGU report usually describe?
| Report term | Meaning |
|---|---|
| Site | Where the narrowing is located: distal, penile, bulbar or posterior. |
| Length | Approximate distance over which the lumen is narrowed. |
| Calibre / severity | How narrow the urethral lumen appears. |
| Near-obliterative / obliterative | Very little or no contrast passes through the scar. |
| False passage | An abnormal tract caused by previous trauma/instrumentation. |
| Diverticulum | A pouch-like outgrowth from the urethra. |
Can RGU underestimate stricture length?
Yes. RGU is a two-dimensional test and may underestimate the length of scar, particularly when the stricture is very tight or the urethra is not adequately stretched. The surgeon interprets the film together with examination, history and sometimes cystoscopy or sonourethrography. The final operative scar can therefore be longer than the number written in the report.
Why is RGU sometimes combined with MCU / VCUG?
If contrast cannot pass through a nearly obliterated stricture, RGU cannot show the urethra above it. MCU/VCUG fills the bladder and images the urethra while the patient passes urine. The two studies together can outline both ends of a tight stricture or the gap after pelvic fracture.
What are the risks?
- Temporary burning or mild urethral discomfort.
- Small amount of bleeding from the meatus.
- Urinary infection, which is uncommon but possible.
- Rare contrast intravasation or allergic reaction.
- Radiation exposure, although the study uses a limited field and short imaging time.
What happens after an abnormal RGU?
The image does not automatically decide the operation. A short primary bulbar stricture may be suitable for VIU in selected patients; penile, long, recurrent or complex disease is more likely to need urethroplasty. Pelvic fracture injury, lichen sclerosus and failed hypospadias require additional reconstructive considerations.
Urgent warning signs after the test
Seek medical advice if you develop fever, inability to pass urine, increasing bleeding, severe pain or worsening swelling after the test.
What to bring for consultation after RGU
- The actual RGU images/film or digital study, not only the written report.
- Any MCU/VCUG images done at the same time.
- Uroflowmetry and post-void residual.
- Urine routine/culture.
- Previous urethral surgery or catheter records.
What an RGU can and cannot tell you
RGU is best thought of as an anatomical road map of the anterior urethra. It can show the site, approximate length and calibre of a stricture and can demonstrate multiple segments, false passages or contrast extravasation. These details are often more useful for reconstructive planning than the written phrase “urethral stricture present.”
There are limitations. A very tight or completely obliterated segment may prevent contrast from defining the proximal urethra, and the apparent length can change with penile stretch and technique. Posterior anatomy is often better assessed by combining RGU with MCU/VCUG, particularly when a suprapubic catheter is present after pelvic trauma. RGU also does not measure bladder contractility or prove that every urinary symptom comes from the narrowing.
For this reason, the most useful study is the actual image series reviewed together with symptoms, uroflow/PVR and, when appropriate, cystoscopy. Patients planning reconstruction should try to bring the films or digital images rather than only the radiology report.
FAQs
Is RGU the same as cystoscopy?
No. RGU is an X-ray outline of the urethra and is good for mapping length. Cystoscopy looks directly inside the urethra and bladder but may not pass through a tight stricture.
Can RGU show the entire urethra?
It usually shows the anterior urethra well. A very tight or posterior narrowing may require MCU/VCUG or antegrade assessment for the proximal segment.
Does an RGU require a catheter into the bladder?
A routine retrograde study generally does not require a bladder catheter; contrast is introduced from the urethral opening. The exact technique varies by unit.
Is the written stricture length exact?
No. It is an estimate from a two-dimensional image. Operative findings and tissue fibrosis ultimately determine the reconstruction.
Can RGU be repeated after urethroplasty?
Yes. Urethrography is also used to check for urine leakage before catheter removal and to assess suspected recurrence in follow-up.
Related reading
- MCU Test for Urethral Stricture
- Uroflowmetry in Urethral Stricture
- Cystoscopy in Urethral Stricture
- Urethral Stricture: Symptoms, Causes and Treatment
- Urethroplasty Surgery Explained
- Urologist in Latur
References
- European Association of Urology. EAU Guidelines on Urethral Strictures: Diagnostic Evaluation, 2026 https://uroweb.org/guidelines/urethral-strictures/chapter/diagnostic-evaluation
- European Association of Urology. EAU Guidelines on Urethral Strictures, 2026 https://uroweb.org/guidelines/urethral-strictures
- European Association of Urology. EAU Guidelines on Urological Trauma, 2026 https://uroweb.org/guidelines/urological-trauma
- American Urological Association. Urethral Stricture Guideline (2023 amendment) https://www.auanet.org/guidelines-and-quality/guidelines/urethral-stricture-guideline