How do you differentiate and treat overactive bladder (OAB) versus benign prostatic hyperplasia (BPH)?

Differentiating and Treating Overactive Bladder vs Benign Prostatic Hyperplasia

In men presenting with lower urinary tract symptoms, differentiate OAB from BPH by focusing on storage symptoms (urgency, frequency, urgency incontinence) versus voiding symptoms (weak stream, hesitancy, incomplete emptying), using digital rectal examination to assess prostate size, and measuring post-void residual volume to detect bladder outlet obstruction. 1, 2

Diagnostic Differentiation

Key Clinical Features

OAB is characterized by:

• Urgency (sudden compelling desire to void that is difficult to defer) as the hallmark symptom 1
• Urinary frequency (>7 voids during waking hours) 1
• Nocturia (interruption of sleep ≥1 time to void) 1
• Urgency urinary incontinence (involuntary leakage with urgency) 1
• Symptoms are primarily storage-related 1, 3

BPH is characterized by:

• Voiding symptoms: weak stream, hesitancy, straining, sensation of incomplete emptying 2
• Storage symptoms may coexist but are secondary to bladder outlet obstruction 2
• Enlarged prostate on digital rectal examination 2
• Elevated post-void residual volume (often >100-150 mL) 2

Essential Diagnostic Workup

For all patients presenting with lower urinary tract symptoms: 1, 2

• Comprehensive medical history documenting duration, severity, and bothersomeness of both storage and voiding symptoms 1
• Physical examination including digital rectal examination in men to assess prostate size, shape, and consistency 2
• Urinalysis (dipstick or microscopic) to exclude infection and microhematuria 1, 2
• Urine culture if urinalysis suggests infection 1

Post-void residual (PVR) measurement is critical when: 1, 2

• Voiding symptoms are present 1
• History of urinary retention exists 1
• Neurological disorders are present 1
• Enlarged prostate is detected 1
• Long-standing diabetes is present 1

A PVR >250-300 mL suggests significant bladder outlet obstruction and is a relative contraindication to antimuscarinic therapy. 2

Treatment Approach

For Isolated OAB (Without BPH)

First-line behavioral therapies should be offered to all OAB patients: 1, 2

• Bladder training with timed voiding and gradual extension of voiding intervals 2
• Pelvic floor muscle training for urge suppression techniques 2
• Fluid management (optimizing timing and volume of intake) 2
• Dietary modifications to reduce bladder irritants (caffeine, alcohol) 2
• Weight loss targeting 8% reduction for obese patients 2

Pharmacotherapy options (can be combined with behavioral therapies): 1, 2

• Beta-3 agonists (mirabegron) are preferred due to lower cognitive risk, particularly in elderly patients 2
• Antimuscarinics (darifenacin, fesoterodine, oxybutynine, solifenacin, tolterodine, trospium) as alternatives 2

Advanced therapies for refractory cases: 1, 2

• Onabotulinumtoxin A bladder injections 2
• Sacral neuromodulation 2
• Percutaneous or implantable posterior tibial nerve stimulation 2

For BPH Without Significant OAB

Monotherapy with alpha-blockers (tamsulosin, doxazosin) to relieve bladder outlet obstruction. 2, 4

5-alpha reductase inhibitors (finasteride) for men with enlarged prostates to: 5

• Improve symptoms 5
• Reduce risk of acute urinary retention 5
• Reduce need for surgery 5

For BPH With Bothersome OAB Symptoms (Combination Presentation)

Combination therapy with an alpha-blocker PLUS either an antimuscarinic or beta-3 agonist provides optimal symptom control. 2

Treatment algorithm: 2, 6

1. Initiate alpha-blocker (e.g., tamsulosin 0.4 mg daily) to relieve bladder outlet obstruction 2, 4
2. Add antimuscarinic (solifenacin 5 mg or trospium 5 mg) OR beta-3 agonist for persistent storage symptoms 2, 6
3. Monitor post-void residual volume when using antimuscarinics 2

Critical Safety Considerations

Antimuscarinic contraindications and precautions: 2

• Relative contraindication: PVR >250-300 mL 2
• Use with caution in narrow-angle glaucoma 2
• Use with caution in impaired gastric emptying 2
• Use with caution in history of urinary retention 2
• Monitor cognitive function in elderly patients 2

Common pitfalls to avoid:

• Do not use antimuscarinics as monotherapy in men with significant BPH without first addressing bladder outlet obstruction with an alpha-blocker 2
• Do not expect complete symptom resolution; most patients experience significant reduction rather than elimination of symptoms 2
• Be aware that patients may develop de novo or worsening OAB symptoms after surgical interventions for BPH 2

Follow-Up and Monitoring

Reassess treatment response at 4-8 weeks by: 1

• Comparing current symptoms to baseline using validated questionnaires 1
• Reviewing bladder diary if available 1
• Assessing for adverse effects, particularly cognitive changes in elderly 1
• Measuring PVR if on antimuscarinic therapy 2

Refer to urology specialist when: 1

• Symptoms persist despite optimized medical management 1
• Hematuria is present 1
• Recurrent urinary tract infections occur 1
• Elevated PVR develops on antimuscarinic therapy 2
• Patient desires advanced therapies (neuromodulation, botulinum toxin) 1