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) LarynxStridor = 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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