A voiding trial (TOV) is a medical assessment to determine a person’s ability to urinate effectively. Performed in a controlled clinical setting, it evaluates whether the bladder can adequately empty itself without assistance, especially after medical interventions or conditions affecting normal bladder function.
Understanding a Voiding Trial
Its main purpose is to confirm the bladder’s functional recovery, often after a period with a urinary catheter. The trial ensures an individual can confidently manage bladder emptying independently before a catheter is permanently removed. This assessment is common following surgical procedures, particularly those involving the urinary tract or pelvic region. It is also used when a catheter has been removed, or when evaluating urinary retention where the bladder struggles to empty. The trial helps healthcare providers understand the bladder’s ability to regain normal function and prevent complications like urinary tract infections or discomfort.
Preparing for a Voiding Trial
Preparation ensures the bladder is ready for evaluation. Patients are encouraged to maintain adequate hydration by drinking fluids, often 500-1000 mL over a few hours before the trial, or 200 mL per hour. This fluid intake helps fill the bladder to a sufficient volume for a realistic assessment.
Monitoring urine output before the trial provides valuable information about baseline bladder activity. A full bladder, generally 200-400 mL or when the individual feels a strong urge to void, is important for the trial to begin. A bladder scan may be performed beforehand to measure initial bladder volume and confirm adequate distension. A comfortable and private environment also supports a more accurate and relaxed voiding attempt.
Steps for Performing a Voiding Trial
Initially, if a catheter is in place, it is removed after the bladder fills to an appropriate volume, sometimes after being backfilled with saline (e.g., 300 mL). The initial urine volume at catheter removal may also be measured. Once the catheter is out, the individual attempts to urinate into a collection device when they feel the urge. The voided urine volume is measured and recorded.
Immediately following this void, a post-void residual (PVR) volume is measured, typically within 10-15 minutes, using a bladder scanner or by re-inserting a catheter. This PVR measurement indicates the amount of urine remaining in the bladder after voiding.
For a successful voiding trial, specific criteria must be met. A voided volume of at least 200 mL is expected. The post-void residual volume should be low, typically less than 100-150 mL. Some protocols consider a PVR of less than 100 mL as a clear success, while others may allow up to 150 mL. If the voided volume is between 100-199 mL, a PVR is recommended to further assess bladder emptying.
Interpreting Results and Next Steps
Interpreting voiding trial results determines the next course of action for bladder management. A successful trial, characterized by adequate voided volume and low post-void residual urine, indicates effective bladder emptying. This outcome generally means the individual can manage their bladder independently without a catheter.
Conversely, an unsuccessful trial suggests the bladder is not emptying sufficiently, indicating continued urinary retention. This can occur if the individual cannot void, voids only small amounts, or has a high post-void residual volume (sometimes exceeding 150-200 mL). In such cases, common next steps often involve re-catheterization to prevent discomfort and potential complications, or teaching self-catheterization techniques.
Further evaluation by a healthcare provider may be necessary to identify underlying causes of bladder dysfunction and determine a long-term management plan. All findings are documented to guide ongoing care.