Rapid review: paediatrics

• This page is a last-minute revision sheet for paediatrics: each block states the presenting picture, the single most likely diagnosis, the best first test, the best first treatment, the common trap, and where the full MedGrasp topic lives.
• Fever in a baby under 3 months is a serious illness until proved otherwise. The NICE traffic-light table and the age-and-temperature rules drive admission, investigation and antibiotics.
• Respiratory distress in an infant is bronchiolitis until the age and voice say otherwise: croup in a toddler with a barking cough, epiglottitis only when drooling and stridor meet a toxic child, asthma in the older wheezy child.
• Two numbers save lives in bronchiolitis: oxygen starting under 90% (92% in babies under 6 weeks or with comorbidity) and a policy of doing nothing else. ^[2]
• Pyloric stenosis is non-bilious projectile vomiting in a 2 to 8 week old with a metabolic alkalosis; intussusception is intermittent colicky pain with vomiting and "redcurrant jelly" stool. ^[7]
• Development comes in domains and milestones, not just "late"; a baby who does not sit by 9 months or walk by 18 months needs assessment, not reassurance.
• A non-blanching rash in a febrile child is meningococcal disease until proved otherwise: give benzylpenicillin (or ceftriaxone) and move. ^[9]
• Infants with Down syndrome, Noonan syndrome or suspected congenital heart disease share cyanosis, failure to thrive or a murmur as their first clue.
• In the newborn, jaundice in the first 24 hours is pathological, temperature control prevents hypoglycaemia, and early-onset infection drives empiric antibiotics.

By the end of this page you should be able to:

1. Risk-stratify a febrile infant and choose the tests and antibiotics the risk group demands.
2. Distinguish bronchiolitis, croup, epiglottitis and asthma by age, sound and posture.
3. Recognise pyloric stenosis and intussusception from the history and bedside findings.
4. Quote the key developmental red flags and say when delay needs referral.
5. Treat a feverish child with a non-blanching rash as an emergency.
6. List the common genetic syndromes and congenital heart lesions that present in infancy.
7. Outline the first steps in the major newborn problems.

A baby aged 1 to 3 months with a temperature of 38 degrees C or higher sits in the NICE high-risk group for serious illness; under 3 months any 38 degrees C is high risk, and 3 to 6 months at 39 degrees C or higher is at least intermediate risk. ^[1] The temperature is the entry point, but the decision rests on the traffic-light table of signs (look, activity, circulation, hydration, breathing), not on the thermometer alone. ^[1]

Presenting picture: a previously well infant with fever and no obvious focus; poor feeding, irritability, grunting or lethargy are the clues that move them from green to amber or red.

Most likely diagnosis: a viral illness is the commonest cause at this age, but urinary tract infection, bacteraemia, pneumonia and (under 1 month) early-onset infection dominate the serious list.

Best first test: urinalysis and urine culture in every febrile infant; full blood count and C-reactive protein for the amber or red groups; lumbar puncture without delay when meningitis is possible, ideally before antibiotics. ^[1] Chest X-ray only when respiratory signs are present. ^[1]

Best first treatment: infants under 3 months suspected of serious bacterial illness receive a third-generation cephalosporin (cefotaxime or ceftriaxone) plus an antibiotic active against listeria, such as ampicillin or amoxicillin, given parenterally. ^[1] Suspected meningococcal disease gets benzylpenicillin or a third-generation cephalosporin at the earliest opportunity. ^[1]

Commonest wrong answer: prescribing oral antibiotics for a fever without apparent source, or treating the fever with antipyretics and assuming the fall in temperature rules out serious illness. ^[1]

Full topic: paediatrics/infant-fever.

The age of the child, the quality of the sound and the posture sort these four out. Bronchiolitis is the default in winter infants under 1 year; croup is a toddler's barking cough; epiglottitis is a medical emergency of drooling, dysphagia and muffled voice; asthma is a wheezy child old enough to have recurrent attacks.

