These answer explanations are and always will be free. However, given multiple email requests, I will post my Venmo (@Adam-Zakaria-SLO) if you want to send a few dollars to show your support for the website.
I also offer reasonably priced Study Guides and Personalized Study schedules, so please reach out using the Tutoring menu option or Study Guides and Personalized Study schedules menu option listed above if you would like personalized support.
Furthermore, I offer personal statement and application review services for residency applicants, so please reach out using the “Residency Advising and Application Preparation” menu option above if interested.
Lastly, please check out my Youtube channel (https://www.youtube.com/channel/UCT1Ukl4pm5QK9iw6h4MB_Hw/playlists) and the “Biostatistics Curriculum” option above for free videos and practice questions reviewing all the essential biostatistics topics covered on NBME exams. Good luck with your exams!
1) A previously healthy 17-year-old girl comes to the physician 4 days after her sexual partner was diagnosed with gonorrhea…
Intramuscular ceftriaxone and oral doxycycline
- Key idea: Patients with suspected chlamydia or gonorrhea infection should be empirically treated for both (Ceftriaxone for gonorrhea and Azithromycin/Doxycycline for chlamydia)
- Key idea: Confirmed gonorrhea treated with both ceftriaxone and azithromycin/doxycycline, whereas confirmed chlamydia can be treated with only azithromycin/doxycycline
- Intramuscular penicillin –> Syphilis treatment
2) An 8-year-old boy is brought to the physician because of a 2-week history of rash and a 1-week history of low-grade fever and a mild…
Lyme disease
- Young boy with a low-grade fever and a rash consistent with erythema chronica migrans (“bullseye rash”) which is basically pathognomonic for Lyme disease
- Key idea: Early localized disease (rash, fatigue, headache, etc.) should be treated with doxycycline or with amoxicillin in children and pregnant woman (concern for bone/teeth abnormalities)
- Key idea: Disseminated/late disease (multiple areas of rash, Bell’s palsy, meningitis, carditis, migratory arthralgias, encephalitis, etc.) should be treated with IV ceftriaxone
- Kawasaki disease –> CRASH and burn (Conjunctivitis, Rash [desquamating], Adenopathy [cervical], Strawberry tongue, Hand-foot change, Fever for 5+ days)
- Herpes simplex and herpes zoster –> Vesicular rash
- Folliculitis and impetigo –> Pustular rash
- Nevus flammeus –> “Stork patch” –> Vascular malformation on back of neck
- Poison ivy dermatitis –> Linear vesicular rash (due to being scraped by bush)
3) Four hours after an elective cesarean delivery at 38 weeks’ gestation, a newborn has nasal flaring and tachypnea. There was no meconium…
Transient tachypnea of newborn
- Key idea: Transient tachypnea of the newborn is the most likely cause of respiratory distress in a term infant especially following C-section delivery
- Key idea: Transient tachypnea of newborn classically leads to bilateral perihilar linear streaking and tends to resolve by day 2 of life
- Key idea: Pathophysiology is due to retained lung liquid with c-section NOT clearing fluid as compared to vaginal delivery –> perinatal epinephrine surge –> lung liquid absorption and mechanical drainage
- Other causes of neonatal respiratory distress to consider –> Respiratory distress syndrome (preterm baby with insufficient surfactant production –> alveolar collapse with diffuse ground-glass appearance on chest x-ray), Persistent pulmonary hypertension (often seen in setting of meconium aspiration, lead to tachypnea and severe cyanosis)
- Bronchopulmonary dysplasia –> Often seen in setting of chronic supplemental oxygen administration in a newborn
4) A 4-month-old girl is admitted to the hospital because of severe coughing for 2 days. The cough is episodic and staccato-like and often…
Droplet isolation
- Infant girl who had rhinitis followed ~1 week later with severe cough leading to post-tussive vomiting and facial petechiae most likely due to B. pertussis infection
- Key idea: Pertussis is highly contagious and patients with exposure (often household contacts) should be treated with a macrolide (most commonly azithromycin), but in this case it would be impractical to provide prophylactic medication to all healthcare workers and the focus should instead be on limiting risk of exposure through Droplet precautions
- Key idea: B. pertussis classically leads to cough with an inspiratory “whoop”
