What evaluation and management options are recommended for a patient with urinary difficulty and a history of above-knee amputation injury?

Evaluation and Management of Urinary Difficulty in a Patient with Above-Knee Amputation

For a patient with urinary difficulty and a history of above-knee amputation injury, retrograde urethrography should be performed to rule out urethral injury before attempting catheterization, followed by appropriate urinary drainage establishment based on findings. 1

Initial Assessment

• Inspect the external urethral meatus for visible abnormalities, including swelling, ecchymosis, discharge, blood, stenosis, or anatomical variations 2
• The presence of blood at the urethral meatus is a critical indicator of potential urethral injury and requires immediate retrograde urethrography 2, 1
• Avoid blind catheterization before imaging in trauma cases, as this may worsen urethral injuries 2, 1
• For patients with pelvic fractures and blood at the meatus, always evaluate for urethral injury before bladder catheterization 2, 1

Diagnostic Approach

• Retrograde urethrography is the first-line diagnostic test for patients with suspected urethral injury, especially those with blood at the urethral meatus after trauma 1

• Proper technique for retrograde urethrogram:

  • Position the patient obliquely with bottom leg flexed at the knee and top leg kept straight
  • If severe pelvic or spine fractures are present, leave the patient supine
  • Introduce a 12Fr Foley catheter or catheter-tipped syringe into the fossa navicularis
  • Place the penis on gentle traction and inject 20 mL undiluted water-soluble contrast material 1

• If a Foley catheter has already been placed, perform a pericatheter retrograde urethrogram to identify potential missed urethral injury 1

• For suspected bladder injury, cystography (conventional radiography or CT-scan) represents the diagnostic procedure of choice 1

Management Options

Urethral Injury Management

• If urethral injury is identified, establish prompt urinary drainage 1
• Options for urinary drainage include:
  • Suprapubic cystostomy (SPT) - may be placed percutaneously or via open technique depending on clinical setting 1
  • Urethral catheter - only if safe passage is possible 1
• Avoid repeated attempts at placing a urethral catheter given the likelihood of increasing injury extent 1, 2

Bladder Management

• For bladder contusions, no specific treatment is required beyond observation 1
• For intraperitoneal bladder rupture, surgical exploration and primary repair is indicated 1
• For uncomplicated extraperitoneal bladder injuries, non-operative management with urinary drainage via urethral or suprapubic catheter is appropriate 1
• Complex extraperitoneal bladder ruptures (bladder neck injuries, lesions associated with pelvic ring fracture) should be explored and repaired 1

Urinary Retention Management

• For patients with urinary retention without urethral injury:
  • Alpha-blockers like tamsulosin (0.4 mg daily) can improve urinary symptoms by relaxing smooth muscle in the prostate and bladder neck 3
  • Finasteride (5 mg daily) may be beneficial for patients with enlarged prostates, showing improvement in symptoms and maximum urinary flow rate 4

Special Considerations for Patients with Above-Knee Amputation

• Patients with above-knee amputations have higher rates of urinary tract complications (13%) compared to the general population 5
• Pressure sores (8%) are also common complications in these patients, which may affect positioning for urological procedures 5
• Consider the functional status of the patient, as those living at home preoperatively and on statin therapy are more likely to maintain independent ambulation despite amputation 6
• Comorbidities such as coronary disease, dialysis, and congestive heart failure identify patients less likely to achieve good functional outcomes 6

Follow-up Recommendations

• For patients with urethral injuries, urethroscopy or urethrogram are the methods of choice for follow-up 1
• For bladder injuries, CT scan with delayed phase imaging is recommended for follow-up 1
• Monitor for post-procedure complications, particularly urinary tract infections, which occur at higher rates in amputation patients 5
• Consider the impact of urinary catheterization on mobility and rehabilitation, as early mobilization is crucial for amputation patients 7

Potential Pitfalls and Complications

• Avoid blind catheterization in suspected urethral trauma cases, as this may worsen injuries 2, 1
• Be aware that patients with above-knee amputations have higher mortality rates (18% hospital mortality) compared to below-knee amputations (9%) 5
• Consider the impact of urinary procedures on rehabilitation potential, as functional outcomes are directly related to the extent of amputation 6
• Monitor for pressure sores, which are common complications in amputation patients and may be exacerbated by limited mobility during urological management 5