Bronchiolitis is a clinical diagnosis in a baby under 12 months, usually between November and March, with a prodrome of coryza followed by respiratory distress. ^[2] Measure oxygen saturation in every baby who presents, including in primary care if a pulse oximeter is available. ^[2]

Presenting picture: dry cough, poor feeding taking under half to three-quarters of the usual milk volume, tachypnoea, intercostal recession, wheeze and fine crackles; illness peaks mid-course. ^[2]

Most likely diagnosis: respiratory syncytial virus (RSV) bronchiolitis, though rhinovirus and other viruses are common.

Best first test: pulse oximetry; do not routinely perform blood tests, a chest X-ray or blood gases. ^[2] Chest X-ray changes can mimic pneumonia and should not trigger antibiotics. ^[2]

Best first treatment: oxygen supplementation if saturation is persistently under 90% in children aged 6 weeks and over, or under 92% in babies under 6 weeks or in children with underlying conditions; feed support by mouth, nasogastric or orogastric tube; and nothing else. ^[2] Do not use antibiotics, hypertonic saline, nebulised adrenaline, salbutamol, montelukast, ipratropium or corticosteroids. ^[2] Consider CPAP for impending respiratory failure. ^[2]

Commonest wrong answer: treating the wheeze with bronchodilators or steroids; prescribing antibiotics because the chest X-ray looks like pneumonia.

Full topic: paediatrics/bronchiolitis.

Croup is a viral illness of the subglottic airway producing the characteristic barking cough, hoarseness and stridor, worse at night. It is usually self-limited. Racemic adrenaline by nebuliser gives rapid relief in severe stridor at rest.

Presenting picture: a toddler with a coryza prodrome, then a barking cough, stridor and hoarseness; often better during the day and worse at night.

Most likely diagnosis: viral croup (parainfluenza most often).

Best first test: none in straightforward cases; keep the child calm and undisturbed.

Best first treatment: a single oral dose of dexamethasone, 0.15 to 0.6 mg/kg, is the standard; the lower dose has shown comparable outcomes in mild to moderate disease. ^[3] Reserve nebulised adrenaline (epinephrine) for stridor at rest or severe distress, with observation afterwards because rebound can occur.

Commonest wrong answer: reaching for antibiotics or repeated doses of steroids, and distressing the child with unnecessary examination.

Full topic: paediatrics/croup.

Epiglottitis is now rare since Hib vaccination, but non-typeable Haemophilus influenzae and other organisms still cause it. ^[4] It remains a threat to the airway.

Presenting picture: a toxic febrile child, often older than the croup child, with sudden onset of sore throat, dysphagia, drooling, a muffled voice, stridor and tripod posture. ^[4]

Most likely diagnosis: acute epiglottitis, usually bacterial.

Best first test: clinical diagnosis; a lateral neck X-ray shows the "thumbprint" sign when the airway is stable, but imaging must not delay treatment. ^[4] Blood culture after the airway is secured confirms the organism. ^[4]

Best first treatment: high-flow oxygen with the child kept as calm as possible, plus urgent airway control by an anaesthetist and ear, nose and throat surgeon in theatre (intubation or tracheostomy). After that, intravenous ceftriaxone, with or without clindamycin. ^[4] Nebulised adrenaline and corticosteroids have been used adjunctively. ^[4]

Commonest wrong answer: looking at the throat or taking blood before the airway is safe, which can precipitate complete obstruction.

Full topic: paediatrics/epiglottitis.

Acute asthma in children is treated as soon as it is recognised, with severity based on work of breathing, saturation and peak flow rather than on the wheeze alone.

Presenting picture: wheeze, cough, breathlessness and chest tightness in a school-age or younger child, often nocturnal, with variability; viral infections and poor adherence are common triggers.

Most likely diagnosis: an acute asthma exacerbation.

Best first test: pulse oximetry and peak expiratory flow measurement; arterial blood gas only in severe or critical disease.

Best first treatment: oxygen to relieve hypoxaemia, repeated inhaled salbutamol (beta-agonist) bronchodilation, and an early oral or intravenous corticosteroid; ipratropium bromide and IV magnesium sulphate are added in more severe attacks. ^[5]

Commonest wrong answer: reaching for antibiotics for "bronchitis" or giving sedatives or cough suppressants.

