Global Primary Care

Diagnostic reasoning cases

Diagnostic reasoning cases for first-level care. Each one starts from a symptom, not a diagnosis, and works through it one question at a time with only the simplest tests. Decide your own answer before you open the model answer; the differential updates as you go. The must-not-miss conditions and the decision to treat, observe or refer come at the end.

WHO Basic Emergency Care and MCPCAbdominal pain in an adultA young woman who fainted with lower abdominal pain: shock recognised early, the pregnancy test that changes everything, signs of a surgical abdomen, and an immediate transfer.Open WHO Basic Emergency CareAn adult who is short of breathA woman seven weeks after giving birth, breathless and pale: an ABCDE start, the history and signs that sort lung, heart and blood causes, two bedside tests, and an urgent referral done safely.Open WHO Basic Emergency Care and HEARTSChest pain in an adultA man with an hour of crushing chest pain and no ECG: the ABCDE start, the history that separates heart, lung, aorta and gut, the aspirin decision, and an immediate transfer.Open WHO Basic Emergency Care and mhGAPAn older adult who is confusedA 79-year-old woman, confused for two days: glucose first, the questions that separate delirium from dementia, a medicine that made it worse, signs of sepsis, and an immediate referral.Open WHO IMCI and Pocket book of hospital care for childrenA child who had a fitA 2-year-old with fever who had a fit at home and now seems better: why a convulsion in this illness is a danger sign, the bedside checks for low sugar, malaria and meningitis, and pre-referral treatment.Open WHO IMCICough and fast breathing in a toddlerA girl of 18 months with cough and fever: counting breaths properly, the signs that make pneumonia severe, a pulse oximeter, and amoxicillin at home with a 3-day review.Open WHO consolidated TB and HIV guidelines and WHO PENCough for three weeksA man with a cough that will not go away: when a cough is presumptive TB, what to ask and look for, which samples and tests to arrange, and why HIV changes the plan.Open WHO diarrhoea treatment guidelines and SphereAcute watery diarrhoea in a cholera outbreakA man in a displacement camp with rice-water stools during a declared cholera outbreak: the dehydration assessment, oral rehydration by weight, when to switch to IV fluids and antibiotics, and protecting everyone else.Open WHO IMCIDiarrhoea and vomiting in a babyA 10-month-old with two days of watery diarrhoea and vomiting: the four signs that grade dehydration, Plan B in the clinic over four hours, zinc, and the reassessment that decides home or referral.Open WHO malaria guidelines and Basic Emergency CareFever in an adultA young woman with three days of fever in a malaria area: triage, the questions that matter, one rapid test, and the decision to treat at the health centre.Open WHO maternal health: PCPNC and MCPCFever after childbirthA woman five days after a long labour at home, with fever, abdominal pain and foul-smelling lochia: spotting organ dysfunction, finding the source, first-dose antibiotics and fluids, and an urgent transfer with her baby.Open WHO IMCIFever in a 3-year-oldA boy of three with two days of fever in a high malaria area: the IMCI danger-sign check, the questions and signs that find a cause, a malaria test, and treatment at the health centre.Open WHO HEARTS, IMAI and meningitis guidelinesHeadache in an adultA woman with five days of headache and blurred vision: the questions that find meningitis, a bleed or pre-eclampsia, a blood pressure of 186/118, and a same-day referral.Open WHO maternal health: MCPC and pre-eclampsia recommendationsHeadache in late pregnancyA first pregnancy at 35 weeks with a headache that will not go and blurred vision: two blood pressure readings, a urine dipstick, the signs of severe pre-eclampsia, magnesium sulfate and a safe urgent transfer.Open WHO IMAI and hepatitis guidanceJaundice in an adultA man with yellow eyes and dark urine after a week of feeling unwell: sorting hepatitis, malaria, alcohol, medicines and obstruction at the bedside, the signs of liver failure, and safe care at home.Open WHO rheumatic fever guideline and IMAIJoint pain in a young adultA 19-year-old with fever and swollen joints that move from one to the next, three weeks after a sore throat: septic arthritis, gonococcal arthritis and rheumatic fever compared, a new murmur, and a same-day referral.Open WHO mhGAPLow mood and poor sleepA woman who asks for sleeping tablets: the mhGAP questions that find depression behind the sleep problem, asking about suicide, ruling out physical causes and bipolar disorder, and a treatment plan at the health centre.Open WHO IMCI and sickle-cell disease guidelineA pale childA 3-year-old who is pale again after two courses of iron: palmar pallor and haemoglobin, ruling out malaria and worms, the history that points to sickle cell disease, and a planned referral for diagnosis.Open WHO IMCI (young infant)A newborn who is not feeding wellA 3-week-old whose mother says she is not feeding well: sorting a sign of serious infection from a feeding problem by watching a breastfeed, and treating the feeding problem, thrush and low weight at home.Open WHO IMCI and Pocket book of hospital care for childrenFever and rash in a childA 4-year-old with fever and a new rash during a measles outbreak: what makes a rash measles, the glass-or-finger test for a rash that does not fade, and why a drowsy child with purpura is treated and sent at once.Open WHO IMAI and PENSwollen legsA young woman with three weeks of swollen legs and a puffy face: one leg or two, heart, kidney, liver or pregnancy, a dipstick showing heavy protein, and a planned referral for kidney assessment.Open WHO IMCI, wasting guideline, TB and HIV guidelinesA child who is not growingA 2-year-old who is thin and has stopped growing: MUAC and the appetite test, the clues to HIV and TB behind the malnutrition, testing mother and child, and a same-day referral after starting care.Open WHO MCPC and PCPNCBleeding in pregnancyA woman at 32 weeks with painless bright red bleeding: why there is no vaginal examination, the signs that separate placenta praevia, abruption and uterine rupture, and an immediate transfer done safely.Open WHO PEN, HEARTS-D and TB screening guidelinesWeight loss in an adultA man who has lost 10% of his weight in three months: TB, HIV, diabetes and cancer each considered in turn, three bedside tests, and treatment started at the health centre.Open

Adapted from WHO guidance; not endorsed by WHO. This page paraphrases and adapts the WHO publications listed under Sources, which are licensed CC BY-NC-SA 3.0 IGO; the adapted text is shared under the same licence for non-commercial education. Reasoning GP is not affiliated with WHO or any other organisation named here. Use it alongside your national guidelines, essential medicines list and formulary, and your clinical judgement. Doses are given only where they come from a WHO source; otherwise follow your national guideline or formulary.