- Note: Staccato-like cough is most classically associated with Chlamydia pneumonia, but that is often associated with eosinophilia and classically presents ~6-8 weeks after birth
5) A 5-year-old boy is brought to the physician because of clumsiness and frequent falls over the past 6 months. He did not walk independently…
X-linked recessive
- 5 year old boy with poor motor development, lower extremity weakness, calf pseudohypertrophy (fatty deposition in calves) and a positive Gower sign, most consistent with muscular dystrophy
- Key idea: Both forms of muscular dystrophy (Duchenne and Becker) are X-linked recessive, meaning that they will almost exclusively be seen in boys
- Duchenne MD –> More severe with onset ~1-5 years of age
- Becker MD –> Less severe with onset in adolescence of early adulthood
6) A 10-year-old boy develops a rash on the chest 2 days after returning from a beach vacation. Over the next 2 weeks…
Psoriasis
- Young boy who develops a widespread rash that is morphologically composed of plaques with overlying scale with fingernail involvement and a positive Auspitz sign (pinpoint bleeding after removing scale) all of which is consistent with psoriasis
- Key idea: Psoriasis is the skin condition that classically demonstrates Koebner phenomenon, meaning that skin lesions will appear/worsen at sites of skin trauma; importantly solar sunburns (which this patient may have had) can also lead to skin trauma and precipitate appearance/worsening of psoriasis rash via Koebner phenomenon
- Key idea: Fingernail involvement is classic for psoriasis and is a reminder of the association between psoriasis and psoriatic arthritis which tends to involve the DIP joints
- Pityriasis rosea –> Herald patch followed by “Christmas tree” distribution of oval plaques on the back
7) A 3714-g (8-lb 3-oz) newborn is delivered at 43 weeks’ gestation to a 32-year-old woman, gravida 4, para 3. Apgar scores are…
Failure of pulmonary vasodilation
- Post-term newborn with meconium-stained skin who is cyanotic and hypoxic with significant right-to-left shunting most concerning for Meconium aspiration syndrome complicated by Persistent Pulmonary Hypertension
- Key idea: Meconium aspiration into lungs –> Increased inflammation in lungs –> Pulmonary vasoconstriction –> Hypoxia –> Increased pulmonary vasoconstriction –> More hypoxia –> etc.
- Key idea: Increased pulmonary vascular resistance (because the vasculature in the lungs uniquely vasoconstricts in areas of hypoxia to shunt blood to more oxygen-rich portions of the lungs) –> Increased resistance of blood flow out of RV outflow tract –> Increased right-to-left shunting (BLOOD WILL FOLLOW THE PATH OF LEAST RESISTANCE!)
- Key idea: Meconium-stained amniotic fluid most commonly seen in post-term babies
- Key idea: 3 major causes of respiratory distress in a newborn are (1) Transient tachypnea of newborn (2) Respiratory distress syndrome (3) Persistent pulmonary hypertension
8) Twelve hours after undergoing circumcision, a 3-day-old boy has persistent bleeding at his circumcision site. He was born at…
Factor VIII deficiency
- Baby boy with persistent bleeding at surgical site found to have a normal PT and an exceedingly elevated aPTT, most consistent with Hemophilia A (Factor 8 deficiency)
- Key idea: Coagulation disorders lead to persistent bleeding at surgical sites and hemarthrosis, whereas platelet disorders more commonly leads to mucosal bleeds (nosebleeds, bleeding gums) and petechiae
- Key idea: Hemophilia A (Factor 8 deficiency) and Hemophilia B (Factor 9 deficiency) are both X-linked, whereas Hemophilia C (Factor 11 deficiency) is autosomal recessive
- Key idea: Hemophilia A is the most common of the hemophilias
- Key idea: Common cause of bleeding in newborns is Vitamin K deficiency if they do not receive the Vitamin K shot at birth with the feared complication being intraventricular hemorrhage (altered mental status with increased head circumference)
- von Willebrand disease –> Normal platelet count, increased bleeding time, upper limit of normal or high aPTT (because vWF is a carrier protein of Factor VIII)
9) A 2-year-old boy is brought to the emergency department 30 minutes after he was found in his grandmother’s bedroom, surrounded by multiple…
Oxycodone
- Child with suspected medication ingestion who presents with respiratory depression (normal respiratory rate in 2 year old is ~30), altered mental status and pinpoint pupils most consistent with opioid intoxication (oxycodone)