Full topic: paediatrics/asthma.

Two patterns dominate vomiting in infancy. Pyloric stenosis produces non-bilious projectile vomiting at every feed with weight loss at 2 to 8 weeks of age. Intussusception produces intermittent colicky abdominal pain with vomiting and often "redcurrant jelly" stool in toddlers. ^[7]

Infantile hypertrophic pyloric stenosis causes gastric outlet obstruction. ^[6]

Presenting picture: a full-term baby, usually 2 to 8 weeks old, with non-bilious projectile vomiting after feeds that becomes worse over days, hunger after vomiting, constipation and visible gastric peristalsis; the child remains eager to feed. ^[6]

Most likely diagnosis: infantile hypertrophic pyloric stenosis.

Best first test: abdominal ultrasound, showing a thickened pyloric muscle (about 4 mm) and a lengthened pyloric canal (about 19 mm); an "olive" may be palpable under the liver. ^[6] Bloods show a hypochloraemic, hypokalaemic metabolic alkalosis from loss of gastric acid. ^[6]

Best first treatment: correct dehydration and the electrolyte abnormality first, then surgical pyloromyotomy (open Ramstedt or laparoscopic). ^[6]

Commonest wrong answer: operating before the chloride and potassium are corrected, and mistaking bilious vomiting (which points to obstruction distal to the ampulla of Vater) for pyloric stenosis.

Full topic: paediatrics/pyloric-stenosis.

Intussusception is telescoping of one segment of bowel into another and is the commonest cause of intestinal obstruction in young children. ^[7]

Presenting picture: sudden episodic colicky abdominal pain with the child drawing up the knees and screaming, with periods of normality between; vomiting, and often a red "redcurrant jelly" stool later. An abdominal mass may be felt and the right lower quadrant can feel empty. ^[7] In one clinical series, abdominal pain occurred in 80% of children, vomiting in 68% and a palpable abdominal mass in 68%. ^[7]

Most likely diagnosis: idiopathic ileocolic intussusception.

Best first test: abdominal ultrasound, which has high sensitivity and specificity and avoids ionising radiation; it shows the "target" or "doughnut" sign. ^[7]

Best first treatment: image-guided non-operative reduction (pneumatic or hydrostatic enema), which carries high success rates in the absence of perforation or peritonitis; surgery is for failed or complicated cases. ^[7]

Commonest wrong answer: barium or air enema in a child with peritonitis or shock, and confusing the episodic pain with "simple colic".

Full topic: paediatrics/intussusception.

Development must be assessed by domain: gross motor, fine motor, language, and social and adaptive. A child is delayed when they fall behind expected milestones; a red flag is worse, because it is a specific absence at an age where almost every child has the skill.

Red flags that should prompt assessment: ^[8]

• Social: no social smile, poor eye contact and failure to share attention.
• Language: no babbling at 9 to 12 months, no meaningful words by 15 to 18 months, no joining of two words by 24 months.
• Motor: not sitting without support by 9 months, no pincer grasp by 10 months, asymmetrical movements, not walking independently by 18 months. ^[8]

Presenting picture: the parent says the child is "not keeping up", "flappy", or "doesn't listen"; the examination shows delay confined to one domain or global.

Most likely diagnosis: global developmental delay, speech and language delay, motor delay from cerebral palsy, or autism spectrum disorder, each with its own pattern.

Best first test: structured developmental assessment (for example, Bayley scales or the age-appropriate screen), hearing and vision testing, and first-line investigations guided by the pattern (brain MRI if motor or neurological signs, genetic testing if syndromic features).

Best first treatment: early intervention services (speech and language therapy, physiotherapy, occupational therapy), plus treatment of any underlying condition such as hypothyroidism.

Commonest wrong answer: reassuring the family that "boys are late" without a proper assessment, or testing the blood without first testing hearing.

Full topic: paediatrics/developmental-delay.

