Here are 20 one-line clinical vignettes to test your spot diagnosis. Read each one, commit to a single best diagnosis before you read on, then check your answers in the section below. They cover common presentations and can't-miss emergencies in a UK exam context, the kind that come up across UKMLA, PLAB, MRCP and MRCGP. Try to name the discriminating clue for each, not just the diagnosis.
Key takeaways
- Commit to a diagnosis before looking at the answer: retrieval is what builds the skill.
- These cover both common conditions and dangerous can't-miss diagnoses.
- For each, name the single discriminating clue that points to the answer.
- Review any you miss, and work out which feature you under-weighted.
- For a fresh case every day, the daily habit is what makes recognition fast.
The 20 vignettes
Commit to an answer for each before scrolling to the answers.
- A 16-year-old boy with sudden severe pain in one testicle and nausea, the testicle lying high and horizontal.
- A 2-year-old with a barking cough and inspiratory stridor that is worse at night.
- A 65-year-old smoker with haemoptysis, weight loss and finger clubbing.
- A woman with a hot, swollen, tender calf two days after a long-haul flight.
- A teenager with type 1 diabetes, abdominal pain, vomiting and deep sighing breathing.
- A young woman with six weeks of amenorrhoea, sudden left iliac fossa pain and shoulder-tip pain.
- A 4-year-old with fever, neck stiffness and a non-blanching purpuric rash.
- A 70-year-old with sudden painless loss of vision in one eye and a pale retina with a cherry-red spot.
- A 60-year-old with sudden tearing chest pain radiating to the back and unequal blood pressures in the arms.
- A student with a sore throat, fever, widespread lymphadenopathy and splenomegaly.
- A 72-year-old woman with a new temporal headache, scalp tenderness and jaw pain on chewing.
- A 2-year-old with five days of fever, red cracked lips, conjunctivitis, a rash and swollen hands.
- A 30-year-old with progressive ascending leg weakness and loss of reflexes after a recent diarrhoeal illness.
- A 45-year-old with a sudden severe headache that peaked within seconds and is the worst they have had.
- A neonate with bilious, green vomiting in the first days of life.
- A 75-year-old man with sudden back and abdominal pain, a pulsatile abdominal mass and low blood pressure.
- A 28-year-old woman with weight loss despite a good appetite, heat intolerance, palpitations and a fine tremor.
- An overweight 13-year-old with a limp and knee pain, holding the hip externally rotated.
- A 50-year-old man woken by severe pain, redness and swelling of the first metatarsophalangeal joint.
- A man with a history of heavy alcohol use presenting with confusion, unsteadiness and abnormal eye movements.
The answers
Try not to read these until you have committed to all 20.
- Testicular torsion. A surgical emergency: sudden pain with a high, horizontal testicle needs urgent exploration, not imaging delay.
- Croup (laryngotracheobronchitis). The barking cough and stridor worse at night are the giveaway in a young child.
- Lung cancer. Haemoptysis, weight loss and clubbing in an older smoker should prompt urgent investigation.
- Deep vein thrombosis. A unilateral hot, swollen, tender calf after immobility points here; assess and investigate appropriately.
- Diabetic ketoacidosis. Abdominal pain, vomiting and deep (Kussmaul) breathing in type 1 diabetes; check ketones and glucose.
- Ruptured ectopic pregnancy. Amenorrhoea plus iliac fossa and shoulder-tip pain is an emergency until excluded.
- Meningococcal sepsis. Fever, neck stiffness and a non-blanching purpuric rash demand immediate action.
- Central retinal artery occlusion. Sudden painless monocular visual loss with a cherry-red spot at the macula.
- Aortic dissection. Tearing chest pain to the back with unequal arm blood pressures.
- Infectious mononucleosis. Sore throat, lymphadenopathy and splenomegaly in a young adult; advise avoiding contact sport.
- Giant cell (temporal) arteritis. New temporal headache, scalp tenderness and jaw claudication; treat promptly to protect vision.
- Kawasaki disease. Five days of fever with mucocutaneous changes and swollen extremities in a young child.
- Guillain-Barré syndrome. Ascending weakness with absent reflexes after a recent infection.
- Subarachnoid haemorrhage. A thunderclap headache that peaks within seconds.
- Malrotation with volvulus. Bilious vomiting in a neonate is a surgical emergency until proven otherwise.
- Ruptured abdominal aortic aneurysm. Back and abdominal pain, a pulsatile mass and hypotension.
- Hyperthyroidism (Graves' disease). Weight loss with good appetite, heat intolerance, palpitations and tremor.
- Slipped upper femoral epiphysis. An adolescent, often overweight, with hip or referred knee pain and external rotation.
- Gout. Acute, severe pain and swelling of the first metatarsophalangeal joint.
- Wernicke's encephalopathy. The triad of confusion, ataxia and ophthalmoplegia with alcohol excess; give thiamine.
How to get a fresh case every day
A single set of vignettes is a snapshot. The skill is built by doing this little and often, so a new case each day is the habit that compounds. Play today's iatroX Rounds for a fresh UK-context case, work through the archive for more, and back it with the free question bank. For the method behind it, see our spot diagnosis guide.
Frequently asked questions
How do I use these clinical vignettes? Read each one-liner, commit to a single best diagnosis and name the discriminating clue, then check the answers. Reviewing the ones you miss, and why, is where the learning happens.
Are these UK exam relevant? Yes. They cover common presentations and can't-miss emergencies in a UK clinical context, the kind tested across UKMLA, PLAB, MRCP and MRCGP.
How can I practise diagnosis every day? A daily diagnostic case is the most efficient habit, because it forces retrieval and spaces practice across days. A free daily diagnosis game is an easy way to keep it consistent.
Should I focus on rare or common conditions? Mostly common ones, since common things are common, but include the dangerous can't-miss diagnoses. Several of the vignettes above are emergencies precisely because missing them matters.
Why commit before looking at the answer? Because generating the answer yourself (retrieval) builds memory far more effectively than recognising it once revealed. Guessing first, then checking, is the point.