Study guide
Pediatrics occupies a substantial share of the Step 2 CK outline (approximately 17-27% of items, subject to change by the testing organization), and it rewards a different kind of pattern recognition than adult medicine. Many vignettes are less about rare disease and more about knowing what is normal at a given age, so that abnormal findings stand out immediately. This chapter covers well-child care and health maintenance, common acute and chronic illnesses, neonatal care, and adolescent medicine, framed around AAP- and CDC-aligned guideline-level standards.
Growth Curves and Developmental Milestones
A large fraction of pediatric health-maintenance questions test whether you can recognize a growth or developmental pattern that has fallen off track. Growth is plotted on standardized curves for weight, length or height, and head circumference, and the exam expects you to notice a child crossing two or more major percentile lines downward as a red flag for failure to thrive, prompting a feeding and psychosocial history before extensive lab testing. Developmental milestones are typically grouped into gross motor, fine motor, language, and social domains. A rough framework: by 6 months, an infant sits with support and babbles; by 12 months, pulls to stand and says a few words; by 18 months to 2 years, walks well and combines two words; by 4 years, hops and speaks in full sentences understandable to strangers. The exam frequently uses a vignette like Baby Theo, who at 18 months is not yet walking and has only one or two words, to test recognition of global developmental delay, where the next best step is a structured developmental screening tool followed by referral for early intervention, not reassurance to simply wait and see. Isolated delay in a single domain (for example, a late walker who otherwise meets milestones) is more often a normal variant, while delay across multiple domains raises more concern. Vision and hearing screening, along with routine developmental screening at defined well-child visits, are part of the same health-maintenance framework the exam tests.
Immunizations and Health Maintenance
Immunization questions test whether you know the general schedule structure well enough to recognize a missed dose, a contraindication, or an appropriate catch-up strategy, rather than requiring you to memorize exact ages down to the week (the CDC schedule is revised periodically, so treat exact timing as approximate and defer to the current published schedule for precise ages). In broad strokes, the primary series for diphtheria-tetanus-pertussis, polio, Haemophilus influenzae type b, pneumococcal conjugate, rotavirus, and hepatitis B begins in early infancy with multiple doses in the first year, followed by boosters in the second year of life and again before school entry. Measles-mumps-rubella and varicella vaccines are generally first given around 12 months, with a second dose before school entry. The exam commonly tests contraindications: a moderate-to-severe acute illness postpones vaccination, but a mild cold with low-grade fever does not. Live vaccines such as MMR and varicella are generally avoided in significantly immunocompromised children and are used cautiously around pregnancy exposure in the household. Health-maintenance vignettes also test anticipatory guidance, such as counseling on safe sleep positioning to reduce sudden infant death syndrome risk (supine sleep, firm surface, no loose bedding), iron-fortified formula or iron supplementation for exclusively breastfed infants after about 4 to 6 months, and lead screening in children with risk factors for exposure. A well-child visit vignette that buries an immunization due date or a missed screening test among other distractors is testing whether you can extract the health-maintenance task the visit is actually for.
Common Acute and Chronic Childhood Illness
Respiratory illness vignettes test the ability to distinguish common, self-limited conditions from those needing urgent intervention. Bronchiolitis, typically caused by respiratory syncytial virus in infants under 2 years, presents with wheezing, tachypnea, and often a preceding upper respiratory prodrome; management is largely supportive (nasal suctioning, hydration, monitoring oxygenation), and the exam expects you to recognize that bronchodilators and antibiotics generally do not change the course of straightforward bronchiolitis. Croup presents with a barky cough and inspiratory stridor, worse at night, and mild cases respond to a single dose of corticosteroid, while stridor at rest warrants nebulized epinephrine and closer observation. Asthma in children follows the same stepwise severity assessment used in adults, with attention to how frequently a child needs rescue therapy to decide whether controller therapy should be added. Gastrointestinal vignettes often test dehydration assessment in a child with vomiting or diarrhea, where the next step depends on the degree of dehydration: mild-to-moderate dehydration is managed with oral rehydration, while severe dehydration with lethargy or hemodynamic compromise requires intravenous fluids. Congenital conditions appear as classic exam patterns, such as a newborn with bilious vomiting raising concern for malrotation with volvulus (a surgical emergency requiring urgent imaging and surgical consultation) versus a well-appearing infant with projectile non-bilious vomiting around 3 to 6 weeks of age suggesting pyloric stenosis, confirmed by ultrasound showing a thickened, elongated pylorus.
