What are the next steps to confirm a diagnosis of urinary retention suspected to be due to benign prostatic hyperplasia (BPH)?

Diagnostic Approach for Urinary Retention Suspected Due to BPH

The next steps to confirm urinary retention due to BPH include a focused history, physical examination with digital rectal examination, urinalysis, PSA testing, and assessment of post-void residual urine volume. 1, 2, 3

Initial Assessment

• Administer the International Prostate Symptom Score (IPSS) questionnaire to objectively quantify both obstructive symptoms (incomplete emptying, intermittency, weak stream, straining) and irritative symptoms (frequency, urgency, nocturia) 2, 4
• Obtain a detailed medical history focusing on:
  • Duration and progression of urinary symptoms 4
  • Medication history, particularly anticholinergics and alpha-adrenergic agonists that may contribute to retention 5, 6
  • Previous episodes of urinary retention or BPH-related complications 1

Physical Examination

• Perform a digital rectal examination (DRE) to assess:
  • Prostate size and consistency 1
  • Presence of nodules that might suggest prostate cancer rather than BPH 1
• Conduct a focused neurological examination to rule out neurogenic causes of urinary retention 5, 6

Essential Diagnostic Tests

• Urinalysis to exclude urinary tract infection, hematuria, or other inflammatory conditions 1, 3
• Serum PSA measurement in patients with at least a 10-year life expectancy or when knowledge of prostate cancer would change management 1, 3
• Measurement of post-void residual (PVR) urine volume:
  • Can be performed using bladder ultrasound or catheterization 1
  • PVR >300 mL measured on two separate occasions and persisting for at least six months defines chronic urinary retention 5

Additional Diagnostic Evaluations

• Uroflowmetry to measure maximum urinary flow rate (Qmax):
  • Qmax <10 mL/sec suggests urodynamic obstruction 1
  • Men with normal flow rates but significant symptoms may have non-BPH causes requiring further investigation 1
• Transabdominal ultrasound to assess:
  • Prostate volume (normal is generally <20 mL) 7
  • Intravesical prostatic protrusion (IPP), which correlates with bladder outlet obstruction 7
  • Post-void residual urine volume 7

Management of Acute Urinary Retention

• Immediate bladder decompression via catheterization is essential 1, 6
• Consider suprapubic catheterization which may improve patient comfort and decrease bacteriuria compared to urethral catheterization 5, 6
• Administration of an alpha blocker (preferably non-titratable such as tamsulosin or alfuzosin) prior to catheter removal increases the chance of successful voiding trial 1
• A voiding trial is more likely to succeed if retention was precipitated by temporary factors 1

Follow-Up Protocol

• First follow-up visit should be scheduled 4-12 weeks after initiating alpha blockers 3
• For 5-alpha reductase inhibitors, first follow-up should be at 3-6 months due to longer onset of action 3
• IPSS should be readministered at each follow-up visit to objectively assess symptom changes 3

Common Pitfalls to Avoid

• Failing to rule out other causes of urinary retention beyond BPH 5, 6
• Not considering prostate size when evaluating treatment response 3
• Neglecting to assess for complications of BPH that may require more urgent intervention, such as renal insufficiency, recurrent UTIs, or bladder stones 1
• Relying solely on symptom scores without considering the patient's level of bother from symptoms 2

Remember that surgical intervention is recommended for patients with renal insufficiency due to BPH, recurrent UTIs, recurrent gross hematuria, or bladder stones due to BPH that are refractory to other therapies 1.