What is the procedure for performing a Trial Without Catheter (TWOC)?

From the Guidelines

To perform a Trial Without Catheter (TWOC), physicians should prescribe an oral alpha blocker, such as alfuzosin or tamsulosin, prior to the procedure, and patients should complete at least three days of medical therapy before attempting TWOC, as this approach has been shown to improve success rates in patients with Acute Urinary Retention (AUR) related to Benign Prostatic Hyperplasia (BPH) 1. When considering TWOC, it is essential to ensure the patient is medically stable and any urinary tract infection has been treated.

• The patient should be started on alpha-blockers like alfuzosin or tamsulosin at least three days before the procedure to relax the prostate and improve success rates, as supported by the AUA guideline 1.
• On the day of TWOC, the catheter should be removed, and the patient should be asked to drink plenty of fluids (about 1.5-2 liters over 4-6 hours) to assess their ability to urinate normally without the catheter.
• The patient should be monitored for successful voiding, measuring post-void residual volume using a bladder scanner or ultrasound, with successful TWOC typically defined as the ability to void with a post-void residual volume less than 150ml.
• If the patient cannot void within 6-8 hours or has a high residual volume, recatheterization is necessary, and multiple attempts at TWOC may be needed for some patients, particularly those with underlying bladder or prostate conditions. The use of alpha-blockers before TWOC has been shown to improve outcomes, with studies demonstrating that men prescribed alfuzosin or tamsulosin had improved AUR signs and symptoms, as measured by TWOC, with pooled results showing successful TWOC with alfuzosin compared to placebo, 60% versus 39% 1.

From the Research

Trial Without Catheter (TWOC) Procedure

To perform a TWOC, the following steps can be considered:

• Catheterization is typically required for acute urinary retention, and the catheter is usually left in place for a few days before attempting TWOC 2, 3.
• Alpha-blockers, such as alfuzosin or tamsulosin, are often prescribed before attempting TWOC to relax prostatic smooth muscle cells and improve urinary flow 2, 4, 5.
• The optimal duration of catheterization before attempting TWOC is not well established, but studies suggest that 3-7 days may be associated with the highest success rates of spontaneous urination 3.
• Factors that may affect the success of TWOC include age, prostatic volume, and the presence of lower urinary tract symptoms 3, 5.

Alpha-Blocker Treatment

Alpha-blockers have been shown to increase the success rates of TWOC:

• A systematic review found that alpha-blockers were associated with a higher rate of successful TWOC compared to placebo, with a risk ratio of 1.55 (95% CI 1.36 to 1.76) 4.
• Another study found that double-dose alpha-blocker treatment (tamsulosin + alfuzosin) was superior to single-dose treatment (tamsulosin) in terms of TWOC success rates 6.
• Alpha-blockers are generally well-tolerated, with low rates of adverse effects such as postural hypotension and dizziness 2, 4, 6.

Predictors of TWOC Success

Several factors have been identified as predictors of TWOC success:

• The use of alpha-blockers before TWOC has been consistently shown to increase the chances of success 2, 4, 5.
• Age, prostatic volume, and the presence of lower urinary tract symptoms may affect the success of TWOC, with older patients and those with larger prostates or more severe symptoms being less likely to succeed 3, 5.
• The type of acute urinary retention (spontaneous or precipitated) may also influence the success of TWOC, with spontaneous AUR being associated with lower success rates 5.