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CAQ-Peds practice questions

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Question 1Pediatrics

A 4-year-old child is brought to the clinic with a 3-day history of low-grade fever, runny nose, and a new harsh barking cough that worsens at night. Lung auscultation reveals inspiratory stridor only when the child is agitated. What is the most likely diagnosis?

  1. Bacterial tracheitis
  2. Viral croup (laryngotracheitis) Correct answer.
  3. Foreign body aspiration
  4. Acute epiglottitis

Explanation

Viral croup typically presents in children aged 6 months to 6 years with a prodrome of coryza and low-grade fever followed by a barking cough, hoarseness, and inspiratory stridor that is often position- and agitation-dependent. Epiglottitis and bacterial tracheitis are more toxic and acute in onset, and foreign body aspiration usually has a sudden choking event without a viral prodrome.

Question 2Pediatrics

Which congenital heart lesion classically produces cyanosis that improves with crying but worsens with feeding?

  1. Tetralogy of Fallot Correct answer.
  2. Coarctation of the aorta
  3. Patent ductus arteriosus
  4. Ventricular septal defect

Explanation

In tetralogy of Fallot, dynamic right ventricular outflow obstruction produces hypercyanotic spells, and crying increases systemic venous return while decreasing systemic vascular resistance, which can worsen right-to-left shunting. Feeding raises pulmonary vascular resistance and can also provoke spells. The other listed lesions are typically acyanotic.

Question 3Pediatrics

A 7-year-old child is diagnosed with acute otitis media. Which antibiotic is the recommended first-line therapy for a child without penicillin allergy or recent antibiotic exposure?

  1. Trimethoprim-sulfamethoxazole
  2. High-dose amoxicillin Correct answer.
  3. Ciprofloxacin
  4. Azithromycin

Explanation

High-dose amoxicillin (80-90 mg/kg/day) is the first-line treatment for uncomplicated acute otitis media because it covers Streptococcus pneumoniae, including many penicillin-nonsusceptible strains, and Haemophilus influenzae. Alternatives are reserved for penicillin allergy or treatment failure.

Question 4Pediatrics

Which finding on a newborn examination is most consistent with developmental dysplasia of the hip?

  1. Bilateral symmetric Moro reflex
  2. Palpable liver edge 2 cm below the costal margin
  3. Single transverse palmar crease
  4. Positive Ortolani sign with asymmetric thigh folds Correct answer.

Explanation

A positive Ortolani maneuver indicates a dislocated hip that can be reduced and is a classic sign of developmental dysplasia of the hip, often accompanied by asymmetric thigh or gluteal folds and limb length discrepancy. The other findings are unrelated to hip dysplasia.

Question 5Pediatrics

A 5-year-old presents with periorbital edema, foamy urine, and hypoalbuminemia. Which condition is most likely?

  1. IgA nephropathy
  2. Minimal change nephrotic syndrome Correct answer.
  3. Acute post-streptococcal glomerulonephritis
  4. Hemolytic uremic syndrome

Explanation

Minimal change disease is the most common cause of nephrotic syndrome in children and presents with the classic tetrad of edema, hypoalbuminemia, proteinuria, and hyperlipidemia. Post-streptococcal glomerulonephritis and IgA nephropathy present with nephritic features such as hematuria and hypertension, while hemolytic uremic syndrome presents with anemia, thrombocytopenia, and renal failure.

Question 6Pediatrics

Which of the following is the most appropriate first-line treatment for an infant with mild atopic dermatitis limited to the cheeks and extensor surfaces?

  1. Oral antihistamines as primary therapy
  2. Topical calcineurin inhibitors as monotherapy
  3. Systemic oral corticosteroids
  4. Topical emollients and low-potency topical corticosteroids Correct answer.

Explanation

The mainstay of atopic dermatitis therapy in infants is aggressive daily emollient use combined with low-potency topical corticosteroids during flares. Systemic steroids are avoided because of rebound flares, and calcineurin inhibitors are generally reserved for sensitive areas or second-line use in older children.

Question 7Pediatrics

A 12-month-old is brought in with fever, irritability, and refusal to bear weight on the left leg. There is no history of trauma. Which diagnosis should be suspected first?

  1. Transient synovitis
  2. Legg-Calvé-Perthes disease
  3. Septic arthritis of the hip Correct answer.
  4. Slipped capital femoral epiphysis

Explanation

Septic arthritis should be suspected in any young child with fever and refusal to bear weight, because delayed treatment causes rapid joint destruction. Transient synovitis typically follows a viral illness and lacks high fever, whereas Legg-Calvé-Perthes and slipped capital femoral epiphysis occur in older children.

Question 8Pediatrics

At what age does the American Academy of Pediatrics recommend introducing single-ingredient complementary foods to a breastfed infant?

