What is the likelihood of a bladder injury from the assault, given the presence of hematuria?

Likelihood of Bladder Injury from Assault with Hematuria

The presence of hematuria following an assault indicates a significant possibility of bladder injury, with approximately 30% of patients presenting with both pelvic fracture and hematuria having bladder injury. 1

Mechanism and Risk Assessment

Bladder injuries typically occur through two main mechanisms:

• Blunt trauma (65-86% of cases)
• Penetrating trauma (14-35% of cases) 1

The likelihood of bladder injury depends on several key factors:

1. Type of hematuria:

   • Gross hematuria is highly predictive of bladder injury with 100% sensitivity and 98.5% specificity 2
   • Microscopic hematuria alone has poor predictive value for significant bladder injury 2

2. Associated injuries:

   • Pelvic fractures significantly increase risk (60-90% of bladder injury patients have pelvic fractures) 1
   • The combination of pelvic fracture and gross hematuria indicates bladder injury in 29% of cases 1

3. Mechanism of assault:

   • High-energy impacts required to damage the bladder 1
   • Penetrating injuries to the pelvis with any hematuria warrant evaluation 1

Types of Bladder Injuries

If a bladder injury is present, it will likely be one of these types:

• Extra-peritoneal bladder rupture (EBR): 60-90% of cases, most common with pelvic fractures
• Intra-peritoneal bladder rupture (IBR): 15-25% of cases
• Combined bladder rupture: 5-12% of cases
• Bladder contusion 1

Diagnostic Approach

For accurate assessment of potential bladder injury:

1. Immediate imaging is indicated if:

   • Gross hematuria is present
   • Pelvic fracture with any hematuria
   • Clinical indicators of bladder rupture (inability to void, low urine output, increased BUN/creatinine, abdominal distention, suprapubic pain) 1

2. Recommended imaging:

   • Retrograde cystography (plain film or CT) is the diagnostic standard
   • CT cystography has comparable accuracy to conventional cystography 3
   • Proper technique requires minimum 300mL of contrast to distend the bladder 1

Clinical Pitfalls to Avoid

1. Do not rely on microscopic hematuria alone to rule out bladder injury - studies show microscopic hematuria is a poor predictor of significant genitourinary tract damage 4

2. Do not use inadequate imaging techniques - simply clamping a Foley catheter to allow excreted IV contrast to accumulate is insufficient and leads to missed injuries 1

3. Do not overlook associated injuries - bladder injuries frequently occur with other pelvic trauma:

   • Prostate-urethral injuries occur in 10-29% of male patients with bladder rupture 1
   • Urethral injuries may coexist and require separate evaluation 1

4. Do not delay surgical repair of intraperitoneal bladder ruptures as this can lead to peritonitis, sepsis and other serious complications 1

In summary, the presence of hematuria following assault warrants careful evaluation for bladder injury, particularly if gross hematuria is present or if there are associated pelvic fractures. The gold standard for diagnosis remains retrograde cystography with adequate bladder distention.