What are the types of urinary retention, particularly in elderly males with benign prostatic hyperplasia (BPH) or neurogenic bladder?

Types of Urinary Retention

Urinary retention is classified into two main types: acute urinary retention (AUR) and chronic urinary retention (CUR), with CUR further subdivided into high-pressure and low-pressure variants based on bladder filling pressures. 1, 2, 3

Acute Urinary Retention (AUR)

Acute urinary retention represents a sudden, painful inability to void despite a full bladder, constituting a urological emergency requiring immediate catheterization. 4, 1

Key Characteristics of AUR:

• Sudden onset with severe suprapubic pain and inability to pass urine 1, 5
• Bladder volumes typically range from 500-1,500 mL at presentation 4
• Most commonly caused by benign prostatic hyperplasia (BPH) in elderly males, accounting for 53% of cases 1, 5
• Precipitating factors include anesthesia, alpha-adrenergic sympathomimetic medications (cold remedies), anticholinergic drugs, and opioids 4, 6

Management Approach for AUR:

• Alpha blockers (alfuzosin or tamsulosin) should be prescribed prior to voiding trial, with alfuzosin demonstrating 60% successful trial without catheter (TWOC) versus 39% for placebo 4
• At least three days of alpha blocker therapy should be completed before attempting TWOC 4
• Patients who pass successful TWOC remain at increased risk for recurrent retention and require close follow-up 4

Chronic Urinary Retention (CUR)

Chronic urinary retention is defined as a non-painful, palpable or percussable bladder after voiding, with significant controversy regarding the post-void residual (PVR) threshold—ranging from >300 mL (American Urological Association) to >1000 mL (UK NICE guidelines). 5, 3

Subtypes of CUR:

High-Pressure Chronic Retention:

• Characterized by elevated bladder filling pressures on urodynamic testing, leading to upper tract dilatation and potential renal insufficiency 4, 2
• Represents an imperative indication for surgical intervention when associated with hydronephrosis or elevated creatinine from obstructive uropathy 4, 7
• Requires urgent urologic referral to prevent irreversible renal damage 7

Low-Pressure Chronic Retention:

• Bladder remains distended with large PVR but without elevated filling pressures 2, 3
• Often associated with detrusor underactivity or acontractility 2
• May be managed with clean intermittent catheterization in neurogenic cases 1, 5

Clinical Presentation of CUR:

• Patients may present with overflow incontinence, recurrent urinary tract infections, or bladder stones 4
• Bladder may be palpable or percussable suprapubically, though this depends on patient habitus and examiner skill 3
• PVR measurements show marked variability and should be repeated to improve diagnostic precision 3

Critical Diagnostic Distinctions

PVR Thresholds by Authority:

• American Urological Association: PVR >300 mL measured on two separate occasions persisting for at least six months defines CUR 5, 3
• UK NICE Guidelines: PVR >1000 mL defines CUR 3
• International Continence Society: Non-painful palpable bladder after voiding, without specific PVR threshold 3

Common Pitfall to Avoid:

The lack of international consensus on PVR thresholds creates diagnostic confusion—most prospective trials exclude CUR patients entirely, yet this group comprises up to 25% of men undergoing TURP in the UK. 3 When encountering borderline PVR values (300-1000 mL), repeat measurements and assess for complications (hydronephrosis, elevated creatinine, recurrent UTIs) to guide management rather than relying solely on arbitrary cutoffs. 5, 3

Etiology-Based Classification

Obstructive Causes:

• Benign prostatic hyperplasia remains the most common cause in elderly males 1, 5
• In women, pelvic organ prolapse and urethral stenosis predominate 2

Neurogenic Causes:

• Cortical, spinal, or peripheral nerve lesions can cause both acute and chronic retention 1, 2
• Fowler's syndrome in women represents urethral sphincter dysfunction diagnosed by electromyography 2

Pharmacologic Causes:

• Anticholinergics, alpha-adrenergic agonists, opioids, and anesthetics account for up to 10% of retention episodes 6
• Elderly patients with pre-existing BPH face compounded risk from polypharmacy 6

Infectious/Inflammatory Causes:

• Prostatitis, cystitis, urethritis, and vulvovaginitis can precipitate acute retention 1

Management Implications by Type

For AUR related to BPH: immediate catheterization followed by alpha blocker initiation increases successful voiding trial rates from 29-39% (placebo) to 47-60% (treatment). 4

For CUR with complications (renal insufficiency, recurrent UTI, bladder stones, gross hematuria): surgical intervention is recommended as definitive management. 4

For CUR from neurogenic bladder: clean intermittent self-catheterization with low-friction catheters represents first-line management. 1, 5

For refractory retention failing catheter removal: surgery is indicated, or if non-surgical candidate, long-term catheterization (intermittent preferred over indwelling) or prostatic stent placement. 4