Retrograde Urethrography Technique for Suspected Urethral Injury
Retrograde urethrography (RUG) is the procedure of choice and must be performed before any urethral catheterization attempt when urethral injury is suspected 1, 2.
When to Perform RUG
Perform RUG immediately when any of these clinical signs are present:
- Blood at the urethral meatus
- Perineal or scrotal hematoma
- High-riding or non-palpable prostate on rectal examination
- Inability to void or difficulty passing a catheter
- Unstable pelvic fracture 3, 1
Critical caveat: Blind catheter passage before RUG should be avoided, as this can cause complete urethral transection, stricture formation, impotence, and urinary incontinence 3, 2.
Standard RUG Technique
Patient Positioning
- Oblique position: Bottom leg flexed at knee, top leg straight
- Alternative for severe pelvic/spine fractures: Keep patient supine with penis on gentle traction 2
Procedure Steps
- Insert catheter: Use a 12Fr Foley catheter or catheter-tipped syringe into the fossa navicularis (just inside the urethral opening)
- Apply gentle traction: Place penis on gentle stretch
- Inject contrast: Administer 20 mL of undiluted water-soluble contrast material (e.g., Iohexol 300 mg I/mL)
- Acquire image: Take radiograph during injection under dynamic fluoroscopy 2, 4
Alternative Simplified Bedside Technique
For resource-limited settings or emergency situations:
- Use a 10-mL syringe without needle directly at the urethral orifice
- Inject contrast medium through the urethral meatus
- Take simple pelvic anteroposterior film (70 kVp, 50 mAs) 4
Interpreting Results
Complete urethral disruption: Contrast extravasation without bladder filling
Partial urethral injury: Contrast extravasation with some bladder filling 1
Management Based on RUG Findings
If RUG Shows Urethral Injury:
- Do not attempt urethral catheterization
- Place suprapubic catheter immediately for urinary drainage 3, 1
- Avoid repeated catheterization attempts, which increase injury extent and delay drainage 2
If Hemodynamically Unstable:
- Postpone RUG entirely
- Place suprapubic catheter immediately
- Perform RUG later when patient stabilizes 1
Special Circumstance - Catheter Already Placed:
If a Foley catheter was placed before evaluation and blood is present at meatus:
- Perform pericatheter RUG: Inject contrast through a 3Fr catheter or angiocatheter held in the fossa navicularis alongside the existing catheter to identify missed injury 2
Important Timing Consideration
In hemodynamically stable patients with suspected urethral injury, the optimal sequence is controversial: Performing RUG before CT can increase false-negative CT scans. When hemodynamic status permits, late contrast CT-scan with urologic study is recommended over isolated RUG 3. However, RUG remains essential before any catheterization attempt.
Alternative Diagnostic Modality
Flexible urethroscopy may be used as an alternative to RUG, particularly in:
- Associated penile injuries
- Female patients (due to short urethra)
- Cases where RUG is technically difficult 1