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NBME Pediatrics Form 4 - Answers & Explanations

Updated: Jul 27, 2020

1) Observe hand-washing techniques

• Poor hand-washing is the major cause of Rotavirus transmission (fecal-oral route)

2) Acute osteomyelitis

• Point tenderness, ↑ ESR, ↑ uptake by bone scan = osteomyelitis

• Metaphysis (highly vascular) is the most common site of osteomyelitis in children (usually develops secondary to hematogenous spread)

3) Increased insulin secretion

• Maternal hyperglycemia in the 2nd and 3rd trimesters → ↑ insulin

• After delivery, fetal insulin production takes time to decrease but maternal glucose exposure ends as soon as the umbilical cord is clamped → neonatal hypoglycemia

4) Placement of the newborn under warming lights

• Neonatal hypothermia

• Acrocyanosis occurs when blood vessels shrink in response to cold temperatures (common in newborns)

5) Sodium

• D5W is isotonic, however the body rapidly consumes the glucose → fluid becomes hypotonic → hyponatremia → seizure

6) Spirochete Borrelia burgdorgeri (spirochete) → Lyme disease • Erythema migrans = red circular lesion with a clear center

7) Administration of adenosine

• Paroxysmal supraventricular tachycardia (PSVT)

• If stable, vagal maneuvers should be attempted to terminate the tachycardia (eg, ice bag); If vagal maneuvers do no convert the SVT to normal sinus rhythm, IV adenosine should be administered

• If unstable → synchronized direct current cardioversion

8) Heat exhaustion

• High heat and humidity impair the the body’s capacity for dissipating heat (via evaporation)

• Heat exhaustion clinical criteria: Athlete has difficulty continuing exercise, ↑ Body temperature, and no significant dysfunction of the CNS (eg, seizure, delirium) is present

• Hyponatremia dehydration would have altered mental status

9) Reassurance that this growth pattern is within normal limits

• This baby is tracking along the 5th percentile - changing the diet is not indicated if the child is just constitutionally small

• Growth failure is either persistent weight below the 5th percentile, or falling of the growth chart (crossing 2 major percentile lines)

10) Administration of methylene blue • Methylene blue is the first line treatment for Methemoglobinemia - reduces Fe3+ to Fe2+

11) Vaginal foreign body

• Toilet paper is the most common vaginal foreign body

• Presents with foul-smelling vaginal discharge, intermittent vaginal bleeding or spotting

12) Acute renal failure • Post-strep glomerulonephritis can occur even if the infection was treated (with penicillin)

13) Twisting of there spermatic cord

• Testicular torsion → absence of cremasteric reflex + acute onset pain 14) Cor pulmonale

• Clinical features of cor pulmonale: peripheral edema, ↑ JVP, loud S2, right sided heave, pulsatile liver/hepatomegaly from congestion

• Decline of FVC during the past year indicates primary chronic lung disease

15) Galactosemia

• Classic galactosemia (absence of galactose-1-phosphate uridyltransferase) presents as soon as lactose is introduced into the diet (present in breast milk) → feeding intolerance, failure to thrive, jaundice, hepatomegaly, and infantile cataracts

• ⊖ dipstick glucose assay and a ⊕ reducing test = substance other than glucose is present in urine (ie, galactose, lactose, and fructose)

• Fructose intolerance doesn’t present until the baby consumes fructose containing food (eg, juice, fruit)

16) Juvenile arthritis • Inflammatory/rheumatologic joint pain is classically worse in the morning

• ↑ WBC/platelet count, ↓ RBC, ↑ inflammatory markers

17) Thyroid dysgenesis

• Inactivity, slow feeding, constipation, ↓ T4 = Hypothyroidism

• The most common cause of congenital hypothyroidism worldwide is thyroid dysgenesis

18) Antibody deficiency

• Bruton agammaglobulinemia → ↓ Ig of all classes → recurrent bacterial infections

• Scant lymph nodes and tonsils (primary follicles and germinal centers absent)

19) Decreased synthesis of global chains • Hypochromic microcytic anemia • Thalassemia has normal RDW and Target cells • RDW would be increased in iron deficiency due to anisocytosis

20) Acute lymphoblastic leukemia • ↓ Hb (pallor), ↓ platelets (petechiae), ↑ WBC, diffuse adenopathy

21) Anemia of chronic disease • JIA → ↑↑↑ acute phase reactants → anemia of chronic disease

22) Blood under the periosteum of the parietal bone

• Cephalohematoma is a subperiosteal hemorrhage that causes no overlying skin discoloration and is limited to one bone only (doesn’t cross suture lines)

• Subgaleal hemorrhage is under the galea aponeurotica

• Caput succedaneum is a soft tissue swelling that can cross suture lines

23) Increased renin production • Umbilical artery catheterization → showers of emboli/thrombi → lodge in renal artery → renal artery thrombosis → ↑ renin release → HTN

