Retrograde Urethrogram is the Most Appropriate Investigation
In a patient with pelvic trauma, open book fracture, and blood at the urethral meatus, retrograde urethrography (RUG) must be performed before any urethral catheterization to evaluate urethral integrity and prevent catastrophic complications. 1, 2
Clinical Rationale
Blood at the urethral meatus is a critical indicator of urethral injury that mandates immediate investigation before catheter placement. 1, 3 The presence of an unstable "open book" pelvic fracture significantly increases the risk of posterior urethral disruption, as these injuries are associated with urethral damage in 7-25% of cases. 1, 2
Why Retrograde Urethrogram is Essential
RUG is the gold standard for diagnosing urethral injuries in hemodynamically stable patients with suspected urethral trauma, as recommended by ATLS guidelines and the World Health Organization. 1
Blood at the meatus is an absolute indication for RUG before attempting any urethral catheterization, as blind catheter insertion can cause complete urethral transection, stricture formation, impotence, and urinary incontinence. 1, 4, 3
The procedure involves instilling contrast medium into the urethra under fluoroscopy, which will demonstrate either complete disruption (no bladder filling) or partial injury (bladder fills with extravasation). 5
Critical Pitfall to Avoid
Never attempt urethral catheterization without prior RUG when blood is present at the meatus. 1, 4, 3 Approximately 23% of urethral injuries are missed at initial evaluation, and blind catheterization increases morbidity and can delay definitive reconstruction. 1, 2
Why Other Options Are Inappropriate
CT scan of the pelvis (Option C) is valuable for evaluating pelvic fractures and hematoma but has limitations in detecting urethral injuries. While CT can identify bladder injuries, it does not adequately visualize the urethra without specific retrograde contrast opacification. 1 Performing RUG before CT may actually increase false-negative rates on subsequent CT scans. 1
Intravenous pyelogram (Option B) has extremely low accuracy (15-25%) for urethral and bladder injuries and is not recommended in modern trauma management. 1
MRI of the pelvis (Option D) may be useful for preoperative planning in stable patients but is inappropriate for acute trauma evaluation due to time constraints and limited availability. 1
Proper Diagnostic Sequence
First, perform digital rectal examination to assess for high-riding or non-palpable prostate, which indicates urethral disruption with superior displacement. 4
Second, obtain retrograde urethrogram using a urethral catheter inserted into the anterior urethra with the cuff inflated to 1-2 mL, instilling up to 350 mL of contrast under fluoroscopic guidance. 1, 5
Third, if urethral injury is confirmed, establish urinary drainage via suprapubic catheter rather than urethral catheterization. 1, 2
Finally, once hemodynamically stable, CT scan with delayed excretion phase can evaluate for associated bladder and ureteral injuries. 1
Management After RUG
If RUG confirms urethral injury, suprapubic catheter placement with delayed cystogram is recommended. 1 In hemodynamically unstable patients, all urethral investigations should be postponed and a suprapubic catheter placed immediately. 5
Answer: A - Retrograde urethrogram