Immediate Management: Bladder Catheterization
The correct answer is (d) catheter to empty bladder—this elderly man with severe oliguria (50 mL over 12 hours) requires immediate bladder ultrasound to measure post-void residual volume, and if urinary retention is confirmed (PVR >300-500 mL), urgent catheterization is indicated to prevent bladder decompensation and potential obstructive uropathy. 1
Why Catheterization Takes Priority
Acute urinary retention in elderly men occurs at a rate of 34.7 episodes per 1,000 patient-years in men aged 70+, most commonly caused by benign prostatic hyperplasia with bladder outlet obstruction. 1
The European Urology guidelines recommend performing immediate bladder ultrasound to measure post-void residual volume, with urinary retention volumes >300-500 mL requiring urgent catheterization. 1
Severe oliguria (50 mL in 12 hours = approximately 4 mL/hour) in an elderly man without pain strongly suggests urinary retention rather than renal failure—the absence of pain is typical for chronic retention with overflow. 2, 1
Why Other Options Are Incorrect
Diuretics (Option a) - Contraindicated
Diuretics are absolutely contraindicated in urinary retention, as they would worsen bladder distention and potentially cause bladder rupture or renal damage if obstruction is present. 1
Before considering diuretics for oliguria, you must first rule out post-renal obstruction with bladder ultrasound. 2
Ultrasound (Option b) - Incomplete Answer
While ultrasound is the correct diagnostic step, it is not the definitive management—ultrasound should be performed immediately, but if retention is confirmed, catheterization must follow. 1
The question asks "what to do," and the complete answer includes both diagnosis (ultrasound) and treatment (catheterization if retention confirmed). 2, 1
Cystoscopy (Option c) - Premature and Invasive
Cystoscopy is not indicated in the acute setting and should only be considered after initial management with catheterization and medical therapy, typically as part of specialized urologic evaluation. 2
The American Urological Association recommends non-invasive evaluation first (ultrasound, flow studies, post-void residual) before considering invasive procedures. 2
Immediate Management Algorithm
Step 1: Confirm Diagnosis (Within Minutes)
Perform bedside bladder ultrasound to measure post-void residual volume—this is non-invasive and provides immediate diagnostic information. 1
A palpable bladder on physical examination is a red flag requiring immediate intervention. 2, 1
Step 2: Catheterization Technique
If PVR >300-500 mL, insert urinary catheter using sterile technique with 14-16 French Foley catheter. 1
Drain bladder slowly (no more than 500-1000 mL initially) to prevent hematuria ex vacuo and hypotension from rapid decompression. 1
Step 3: Concurrent Alpha-Blocker Initiation
Alpha-blockers (tamsulosin 0.4 mg daily) should be initiated at the time of catheter insertion to increase chances of successful voiding trial, with effectiveness typically assessed after 2-4 weeks. 3, 1
This improves the likelihood of successful catheter removal and prevents recurrent retention. 3
Critical Post-Catheterization Monitoring
Monitor for post-obstructive diuresis—patients may produce large volumes of urine (>200 mL/hour) after relief of chronic obstruction, requiring fluid replacement. 1
Check renal function (creatinine/eGFR) and electrolytes after catheterization, as chronic obstruction may have caused obstructive uropathy. 3, 1
Document total volume drained and monitor urine output hourly for the first 4-6 hours. 1
Mandatory Urologic Referral Criteria
Recurrent or refractory urinary retention despite medical therapy requires immediate urologic referral. 3, 1
Rising creatinine with evidence of hydronephrosis (obstructive uropathy) requires urgent urologic referral. 3, 1
Severe obstruction with maximum flow rate (Qmax) <10 mL/second on uroflowmetry requires consideration of surgical intervention. 2, 3
Common Pitfalls to Avoid
Do not assume oliguria is renal in origin without first ruling out post-renal obstruction—this is a reversible cause that becomes irreversible if delayed. 1
Do not delay catheterization while waiting for specialty consultation—bladder decompensation and renal damage can occur within hours. 3, 1
Do not remove the catheter without initiating alpha-blocker therapy first—this significantly reduces the risk of recurrent retention. 3, 1
Do not overlook the possibility of chronic retention with overflow incontinence—the absence of pain does not rule out severe retention. 1, 4