INTRODUCTION
Acute urinary retention (AUR) constitutes a urological emergency characterized by the sudden inability to voluntarily void despite a full bladder, affecting approximately 10% of men over 70 years and 7% of women over 80 years annually [1,2]. In hos-pitalized patients, AUR represents a pervasive complication occurring in 4%–25% of postoperative patients and 8%–12% of medical admissions [3,4]. The heterogeneous etiology of AUR, ranging from obstructive pathology to neurogenic dysfunction and pharmacological effects, presents significant management challenges [5,6].
While immediate bladder decompression via catheterization provides symptomatic relief, the critical question of when patients will recover spontaneous voiding lacks evidence-based guidance [7,8]. Premature catheter removal risks reretention and emergency re-catheterization, while prolonged catheterization increases catheter-associated urinary tract infections, urethral trauma, and patient discomfort [9,10]. Current literature predominantly focuses on specific populations such as men with benign prostatic hyperplasia or women following pelvic surgery, limiting generalizability [11,12]. The absence of validated clinical prediction tools leads to arbitrary voiding trial schedules and inefficient resource utilization [13-15].
This study addresses this gap by developing and validating a universally applicable prediction model for recovery from AUR. Our objective was to identify readily available clinical parameters that reliably predict successful voiding within 14 days—a timeframe balancing risks of prolonged catheterization against likelihood of spontaneous recovery.
MATERIALS AND METHODS
Study Design and Participants
We conducted a prospective observational cohort study at a 1,200-bed tertiary care academic medical center between March 2024 and July 2025. The Institutional Review Board (IRB) approved the study protocol (IRB #1981-006-382), and all participants provided written informed consent. The study followed Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis Or Diagnosis (TRIPOD) guidelines for prediction model development [16].
Adult patients aged ≥18 years with new-onset AUR requiring urological consultation were eligible if they had bladder volume ≥300 mL on initial catheterization and could provide informed consent. Exclusion criteria included chronic urinary retention (previous episodes within 6 months), prostate volume >30 g in males, active urinary tract infection, established neurogenic bladder, urethral stricture or bladder neck contracture, current urological malignancy, indwelling catheter within 30 days, or cognitive impairment precluding trial participation.
Data Collection
Trained research coordinators collected baseline data using standardized forms. Variables included demographics (age, sex, body mass index), clinical context (postoperative vs. spontaneous onset, surgery type, time from surgery), comorbidities (hypertension, diabetes mellitus, cerebrovascular accident, spinal disease), medications (alpha-blockers, anticholinergics, opioids), laboratory values (creatinine, electrolytes), and retention characteristics (initial volume, hematuria, bladder wall thickness). For males, prostate parameters including volume and prostate-specific antigen were recorded when available.
Management Protocol
All patients received standardized care with 16–18 French Foley catheter insertion and continuous drainage. Males without contraindications received tamsulosin 0.4 mg daily. Voiding trials occurred every 3–4 days following this protocol: bladder instillation with 300-mL sterile saline, catheter removal, voiding attempt with uroflowmetry when feasible, and postvoid residual (PVR) measurement via ultrasound within 10 minutes. Success was defined as PVR <100 mL; failure (PVR ≥100 mL) resulted in immediate recatheterization.
Statistical Analysis
Sample size calculation based on 10 events per predictor variable with anticipated 8–10 predictors and 70% success rate yielded minimum requirement of 100 patients [17]. Continuous variables were summarized as means±standard deviation or medians (interquartile range, IQR); categorical variables as frequencies (percentages). Associations between predictors and primary outcome were assessed using t-test, Mann-Whitney Utest, chi-square, or Fisher exact test.
Variables with P<0.20 in univariable analysis or strong clinical rationale entered multivariable logistic regression with backward stepwise selection (P<0.05 for retention). Multicollinearity was assessed (variance inflation factor <5). Model performance was evaluated using area under receiver operating characteristic curve (AUC-ROC) for discrimination and Hosmer-Lemeshow test for calibration. Bootstrap resampling (1000 iterations) assessed optimism-corrected performance. Sensitivity analyses excluded specific comorbidities and used alternative PVR thresholds (50 mL, 150 mL). Analysis used R ver. 4.0.3 (R Foundation for Statistical Computing, Austria).