  1. At 12 months
  2. At 9 months
  3. At 2 months
  4. Around 6 months Correct answer.

Explanation

The AAP recommends exclusive breastfeeding for about the first 6 months, with introduction of iron-rich complementary foods starting around 6 months when the infant shows developmental readiness. Earlier introduction at 2 months is not appropriate, and delaying to 9 or 12 months risks nutritional deficiencies.

Question 9Pediatrics

A 9-year-old with a history of asthma presents with a 4-week history of nighttime cough and decreased exercise tolerance. Spirometry shows an FEV1/FVC ratio of 0.72 with a 15% improvement after a bronchodilator. What is the most appropriate next step in management?

  1. Refer for bronchoscopy
  2. Add a long-acting beta-agonist as monotherapy
  3. Prescribe a short course of oral corticosteroids
  4. Initiate daily inhaled corticosteroid therapy Correct answer.

Explanation

Reversible airflow obstruction with chronic symptoms and nighttime cough indicates persistent asthma, for which daily inhaled corticosteroids are the preferred controller therapy. Long-acting beta-agonists must never be used as monotherapy in asthma, and oral steroids are reserved for exacerbations.

Question 10Pediatrics

A 3-year-old presents with fever to 40°C for 5 days, bilateral non-exudative conjunctivitis, cracked lips, a strawberry tongue, and a polymorphous rash. Which diagnosis is most likely?

  1. Stevens-Johnson syndrome
  2. Scarlet fever
  3. Kawasaki disease Correct answer.
  4. Measles

Explanation

Kawasaki disease is diagnosed clinically with fever for at least 5 days plus four of five principal features: conjunctivitis, oral mucosal changes, rash, extremity changes, and cervical lymphadenopathy. The combination of prolonged high fever, conjunctivitis, and mucocutaneous changes in a toddler strongly suggests this diagnosis, and prompt IVIG reduces coronary artery complications.

Question 11Pediatrics

A 15-year-old girl presents with primary amenorrhea, short stature, webbed neck, and widely spaced nipples. Which karyotype is expected?

  1. 47,XXY
  2. 47,XX,+21
  3. 46,XY
  4. 45,X Correct answer.

Explanation

Turner syndrome results from complete or partial loss of one X chromosome, classically 45,X, and presents with short stature, gonadal dysgenesis, webbed neck, and cardiac anomalies such as coarctation. The other karyotypes correspond to Klinefelter syndrome, trisomy 21, and normal male karyotype, respectively.

Question 12Pediatrics

A 6-week-old infant presents with projectile nonbilious vomiting after feeds and a palpable olive-shaped mass in the epigastrium. Which electrolyte abnormality is most likely on initial laboratory testing?

  1. Hyperkalemic metabolic acidosis
  2. Hypochloremic hypokalemic metabolic alkalosis Correct answer.
  3. Respiratory alkalosis with normal electrolytes
  4. Hyperchloremic metabolic acidosis

Explanation

Hypertrophic pyloric stenosis causes repeated vomiting of gastric contents rich in hydrogen and chloride, leading to hypochloremic hypokalemic metabolic alkalosis with paradoxical aciduria. The other patterns are not typical of gastric outlet obstruction.

Question 13Pediatrics

A 10-year-old with sickle cell disease presents with fever of 39°C, cough, and hypoxemia. Which initial management step is most important?

  1. Initiation of hydroxyurea
  2. Observation with antipyretics and reassessment in 24 hours
  3. Prompt administration of broad-spectrum antibiotics after cultures Correct answer.
  4. Immediate exchange transfusion

Explanation

Children with sickle cell disease are functionally asplenic and at high risk for overwhelming sepsis from encapsulated organisms, so fever requires prompt cultures and empiric broad-spectrum antibiotics. Observation is unsafe, exchange transfusion is reserved for severe acute chest syndrome or stroke, and hydroxyurea is a chronic therapy.

Question 14Pediatrics

A 2-year-old is brought after a generalized tonic-clonic seizure lasting 3 minutes that has now stopped. He is alert and afebrile with a normal exam. Which factor most strongly predicts recurrence of febrile seizures?

  1. Male sex
  2. Young age at first seizure and family history of febrile seizures Correct answer.
  3. History of cesarean delivery
  4. Presence of mild iron deficiency anemia

Explanation

Risk factors for recurrent febrile seizures include young age at first episode (under 18 months), family history of febrile seizures, and a relatively brief duration between fever onset and seizure. Male sex, delivery mode, and mild anemia are not established predictors.

Question 15Pediatrics

A 4-year-old with nephrotic syndrome achieves remission on prednisone but relapses 3 weeks after completing the taper. Which factor most strongly predicts a steroid-dependent course?

