PLAB PLAB Pediatrics & Child Health 1 — Questions and Answers
Question 1: A 2-year-old child presents with a barking cough, stridor, and low-grade fever. Symptoms are worse at night. What is the most likely diagnosis?
- Epiglottitis
- Croup (laryngotracheobronchitis) (Correct answer)
- Foreign body aspiration
- Bacterial tracheitis
Correct answer: Croup (laryngotracheobronchitis)
Croup (laryngotracheobronchitis) is caused most commonly by parainfluenza virus, presenting with the characteristic barking 'seal-like' cough, inspiratory stridor, and nocturnal worsening in children aged 6 months to 3 years.
Question 2: Which vaccine is administered at birth as part of the standard UK immunization schedule for infants born to hepatitis B-positive mothers?
- BCG vaccine
- Hepatitis A vaccine
- Hepatitis B vaccine (Correct answer)
- Rotavirus vaccine
Correct answer: Hepatitis B vaccine
Infants born to hepatitis B surface antigen-positive mothers receive hepatitis B vaccine at birth (along with HBIG if high-risk) to prevent perinatal transmission, which carries high risk of chronic infection.
Question 3: A 6-week-old male infant presents with projectile non-bilious vomiting after every feed, is hungry immediately after vomiting, and has a palpable olive-shaped mass in the right upper quadrant. What is the diagnosis?
- Duodenal atresia
- Pyloric stenosis (Correct answer)
- Gastroesophageal reflux
- Intussusception
Correct answer: Pyloric stenosis
Pyloric stenosis classically presents at 3–6 weeks of age with forceful projectile non-bilious vomiting, persistent hunger, and a palpable pyloric 'olive' mass; it is more common in firstborn males.
Question 4: What is the first-line treatment for a febrile seizure in a child who is currently seizing for more than 5 minutes?
- IV phenytoin
- Rectal diazepam or buccal/intranasal midazolam (Correct answer)
- Oral paracetamol
- IV lorazepam only
Correct answer: Rectal diazepam or buccal/intranasal midazolam
Prolonged febrile seizures (>5 minutes) are treated as status epilepticus; rectal diazepam or buccal/intranasal midazolam are the first-line benzodiazepines recommended when IV access is unavailable in the community or prehospital setting.
Question 5: A 9-month-old infant is brought in with a 2-day history of diarrhea, vomiting, and mild dehydration. Stool examination shows no blood. What is the most likely causative organism?
- Salmonella
- Rotavirus (Correct answer)
- Campylobacter
- Escherichia coli O157:H7
Correct answer: Rotavirus
Rotavirus is the most common cause of acute gastroenteritis in infants and young children aged 6–24 months, causing watery (non-bloody) diarrhea and vomiting, particularly in the winter months.
Question 6: Which developmental milestone should a child typically achieve by 18 months of age?
- Speaking in 4–6 word sentences
- Walking independently (Correct answer)
- Reading simple words
- Riding a tricycle
Correct answer: Walking independently
Independent walking is typically achieved between 9–15 months, and failure to walk by 18 months is a developmental red flag requiring assessment; most children walk confidently by 12–15 months.
PLAB PLAB Pediatrics & Child Health 1
A 2-year-old child presents with a barking cough, stridor, and low-grade fever.
Symptoms are worse at night.
What is the most likely diagnosis?