Tamsulosin Dose Escalation or Silodosin Switch Before Trial Without Catheter in BPH-Related Acute Urinary Retention

This randomized controlled trial will compare three medication strategies before trial without catheter in men with acute urinary retention due to benign prostatic hyperplasia who were already taking tamsulosin 0.4 mg once daily before the retention episode. After urethral catheterization, eligible participants will be randomly assigned to one of three groups for 7 days: continuation of tamsulosin 0.4 mg once daily, escalation to tamsulosin 0.8 mg once daily, or switching to silodosin 8 mg once daily. The urethral catheter will be removed on Day 7, and the ability to void successfully without re-catheterization will be assessed. Follow-up will continue to Day 30, with additional recording of catheter-free status, recurrent urinary retention, urinary flow, post-void residual urine, symptom scores, adverse drug events, catheter-related complications, and the need for later benign prostatic hyperplasia-related surgery.

Inclusion Criteria: * Male patients aged 50 years or older. * Acute urinary retention requiring urethral catheterization. * Presumed acute urinary retention secondary to benign prostatic enlargement or benign prostatic obstruction. * Already receiving tamsulosin 0.4 mg once daily for at least 4 weeks before the acute urinary retention episode. * Successful urethral catheterization at presentation. * Initial catheterized urine volume ≤1000 mL, with a clinical presentation consistent with painful acute urinary retention. * Prostate enlargement on ultrasound or clinical assessment consistent with benign prostatic hyperplasia or benign prostatic obstruction. * Ability to provide written informed consent. Exclusion Criteria: * Known or suspected prostate cancer. * Previous prostate surgery. * Previous urethral stricture disease or urethral surgery. * Neurogenic bladder or known neurological disease affecting voiding. * Chronic urinary retention rather than acute painful retention. * Acute urinary retention due to non-BPH causes, including clot retention, bladder stone obstruction, acute prostatitis, urethral trauma, or drug-induced retention. * Severe urinary tract infection, sepsis, or fever at presentation. * Gross hematuria requiring irrigation. * Failed urethral catheterization or need for suprapubic catheterization. * Current use of silodosin, alfuzosin, doxazosin, terazosin, tadalafil, anticholinergics, beta-3 agonists, or other drugs that may significantly affect voiding. * Severe renal impairment requiring urgent intervention. * Symptomatic postural hypotension or recurrent syncope. * Known hypersensitivity to silodosin. * Severe hepatic impairment. * Inability to comply with follow-up.