NBME Pediatrics Form 3 - Answers & Explanations
Updated: Feb 25
1) Clostridium difficile
• Always consider Pseudomembranous colitis in a child with fever + bloody diarrhea who took antibiotics within the last 21 days
○ C.diff can also present with prolonged watery diarrhea
• Although clinical manifestations of Shigella can include fever and bloody diarrhea, this is mainly due to Shigella dysenteriae 1 or Shigella flexneri. Shigella sonnei presents as more of a watery diarrhea. There is also no mention of daycare, travel or immigration from a developing country, making C.diff colitis more likely
2) Cefotaxime • 3rd generation cephalosporins are 1st line for UTI in children
3) Extracardiac left-to-right shunt • PDA = extracardiac left to right blood shunting
4) Pertussis
• Paroxysmal phase: cough with inspiratory “whoop”, posttussive emesis
Dx: Pertussis culture or PCR
Tx: Macrolides
5) Posterior urethral valves
• Most common cause of urinary tract obstruction in newborn boys
6) Thrombocytopenia from platelet sequestration • Hemangioma, thrombocytopenia, and consumptive coagulopathy = Kasabach-Merritt syndrome (infrequent but fatal complication of rapidly growing vascular lesion in infants)
7) Cl 84, K 2.8, pH 7.50 • Hypokalemic hypochloremic metabolic alkalosis due to vomiting
8) Intravenous administration of dopamine
• “Cold septic shock” = septic shock that turned into cardiogenic shock (myocardial dysfunction from inflammatory cytokines)
• Dopamine → ↑ CO (inotropic), ↑ renal blood flow
• Patient is already receiving fluids and is still hypotonic (more IV fluids wouldn’t help)
9) Testing for Chlamydia trachomatis and Neisseria gonorrhoeae
• All patients below 25 years old that are sexually active should be screen for both chlamydia and gonorrhea
10) Intussusception • Sudden, intermittent abdominal pain • Most common cause of intestinal obstruction in children age 3-36 months
11) Physiologic jaundice • Presents on day 2-4 of life • Mothers blood group is B (rules out ABO hemolytic disease) • Mother is Rh ⊕ (rules out Rh hemolytic disease)
12) Trichophyton tonsurans • Tinea capitis (most common in African American children)
• Tx: oral griseofulvin or terbinafine
13) Impaired T-lymphocyte function • Recurring viral/fungal infections are due to T-cell dysfunction/absence
14) Trisomy 18 • Edward syndrome (trisomy 18) = prominent occiput, micrognathia, clenched fists with overlapping fingers, rocker bottom feet
15) Ventricular septal defect • VSD causes shunting of blood from left to right → ↑ blood in pulmonary circulation → ↑ blood in left atrium (LA) → enlargement of LA
16) Iron
• Hypochromic microcytic anemia
• Cow’s milk has low iron content and bioavailability - children shouldn’t be given cow’s milk until 12 months of age
17) Bronchiectasis
• Right middle lobe syndrome (chronic right middle lobe collapse, usually associated with bronchiectasis)
• Medication didn’t relieve symptoms ≠ asthma
18) Insertion of a nasogastric tube
• Polyhydramnios with excess oral secretions and coughing (most prominent after the first feed) = esophageal atresia (with distal TEF)
• Nasogastric tube will fail to pass into the stomach
19) Intravenous administration of 20 mL/kg of 0.9% saline
• High-flow 0.9% normal salines initially recommended; add dextrose 5% when serum glucose is ≤ 200
• Add IV potassium if serum potassium ≤ 5.2
20) Ultrasonography of the abdomen
• WAGR syndrome: Wilms tumor, Aniridia (absence of iris), Genitourinary malformation, mental Retardation/intellectual disability
• Wilms tumor doesn’t cross midline (vs Neuroblastoma which crosses midline)
21) Larynx • Stridor = upper airway obstruction
22) Thyroid-stimulating
• Hypothyroidism → ↑ TSH release (in an attempt to stimulate the thyroid gland)
• DM1 is associated with Hypothyroidism (HLA DR3)
23) Malignant pleural effusion
• Bloody effusion = malignancy, TB or traumatic effusion
• Superior mediastinal mass (possible malignancy) → SVC syndrome (JVD, upper extremity and facial edema)
• If tumor presses on trachea → wheezing and ↑ work of breathing
24) Neuroblastoma
• Crosses midline with CT calcification
• Metastasis to skin → wrist swelling
25) Ultrasonography of the abdomen • Pyloric stenosis • Dx: thickened pylorus on abdominal U/S
26) A • Benign intracranial HTN (pseudotumor cerebri) • Risk factors: female gender, tetracycline, obesity, vitamin A excess
