What is the approach for a trial of void in patients with urinary retention?

Trial of Void Protocol for Patients with Urinary Retention

For patients with urinary retention, a trial of void should be attempted after catheter removal, with concomitant alpha blocker administration (such as tamsulosin 0.4mg daily) to improve success rates, followed by post-void residual measurement to determine if the trial was successful. 1

Preparation for Trial of Void

• Alpha blocker administration: Start a non-titratable alpha blocker (tamsulosin 0.4mg or alfuzosin) prior to catheter removal to improve chances of successful voiding 1

  • Alpha blockers have been shown to significantly improve AUA symptom scores and peak urine flow rates compared to placebo 2
  • Exception: Avoid in patients with prior alpha blocker side effects or unstable medical comorbidities (orthostatic hypotension, cerebrovascular disease) 1

• Timing of catheter removal: Remove catheter after a period of bladder drainage (typically 3-7 days for acute retention) 3

  • For post-surgical patients, consider removing the catheter at six hours postoperatively 4

Trial of Void Procedure

Two Main Techniques:

1. Back Fill Method (Preferred):

   • Fill bladder with 300cc of sterile saline before catheter removal 5
   • Better predictor of adequate bladder emptying (κ = 0.91) compared to auto fill method 5

2. Auto Fill Method:

   • Remove catheter and allow bladder to fill naturally through normal fluid intake 5
   • Less reliable predictor (κ = 0.56) than back fill method 5

Assessment Protocol:

1. Instruct patient to void when they feel the urge
2. Measure voided volume
3. Perform post-void residual (PVR) measurement within 15 minutes of voiding using:
   • Bladder ultrasound (non-invasive) 4
   • Straight catheterization (more invasive but definitive) 5

Interpretation of Results

• Successful trial: Patient voids at least two-thirds of total bladder volume (voided volume + PVR) 5
• Failed trial: PVR >150-200mL indicates significant retention 4, 3
  • Patients with baseline PVR >200mL are at significantly higher risk (40% vs 10.9%) of failing trial of void 3

Management Based on Trial Results

Successful Trial:

• Discontinue catheter
• Schedule follow-up to ensure continued successful voiding
• Consider continuing alpha blocker therapy if retention was related to BPH 1, 2

Failed Trial:

1. Replace catheter (urethral or consider suprapubic for longer-term management) 6
2. Evaluate for underlying cause of retention:
   • Urodynamic studies may be indicated for persistent retention 1
   • Cystoscopy if anatomical obstruction is suspected 1
3. Plan for next attempt:
   • Continue alpha blocker therapy 1
   • Consider longer duration of catheterization (additional 7-14 days) 3
   • For patients with neurogenic causes, teach clean intermittent self-catheterization 6

Special Considerations

• BPH patients: Higher success rates with alpha blockers started at time of catheterization 1, 2
• Post-surgical patients: Implement standardized protocol with bladder scan after first void and limit re-catheterization to PVR >150mL 4
• Risk factors for failed trial: Advanced age, medications with anticholinergic properties, preexisting urinary dysfunction, high baseline PVR 4, 3
• Detrusor underactivity: May require double voiding technique (several toilet visits in close succession) 1

Follow-up After Successful Trial

• Monitor for symptoms of incomplete emptying or recurrent retention
• Measure PVR if symptoms recur
• Consider definitive treatment of underlying cause (e.g., surgery for BPH if medical therapy fails) 1

Complications to Monitor

• Urinary tract infection (higher risk in patients with failed trial of void - 20% vs 4.7%) 3
• Bladder overdistension and detrusor damage with prolonged retention 7
• Renal insufficiency in severe cases of chronic retention 1