Retrograde Urethrogram (RUG) & Voiding Cystourethrogram (VCUG)
At a glance
RUG maps the anterior urethral lumen; VCUG adds the voiding outlet and proximal segment. Use them together when a tight or obliterative lesion prevents reliable definition of its proximal extent. Cystoscopy, sonourethrography and selected MRI answer additional questions.[1][2]
- Do not add a fixed centimeter to each stricture shoulder. Magnification, positioning, distension and scar outside the lumen affect measurements; RUG does not determine the final graft or excision length.[1][3]
- Separate a pre-catheter-removal leak assessment from long-term recurrence surveillance. Neither is a universal “three-month RUG for everyone.”[4][5]
- A silhouette is not a pressure study. A VCUG alone cannot diagnose detrusor-sphincter dyssynergia or measure storage pressure; video-urodynamics supplies the functional context when indicated.[6]
1. Choose the Study
| Question | Useful approach | What may remain unresolved |
|---|---|---|
| Male anterior stricture before reconstruction | RUG; endoscopy as needed | Periurethral fibrosis, very distal narrowing or a non-opacified proximal segment.[1] |
| Near-obliteration or delayed PFUI planning | Combined RUG and VCUG; consider antegrade/retrograde endoscopy | A closed bladder neck may hide the proximal stump; apparent gap length can be misleading.[1][2] |
| Bladder neck or vesicourethral anastomotic stenosis | Endoscopy with appropriate contrast imaging | Post-prostatectomy VUAS is anatomically distinct from native bladder-neck stenosis.[2] |
| Female obstructive voiding symptoms | Flow/PVR, examination, cystoscopy and VCUG or video-urodynamics according to the question | Functional obstruction and other causes can mimic a fixed narrowing.[7] |
| Suspected vesicoureteral reflux | VCUG when indicated | Grade describes anatomy; it does not alone dictate antibiotics or surgery.[8] |
| Suspected postoperative extravasation | Pericatheter RUG, RUG or VCUG matched to repair and catheter plan | The significance of a small leak depends on its extent and clinical setting.[4] |
2. Preparation and Technique
Before imaging
Confirm the indication, previous reconstruction, recent instrumentation, catheter route, symptoms suggesting infection and prior contrast reactions. Explain discomfort and the possibility of an incomplete study. Choose an atraumatic seal and a local radiology protocol appropriate to the anatomy; do not force a large catheter through a distal narrowing merely to obtain an image.[1][9]
Contrast is water-soluble iodinated material. Agent concentration, dilution and volume vary with the equipment and patient. A single 50:50 dilution or 16–18 Fr catheter is not a universally required protocol. Iohexol is a low-osmolality nonionic agent, not an iso-osmolar agent.[10][11]
RUG: practical sequence
- Position obliquely and gently extend the penis to separate overlapping segments. Published protocols commonly use approximately 30–45°; confirm the resulting anatomy rather than treating one angle as sufficient in every patient.[10]
- Prepare the meatus and use a suitable catheter-tip adapter or clamp seal. Minimize balloon manipulation in the fossa navicularis. A small randomized comparison found better tolerance with a clamp method, but device choice still depends on local expertise and anatomy.[9]
- Introduce contrast gently while observing filling. Stop and reassess pain, resistance, extravasation or intravasation; do not increase force to prove luminal continuity.[1][9]
- Save images that include the relevant distal and proximal margins and document segments that could not be assessed. Obtain complementary imaging rather than labeling an unfilled segment normal.[1][2]
Use collimation and the lowest practical fluoroscopic exposure consistent with a diagnostic study. Actual dose depends on technique and equipment; the site does not prescribe a universal frame rate or a guaranteed percentage dose reduction. See radiation safety.
