USMLE Step 3 Medical Prep practice questions and answers 2026. Tap an option to test yourself — you'll see the correct answer and a plain-English explanation for every question. Free, no login.
Q11A 20-month-old boy is brought to the office for a routine well-child visit. The parents express concern that he is not yet speaking in two-word phrases like his older sibling did at this age. Developmental surveillance at previous visits showed age-appropriate gross motor and social skills. The child makes good eye contact, points to objects of interest, and engages in pretend play. Physical examination shows no abnormalities. Hearing screening at 12 months was normal. The physician administers a standardized developmental screening tool, which yields scores within normal limits for all domains. However, the parents remain concerned about the language delay. Which of the following is the most appropriate next step in management? Age (months) Recommended Screening Action if Concern Present 9 General developmental surveillance Document, educate, follow-up 18 General developmental + autism-specific (M-CHAT) Refer to early intervention if delays; repeat autism screen at 24 months 24 General developmental + autism-specific (M-CHAT) Refer to early intervention and audiology if speech delay; developmental pediatrics if red flags 30 General developmental surveillance Refer as indicated by findings
✓ Correct answer: D. Refer to early intervention services and audiology for hearing evaluation
Despite normal screening scores, parental concern about language development warrants action. Guidelines recommend referral to early intervention (IDEA Part C for children under 3) and audiology evaluation when speech or language delays are present, even if autism-specific screening is normal. Early intervention does not require a diagnosis. Distractor 1 delays necessary evaluation. Distractor 2 is premature without hearing and developmental assessments. Distractor 3 ignores valid parental concern. Distractor 4 inappropriately delays referral pending further observation.
Q12A 30-month-old girl is brought to the office because her parents noticed that over the past 2 months she has stopped using the 10–15 words she previously spoke consistently. She previously responded to her name and waved goodbye but no longer does so. She was walking independently at 14 months but now has an unsteady gait. Growth parameters show weight and height at the 40th percentile, unchanged from prior visits. Temperature is 37.0°C (98.6°F), pulse is 110/min, and blood pressure is 95/60 mm Hg. Physical examination shows mild hypotonia and intermittent hand-wringing movements. The child does not make eye contact during the examination. Which of the following is the most appropriate next step in management?
✓ Correct answer: A. Urgent referral to pediatric neurology for evaluation of regression
Loss of previously acquired skills (regression) is a red flag requiring urgent multidisciplinary evaluation by developmental pediatrics or neurology. This child demonstrates regression in language, social skills, and motor function, plus abnormal movements—concerning for neurodevelopmental or neurometabolic disorders. Regression takes priority over additional screening. Distractor 1 inappropriately delays evaluation. Distractor 2 addresses only one aspect. Distractor 3 is insufficient for regression. Distractor 4 uses an autism screen when neurological evaluation is more urgent.
Q13A 13-year-old girl comes to the office for a health maintenance visit. She has no chronic medical conditions and takes no medications. Immunization records show she completed the primary infant series and received DTaP, IPV, MMR, and varicella boosters at age 5 years. She has not received any vaccines since then. Her last influenza vaccination was 2 years ago. Which of the following vaccine combinations is most appropriate to administer today? Vaccine Recommended Age Minimum Interval if Catch-up Needed Tdap booster 11–12 years If no Td/Tdap since age 7, give now HPV series (2 or 3 doses) 11–12 years (can start at 9) If started <15 years: 2 doses, 6–12 months apart; ≥15 years: 3 doses MenACWY 11–12 years, booster at 16 4 weeks between doses if catch-up Influenza Annually, ≥6 months Annual, regardless of prior doses
✓ Correct answer: C. Tdap, HPV (first dose), MenACWY, and influenza vaccine
At age 13, this patient is due for Tdap (adolescent booster), HPV series initiation (recommended starting 11–12 years; she qualifies for the 2-dose schedule since starting before age 15), MenACWY (routine at 11–12 years), and annual influenza vaccine. All four are appropriate today. Distractor 1 omits HPV. Distractor 2 incorrectly includes MMR (already immune). Distractor 3 omits MenACWY. Distractor 4 suggests deferring vaccines that are currently due.
Q14A 15-month-old boy is brought to the office for a well-child visit. The mother reports he has been a picky eater for the past 4 months, often refusing meals and preferring to drink whole milk throughout the day. Serial growth measurements are shown below. Physical examination shows a pale, active toddler with no organomegaly or dysmorphic features. Which of the following is the most likely cause of the growth pattern? Age (months) Weight (percentile) Length (percentile) Weight-for-Length 6 50th 50th 50th 9 40th 50th 25th 12 25th 48th 10th 15 15th 47th 5th
✓ Correct answer: E. Inadequate caloric intake
The child shows progressive weight deceleration (crossing percentile lines downward from 50th to 15th) while length remains stable near 50th percentile, and weight-for-length has declined to the 5th percentile. This pattern—poor weight gain with preserved linear growth—suggests inadequate caloric intake rather than systemic disease or endocrine disorder. The history of excessive milk intake and meal refusal supports this. Distractor 1 would show both weight and length deceleration. Distractor 2 would affect length more than weight. Distractor 3 typically presents with other findings. Distractor 4 would show weight gain, not loss.
Q15A 16-year-old girl comes to the office without her parents for a health maintenance visit. During the confidential portion of the visit, she reports she has been sexually active with her boyfriend for 3 months and asks about contraception. She also mentions feeling sad and having difficulty sleeping for the past month but asks the physician not to tell her parents because "they will be upset." She denies suicidal ideation, self-harm, or feeling unsafe at home. Which of the following is the most appropriate initial response by the physician?
