What is the differential diagnosis for a patient experiencing urinary retention (inability to empty the bladder) and how to evaluate it?

From the Guidelines

The differential diagnosis for a patient experiencing urinary retention should include urethral stricture, benign prostate enlargement, bladder outlet obstruction, and abnormal detrusor function, and evaluation should begin with a history, physical examination, and urinalysis, followed by non-invasive measures such as uroflowmetry and ultrasound post-void residual assessment. The evaluation of urinary retention requires a comprehensive approach to identify the underlying cause. According to the American Urological Association guideline 1, urethral stricture should be considered in the differential diagnosis of men who present with decreased urinary stream, incomplete emptying, dysuria, urinary tract infection (UTI), and rising post-void residual (PVR).

Key Considerations in Differential Diagnosis

• Urethral stricture: characterized by decreased urinary stream, incomplete emptying, and rising post-void residual (PVR) 1
• Benign prostate enlargement: may cause bladder outlet obstruction, leading to urinary retention 1
• Bladder outlet obstruction: can cause incomplete emptying and rising post-void residual (PVR) 1
• Abnormal detrusor function: can cause urinary retention due to impaired bladder contractility 1

Evaluation Approach

• Initial evaluation: history, physical examination, and urinalysis 1
• Non-invasive measures: uroflowmetry and ultrasound post-void residual assessment to assess flow rate and bladder emptying 1
• Definitive evaluation: urethro-cystoscopy, retrograde urethrography (RUG), voiding cystourethrography (VCUG), or ultrasound urethrography to confirm the diagnosis and assess stricture severity 1

Importance of Prompt Evaluation

Prompt evaluation is crucial to prevent complications such as urinary tract infections, bladder stones, and kidney damage from backflow pressure. The American Urological Association guideline 1 recommends a comprehensive approach to evaluate urinary retention, including non-invasive measures and definitive evaluation to confirm the diagnosis and assess stricture severity.

From the FDA Drug Label

The improvement in BPH symptoms was seen during the first year and maintained throughout an additional five years of open extension studies Symptoms were quantified using a score similar to the American Urological Association Symptom Score, which evaluated both obstructive symptoms (impairment of size and force of stream, sensation of incomplete bladder emptying, delayed or interrupted urination) and irritative symptoms (nocturia, daytime frequency, need to strain or push the flow of urine) Effect on Acute Urinary Retention and the Need for Surgery In A Long-Term Efficacy and Safety Study, efficacy was also assessed by evaluating treatment failures Treatment failure was prospectively defined as BPH-related urological events or clinical deterioration, lack of improvement and/or the need for alternative therapy. BPH-related urological events were defined as urological surgical intervention and acute urinary retention requiring catheterization.

The differential diagnosis for a patient experiencing urinary retention (inability to empty the bladder) includes:

• Benign Prostatic Hyperplasia (BPH): a common condition in older men where the prostate gland enlarges, causing obstructive symptoms such as urinary retention.
• Urinary Tract Infections (UTIs): bacterial infections that can cause irritative symptoms such as frequency, urgency, and dysuria.
• Neurogenic Bladder: a condition where the nerves that control the bladder are damaged, leading to urinary retention or incontinence.
• Bladder Outlet Obstruction: a blockage of the flow of urine from the bladder, which can be caused by BPH, bladder stones, or other conditions. To evaluate urinary retention, the following steps can be taken:
• Medical History: take a thorough medical history to identify any underlying conditions that may be contributing to the urinary retention.
• Physical Examination: perform a physical examination to assess for any abnormalities of the prostate gland or other pelvic organs.
• Urinalysis: perform a urinalysis to check for signs of infection or other abnormalities.
• Imaging Studies: consider imaging studies such as ultrasound or CT scans to evaluate the prostate gland and urinary tract.
• Urodynamic Studies: consider urodynamic studies to assess the function of the bladder and urethra. 2