Pediatrics
Age-appropriate differentials. Newborn vs infant vs toddler vs school-age vs adolescent. Developmental milestones. Vaccines and well-child care drive primary care questions.
Chief complaints
Vignettes enter through one of these doors. Each complaint lays out the full differential, marks the can't-miss diagnoses, and tells you the next right action for each.
Fever in children
Age divides the workup. Neonates get a full sepsis workup.
< 28 days: full sepsis workup (CBC, blood cx, urine, CSF, CXR if resp), admit, empiric antibiotics. 1–3 months: risk stratify (well-appearing, labs normal → may be outpatient with close follow-up). > 3 months: source-directed evaluation. Immunized children have very low risk of occult bacteremia.
| Diagnosis | Key features / clues | Next step |
|---|---|---|
| Neonatal sepsis | Any fever < 28 days. Or hypothermia, lethargy, poor feeding. | Full sepsis workup (blood + urine + CSF) · admit · empiric ampicillin + gentamicin (± acyclovir if HSV risk) |
| Meningitis | Fever + fontanelle bulging, irritability, poor feeding in infants. Neck stiffness in older children. | LP · empiric antibiotics (ceftriaxone + vanc ± ampicillin if young) + dexamethasone |
| Kawasaki disease | Fever > 5 days + 4 of 5: conjunctivitis, mucositis (strawberry tongue, cracked lips), rash, extremity changes (palmar erythema, desquamation), cervical lymphadenopathy. | IVIG + high-dose aspirin · echo (coronary aneurysms) |
| UTI | Often the only source in young children. Fever without localizing source. | Catheterized urine · antibiotics |
| Otitis media | Ear pain, fever, bulging red tympanic membrane, decreased mobility. | Amoxicillin (high-dose) · observation in select cases |
| Viral URI / roseola / fifth disease / hand-foot-mouth | Exam + age-typical rash patterns. | Supportive |
| Occult bacteremia | Fever without source in vaccinated child. Rare now post-HiB/Prevnar. | Observation if well-appearing · labs and treatment if concerning |
Rash
Age + distribution + associated features. Many are classic pattern recognition.
Vesicular (varicella, HSV, hand-foot-mouth), maculopapular (measles, rubella, roseola, erythema infectiosum), petechial/purpuric (HSP, ITP, meningococcemia, leukemia), urticarial, atopic.
| Diagnosis | Key features / clues | Next step |
|---|---|---|
| Meningococcemia | Fever, petechial/purpuric rash, rapidly progressive, shock. | Empiric ceftriaxone + vancomycin + isolation · cultures · LP when stable |
| HSP (IgA vasculitis) | Palpable purpura on buttocks/legs + abdominal pain + arthralgia + hematuria. Preceded by URI. | Supportive · monitor renal function · steroids for severe abdominal pain |
| Measles | Fever + 3 C's (cough, coryza, conjunctivitis) + Koplik spots + cephalocaudal maculopapular rash. | Supportive · vitamin A · report · airborne isolation |
| Varicella | Vesicles on erythematous base, in crops at different stages, pruritic. | Supportive if healthy · acyclovir for adolescents, immunocompromised, severe |
| Fifth disease (erythema infectiosum) | Slapped cheek + lacy reticular rash on trunk/extremities. Parvovirus B19. | Supportive · risks: aplastic crisis in sickle cell, hydrops in pregnancy |
| Hand-foot-mouth | Coxsackie A. Vesicles on palms, soles, oral mucosa. | Supportive |
| Atopic dermatitis | Chronic pruritic rash, flexural in older children, extensor in infants. Family history of atopy. | Emollients, low-potency topical steroids, avoid triggers |
Failure to thrive
Weight crosses 2 percentiles down. Inadequate intake, poor absorption, or increased demand.
Detailed feeding history is the highest-yield test. Labs as needed: CBC, BMP, UA, TSH, celiac serology, lead, sweat chloride. Observe a feed. Social work for psychosocial.
| Diagnosis | Key features / clues | Next step |
|---|---|---|
| Inadequate intake (most common) | Feeding errors, neglect, poverty, oromotor dysfunction. | Observed feed · nutritional counseling · social work |
| Malabsorption | Celiac, cystic fibrosis, lactose intolerance, chronic infection. | Celiac serology · sweat chloride · stool studies |
| Increased demand | Congenital heart disease, hyperthyroidism, chronic infection, malignancy. | Echo · TSH · CBC · directed workup |
| Gastroesophageal reflux | Spitting up, irritability, poor weight gain. | Feeding modifications · PPI trial if symptomatic |
Respiratory distress
Wheezing vs stridor differentiates upper from lower airway.
