Low Urine Output ๐ฝ
Clinical guide for assessing low urine output and oliguria. AKI calculator, fluid status assessment, causes, and management for on-call doctors.
๐ง Definition & Relevance
- Oliguria: < 0.5 mL/kg/hr of urine output
- Can indicate renal impairment, hypovolaemia, obstruction or critical illness
- Always assess in context of recent intake, baseline renal function and clinical picture
๐ What to Ask / Orders to Make
- If catheterised - when was catheter last flushed or changed?
- Is there pain or discomfort?
- Any known urological issues or previous retention?
- Ask nurse to: check for kinks, bladder scan, document volume over last few hours
- Ensure fluid balance chart is accurate
๐ Common Causes
- Pre-renal: dehydration, hypovolaemia, shock
- Renal: acute kidney injury (e.g. sepsis, nephrotoxins)
- Post-renal: obstruction (e.g. enlarged prostate, blocked catheter)
๐งพ History
- Fluid intake and losses (IV/oral)
- Symptoms of infection, pain, obstruction (e.g. suprapubic pain)
- Medications (diuretics, nephrotoxic drugs)
- Previous renal disease or urology history
๐ฉบ Examination
- Check vitals: HR, BP, temp, RR, SpOโ
- Signs of fluid status: dry mucosa, JVP, cap refill, peripheral oedema
- Palpate bladder (distension = retention)
- Inspect catheter if present โ kinks, displacement, occlusion
๐ Investigations
- Bladder scan โ normal post-void residual is typically <100 mL; >300โ400 mL may indicate retention
- Urinalysis + send urine sample
- Bloods: U&Es, FBC, CRP
- Consider VBG for lactate if unwell
- ECG if hyperkalaemia suspected
๐ Initial Management
- Flush catheter if blocked
- Insert catheter if not already present - first discuss with senior
- Give fluid bolus (e.g. 250โ500ml crystalloid) if hypovolaemic
- Treat underlying cause: sepsis, obstruction, nephrotoxic meds
- Strict input/output monitoring
โ ๏ธ When to Escalate
- Oliguria persists despite resuscitation
- Anuria
- Suspected obstructive uropathy with AKI
- Unstable vitals or hyperkalaemia
- Sepsis not responding to initial treatment
AKI Calculator
Calculate acute kidney injury stage
Assessment Result
Enter at least creatinine or urine data.
Related NICE guidance
NICENICE NG148 โ Acute kidney injury: prevention, detection and management
Full guidance on nice.org.uk. BetterCall is not endorsed by NICE.
Note Template
Ready-to-use clinical note structure
๐ 16 / 10 / 2026 โ 16:03 ATRP re: low urine output Patient: [age] [sex] Admission Dx: [reason for admission] PMHx: [renal disease / diabetes / heart failure / other] ๐งพ Hx: โข Onset: [sudden / gradual] โข Associated symptoms: [pain / swelling / fever] โข Recent fluid intake/output โข Medications: [diuretics, NSAIDs, ACEi] ๐ฉบ Exam: โข Vitals: HR __ BP __ RR __ SpOโ __ Temp __ โข Abdo: [tenderness / distension / masses] โข Bladder scan / catheter status โข Oedema: [peripheral / sacral] ๐ Impression: Likely cause: โข Pre-renal: [hypovolaemia, sepsis, heart failure] โข Renal: [acute tubular necrosis, glomerulonephritis] โข Post-renal: [obstruction, catheter blockage] ๐ Plan: โข Urgent bloods: U&E, creatinine, CK โข Bladder scan and catheterise if indicated โข Fluid challenge if hypovolaemic โข Review meds, stop nephrotoxics โข Imaging if obstruction suspected (US KUB) โข Refer nephrology/urology as needed โข Monitor urine output and electrolytes closely ๐ค [Your Name], [Role] IMC: _______
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