MBBS OSCE · General Medicine
OSCE — Contrast-Associated AKI (Contrast Nephropathy) & Acute Tubular Necrosis vs Pre-Renal AKI
Eight-minute OSCE station on Contrast-Associated AKI (Contrast Nephropathy) & Acute Tubular Necrosis vs Pre-Renal AKI: focused history, examination priorities, investigations, emergency and definitive management.
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Brief (to candidate)
You will assess a patient with a presentation consistent with Contrast-Associated AKI (Contrast Nephropathy) & Acute Tubular Necrosis vs Pre-Renal AKI.
You have 8 minutes to take a focused history, outline examination, investigations, and management including red flags.
Clinical context
Contrast-associated AKI (CA-AKI, contrast nephropathy) is an intrinsic AKI developing within 48 to 72 hours of iodinated contrast, driven by renal medullary vasoconstriction and direct tubular cytotoxicity, highest-risk in CKD and diabetes. It is one cause of acute tubular necrosis (ATN), which must be distinguished from pre-renal AKI at the bedside: pre-renal (hypovolaemia, hypoperfusion with intact tubules) shows a FENa under 1 percent, urine sodium under 20, urine osmolality over 500, BUN/Cr over 20 and responds to fluids; ATN (ischaemia, nephrotoxins, contrast) shows a FENa over 2 percent, urine sodium over 40, urine osmolality under 350, muddy brown granular casts and a slower recovery
Candidate tasks
- Clarify onset, severity, associated features, and red-flag symptoms.
- State focused examination priorities.
- List first-line investigations and any named score/criteria.
- Give immediate resuscitation steps.
- Outline definitive management with doses/routes where standard.
- Name complications and disposition (ward / HDU / theatre / discharge safety-net).
- Mention one special-population modifier (pregnancy, child, elderly, CKD).
Examiner checklist
| Domain | Pass behaviours |
|---|---|
| Definition | Correct working diagnosis language |
| Assessment | Focused, prioritised, red flags sought |
| Investigations | Appropriate first-line + interpretation |
| Emergency care | ABC / time-critical actions first |
| Definitive care | Specific drugs/procedures, not generic phrases |
| Safety | Rising creatinine within 48 to 72 hours of iodinated contrast - contrast-associa |
| Safety | AKI with FENa over 2 percent, high urine sodium and muddy brown granular casts - |
| Safety | AKI after aminoglycosides, NSAIDs, amphotericin B or rhabdomyolysis - nephrotoxi |
| Communication | Clear plan and safety-netting |
Model outline
Lead with the working diagnosis and life threats. Resuscitate before definitive tests when unstable. Use guideline-standard therapy with named agents and doses. Document escalation criteria and follow-up. A safe candidate is specific, structured, and never delays critical care for non-urgent imaging.