  1. Presence of microscopic hematuria at presentation
  2. Frequent relapses and short time to first relapse Correct answer.
  3. Age over 10 years at onset
  4. Response to prednisone within 4 weeks

Explanation

Steroid-dependent nephrotic syndrome is predicted by frequent relapses and a short interval to the first relapse after completing therapy. Age over 10 years, hematuria at presentation, and a prompt steroid response are not the strongest predictors of dependence.

Question 16Pediatrics

A 14-year-old presents with a 2-month history of weight loss, polyuria, and polydipsia. Blood glucose is 420 mg/dL, venous pH is 7.38, and serum bicarbonate is 24 mEq/L. Which statement best describes the diagnosis?

  1. The presentation is consistent with new-onset type 1 diabetes without diabetic ketoacidosis Correct answer.
  2. Diabetic ketoacidosis is present because of the elevated glucose
  3. The findings are most consistent with diabetes insipidus
  4. The findings indicate type 2 diabetes with hyperosmolar hyperglycemic state

Explanation

Diabetic ketoacidosis requires metabolic acidosis with elevated anion gap and ketonemia, which this patient lacks despite significant hyperglycemia. The classic triad of polyuria, polydipsia, and weight loss in an adolescent suggests new-onset type 1 diabetes without DKA.

Question 17Pediatrics

A 6-month-old infant has a hemoglobin of 8.5 g/dL, MCV of 62 fL, and a low reticulocyte count. He was exclusively breastfed without iron supplementation. Which is the most appropriate next step?

  1. Initiate oral ferrous sulfate and dietary counseling Correct answer.
  2. Transfuse packed red blood cells immediately
  3. Start oral folic acid
  4. Begin intramuscular vitamin B12

Explanation

This microcytic anemia in an exclusively breastfed infant is classic for iron deficiency anemia, and treatment is oral iron supplementation with dietary counseling and follow-up reticulocyte response. Transfusion is reserved for severe symptomatic anemia, and folate or B12 deficiencies cause macrocytic anemia.

Question 18Pediatrics

A 5-year-old with a 2-week history of fever, fatigue, and petechiae is found to have a white blood cell count of 45,000/µL with blasts, hemoglobin of 7 g/dL, and platelets of 30,000/µL. Which finding is most consistent with the diagnosis?

  1. Bone marrow with 4% blasts and normal trilineage hematopoiesis
  2. Elevated hemoglobin F with target cells
  3. Bone marrow with 30% lymphoblasts Correct answer.
  4. Hypercellular marrow with megakaryocytic hyperplasia

Explanation

Acute lymphoblastic leukemia is diagnosed when bone marrow contains at least 20-25% lymphoblasts, and it presents with cytopenias due to marrow replacement. Normal trilineage hematopoiesis and megakaryocytic hyperplasia do not support leukemia.

Question 19Pediatrics

A previously healthy 3-year-old develops bloody diarrhea followed 5 days later by pallor, oliguria, and petechiae. Laboratory studies show hemoglobin of 7 g/dL, platelets of 40,000/µL, and schistocytes on smear. Which is the most likely cause?

  1. Streptococcus pneumoniae sepsis
  2. Acute lymphoblastic leukemia
  3. Shiga toxin-producing Escherichia coli infection Correct answer.
  4. Idiopathic thrombocytopenic purpura

Explanation

Hemolytic uremic syndrome is classically triggered by Shiga toxin-producing E. coli (often O157:H7) and presents with microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury after a bloody diarrheal illness. The other options do not produce this triad.

Question 20Pediatrics

A 12-year-old with a BMI at the 99th percentile has acanthosis nigricans, elevated ALT, and a fasting glucose of 105 mg/dL. Which screening test is most appropriate for identifying prediabetes or type 2 diabetes in this patient?

  1. Hemoglobin A1c Correct answer.
  2. Random urine cortisol
  3. Islet cell autoantibodies
  4. Fasting C-peptide

Explanation

The American Diabetes Association recommends hemoglobin A1c, fasting plasma glucose, or an oral glucose tolerance test to screen for type 2 diabetes in youth with obesity and additional risk factors. C-peptide, autoantibodies, and urine cortisol do not screen for diabetes.

Question 21Pediatrics

A 10-year-old with type 1 diabetes presents with vomiting, abdominal pain, and Kussmaul respirations. Blood glucose is 480 mg/dL, venous pH is 7.12, and serum bicarbonate is 10 mEq/L. Which initial fluid strategy is most appropriate?