RESULTS
Patient Characteristics
Of 168 screened patients, 126 (75%) met inclusion criteria and completed follow-up. Exclusions included prostate >30 g (n=18), chronic retention (n=12), declined consent (n=8), and incomplete data (n=4). The cohort comprised 84 males (66.7%) and 42 females (33.3%), mean age 71.9±12.5 years. Postoperative retention occurred in 79 patients (62.7%). Mean initial retention volume was 602.6±237.1 mL (Table 1).
Recovery Patterns
Overall, 103 patients (81.7%) achieved successful voiding within 14 days. Median time to recovery was 8 (IQR, 4–13) days. Recovery rates within 14 days differed significantly by age (<70 years: 84.4% vs. ≥70 years: 80.2%, P=0.042), sex (males: 85.7% vs. females: 73.8%, P=0.098), etiology (postoperative: 88.6% vs. spontaneous: 70.2%, P=0.009), and retention volume (≤450 mL: 88.4% vs. >450 mL: 78.0%, P=0.003). Recovery rates varied significantly across clinical subgroups (Fig. 1). Kaplan-Meier curves demonstrated divergent recovery trajectories between subgroups (Fig. 2).
Prediction Model Development
The final logistic regression model incorporated 4 independent predictors (Table 2). The model demonstrated excellent discrimination (AUC, 0.83; 95% CI, 0.76–0.90) and good calibration (Hosmer-Lemeshow chi-square=6.82, P=0.42). ROC analysis identified optimal probability threshold of 0.68, yielding sensitivity 78.6% and specificity 82.6% (Fig. 3).
Model Validation and Secondary Outcomes
Bootstrap validation confirmed model stability with optimismcorrected AUC of 0.81. All predictors were selected in >85% of bootstrap samples. Among recovered patients, 18 (17.5%) experienced reretention within 30 days, associated with female sex (odds ratio [OR], 2.84; P=0.031) and spontaneous etiology (OR, 2.41; P=0.048). Complications included urinary tract infection (6.3%), hematuria (3.2%), and urethral trauma (1.6%). Five patients (4.0%) required surgical intervention.
Model performance remained stable in sensitivity analyses: excluding diabetics (AUC, 0.82), PVR <50-mL threshold (AUC, 0.81), PVR <150-mL threshold (AUC, 0.84), and excluding cerebrovascular accident history (AUC, 0.83).
DISCUSSION
This prospective study successfully developed and validated a clinical prediction model for AUR recovery within 14 days, demonstrating excellent discriminative ability (AUC, 0.83) using 4 simple bedside parameters: age, sex, etiology, and retention volume. The model’s simplicity enables immediate risk stratification without specialized testing or complex calculations.
The identification of age <70 years as favorable (OR, 4.11) aligns with physiological principles. Aging associates with decreased detrusor contractility, increased collagen deposition, and comorbidities affecting lower urinary tract function [18,19]. This threshold provides objective risk stratification for clinical decision-making.
The striking sex disparity, with females having only oneninth the odds of recovery compared to males, reflects fundamental pathophysiological differences. Female AUR often indicates complex pelvic floor dysfunction, prolapse, or primary bladder pathology rather than simple outlet obstruction [20,21]. This challenges current practice patterns extrapolated from male-predominant studies and suggests women require intensive evaluation and different management strategies.
Postoperative retention’s superior prognosis (OR, 4.38) provides reassurance, as it typically results from transient factors— anesthetic effects, opioid-induced suppression, and temporary nerve dysfunction—that resolve predictably [22,23]. Conversely, spontaneous retention often signals progressive pathology requiring comprehensive evaluation.
The 450-mL volume threshold represents critical inflection for bladder injury. Exceeding this is associates with ischemic detrusor damage and neural injury, causing prolonged dysfunction [24,25]. This emphasizes prompt AUR recognition and decompression to preserve function.
Implementation enables risk-stratified pathways: high probability (>80%) patients undergo early trials (days 3–4) with out-patient management consideration; intermediate probability (50%–80%) follow standard protocols; low probability (<50%) benefit from delayed trials, early consultation, and comprehensive evaluation.
Study strengths include prospective design minimizing bias, heterogeneous population enhancing generalizability, rigorous TRIPOD-compliant methodology, and internal validation confirming stability. Limitations include single-center design, exclusion of large prostates, lack of external validation, and small female sample size.
Future research should pursue external validation in multicenter cohorts, model refinement with novel biomarkers, intervention studies testing risk-stratified protocols, long-term functional outcomes, and economic impact analysis.
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