Rapid pattern recognition is the skill here. A feverish child with a non-blanching petechial or purpuric rash is meningococcal disease until shown otherwise. ^[9] The non-blanching rash may start as a blanching erythema and the whole body, including the nappy area and conjunctivae, must be examined. ^[9]

Presenting picture: a febrile unwell child with an evolving rash of any kind.

Most likely diagnosis: a viral exanthem (measles, rubella, varicella, roseola, parvovirus B19 "slapped cheek", hand-foot-and-mouth disease) for the well child; bacterial (meningococcal, scarlet fever) for the ill one.

Best first test: clinical diagnosis; if meningococcal disease is suspected, lumbar puncture is considered only when safe, and blood cultures are taken; the rash itself is a sign, not a test.

Best first treatment: suspect meningococcal disease when there is a haemorrhagic non-blanching rash with lesions larger than 2 mm, a rapidly spreading non-blanching rash, or any features of bacterial meningitis combined with a non-blanching rash; give intravenous or intramuscular ceftriaxone or benzylpenicillin as soon as possible, unless it delays transfer, and move to hospital. ^[9] Do not delay transfer to give antibiotics when transfer will be quick. ^[9]

Commonest wrong answer: passing off a meningococcal rash as a viral exanthem or Henoch-Schonlein purpura, or failing to re-examine a blanching rash.

Full topic: paediatrics/childhood-infections.

Recognising the common syndromes early channels the child into appropriate screening and family support.

• Down syndrome (trisomy 21): hypotonia, upslanting palpebral fissures, single palmar crease, congenital heart disease (especially atrioventricular septal defect), and feeding difficulties; screen for cardiac lesions, thyroid dysfunction, hearing and vision.
• Turner syndrome (45,X): short stature, webbed neck, lymphoedema of the hands and feet in the newborn, coarctation of the aorta; check karyotype in a female infant with lymphoedema.
• Noonan syndrome: pulmonary valve stenosis, short stature, hypertelorism, pectus excavatum; overlapping with Turner phenotype but with cardiac lesions of the right heart.
• Marfan syndrome: tall habitus, arachnodactyly, lens dislocation, aortic root dilatation and mitral valve prolapse; family screening and echocardiography.
• DiGeorge (22q11.2 deletion) syndrome: conotruncal heart defects, hypocalcaemia, immune deficiency and palate abnormalities; a clue is a neonate with cardiac disease and hypocalcaemic seizures.

Presenting picture: dysmorphism, growth or developmental delay, cardiac anomaly, or a predictable pattern recognised at birth or later.

Most likely diagnosis: a chromosomal or monogenic syndrome; Down syndrome is the commonest identifiable one.

Best first test: karyotype or microarray for suspected chromosomal disorders; targeted gene testing or echocardiography and endocrine screening as the phenotype dictates.

Best first treatment: there is none that cures the syndrome; management is surveillance, early intervention, family counselling and treatment of complications.

Commonest wrong answer: anchoring on one feature (for example, hypotonia alone) without looking for the associated heart lesion or hypocalcaemia; and assuming a normal screening scan excludes Down syndrome.

Full topic: paediatrics/genetic-syndromes.

The NICE guidance on when to suspect maltreatment (last updated December 2025) gives age-specific alerting features; the safeguarding response depends on the combination of features rather than any single finding. ^[10]

Presenting picture: an injury whose explanation is inconsistent with the child's age or development, unwitnessed, delayed, or changing; bruising in a non-mobile infant; multiple injuries at different stages; burns with a glove or stocking distribution; oral, genital or anal injuries.

Most likely diagnosis: accidental injury where the story fits the development of the child; consider physical abuse when it does not. ^[10]

Best first test: careful documentation of the injury with measurements or photographs; skeletal survey when occult fractures are suspected, and CT of the head if neurological signs; blood tests for bleeding or metabolic disorders where appropriate, with a low threshold for discussion with child protection services. ^[10]

Best first treatment: ensure immediate safety, admit or keep in hospital if needed, and involve paediatric and safeguarding teams and, in the United Kingdom, social care from the outset. ^[10]

Commonest wrong answer: performing a long series of coagulation tests to "explain" a pattern that is not compatible with the history, or discharging a non-mobile infant before safeguarding is arranged.