  1. Hypotonic saline bolus followed by free water replacement
  2. Isotonic saline bolus followed by isotonic saline maintenance until glucose falls below 250 mg/dL, then add dextrose Correct answer.
  3. Immediate insulin bolus before any fluids
  4. Rapid correction of sodium to 150 mEq/L

Explanation

In pediatric DKA, initial management is isotonic fluid resuscitation followed by isotonic maintenance, with insulin infusion started after fluids and dextrose added when glucose falls to about 250 mg/dL to allow continued insulin delivery. Rapid osmotic shifts increase the risk of cerebral edema.

Question 22Pediatrics

A 6-week-old male presents with poor feeding, tachypnea, and hepatomegaly. Echocardiography shows a large left-to-right shunt through a ventricular septal defect and decreased systemic output. Which factor most strongly determines the timing of surgical repair?

  1. The absolute size of the defect measured in millimeters
  2. The child's sex
  3. Presence of failure to thrive and pulmonary overcirculation refractory to medical therapy Correct answer.
  4. The presence of a systolic murmur

Explanation

Timing of surgical repair for a ventricular septal defect is driven by clinical status, particularly failure to thrive, recurrent respiratory infections, and pulmonary overcirculation that persists despite diuretics and nutritional support. Absolute defect size and murmur presence guide monitoring but do not alone dictate timing.

Question 23Pediatrics

A 3-year-old is evaluated for recurrent sinopulmonary infections, failure to thrive, and steatorrhea. Sweat chloride testing is 68 mmol/L on two occasions. Which additional finding is most consistent with the diagnosis?

  1. Elevated serum immunoglobulins with normal sweat chloride
  2. Normal pancreatic function
  3. Absent vas deferens on examination Correct answer.
  4. Low sweat chloride on repeat testing

Explanation

Sweat chloride above 60 mmol/L on two occasions is diagnostic of cystic fibrosis, which causes obstructive azoospermia from congenital bilateral absence of the vas deferens in males and pancreatic insufficiency with steatorrhea. Normal sweat chloride and normal pancreatic function would argue against the diagnosis.

Question 24Pediatrics

A 13-year-old presents with 3 weeks of low-grade fever, malaise, and a new heart murmur. Blood cultures grow viridans streptococci. Which underlying condition most strongly predisposes to this presentation?

  1. Mild tricuspid regurgitation with a structurally normal heart
  2. Patent foramen ovale
  3. Congenital bicuspid aortic valve Correct answer.
  4. Secundum atrial septal defect with small shunt

Explanation

Infective endocarditis most often occurs on a previously abnormal valve or with high-velocity turbulent flow, and a bicuspid aortic valve is a common predisposing lesion in children. Secundum atrial septal defects, patent foramen ovale, and mild tricuspid regurgitation with a normal heart carry low risk.

Question 25Pediatrics

A 4-year-old with a known ventricular septal defect develops fever, lethargy, and a new diastolic murmur. Blood cultures are pending. Which management decision is most appropriate?

  1. Obtain multiple blood cultures and start empiric intravenous antibiotics promptly Correct answer.
  2. Obtain an echocardiogram in 1 week as an outpatient
  3. Wait for culture results before starting antibiotics
  4. Start oral amoxicillin and discharge home

Explanation

Suspected infective endocarditis in a child with congenital heart disease requires multiple blood cultures followed by prompt empiric intravenous antibiotics, because delayed therapy increases morbidity and mortality. Outpatient oral therapy and delayed echocardiography are inappropriate for suspected endocarditis.

Question 26Pediatrics

A 7-year-old boy is brought to the clinic with a 2-day history of sore throat, fever to 38.9°C, and tender anterior cervical lymphadenopathy. Examination reveals tonsillar exudates and no cough. A rapid antigen detection test is negative. What is the most appropriate next step in management?

  1. Prescribe amoxicillin immediately based on clinical findings
  2. Obtain a throat culture and await results before deciding on antibiotics Correct answer.
  3. Reassure the family and provide symptomatic care only
  4. Obtain a throat culture and start penicillin VK immediately

Explanation

In a child with clinical features suggesting group A streptococcal pharyngitis and a negative rapid antigen test, current guidelines recommend confirming with a throat culture (or molecular testing) before committing to antibiotics, because the rapid test can be falsely negative. Antibiotics should not be started empirically solely on clinical grounds when testing is available, to avoid unnecessary treatment and resistance. Symptomatic care alone would risk missing a true infection and its complications.

Question 27Pediatrics

A 4-year-old girl presents with a 3-day history of low-grade fever, runny nose, and a new barking cough with inspiratory stridor that worsens at night. She is hoarse and has moderate subcostal retractions. What is the most appropriate first-line pharmacologic treatment?

