Radiography — Advice Letter on Preparation for a CT Scan with Oral Contrast
A radiographer writes an advice letter to a 57-year-old woman explaining how to prepare for a CT abdomen and pelvis with oral contrast scheduled in 5 days. This intermediate case requires selecting the preparation instructions relevant to this specific patient — including a metformin hold — from a detailed set of clinical notes.
Letter type
Advice
Write to
Patient
Target length
190–210 words
The case notes
Patient: Mrs Sandra Kamau, 57 years old; type 2 diabetes, on metformin; scheduled CT abdomen and pelvis with IV and oral contrast in 5 days
Fasting: Nil by mouth (food and milk) for 4 hours before the appointment; clear fluids (water only) are permitted up to 2 hours before
Oral contrast preparation: Patient will be asked to drink 1 litre of oral contrast (dilute Gastrografin solution) over 60 minutes starting 90 minutes before the scan; the liquid is colourless and slightly flavoured; it may cause mild diarrhoea after the scan
IV contrast — metformin: Patient is on metformin — must hold metformin for 48 hours AFTER the CT scan (not before); risk of lactic acidosis if IV contrast causes acute kidney injury and metformin is continued; patient must inform the radiographer about the metformin before the scan begins
Creatinine/renal function check: eGFR must be checked before the scan — GP has been asked to arrange this; patient must bring a copy of the result or confirm it has been sent to the department
On the day: Arrive 30 minutes early; wear comfortable loose clothing (no metal fasteners); leave jewellery at home; bring a list of current medications; inform the team of any allergies
What to expect: Scan takes approximately 20–30 minutes; IV cannula inserted; mild warmth or flushing sensation when IV contrast is given (normal); may feel like urinating briefly (normal, does not actually happen)
Task: Write an advice letter to Mrs Kamau explaining how to prepare for her CT scan, with particular attention to the metformin instruction.
Writing task
Write an advice letter to Mrs Kamau explaining how to prepare for her CT scan, with particular attention to the metformin instruction.
What to include, what to cut
The hardest mark to win is selection. The same case notes contain decision-relevant facts and distractors. Here is what an examiner expects to see in a Grade B letter for this scenario, and what should be left out.
Include
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Hold metformin for 48 hours AFTER the CT scan, not before — and why
This is the most important and non-obvious instruction in this letter. Patients commonly assume they should hold medications before a scan, not after. The reason — risk of a rare but serious complication if IV contrast causes any kidney injury — motivates compliance without alarming the patient unnecessarily.
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The fasting instruction: no food or milk for 4 hours, clear water until 2 hours before
An incorrect fast — either too strict (no water) or too lax (milk until an hour before) — compromises the scan. The distinction between no food/milk and the water allowance must be explicit.
-
Oral contrast: 1 litre over 60 minutes starting 90 minutes before, mild diarrhoea possible
The oral preparation is a significant patient experience. The patient who does not know about oral contrast will be surprised, and may not drink it all. Pre-warning with the reason (highlights bowel for the CT) improves compliance.
Leave out
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The technical explanation of how CT scans work
One sentence: 'The CT scanner uses X-ray technology to produce detailed cross-section images of your abdomen.' The patient does not need to understand CT physics to prepare for the scan.
-
The kidney function check detail beyond 'bring the result'
The GP has been asked to arrange this. The patient's action is simple: confirm it has been arranged and bring the result. The clinical rationale for contrast nephropathy screening is not needed in the patient letter.
Criterion in focus · Content
A radiology preparation advice letter for a patient on metformin has a non-negotiable Content requirement: the metformin hold instruction must be present, must specify the timing (48 hours AFTER the scan, not before), and must give the reason in plain language. Omitting the metformin instruction, misstating the timing (before instead of after), or omitting the reason all constitute Content failures. This is a 2026 patient-safety priority in radiology patient letters.
Now write the letter — and find out what is blocking your Grade B
Write a 190–210 words advice letter from these notes, paste it into the free checker for an instant read, then submit it for a human grade against all six criteria. Dr Mariam's team returns line-by-line feedback, from $12.