Full topic: paediatrics/child-abuse.

Congenital heart disease presents in three common ways: a murmur on examination, heart failure (poor feeding, breathlessness, sweating, failure to thrive), or cyanosis (blue lips and tongue, worse with crying).

Acyanotic lesions with left-to-right shunting: ventricular septal defect (most common), atrial septal defect, patent ductus arteriosus, and atrioventricular septal defect, which is closely linked to Down syndrome. These are loud in infancy and may develop pulmonary hypertension if large.

Obstructive (acyanotic) lesions: coarctation of the aorta (check femoral pulses), pulmonary and aortic stenosis.

Cyanotic lesions: tetralogy of Fallot (the commonest cyanotic lesion, with a murmur and "tet spells"), transposition of the great arteries (cyanosis from birth, not improved by oxygen), and tricuspid atresia. Transposition in particular needs an urgent balloon atrial septostomy to allow mixing.

Presenting picture: a newborn or infant with cyanosis, a murmur, heart failure or circulatory collapse, sometimes precipitated by duct closure in the first weeks of life (coarctation, hypoplastic left heart).

Most likely diagnosis: depends on the clinical picture; coarctation should be suspected in any infant with weak or absent femoral pulses, and transposition in any cyanotic newborn.

Best first test: pulse oximetry (pre- and post-ductal) and a chest X-ray; echocardiography by a paediatric cardiologist confirms the lesion.

Best first treatment: stabilise with oxygen, prostaglandin E1 infusion to keep the ductus arteriosus open in duct-dependent lesions, and diuretics or inotropes for heart failure while arranging definitive surgery or catheter intervention. ^[5]

Commonest wrong answer: giving oxygen alone for transposition (it does not help), and forgetting to check femoral pulses.

Full topic: paediatrics/congenital-heart-disease.

Jaundice in the first 24 hours of life is pathological until proved otherwise and needs urgent bilirubin measurement within 2 hours, then every 6 hours until the level is below the treatment threshold and stable or falling. ^[11] After 24 hours, babies who are visibly jaundiced should have their bilirubin measured within 6 hours, and transcutaneous bilirubinometry is acceptable under 250 micromol per litre. ^[11] Factors that increase the risk of severe jaundice include prematurity, blood group incompatibility, infection and bruising. ^[11]

Presenting picture: yellow staining of the sclerae and skin, with pale stools or dark urine in prolonged jaundice.

Most likely diagnosis: physiological jaundice in term infants from day 2 or 3; pathological if onset under 24 hours or conjugated (direct) bilirubin is predominant.

Best first test: serum bilirubin with maternal and baby blood groups, direct antiglobulin test, and FBC; ultrasound or infection screening if cholestasis is suspected.

Best first treatment: phototherapy according to gestation- and age-based thresholds; intravenous immunoglobulin for significant rhesus or ABO incompatibility; exchange transfusion when levels are at or above the exchange threshold. ^[11]

Commonest wrong answer: using the visual colour of the skin to guess the bilirubin in darker-skinned babies, or forgetting to check a direct bilirubin and urine when jaundice is prolonged.

Full topic: paediatrics/neonatal-jaundice.

Early-onset neonatal infection presents with non-specific signs (temperature instability, poor feeding, tachypnoea, hypotonia) early in life and is often related to Group B streptococcus, Escherichia coli and Listeria. ^[12] Risk factors include maternal fever or chorioamnionitis, prolonged rupture of membranes and preterm birth. Presenting picture: an unwell newborn with subtle, multi-system deterioration; temperature may be low rather than high.

Most likely diagnosis: early-onset bacterial sepsis or meningitis.

Best first test: blood culture (and lumbar puncture if meningitis is suspected), full blood count, C-reactive protein, together with a chest X-ray if respiratory signs are present.

