What is the likely diagnosis in a patient with oliguria and suprapubic pain without fever?

Acute Urinary Retention

The most likely diagnosis is acute urinary retention (AUR), which presents classically with scanty or absent urine output and painful suprapubic distension without fever. 1, 2

Clinical Presentation

• Painful hypogastric (suprapubic) distension with inability to void is the hallmark of AUR, though notably 28% of cases may present without pain 1, 2, 3
• Absence of fever distinguishes this from infectious etiologies like pyelonephritis or complicated UTI, which typically present with fever ≥38°C 4, 5
• Abdominal examination reveals a palpable, distended bladder with dull percussion note over the suprapubic region 2, 6
• The mean retention volume is approximately 950 mL in emergency presentations 3

Key Differential Considerations

The absence of fever is critical for narrowing the diagnosis:

• Pyelonephritis is excluded because it requires fever >38°C, costovertebral angle tenderness, and systemic symptoms like nausea/vomiting 5, 7
• Uncomplicated cystitis presents with dysuria, frequency, and urgency but does not cause painful suprapubic distension with anuria 4
• Ureteral spasm/colic causes severe flank pain radiating to the costovertebral angle with hematuria, not isolated suprapubic pain with oliguria 8

Immediate Management Algorithm

Step 1: Confirm diagnosis with physical examination

• Palpate for suprapubic mass and percuss for dullness 2, 6
• Perform digital rectal examination in men to assess prostate size, consistency, and rule out fecal impaction 6

Step 2: Immediate bladder decompression

• Insert urethral catheter as first-line treatment for prompt and complete drainage 2, 6
• If urethral catheterization fails, urgent urological consultation for suprapubic catheter placement is required 2, 6
• Suprapubic catheters cause less urinary tract infection (P<0.05), are more comfortable, and allow assessment of voiding ability before removal 9

Step 3: Obtain post-catheterization specimens

• Send urine for urinalysis and culture to rule out infection 6
• Check renal function (creatinine, BUN) to assess for upper tract damage 6
• Do not obtain PSA immediately as it will be falsely elevated from bladder distension and catheterization 6

Step 4: Determine disposition

• Admit if: patient has urosepsis, abnormal renal function requiring monitoring, acute neurological findings, or cannot manage catheter at home 6
• Discharge with catheter if: patient is stable, renal function normal, no infection, and can manage catheter care 6

Common Pitfalls to Avoid

• Do not delay catheterization while pursuing imaging or laboratory studies; immediate decompression prevents renal damage and urosepsis 1, 2
• Do not assume all suprapubic pain with oliguria is infection; the absence of fever makes AUR far more likely than pyelonephritis or complicated UTI 5, 1
• Do not attribute urinary symptoms solely to bacteriuria in the absence of fever and systemic signs, as asymptomatic bacteriuria is common and does not require treatment 4
• Plan trial without catheter within 2-3 days to allow natural voiding recovery, particularly in spontaneous AUR 6

Underlying Etiology Considerations

• Benign prostatic hyperplasia is the most common cause in men, particularly those >70 years 2, 6
• AUR can be spontaneous (53%) or precipitated (46%) by recent surgery, medications (anticholinergics, alpha-agonists), hematuria, or infection 2, 3
• In women, pelvic organ obstruction is the most common obstructive cause 2