Stridor = upper airway (croup, epiglottitis, foreign body, vascular ring, laryngomalacia). Wheezing = lower airway (bronchiolitis, asthma, aspiration, bronchiolitis obliterans).
| Diagnosis | Key features / clues | Next step |
|---|---|---|
| Epiglottitis | Abrupt fever, drooling, dysphagia, tripod position, toxic appearance. Unvaccinated. Thumbprint sign on lateral neck X-ray. | Do NOT examine pharynx · take to OR for airway management · ceftriaxone |
| Foreign body | Sudden choking episode, unilateral wheeze or decreased breath sounds. | Inspiratory and expiratory films (air trapping on expiratory) · bronchoscopy |
| Anaphylaxis | Rapid onset, urticaria, wheezing, stridor, hypotension, known allergen. | IM epinephrine 0.01 mg/kg lateral thigh |
| Croup | 6 mo–3 yr, barking cough, stridor, fever. Steeple sign on AP neck X-ray. | Mild: cool mist, dexamethasone. Moderate-severe: dex + nebulized epinephrine |
| Bronchiolitis | < 2 yr, wheezing, URI prodrome, RSV. Winter. | Supportive: nasal suction, hydration, O2 if needed. No role for steroids or bronchodilators routinely |
| Asthma | Recurrent wheezing, atopic history, triggers. | Albuterol · steroids for exacerbation |
Disease deep dives
Once you've identified the likely diagnosis from the chief complaint, these pages give you the presentation, workup, management, and exam pearls in depth.
Bronchiolitis
RSV in infants. Hydration and oxygen. Steroids and bronchodilators mostly don't help.
< 2 years old. URI prodrome, then wheezing, tachypnea, retractions, feeding difficulty. Peak severity days 3–5.
- Clinical diagnosis. Typical age, typical presentation.
- RSV testing. Not required routinely but can guide cohorting.
- CXR. Not routine. Consider if fever, severe, or atypical.
- Supportive. Nasal suctioning, hydration, supplemental O2 to SpO2 ≥ 90%.
- HFNC. For severe respiratory distress. Reduces intubation rates.
- Not recommended. Bronchodilators, epinephrine nebs, steroids, antibiotics (unless bacterial superinfection), hypertonic saline.
- Palivizumab. Monthly RSV prophylaxis for very high-risk infants (extreme prematurity, hemodynamically significant CHD). Nirsevimab now available for most infants as single-dose prophylaxis.
Kawasaki Disease
Fever ≥ 5 days + 4 of 5 criteria. IVIG + aspirin. Watch coronaries.
Fever ≥ 5 days PLUS ≥ 4 of: bilateral non-exudative conjunctivitis, mucositis (cracked red lips, strawberry tongue), rash (polymorphous, not vesicular), extremity changes (palmar/plantar erythema, edema, later desquamation), cervical lymphadenopathy (≥ 1.5 cm, usually unilateral).
- Clinical diagnosis. No specific lab test. Labs: elevated ESR/CRP, thrombocytosis (second week), sterile pyuria, elevated LFTs.
- Echo. At diagnosis, 2 weeks, 6–8 weeks. Coronary aneurysms are the feared complication.
- IVIG. 2 g/kg over 10–12 hours. Within 10 days of fever onset, ideally within 7.
- Aspirin. High-dose (80–100 mg/kg/day) until afebrile, then low-dose (3–5 mg/kg/day) for 6–8 weeks (longer if aneurysms).
- Refractory. Persistent fever after IVIG, second IVIG dose or steroids or infliximab.
Henoch-Schönlein Purpura (IgA Vasculitis)
Palpable purpura, arthralgia, abdominal pain, hematuria. Usually self-limited. Watch kidneys.
Child 3–10 years, often post-URI. Palpable purpura on buttocks and extensor surfaces of lower extremities, arthralgia (knees, ankles), abdominal pain (intussusception risk), hematuria/proteinuria.
- Clinical. Palpable purpura plus one of: abdominal pain, IgA deposition on biopsy, arthritis/arthralgia, renal involvement.
- Renal workup. UA (hematuria, proteinuria), Cr, BP. Repeat for 6 months after resolution.
- Abdominal ultrasound. If severe pain, rule out intussusception.
- Supportive. Hydration, analgesia (acetaminophen). Most resolve in 4–6 weeks.
- Steroids. For severe abdominal pain, severe arthritis, nephritis.
- Follow-up. UA and BP monthly for 6 months. Nephritis can present late.
Pyloric Stenosis
Projectile non-bilious vomiting at 3–6 weeks. Olive-shaped mass, hypochloremic metabolic alkalosis.
First-born male, 3–6 weeks old. Projectile non-bilious vomiting after feeds. Hungry after vomiting. Visible peristalsis. Palpable olive in epigastrium.
- BMP. Hypochloremic, hypokalemic metabolic alkalosis (from vomiting HCl).
- Abdominal US. Muscle thickness > 3 mm, channel length > 14 mm.
- Fluid resuscitation. Correct electrolytes and acid-base BEFORE surgery.
- Pyloromyotomy. Definitive treatment. Excellent prognosis.
Intussusception
Telescoping bowel in 6 months–3 years. Currant jelly stool. Air or contrast enema is both diagnostic and therapeutic.
Episodic crampy abdominal pain with pain-free intervals, vomiting (may become bilious), currant jelly stool (late, from mucosal ischemia). Sausage-shaped mass RUQ, empty RLQ (Dance sign).
- Abdominal US. Target sign. First-line.
- Air or contrast enema. Diagnostic and therapeutic, reduces the intussusception in 70–80%.
- Enema reduction. Unless peritonitis or perforation suspected.
- Surgery. If enema fails, peritonitis, or recurrent.