What is the recommended protocol for a voiding trial?

Voiding Trial Protocol

For postoperative voiding trials, use the backfill technique: instill 300 mL of normal saline into the bladder via catheter, remove the catheter, have the patient void immediately, and measure post-void residual (PVR) to determine success.

Backfill Technique (Preferred Method)

The backfill method is superior to spontaneous bladder filling for predicting successful voiding after surgery 1.

Step-by-step protocol:

• Fill the bladder with 300 mL normal saline through the indwelling catheter (or until patient reports urgency to void) 2
• Remove the catheter 2
• Prompt the patient to void immediately 2
• Measure PVR either by bladder ultrasound or catheterization 2

Determining Success Without Measuring PVR

An efficient algorithm eliminates the need for PVR measurement in 85% of cases 2:

• Voided volume ≥200 mL: Trial is successful, no PVR needed (97% pass rate) 2
• Voided volume 100-199 mL: Indeterminate result, measure PVR to determine success 2
• Voided volume <100 mL: Trial has failed, recatheterization needed (96.7% failure rate) 2

When PVR measurement is required, success is defined as voiding two-thirds or greater of total bladder volume (voided volume plus PVR) 1.

Special Considerations for BPH-Related Retention

For acute urinary retention related to benign prostatic hyperplasia, administer at least 3 days of alpha-blocker therapy before attempting the voiding trial 3.

• Use non-titratable alpha-blockers for this indication 3
• Voiding trials are more likely to succeed when retention was precipitated by temporary factors such as anesthesia or postoperative pain 3
• Do not abandon alpha-blocker therapy prematurely 3

Timing and Patient Selection

Assessment of urinary voiding should be done on a case-by-case basis for selected patients or procedures during emergence and recovery 4.

For patients with neurogenic lower urinary tract dysfunction who spontaneously void, perform PVR measurement at initial evaluation and periodically thereafter to monitor changes in bladder emptying 4.

Management After Failed Voiding Trial

If the voiding trial fails:

• For surgical candidates with refractory retention, proceed to surgical intervention 3
• For non-surgical candidates, options include intermittent catheterization, indwelling urethral catheter, or urethral/prostatic stent placement 3
• Reassess for reversible factors and ensure adequate medical therapy before declaring treatment failure 3

Critical Follow-Up

Patients who pass a successful voiding trial remain at increased risk for recurrent retention 3.

• Close follow-up is essential even after successful catheter removal 3
• Many patients experience subsequent retention days to months later 3
• Counsel all patients about recurrence risk before discharge 3

Common Pitfalls to Avoid

• The backfill technique correlates better with successful voiding (κ = 0.91) compared to spontaneous filling (κ = 0.56) 1
• Do not use the auto-fill method as it is a poor predictor of adequate postoperative bladder emptying 1
• Ensure adequate alpha-blocker therapy duration (minimum 3 days) before attempting catheter removal in BPH-related retention 3