  1. Nebulized albuterol
  2. Oral dexamethasone Correct answer.
  3. Nebulized racemic epinephrine
  4. Oral amoxicillin

Explanation

This presentation is classic for viral croup (laryngotracheobronchitis), which is treated with a single dose of oral dexamethasone to reduce airway edema and inflammation. Nebulized epinephrine is reserved for moderate-to-severe distress or impending airway obstruction and is not first-line for moderate croup without severe retractions or hypoxia. Antibiotics and bronchodilators have no role in uncomplicated viral croup.

Question 28Pediatrics

A 2-year-old boy is brought to the emergency department after a 5-minute generalized tonic-clonic seizure. His temperature is 39.2°C, and he has a runny nose and inflamed tympanic membranes. He is now alert and playful. There is no meningismus. What is the most appropriate management?

  1. Give antipyretics and discharge with parental education Correct answer.
  2. Start daily anticonvulsant prophylaxis with levetiracetam
  3. Admit for intravenous antibiotics and lumbar puncture
  4. Perform an immediate lumbar puncture and start acyclovir

Explanation

A simple febrile seizure lasts less than 15 minutes, occurs once in 24 hours, and affects a child 6 months to 5 years without evidence of CNS infection. For a simple febrile seizure in a well-appearing child, the standard of care is antipyretic treatment and reassurance with education; lumbar puncture and antibiotics are not indicated in the absence of meningeal signs. Daily anticonvulsants are not recommended for simple febrile seizures because risks outweigh benefits.

Question 29Pediatrics

A 6-month-old infant is brought for a well-child visit. The parents report that he has been reaching for objects and bringing them to his mouth, but he cannot yet sit without support. He was born at term and has had an unremarkable perinatal history. What is the most appropriate next step?

  1. Order an immediate MRI of the brain
  2. Prescribe physical therapy for suspected cerebral palsy
  3. Refer for a developmental evaluation and consider early intervention services
  4. Reassure the parents that this is within normal limits and continue routine monitoring Correct answer.

Explanation

Sitting without support is a gross motor milestone typically achieved between 6 and 9 months of age. A 6-month-old who is not yet sitting independently but has otherwise appropriate fine motor and social development is within the normal range and warrants continued surveillance rather than immediate referral. Referral for early intervention is indicated when there is a persistent delay or loss of skills.

Question 30Pediatrics

A 3-year-old girl is brought to the clinic because her mother noticed a white, cottage-cheese-like discharge from the vagina and vulvar redness for the past 4 days. She has no fever, dysuria, or history of sexual abuse. What is the most likely diagnosis?

  1. Candidal vulvovaginitis Correct answer.
  2. Chemical irritant dermatitis
  3. Streptococcal vulvovaginitis
  4. Neisseria gonorrhoeae vaginitis

Explanation

Candidal vulvovaginitis in a prepubertal girl typically presents with vulvar erythema, itching, and a thick white discharge; it is often associated with recent antibiotic use, diabetes, or immunosuppression, but can occur otherwise. Gonococcal infection is uncommon without sexual abuse and usually causes a purulent discharge. Streptococcal vulvovaginitis is a common cause of vulvar redness but typically produces a thin, serosanguineous or mucoid discharge rather than cottage-cheese material.

Question 31Pediatrics

A 15-year-old boy presents with a 2-day history of fever, sore throat, and severe fatigue. Examination shows exudative pharyngitis, posterior cervical lymphadenopathy, and splenomegaly. A heterophile antibody test is negative. Which test is most likely to confirm the diagnosis?

  1. Epstein-Barr virus viral capsid antigen IgM Correct answer.
  2. Cytomegalovirus urine culture
  3. Throat culture for Corynebacterium diphtheriae
  4. Rapid antigen detection test for group A streptococcus

Explanation

Infectious mononucleosis due to Epstein-Barr virus can present with a negative heterophile antibody test, especially in the first week of illness or in younger children. Detection of EBV viral capsid antigen IgM is sensitive and specific for acute infection. Rapid streptococcal testing and diphtheria culture address other causes of exudative pharyngitis but would not confirm EBV.

Question 32Pediatrics

A 10-year-old boy with a history of asthma is brought to the emergency department with acute respiratory distress. He is speaking in short phrases, has an oxygen saturation of 89% on room air, and has diffuse expiratory wheezing with subcostal retractions. He has already received three albuterol nebulizer treatments with minimal improvement. What is the most appropriate next step in management?

  1. Administer oral prednisone and observe
  2. Perform immediate endotracheal intubation
  3. Give supplemental oxygen and nebulized ipratropium bromide Correct answer.
  4. Start intravenous antibiotics

Explanation

This child has severe asthma exacerbation with hypoxemia and inadequate response to albuterol. Guidelines recommend supplemental oxygen to maintain saturation ≥90% and adding nebulized ipratropium bromide to albuterol for severe exacerbations. Systemic corticosteroids should also be given, but oxygen and ipratropium are the immediate next step after initial bronchodilators.

