Synopsis
Assess renal and hypersensitivity risk before iodinated contrast, preserve time-critical imaging, and apply hydration, metformin, documentation, and escalation rules proportionately.
- Do not delay emergency contrast CT that is required to prevent loss of life, limb, or immediate definitive therapy while waiting for renal tests.
- For routine intravenous contrast, acute kidney injury or eGFR below 30 mL/min/1.73 m² triggers individual risk-benefit review and preventive planning.
- A previous reaction to the specific contrast agent is the key hypersensitivity history; identify agent, timing, features, severity and treatment.
Key red flags
Current acute kidney injury or eGFR below 30 mL/min/1.73 m² makes routine intravenous contrast a specialist risk-benefit decision.
A previous moderate or severe reaction to the intended contrast agent requires alternative planning and appropriate emergency capability.
Hypotension, hypoxia, airway swelling, severe bronchospasm or collapse after injection demands immediate emergency treatment.
A delayed rash with mucosal involvement, blistering, systemic illness or organ injury requires urgent specialist assessment.
Urticaria, angioedema, bronchospasm, hypotension or anaphylaxis begins within an hour in most cases and needs severity-based treatment.
Reasoning priorities
Stratify renal risk for non-emergency intravascular contrast.
Use a suitably recent result matched to clinical stability; acute kidney injury cannot be excluded by a single reassuring eGFR.
Worked reasoning
An unstable patient needs enhanced CT to direct immediate haemorrhage control.
- Context: confirm that delay threatens life, limb or access to definitive treatment and continue simultaneous resuscitation.
- Reasoning: recognise that renal blood testing, diabetes, metformin use or fluid preparation must not postpone the emergency scan.
- Outcome: perform the necessary diagnostic contrast examination with an appropriate low- or iso-osmolar agent and no avoidable phases.
- Verification: document the emergency justification, review renal function and urine output afterwards, and manage any deterioration clinically.
A stable patient with acute kidney injury or eGFR below 30 is proposed for intravenous contrast.