24) Triamcinolone • Triamcinolone is a synthetic corticosteroid • Eczema (atopic dermatitis) tends to happen in people with allergies or asthma

• Eczema should be treated with long-acting steroids or emollients

25) Staphylococcus aureus

• Large dense consolidation and fixed effusion are consistent with an abscess (Staph aureus loves to dorm abscesses)

Staph aureus resistent to amoxicillin

26) Exchange transfusion

• Most likely due to Rh hemolytic disease of newborn

• Total Bilirubin >25 (or trending that way) and resistant to phototherapy → exchange transfusion

• Bilirubin is toxic to cochlear nuclei; hyperbilirubinemia → hearing loss in newborns

27) IgA nephropathy

• Episodic hematuria that occurs concurrently with respiratory or GI infections

• PSGN typically occurs 2-3 weeks after an infection and would have decreased complement levels

28) Reassurance that this is a benign murmur

• Features of a benign murmur: early or mid-systolic, grade ≤ 2/6, low-low-pitched musical pure, insignificant medical history

29) Partial obstruction of the right main stem bronchus

• Majority of aspirated foreign bodies end up in right mainstream bronchus → focal monophonic wheezing

• Foreign body creates a kind of one-way valve → hyperinflation

30) Decrease his intake of milk and fruit juice

• > 95th percentile for weight and BMI = obese

• Milk and fruit juices have a lot of sugar

31) Cellular shift • Ketotic metabolic acidosis → H+ moves into cells in exchange for K+ moving out

32) HIV infection • Given the patients age, he most likely has an acquired immunodeficiency (eg, HIV)

33) Administration of 0.9% saline, intravenously Management should begin with a bolus of normal saline

34) Pneumococcal meningitis • Low glucose with granulocytic predominance on CSF analysis is consistent with bacterial meningitis

35) Intramuscular lorazepam

• PCP intoxication → treat their aggression and calm them down with a benzo

36) Cystic fibrosis

• Highly viscous mucus → Impaired mucociliary escalator (→ history or respiratory problems) and bronchiectasis

37) Congenital heart disease with right-to-left shunt

Tetralogy of Fallot tet spell

• Baby cries and becomes agitated → RVOT (right ventricular outflow obstruction) worsens → reversal of shunt across VSD → cyanosis

• RVOT → ↓ blood flow through lungs → ↓ pulmonary vascularity

• Systolic murmur is coming from the RVOT, not from the VSD

38) Herpes zoster • Immunosuppression (chemo) + painful vesicular rash in dermatomal distribution

• HSV is usually in peri-oral and genital areas (not confined to a dermatome)

39) Reassure him that this is normal

• Pubertal gynecomastia is seen in 50-70% of pubertal boys

• Typically resolves without treatment in a few months

40) Epidural hematoma • Head injury over parietal bone → pterion skull fracture → middle meningeal artery rupture → lens-shaped hyper-density that doesn’t cross suture lines

41) Malabsorption of fats and carbohydrates

• Giardiasis disrupts microvilli on enterocytes in the small intestine → malabsorption and loose oily foul-smelling stools

• If untreated → severe weight loss and vitamin deficiency

42) Congenital melanocytic nevus Benign melanocyte proliferation with ↑ density of hair follicles

43) Increased vascular permeability

• Sepsis status post mechanical ventilation → ↑ vascular permeability → ARDS

• Waterhouse-Friderichsen syndrome: Neisseria → vascular collapse and permeability

→ petechiae

44) Fluids

• Give fluids to replace what was lost to the 3rd space

45) Medulloblastoma

• Affects the cerebellum medially (vermis) → truncal ataxia (eg, unsteady gait)

• Pilocytic astrocytoma affects the cerebellum peripherally (hemisphere) → limb ataxia (eg, dysmetria)

• Medullo = Medial, Pilocytic = Peripheral

46) Nonsteroidal anti-inflammatory drug therapy • Primary dysmenorrhea (normal physical exam) first-line treatment is NSAIDs and/or OCP

47) Decreased biliary excretion

• Liver is able to conjugate bilirubin, but cant excrete it → direct hyperbilirubinemia (all other answer choices would lead to indirect hyperbilirubinemia)

• Wouldn’t develop kernicterus because conjugated bilirubin doesn’t cross BBB

48) Ulcerative colitis • Abdominal cramps relieved by passing stool + bloody bowel movements

• Arthritis is the most common non-GI related issue in UC

49) Thyroid dysfunction

Clinical manifestation of congenital hypothyroidism: lethargy, enlarged fontanelle, protruding tongue, hypotonia, umbilical hernia, constipation, jaundice

50) Needle decompression • Hyper-resonance + tracheal deviation = tension pneumothorax • Needle decompression would relieve air pressure surrounding the left lung and allow it to expand

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