Best first treatment: prompt empiric intravenous antibiotics, chosen and dosed by weight and gestation according to local guidance, without waiting for culture results in an unwell baby. ^[12]Commonest wrong answer: waiting for a confirmed culture before starting antibiotics in an unwell neonate; relying on a normal temperature to exclude infection.

Full topic: paediatrics/neonatal-infection.

Respiratory distress syndrome from surfactant deficiency is the commonest breathing problem of preterm infants, worsening over the first hours of life with grunting, nasal flaring and recession. Transient tachypnoea of the newborn, meconium aspiration and persistent pulmonary hypertension are the main differentials.

Presenting picture: preterm or late-preterm baby with progressive tachypnoea, hypoxaemia and poor inflation on chest X-ray showing a "ground glass" pattern and air bronchograms.

Most likely diagnosis: respiratory distress syndrome.

Best first test: chest X-ray and arterial blood gas.

Best first treatment: early continuous positive airway pressure; surfactant replacement (endotracheal) for significant disease; gentle ventilation strategies to avoid lung injury.

Commonest wrong answer: over-oxygenating or over-ventilating a preterm baby and causing retinopathy of prematurity or bronchopulmonary dysplasia.

Full topic: paediatrics/respiratory-distress-syndrome.

A cold baby becomes hypoglycaemic; an unwell or small-for-gestational-age baby can be hypoglycaemic without warning.

Presenting picture: jitteriness, hypotonia, poor feeding, apnoea or seizures in a neonate.

Most likely diagnosis: neonatal hypoglycaemia.

Best first test: point-of-care blood glucose (whole blood), with laboratory confirmation.

Best first treatment: oral or nasogastric glucose gel or feed; intravenous glucose if the baby is unwell, symptomatic, or unable to feed.

Commonest wrong answer: letting the baby sleep through the night without feeding in the first days if small or at risk.

Full topic: paediatrics/neonatal-hypoglycaemia.

• A baby under 3 months with a temperature of 38 degrees C or more is a suspect serious illness; risk stratify with the NICE traffic-light table and investigate and treat by risk group, not by temperature alone. ^[1]
• Bronchiolitis: oxygen only under 90% (92% under 6 weeks or with comorbidity) and supportive care; do not give bronchodilators, steroids, antibiotics, hypertonic saline, adrenaline or routine chest X-ray. ^[2]
• Croup: a single oral dose of dexamethasone 0.15 to 0.6 mg/kg; nebulised adrenaline for stridor at rest. ^[3]
• Epiglottitis is an airway emergency: keep the child calm, secure the airway in theatre, then give intravenous antibiotics; never look in the throat first. ^[4]
• Acute asthma: oxygen, salbutamol and an early systemic corticosteroid, with ipratropium and magnesium for more severe disease. ^[5]
• Pyloric stenosis: 2 to 8 week old baby, non-bilious projectile vomiting, hypochloraemic hypokalaemic metabolic alkalosis, ultrasound diagnosis, pyloromyotomy after rehydration. ^[6]
• Intussusception: episodic colicky pain, vomiting, redcurrant-jelly stool, ultrasound target sign, enema reduction if no peritonitis. ^[7]
• Red flags for developmental delay: not sitting by 9 months, no words by 15 to 18 months, not walking by 18 months. ^[8]
• A febrile child with a non-blanching rash gets ceftriaxone or benzylpenicillin immediately and transfer to hospital. ^[9]
• Child maltreatment suspicion is driven by injuries inconsistent with age or development, bruising in non-mobile infants and burns with an unusual distribution, all requiring safeguarding. ^[10]
• Jaundice under 24 hours old is pathological; use serum bilirubin, gestation-based phototherapy thresholds and exchange transfusion when needed. ^[11]
• Early-onset neonatal infection has non-specific signs and risk factors that drive early empiric benzylpenicillin and gentamicin. ^[12]- Congenital heart disease presents with murmur, heart failure or cyanosis; keep the duct open with prostaglandin E1 in duct-dependent lesions and arrange paediatric cardiology review.