Trial without catheter (TWOC) determines whether a patient with acute urinary retention can achieve catheter-free status. In clinical practice, it is common to repeat TWOC in patients who fail to void without a catheter on the first TWOC attempt. This study investigated the outcomes and significance of repeat TWOC in male and female patients, and we aimed to identify predictors of successful outcomes of repeat TWOC based on patient background.

Patients with acute urinary retention who underwent TWOC at a single center between 2010 and 2019 were enrolled and retrospectively analyzed. In TWOC, the urinary catheter was removed after instillation of warm saline (200-300 mL), and residual urine was measured after the first void. The trial was defined as unsuccessful if the patient had difficulty voiding with abdominal discomfort or pain. The decision to repeat TWOC for patients with a failed first trial was up to each physician. Patients were divided into single-trial and repeat-trial groups, and clinical factors predicting the successful outcome of each TWOC were analyzed using a multivariate logistic regression model.

Consecutive 681 patients (577 males and 104 females) were diagnosed with acute urinary retention and underwent TWOC over 10 years. Of the 577 male patients, 441 patients (76.4%) underwent TWOC only once (single-trial group) and 136 patients (23.6%) twice or more (repeat-trial group). Of the 104 female patients, 84 (80.8%) and 20 (19.2%) underwent single and repeat TWOC, respectively. The overall success rate of TWOC for single and repeat trial groups showed no significant differences in both sexes; 61.9% (273/441, single-trial) and 55.1% (75/136, repeat-trial) in male (P=0.159), and 58.3% (49/84, single-trial) and 55.0% (11/20 repeat-trial) in female (P=0.786).
In repeat-trial group, patient characteristics were not significantly different between the successful and failure groups in both sexes (Table 1). In single-trial group, male patients with successful TWOC consisted of younger age (P=0.048), lower PS (P=0.001) and fewer past history of dementia (P=0.011) than those with failed TWOC. Whilst, in female, there were no significant differences in patient characteristics comparing between successful and failed groups.
In the repeat-trial group, the multivariate logistic regression model showed that younger age was involved in the final model to predict successful outcome of TWOC in both sexes, but with no statistical significance (Table 2). While, in single-trial group, low ECOG-PS (odds ratio: 1.725 [1.2-2.5], P=0.002) and absence of dementia (odds ratio: 3.148 [1.0-9.7], P=0.046) were identified as independent predictors of successful trial in male patients. In the female single-trial of TWOC, high serum albumin was likely indicated as an independent predictor of trial success.

This is the first study to investigate the significance of repeat TWOC for both male and female. Equivalent success rate of TWOC for single-trial and repeat-trial groups for both male and female, indicating that repeat trials of TWOC are as worthy to undergo as single trials, and suggesting the significance of trying repeat TWOC for patients of both sexes. This study also showed that predicting successful TWOC based on patient characteristics is challenging in repeat TWOC, but may be possible in first TWOC. This study reflected real-world clinical data on repeat TWOC, and it was important to provide some perspective on repeat TWOC.

In this study, there was no significant difference in the overall success rate of TWOC for single-trial and repeat-trial groups, and no significant differences in the group comparison of successful and failure patients who attempted repeat TWOC in both sexes. Although it may be difficult to predict the success of repeat TWOC, the predictors of first TWOC may be ECOG-PS and presence of dementia in male, and serum albumin level in female.