Question 33Pediatrics

A 2-week-old infant is brought to the clinic because the mother noticed a bluish discoloration around the lips and face when the baby cries. The infant is otherwise feeding well and gaining weight. Physical examination reveals a grade 2/6 systolic murmur at the left upper sternal border and mild cyanosis that resolves with crying. What is the most likely diagnosis?

  1. Tetralogy of Fallot Correct answer.
  2. Transposition of the great arteries
  3. Peripheral cyanosis from cold exposure
  4. Tricuspid atresia

Explanation

Tetralogy of Fallot may present in the neonatal period with cyanotic spells (hypercyanotic episodes) that occur during crying or feeding, often with a systolic murmur from right ventricular outflow tract obstruction. The cyanosis is central and may worsen with agitation. Transposition of the great arteries typically presents with cyanosis in the first hours to days of life and does not improve with crying alone.

Question 34Pediatrics

A 5-year-old boy is brought to the clinic with a 2-day history of fever, ear pain, and decreased hearing on the right. Otoscopy reveals a bulging, erythematous tympanic membrane with decreased mobility. He has no history of antibiotic allergy. What is the most appropriate first-line antibiotic?

  1. Azithromycin
  2. Trimethoprim-sulfamethoxazole
  3. Amoxicillin Correct answer.
  4. Ciprofloxacin

Explanation

High-dose amoxicillin is the first-line antibiotic for acute otitis media in children without penicillin allergy, because it covers the most common pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis). Azithromycin and trimethoprim-sulfamethoxazole have higher rates of resistance and are not preferred. Ciprofloxacin is not appropriate for acute otitis media due to poor coverage of pneumococcus.

Question 35Pediatrics

A 7-year-old girl is brought for evaluation of a 3-month history of recurrent abdominal pain that occurs almost daily, periumbilical, and is relieved by defecation. She has no weight loss, fever, or gastrointestinal bleeding. Physical examination and growth are normal. What is the most likely diagnosis?

  1. Functional abdominal pain Correct answer.
  2. Celiac disease
  3. Lactose intolerance
  4. Crohn disease

Explanation

Functional abdominal pain is common in school-aged children and is characterized by chronic, recurrent abdominal pain without evidence of organic disease, often periumbilical and relieved by defecation. Normal growth, lack of systemic symptoms, and normal examination support this diagnosis. Inflammatory bowel disease and celiac disease typically present with weight loss, diarrhea, or growth failure.

Question 36Pediatrics

A 9-year-old boy presents with a 2-week history of fatigue, pallor, and bruising. Laboratory studies show a hemoglobin of 7.5 g/dL, platelet count of 20,000/µL, and white blood cell count of 2,500/µL. Bone marrow aspirate shows decreased cellularity with fatty replacement. What is the most likely diagnosis?

  1. G6PD deficiency
  2. Immune thrombocytopenic purpura
  3. Acute lymphoblastic leukemia
  4. Aplastic anemia Correct answer.

Explanation

Aplastic anemia is characterized by pancytopenia with a hypocellular bone marrow and fatty replacement, presenting with fatigue, pallor, and bruising. Acute lymphoblastic leukemia typically shows a hypercellular marrow with blasts, not hypocellularity. Immune thrombocytopenic purpura causes isolated thrombocytopenia with normal hemoglobin and white cell count.

Question 37Pediatrics

A 14-year-old girl presents with a 2-day history of fever, dysuria, and flank pain. Urinalysis shows pyuria and bacteriuria. She is diagnosed with acute pyelonephritis. Which organism is the most common cause?

  1. Enterococcus faecalis
  2. Staphylococcus saprophyticus
  3. Proteus mirabilis
  4. Escherichia coli Correct answer.

Explanation

Escherichia coli is the most common cause of urinary tract infections, including pyelonephritis, in children and adolescents, accounting for the majority of cases. Staphylococcus saprophyticus is a common cause in sexually active adolescent females but is less frequent than E. coli. Proteus and Enterococcus are less common and often associated with structural abnormalities or instrumentation.

Question 38Pediatrics

A 10-year-old boy is brought to the clinic with a 2-week history of a slowly enlarging, painless neck mass. He has no fever, weight loss, or night sweats. Examination reveals a 2-cm firm, mobile, nontender mass in the anterior triangle of the neck. What is the most appropriate next step in evaluation?

  1. Fine-needle aspiration biopsy Correct answer.
  2. Observation for 6 weeks
  3. Excisional biopsy
  4. Trial of antibiotics

Explanation

A persistent, painless neck mass in a child that is firm and enlarging warrants further evaluation to exclude malignancy or atypical infection. Fine-needle aspiration biopsy is a minimally invasive initial diagnostic test for such masses. Observation or antibiotics are appropriate for reactive lymphadenopathy or infectious causes, but the characteristics here raise concern.