✓ Correct answer: B. Address contraception and mental health; maintain confidentiality unless safety concerns arise
Adolescents have the right to confidential discussions about sexual health and mental health screening. The physician should address both issues while respecting confidentiality, as there are no immediate safety concerns (no suicidal ideation or harm). If safety concerns emerge, confidentiality can be breached. Distractor 1 inappropriately breaches confidentiality without cause. Distractor 2 avoids addressing mental health. Distractor 3 defers necessary care. Distractor 4 prioritizes only one issue and delays mental health assessment.
Q16A 28-month-old boy is brought to the office because of delayed speech development. He says fewer than 10 single words and does not combine words. He walked at 16 months. He plays with toys appropriately, makes eye contact, and points to desired objects. Physical examination shows no abnormalities. Hearing screening at 18 months was normal. Standardized developmental screening confirms isolated expressive language delay. Which of the following is the most appropriate next step in management?
✓ Correct answer: D. Refer to early intervention services and audiology for repeat hearing evaluation
For a child under 3 years with identified speech delay, immediate referral to early intervention (IDEA Part C) is appropriate, along with audiology evaluation to rule out hearing loss, even if prior screening was normal. Early intervention provides speech therapy without requiring a diagnosis. Concurrent evaluations (audiology, EI) should not be delayed. Distractor 1 defers necessary services. Distractor 2 addresses only audiology. Distractor 3 is not the primary referral for children under 3. Distractor 4 delays specialist evaluation unnecessarily.
Q17A 9-month-old girl is brought to the office for a well-child visit. The mother reports the child is "doing everything her older brother did at this age." During the visit, the physician asks the mother whether the child can sit without support, transfer objects between hands, and respond to her name. The mother answers yes to all questions. The physician does not directly observe these milestones during the examination. Based on this assessment approach, which of the following potential issues is most likely? Assessment Method Reliability Potential Pitfall Parental recall only Moderate Recall bias; overestimation of skills Direct observation High Limited by time and setting Standardized screening tool High Requires administration time; may miss context Combined approach (tool + observation) Highest Time-intensive but most accurate
✓ Correct answer: A. Misclassification of development due to parental recall bias
Relying solely on parental recall without direct observation or a validated screening tool risks misclassification. Parents may overestimate skills or misremember timing. Best practice combines parental report with direct observation and standardized tools to ensure accuracy. Distractor 1 is a benefit, not a risk. Distractor 2 is possible but less likely than misclassification. Distractor 3 is not the primary concern here. Distractor 4 is not a risk of this approach.
Q18A 2-month-old boy is brought to the office for his first well-child visit since hospital discharge. He was born at 39 weeks' gestation via uncomplicated vaginal delivery. Birth weight was 3.2 kg (7 lb). He received hepatitis B vaccine at birth. The mother is healthy and has no history of immunocompromising conditions. She reports the infant is feeding well and has no concerns. Physical examination shows a healthy, thriving infant with no abnormalities. Which of the following vaccine combinations is most appropriate to administer today?
✓ Correct answer: C. DTaP, Hib, IPV, PCV13, rotavirus, and hepatitis B
At 2 months, infants should receive the primary series: DTaP, Hib, IPV, PCV13, and rotavirus (all starting at 2 months), plus hepatitis B (second dose; first was at birth). All six vaccines are appropriate and can be administered simultaneously. Rotavirus is a live vaccine but is not contraindicated in healthy infants. Distractor 1 incorrectly omits rotavirus. Distractor 2 incorrectly includes MMR (not due until 12 months). Distractor 3 unnecessarily defers vaccines. Distractor 4 incorrectly omits hepatitis B.
Q19A 22-month-old boy is brought to the office because of poor weight gain. He was born at term with no complications. Growth chart review shows weight dropping from the 40th percentile at 12 months to below the 5th percentile currently; length remains at the 35th percentile. The parents report he eats small amounts at meals and drinks 32 oz of whole milk daily. The family has limited financial resources. Physical examination shows a thin, irritable toddler with conjunctival pallor. Which of the following is the most appropriate initial evaluation? Evaluation Component Indication Priority Detailed dietary history Assess intake, food access High Complete blood count Evaluate for anemia High Basic metabolic panel Assess for electrolyte abnormalities, renal function Moderate Thyroid function tests Screen for hypothyroidism if growth velocity low Moderate Stool studies Evaluate for malabsorption if diarrhea present Low (as initial test) Social work referral Address food insecurity, access to resources High
✓ Correct answer: E. Dietary history, CBC, basic metabolic panel, and social work referral
Initial evaluation of poor growth should include detailed dietary history, basic labs (CBC for anemia given pallor and excessive milk intake, metabolic panel), and addressing socioeconomic factors (social work for food insecurity). Excessive milk intake can cause iron deficiency anemia and displace solid foods. Distractor 1 omits essential metabolic evaluation. Distractor 2 is premature without basic workup. Distractor 3 includes too extensive testing initially. Distractor 4 omits labs and social support.
Q20A 2-year-old boy is brought to the office for a health maintenance visit. The parents report he has frequent temper tantrums when limits are set. They ask for advice on discipline strategies. They also mention he watches 4 hours of television daily while the parents work from home. The family has a swimming pool in the backyard. Which of the following anticipatory guidance topics is most appropriate to address during this visit?
✓ Correct answer: B. Positive discipline techniques, screen time limits, and water safety
For toddlers and preschoolers, key anticipatory guidance includes: discipline strategies (positive reinforcement, consistent limits for tantrums), screen time limits (AAP recommends <1 hour/day of high-quality programming for ages 2–5), and injury prevention including water safety (drowning is a leading cause of death; supervision and barriers are critical). All three topics are appropriate for this visit. Distractor 1 omits water safety. Distractor 2 includes unnecessary car seat detail and omits screen time. Distractor 3 includes irrelevant content. Distractor 4 defers important guidance.
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