Contrast Reaction During an Intravenous Urogram
A 52-year-old man with a history of asthma and hypertension attends the radiology department for an intravenous urogram (IVU) because of recurrent right flank pain and suspected renal stone. His latest eGFR is 55 mL/min/1.73 m². He has no previous contrast reaction, but he uses a salbutamol inhaler daily. The radiographer administers 50 mL of iohexol 300 mg I/mL intravenously after checking identity and consent. Four minutes later he complains of itching and warmth; the radiographer sees urticaria on the neck and chest, hears audible wheeze, and records BP 100/65 mmHg, pulse 110/min, respiratory rate 26/min and SpO2 93% on room air. The department has oxygen, adrenaline 1:1000, salbutamol nebuliser, hydrocortisone, chlorphenamine and a crash cart, but no anaesthetist on site. The radiologist is in the reporting room next door. The IVU is at the early nephrogram phase.
1. Outline your immediate management of this patient, including the drugs and doses you would expect to use and the reasoning behind each step.
Read the worked answer
This is an acute contrast reaction with urticaria, wheeze and early cardiovascular involvement. I would stop the injection immediately and call the radiologist and emergency team.
Immediate management:
- Assess ABC, sit the patient upright if that helps breathing, give high-flow oxygen and monitor SpO2, pulse and BP.
- Give intramuscular adrenaline 1:1000, 0.5 mg into the anterolateral thigh, because wheeze plus hypotension/tachycardia indicates anaphylaxis rather than simple urticaria. Repeat after 5 minutes if there is no improvement.
- Start a salbutamol nebuliser for bronchospasm and give hydrocortisone 200 mg IV and chlorphenamine 10 mg IV/IM as adjuncts; these do not replace adrenaline.
- Secure IV access and give a crystalloid bolus if hypotension develops. Do not give IV adrenaline unless trained and monitored, because of arrhythmia risk.
- Record the time of each drug and vital sign. The patient has asthma, so bronchospasm may be severe; the eGFR of 55 is relevant to contrast nephropathy but not to this immediate allergic reaction.
- Keep the crash cart and defibrillator available until stable.
2. Should the IVU be completed after the patient is stabilised? Justify your answer.
Read the worked answer
No. The study should be aborted, not completed. The patient has had a systemic hypersensitivity reaction with respiratory and cardiovascular features; further contrast would risk a more severe reaction and cannot be justified for a non-emergency investigation.
Reasoning:
- The images already obtained in the nephrogram phase may show enough to help the clinician, but diagnostic yield does not outweigh the immediate danger.
- The clinical question is suspected renal stone; after stabilisation, alternative imaging such as ultrasound or a non-contrast CT pathway can be discussed with the radiologist and referring clinician.
- Re-injection in the same session is contraindicated. Any future contrast study would need a formal allergy assessment, a clear risk–benefit discussion, and resuscitation facilities immediately available.
- I would document the reaction, the contrast agent and dose, the timing, the treatment given and the decision to stop the study in the radiology record and in the patient's notes.
3. What would you tell the patient and the referring team afterwards, and what documentation is essential?
Read the worked answer
I would explain in plain language that he had an allergic-type reaction to the contrast, that it was treated promptly, and that he should not receive the same contrast again without telling the medical staff. I would give him a written record or advise him to carry the information in his personal health records.
Essential documentation:
- The contrast agent, concentration, volume (50 mL iohexol 300) and route.
- Time of injection and time of onset of symptoms.
- Vital signs and clinical findings: urticaria, wheeze, BP 100/65, pulse 110, SpO2 93%.
- Drugs and doses given, including adrenaline, and the response.
- Decision to stop the study and the advice given about future contrast exposure.
- Communication with the referring team and the radiologist.
I would also report the reaction through the hospital's adverse-event or pharmacovigilance system, and ensure that the allergy is flagged prominently in the patient's record so that future staff do not inadvertently re-expose him.