Neonatal Care
Neonatal vignettes test recognition of findings that are normal in the first days of life versus findings that require intervention. Physiologic jaundice, appearing after the first 24 hours and peaking around day 3 to 5, is common and generally benign, while jaundice appearing within the first 24 hours of life is never considered physiologic and should prompt urgent evaluation for hemolysis or other pathologic causes. Treatment decisions for significant hyperbilirubinemia are guided by age-in-hours-specific bilirubin thresholds (phototherapy for high levels, exchange transfusion for extreme levels), reflecting standardized nomograms rather than a single fixed number for all infants. Respiratory distress in a newborn raises a differential that includes transient tachypnea of the newborn (more common after cesarean delivery, generally resolving within a day or two), respiratory distress syndrome from surfactant deficiency (more common in preterm infants, presenting with grunting and retractions), and meconium aspiration syndrome (in infants born through meconium-stained fluid). The Apgar score, assessed at 1 and 5 minutes, is a quick summary of a newborn's transition rather than a diagnostic or prognostic tool on its own. Screening tests performed shortly after birth, including the newborn metabolic and hearing screens, are part of routine neonatal health maintenance, and an abnormal screen calls for confirmatory testing rather than immediate treatment in most cases. Necrotizing enterocolitis, presenting with feeding intolerance, abdominal distension, and bloody stools in a preterm infant, is a classic vignette testing recognition of a surgical emergency versus routine feeding intolerance.
Adolescent Medicine
Adolescent vignettes shift the focus toward confidentiality, puberty, and risk-screening conversations layered on top of standard illness presentations. The exam expects familiarity with the general sequence of pubertal development: in females, thelarche (breast budding) is typically the first sign, followed by pubarche and then menarche; in males, testicular enlargement is typically the first sign, followed by pubarche and growth spurt later than in females. A vignette describing a 13-year-old girl who has not yet had any breast development, or a 14-year-old boy with no testicular enlargement, is testing recognition of delayed puberty warranting further endocrine evaluation. Confidentiality is a recurring theme: an adolescent is generally entitled to confidential care for certain sensitive services, such as contraception, sexually transmitted infection testing and treatment, and substance use counseling, and the exam expects you to recognize that routine confidentiality can still be broken when there is risk of serious harm, such as active suicidality or evidence of abuse. Screening for depression, substance use, and risk behaviors using structured, validated tools is considered a standard part of adolescent health maintenance, tested through vignettes where a teenager's vague physical complaints are actually a presentation of an underlying mood or substance concern. Scoliosis screening, acne management, and counseling around safe driving and helmet use round out the health-maintenance content the exam associates with this age group.
Key terms
- Failure to thrive
- — Inadequate weight gain or growth in a child, often identified by crossing downward across major percentile lines on a growth curve.
- Global developmental delay
- — Significant delay across multiple developmental domains (gross motor, fine motor, language, social), warranting screening and early intervention referral.
- Anticipatory guidance
- — Preventive counseling given at well-child visits about upcoming developmental, safety, and health issues before they arise.
- Bronchiolitis
- — A viral lower respiratory infection, commonly from RSV, causing wheezing and tachypnea in infants, managed mainly with supportive care.
- Croup
- — A viral upper airway infection causing a barky cough and inspiratory stridor, treated with corticosteroids and, if severe, nebulized epinephrine.
- Pyloric stenosis
- — Hypertrophy of the pyloric muscle causing projectile, non-bilious vomiting in early infancy, diagnosed by ultrasound.
- Malrotation with volvulus
- — A congenital bowel rotation abnormality that can twist and obstruct blood flow, presenting with bilious vomiting and requiring emergent evaluation.
- Physiologic jaundice
- — Common, benign newborn jaundice appearing after 24 hours of life and peaking around day 3 to 5; jaundice in the first 24 hours is not physiologic.
- Necrotizing enterocolitis
- — A serious intestinal condition mainly in preterm infants, presenting with feeding intolerance, distension, and bloody stools.
- Thelarche
- — Breast budding, typically the first physical sign of puberty in females.
- Adolescent confidentiality
- — The principle that teens generally receive confidential care for sensitive services, with exceptions for serious safety risks such as suicidality or abuse.
Exam tips
- Anchor every pediatric vignette to the child's age first; the same finding (vomiting, a murmur, a rash) means different things at different ages.
- When a stem gives an immunization or screening history buried among other details, check it against expected health-maintenance timing before answering.
- Distinguish red-flag jaundice (first 24 hours of life) from common physiologic jaundice (after 24 hours) as a fast way to sort emergent from routine cases.
- For adolescent vignettes, default to confidentiality unless the stem clearly signals danger to the patient or others.
- Treat exact immunization ages and bilirubin thresholds as guideline-based and subject to periodic revision; focus on the pattern of reasoning rather than memorizing every number to the week.