27) Growing pains • Pain that is worse at night and resolves by the morning • Affects bilateral lower extremities • No systemic symptoms with normal physical exam and activity
28) Septic arthritis • Acute onset fever and joint pain, fatigue, refusal to bear weight due to pain
• Erythema, warmth and swelling of the joint • Pain with active and passive ROM • If it were transient synovitis, the patient would be able to bear weight
29) Fundoplication
• Procedure used to treat severe GERD
• Fundus wrapped around backside of esophagus to anchor lower esophagus below diaphragm
30) Measurement of serum C1 esterase inhibitor concentration • Hereditary angioedema - may cause GI tract edema in addition to typical subcutaneous edema → abdominal pain and diarrhea
31) Failure of normal bowel rotation
• Congenital malformation of the midgut with volvulus → abnormal position of small intestine with formation of fibrous bands → obstruction and constriction of blood flow
• Presents in neonate with bilious vomiting and abdominal distention
• Dx: upper GI series showing “corkscrew” pattern; ligament of Treitz on the right side
of abdomen
• Untreated volvulus can progress to bowel ischemia and perforation (surgical emergency)
32) Oral ibuprofen • Dx: Transient synovitis (most common cause of hip pain in children)
• Tx: Rest and NSAIDs (Ibuprofen), follow up in 1 week
33) Reassurance • Absence of 2° pubertal development is normal in girls ≤ 14, and boys ≤ 15
34) Antigen-antibody immune complex • Post-streptococcal glomerulonephritis (type III HSR = antibody immune complex deposition)
35) Sodium nitroprusside • Newer guidelines suggest IV labetalol or nicardipine rather that either hydralazine
(long onset of action, overshoot hypotension) or sodium nitroprusside (cyanide toxicity)
36) Drain cleaner
• Caustic ingestion → chemical burn or liquefactive necrosis → ulcers involving lips and tongue
• Upper GI endoscopy should be used to evaluate extent of injury
37) Minimal change nephrotic syndrome
• URIs can provoke idiopathic nephropathies (minimal change disease = most common cause of nephrotic syndrome in children)
• Proteinuria > 3.5 g/day with no RBCs or casts = nephrotic syndrome
38) Radial nerve • Radial nerve injury → wrist drop
39) Measurement of morning serum fasting cortisol concentration • Weight gain, striae, and irregular menses are suspicious for excess cortisol
40) “Have you talked to your parents about this?” • Must inquire what the parents told their child and what the child already knows - confirm only what his parents already told him
41) Administration of oxygen
• Bronchiolitis (RSV viral infection in fall/winter) affects small airways → low grade fever, rhinorrhea, cough, respiratory sxs
• Give O2 to improve the current saturation of 84%
42) Acceleration-deceleration head injury • Shaken baby syndrome: subdural hematoma and retinal hemorrhages
43) Serous otitis media • Middle ear effusion without acute inflammation (absence of fever and no bulging of the tympanic membrane)
44) Myocarditis
• Preceded by viral prodrome, followed by chest pain and respiratory distress from acute left heart failure and pulmonary edema
• Dilated cardiomyopathy with mitral regurgitation → S3 gallop and holosystolic murmur
45) Gonadal dysgenesis 45,X (Turner syndrome)
• Presents with short stature, primary amenorrhea, absent thelarche (breast development)
• Turner syndrome → abnormal development of lymphatic system (congenital lymphedema)
46) Hodgkin disease
• Leukemias and lymphomas both often present with normal leukocyte counts (unreliable lab in question stem)
• Hodgkins has bimodal distribution; Thymoma is more common between ages 40-60
• Hodgkins → ↑ eosinophils and cytokines → pruritis
47) Autosomal dominant
• Neurofibromatosis
48) Hypoparathyroidism
• DiGeorge syndrome (failure to develop 3rd & 4th pharyngeal pouches)
• CATCH: Cardiac defects (conotruncal abnormalities), Abnormal facies, Thymic hypoplasia, Cleft palate, Hypocalcemia (secondary to parathyroid aplasia)
49) HPV, meningococcal, and tetanus-diphtheria-acellular pertussis (TdaP)
• HPV given between 11-26 in females, and between 11-21 in males • Meningococcal given between 11-18 • Kids 10-18 should receive a booster of TdaP
50) Rubeola • Cough, Coryza, Conjunctivitis
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