Question 39Pediatrics

A 3-year-old boy is brought to the emergency department with a 1-day history of fever, drooling, and difficulty swallowing. He is sitting upright and leaning forward, and his voice is muffled. He has not received all recommended immunizations. What is the most appropriate immediate management?

  1. Obtain a lateral neck radiograph
  2. Start oral antibiotics and discharge
  3. Prepare for emergent airway management Correct answer.
  4. Inspect the throat with a tongue depressor

Explanation

This presentation is highly suspicious for epiglottitis, a medical emergency that can rapidly progress to complete airway obstruction. The priority is to secure the airway in a controlled setting with anesthesia and ENT backup; any attempt to visualize the throat or force the child to lie down can precipitate obstruction. Radiographs may be obtained only if the child is stable and the diagnosis is uncertain, but airway management takes precedence.

Question 40Pediatrics

A 12-year-old girl presents with a 3-month history of fatigue, weight gain, cold intolerance, and constipation. She has dry skin and bradycardia. Laboratory tests show an elevated TSH and low free T4. Which of the following is the most likely cause?

  1. Subacute thyroiditis
  2. Pituitary adenoma
  3. Graves disease
  4. Hashimoto thyroiditis Correct answer.

Explanation

Hashimoto thyroiditis is the most common cause of acquired hypothyroidism in children and adolescents in iodine-sufficient areas, presenting with symptoms of hypothyroidism and elevated TSH with low free T4. Graves disease causes hyperthyroidism with suppressed TSH. Subacute thyroiditis often presents with a painful goiter and transient thyrotoxicosis, and pituitary adenoma would cause central hypothyroidism with low or inappropriately normal TSH.

Question 41Pediatrics

A 16-year-old girl presents with a 6-month history of amenorrhea, weight loss, and excessive exercise. She has a BMI of 16.5 kg/m² and reports feeling fat despite being underweight. Which of the following is the most likely diagnosis?

  1. Hypothalamic amenorrhea from stress
  2. Anorexia nervosa Correct answer.
  3. Bulimia nervosa
  4. Polycystic ovary syndrome

Explanation

Anorexia nervosa is characterized by restriction of energy intake, significantly low body weight, intense fear of gaining weight, and disturbance in self-perceived body image, often leading to amenorrhea. Bulimia nervosa typically involves binge-purge behaviors with normal or near-normal weight. PCOS causes irregular menses and hyperandrogenism but not profound weight loss and body image disturbance.

Question 42Pediatrics

A 2-year-old boy is brought to the clinic with a 2-day history of low-grade fever, irritability, and decreased oral intake. Examination reveals multiple vesicular lesions on the tongue and buccal mucosa, and a few on the palms and soles. What is the most likely causative agent?

  1. Herpes simplex virus type 1
  2. Epstein-Barr virus
  3. Coxsackievirus A16 Correct answer.
  4. Cytomegalovirus

Explanation

Hand, foot, and mouth disease is typically caused by coxsackievirus A16 and presents with fever, oral vesicles, and a vesicular rash on the hands and feet. Herpes simplex virus causes gingivostomatitis with lesions primarily in the mouth and lips, not on the palms and soles. EBV and CMV do not typically cause this distribution of vesicles.

Question 43Pediatrics

A 9-year-old boy is brought to the clinic because his teacher noticed that he has been blinking frequently and making repetitive throat-clearing sounds for the past 6 months. These movements are brief and can be suppressed temporarily. He has no other neurologic symptoms. What is the most likely diagnosis?

  1. Attention-deficit/hyperactivity disorder
  2. Stereotypic movement disorder
  3. Obsessive-compulsive disorder
  4. Tourette syndrome Correct answer.

Explanation

Tourette syndrome is characterized by multiple motor tics and at least one vocal tic lasting more than 1 year, with onset before age 18. The tics are brief, can be suppressed temporarily, and are often preceded by an urge. ADHD and OCD are common comorbidities but do not explain the tics themselves; stereotypic movement disorder involves repetitive movements that are not tics.

Question 44Pediatrics

A 4-year-old girl presents with a 1-day history of fever, irritability, and a petechial rash on her legs and buttocks. She is alert but has neck stiffness and photophobia. A lumbar puncture is performed. Which of the following cerebrospinal fluid findings is most consistent with bacterial meningitis?

  1. Elevated protein, normal glucose, and lymphocytic pleocytosis
  2. Elevated protein, low glucose, and neutrophilic pleocytosis Correct answer.
  3. Normal protein, normal glucose, and lymphocytic pleocytosis
  4. Low protein, high glucose, and neutrophilic pleocytosis

Explanation

Bacterial meningitis typically shows an elevated opening pressure, neutrophilic pleocytosis, elevated protein, and low glucose (CSF-to-serum glucose ratio <0.4). Viral meningitis usually shows a lymphocytic pleocytosis with normal glucose and mildly elevated protein. The other options do not fit the typical bacterial profile.