VCUG and a suprapubic catheter
Fill the bladder through an appropriate established route according to capacity, symptoms and the examination protocol; a fixed adult volume is inappropriate for every child, contracted bladder or recent repair. Acquire the outlet during actual voiding where possible and document failure to void. A suprapubic route can provide access when a urethral lesion cannot be traversed.[2][9]
For delayed PFUI assessment, combine proximal filling/voiding information with retrograde imaging. A poorly opening bladder neck or inadequately visualized proximal urethra can exaggerate the gap. Antegrade cystoscopy may identify the proximal lumen and associated pathology when the contrast study is incomplete.[1][2]
3. Interpretation and Reporting
| Report element | Include | Avoid inferring |
|---|---|---|
| Location | Meatal/fossa, penile, bulbar, bulbomembranous or other postoperative segment | Etiology solely from its location. |
| Length and multiplicity | Each narrowing, intervening segment, calibration/magnification limitations | A fixed “true length” correction or predetermined graft length. |
| Lumen and proximal extent | Narrowing, passage/nonpassage of contrast, what was not visualized | Complete obliteration merely because a technically limited study did not fill. |
| Additional findings | False passage, fistula, diverticulum, extravasation and bladder findings | Tissue viability or depth of spongiofibrosis from luminal contour alone. |
| Comparison | Prior anatomy, interval instrumentation and repair | A new treatment indication from a small imaging change without clinical context. |
These are practical reporting prompts synthesized from the diagnostic pathway and prospective imaging comparison; they are not a validated score.[2][3]
Apparent sphincter-level narrowing during retrograde filling can be physiological. Persistent or clinically concerning narrowing warrants correlation with voiding images and/or endoscopy. Neither a universal French-size cutoff nor the statement “membranous narrowing is almost always normal” safely resolves that distinction.[2]
Sonourethrography can characterize the anterior periurethral tissues, and MRI can help in selected posterior or complex cases. A prospective comparison in 55 men found modality-dependent agreement with operative length; that evidence does not support treating one fixed correction factor as applicable to every study.[3]
4. Pelvic Fracture Urethral Injury
Acute assessment differs from elective gap mapping. Resuscitate and manage associated injuries first. AUA recommends RUG for blood at the meatus after pelvic trauma; CT findings alone cannot classify every urethral injury. Establish urinary drainage through the appropriate pathway without repeated blind attempts.[12]
During delayed reconstruction planning, assess the proximal/distal segments, bladder neck, fistulae, false passages and prior procedures. Gap length is one input; it does not independently mandate inferior pubectomy, a transpubic approach or staging. Surgical access also depends on displacement, scar, tissue mobility and associated injury.[1][2]
A non-funneling bladder neck on one incomplete voiding study is not proof of stenosis or incompetence. If bladder-neck integrity will change reconstruction or continence counseling, resolve the uncertainty with additional assessment.[2]
5. Female Urethral Assessment
Female urethral stricture is a fixed anatomic narrowing evaluated in the context of symptoms and examination. Published caliber definitions vary; a VCUG “wine-glass sign” is not a stand-alone pathognomonic criterion. VCUG/video-urodynamics can demonstrate outlet obstruction, but catheterization itself may be difficult and other causes of poor emptying must be considered.[7]
Use MRI when a diverticulum, mass or other complex periurethral lesion is suspected. Do not equate a short-urethra imaging artifact with an indication for dilation or reconstruction. See MRI and female urethral stricture.
6. Vesicoureteral Reflux
VCUG describes the extent of reflux and ureteral/collecting-system dilatation. Low grades have less upper-tract dilatation; grades IV–V describe more substantial distortion. Use the formal International Reflux Study grading definitions when reporting rather than combining a grade with an automatic treatment order.[8]
Grade V is not, by itself, an instruction for urgent surgery, and grade I is not a guarantee of zero renal risk. Age, febrile breakthrough infection, renal parenchymal status, bladder/bowel dysfunction, persistence and family preferences influence pediatric management. Adult secondary reflux needs assessment of the underlying outlet or bladder disorder; do not transplant a pediatric primary-reflux algorithm unchanged.[8][6]
7. After Urethroplasty
Before catheter removal
Assess for meaningful extravasation using the technique appropriate to the repair. EAU describes RUG, pericatheter RUG and VCUG as options. Persistent substantial leakage usually leads to continued drainage and repeat assessment; minor findings need interpretation by the operating team rather than a universal rule.[4]
Recurrence surveillance
Follow symptoms, patient-reported outcomes, flow and residual urine, with anatomical assessment matched to recurrence risk and the postoperative protocol. EAU offers risk-adapted schedules and an early anatomical assessment; it does not require a fluoroscopic RUG as the only test for every patient at three months.[5]
A Qmax threshold of 10 or 15 mL/s alone neither proves nor excludes recurrence. Voided volume, detrusor function, age and the patient's own postoperative baseline matter. Similarly, PVR is not a stand-alone recurrence diagnosis. Not every asymptomatic anatomic narrowing requires treatment.[5]
Keep treatment selection on the urethral reconstruction atlas, rather than converting radiographic caliber into an automatic DVIU or urethroplasty decision.
References
1. EAU. Urethral Strictures: diagnostic evaluation. 2026. Guideline. Accessed September 11, 2026.
2. AUA. Urethral Stricture Disease Guideline, amended 2023. Guideline. Amendment.
3. Retrograde urethrography, sonouretrography and magnetic resonance urethrography in evaluation of male urethral strictures. Should the novel methods become the new standard in radiological diagnosis of urethral stricture disease? 2021. Prospective study, 55 men. Full study.
4. EAU. Urethral Strictures: perioperative care of urethral surgery. 2026. Guideline. Accessed September 11, 2026.
5. EAU. Urethral Strictures: follow-up. 2026. Guideline. Accessed September 11, 2026.
6. EAU. Neuro-urology: diagnostic evaluation and urodynamics. 2026. Guideline. Accessed September 11, 2026.
7. EAU. Urethral Strictures: disease management in females. 2026. Guideline. Accessed September 11, 2026.
8. EAU. Paediatric Urology: vesicoureteric reflux. 2026. Guideline. Accessed September 11, 2026.
9. Berná-Mestre JD, Berná-Serna JD, Aparicio MD. Urethrography in men: conventional technique versus clamp method. Radiology. 2009;252:240–246. doi:10.1148/radiol.2522082064. PubMed.
10. An innovative method for occluding the urethral meatus and accessing urethra strictures in retrograde urethrography in males. 2023. Primary technical study. Its specific device is not presented here as a standard of care.
11. ACR. Manual on Contrast Media. 2026. Manual. Accessed September 11, 2026.
12. AUA. Urotrauma guideline, amended 2020. Guideline PDF. Accessed September 11, 2026.