Question 45Pediatrics

A 6-year-old boy is brought to the clinic with a 2-week history of perianal itching that is worse at night. His mother reports seeing small white worms in the perianal area. What is the most appropriate treatment?

  1. Albendazole
  2. Mebendazole Correct answer.
  3. Permethrin cream
  4. Metronidazole

Explanation

Pinworm infection (enterobiasis) is caused by Enterobius vermicularis and is treated with mebendazole (or albendazole) as a single dose, repeated in 2 weeks. Permethrin is used for scabies or lice, not pinworms. Metronidazole treats protozoal infections and anaerobic bacteria, not helminths.

Question 46Pediatrics

A 15-year-old boy is brought to the emergency department after a fight at school. He has a swollen, ecchymotic right ear and hearing loss. Examination reveals a hematoma between the auricular cartilage and perichondrium. What is the most appropriate immediate management?

  1. Incision and drainage of the hematoma Correct answer.
  2. Observation and ice packs
  3. Oral antibiotics and outpatient follow-up
  4. Application of a compression dressing only

Explanation

An auricular hematoma (cauliflower ear) requires prompt incision and drainage to prevent cartilage necrosis and permanent deformity. The hematoma separates the perichondrium from the cartilage, compromising blood supply. Observation, compression alone, or antibiotics without drainage can lead to cartilage damage and cosmetic deformity.

Question 47Pediatrics

A 5-year-old boy is brought to the clinic because his mother noticed a painless, firm swelling in the left scrotum that has been present since birth and has not changed in size. The swelling transilluminates. The testicle is palpable separately from the swelling. What is the most likely diagnosis?

  1. Testicular torsion
  2. Varicocele
  3. Inguinal hernia
  4. Hydrocele Correct answer.

Explanation

A hydrocele is a collection of fluid in the tunica vaginalis that presents as a painless, transilluminating scrotal swelling; the testicle can be palpated separately. Inguinal hernias do not transilluminate and may be reducible. Varicoceles feel like a bag of worms and do not transilluminate, and testicular torsion is acutely painful.

Question 48Pediatrics

A 13-year-old girl presents with a 1-week history of low-grade fever, fatigue, and a rash on her cheeks that spares the nasolabial folds. She also reports joint pain in her hands and knees. Laboratory tests show leukopenia, thrombocytopenia, and a positive antinuclear antibody test. What is the most likely diagnosis?

  1. Systemic lupus erythematosus Correct answer.
  2. Juvenile idiopathic arthritis
  3. Dermatomyositis
  4. Kawasaki disease

Explanation

Systemic lupus erythematosus in adolescents often presents with malar (butterfly) rash, photosensitivity, arthritis, cytopenias, and positive ANA. Juvenile idiopathic arthritis typically presents with chronic arthritis without the characteristic rash and cytopenias. Dermatomyositis causes heliotrope rash and Gottron papules, and Kawasaki disease presents with fever, conjunctivitis, and mucocutaneous changes but not positive ANA.

Question 49Pediatrics

A 2-year-old boy is brought to the emergency department with a 1-day history of fever, irritability, and refusal to move his left arm. He has no history of trauma. Examination reveals swelling and tenderness over the left proximal humerus. Radiographs show a lytic lesion with periosteal reaction. What is the most likely causative organism?

  1. Staphylococcus aureus Correct answer.
  2. Salmonella species
  3. Streptococcus pyogenes
  4. Kingella kingae

Explanation

Acute hematogenous osteomyelitis in children is most commonly caused by Staphylococcus aureus, which accounts for the majority of cases. Streptococcus pyogenes is a less common cause. Salmonella is associated with sickle cell disease, and Kingella kingae is more common in children under 4 but is less frequent than S. aureus overall.

Question 50Pediatrics

A 10-year-old girl is brought to the clinic because she has been experiencing episodes of sudden, brief loss of muscle tone triggered by laughter, causing her to slump forward or fall. She also reports excessive daytime sleepiness. What is the most likely diagnosis?

  1. Attention-deficit/hyperactivity disorder
  2. Narcolepsy Correct answer.
  3. Epilepsy
  4. Syncope

Explanation

Narcolepsy with cataplexy is characterized by excessive daytime sleepiness and sudden loss of muscle tone (cataplexy) triggered by emotions such as laughter. Epilepsy causes seizures with altered consciousness or convulsions, not emotion-triggered atonia. Syncope is a transient loss of consciousness due to cerebral hypoperfusion, not triggered by laughter.