- Aspirin overdose –> Early respiratory alkalosis followed by Anion-gap metabolic acidosis
- Imipramine (TCA) overdose –> Anti-histamine effects (altered mental status), anti-alpha 1 effects (hypotension, tachycardia), anti-cholinergic effects (dry mouth, urinary retention) and widened QRS on ECG –> Treated with IV sodium bicarbonate
- Iron overdose –> GI symptoms (abdominal pain + hematemesis + diarrhea) with visualization of radiopaque pills on x-ray
- Phenobarbitol overdose –> Altered mental status primarily
10) A 13-year-old girl is brought to the physician because of a 2-week history of mild neck tenderness. She has not had fever, fatigue, sensitivity to hot…
Chronic lymphocytic (Hashimoto) thyroiditis
- Adolescent girl with family history of autoimmune disease who presents with diffusely enlarged thyroid gland with increased anti-TPO antibody levels without clinical or laboratory symptoms of thyroid dysfunction most consistent with early Hashimoto thyroiditis
- Key idea; Goiter is often the first sign of Hashimoto thyroiditis and can present months before onset of thyroid hormone alterations
- Key idea: Hashimoto’s thyroiditis associated with anti-TPO, anti-thyroglobulin and anti-microsomal antibodies
11) A 1-month old boy is brought for a well-child examination. He was born at term following an uncomplicated pregnancy. Fifteen minutes…
Decreased pulmonary vascular resistance
- Key idea: Pulmonary vascular resistance is exceedingly high in utero because blood is shunted through the foramen ovale from the RA –> LA, and therefore the pulmonary vascular resistance will still be quite high at birth and will steadily decrease over the first several days of life as the lungs and their vasculature open up
- Key idea: If a patient has a VSD (which leads to left –> right shunting), the amount of shunting will be low at birth because of the high pulmonary vascular resistance, with an increasing amount of shunting as pulmonary vascular resistance decreases because that makes it more favorable for shunting to occur (BLOOD WILL FOLLOW THE PATH OF LEAST RESISTANCE!)
- Key idea: Most common congenital heart defect is a ventricular septal defect which classically leads to a holosystolic murmur along the left sternal border and does NOT lead to early cyanosis (because it leads to left –> right shunting)
12) An 11-year-old girl with spina bifida is brought to the physician because of right thigh pain for 2 days. She is paraplegic and has limited…
X-ray of the lower extremity
- Adolescent girl with numbness below the waist presents with thigh pain with associated swelling which should be worked up with a lower extremity x-ray to rule out fracture
- Key idea: Because the patient has sensory abnormality, we cannot solely rely on her perception of pain to determine how concerned we are about the presentation
13) A 14-year-old boy with a cardiac murmur is brought to the physician for a school physical examination. He reports that during this past…
Left ventricular volume overload
- Adolescent boy with a diastolic blowing murmur at the upper right sternal border presenting with exertional shortness of breath, widened pulse pressure and bounding pulses most consistent with aortic regurgitation –> LV volume overload
- Aortic stenosis –> Systolic ejection murmur at right 2nd intercostal space
- Aortic regurgitation –> Blowing diastolic murmur at right 2nd intercostal space
- Mitral regurgitation –> Holosystolic mumur at the cardiac apex +/- radiation to the axillae
- Mitral stenosis –> Diastolic click followed by a decrescendo murmur at the cardiac apex
14) A previously healthy 13-month-old boy is brought to the emergency department 1 hour after the acute onset of mild difficulty breathing…
Endoscopic examination of the patient’s airway
- Key idea: Afebrile child with no history of atopy who presents with dyspnea, cough and focal wheezing REFRACTORY to albuterol should make you highly suspicious for foreign body aspiration
- Key idea: Chest x-ray is NOT FULLY SENSITIVE for detection of foreign body and therefore if the remainder of the clinical picture is compatible (such as in this case), then you should proceed with endoscopic evaluation to determine what was aspirated and to remove it if needed (https://pubmed.ncbi.nlm.nih.gov/23472427/)
- Key idea: Most aspirated items will lodge in the right airway/lung because the right bronchus is wider and more vertically oriented –> Right lung hyperinflation and wheezes on the right
- Oral steroids –> Asthma attack (diffuse wheezing in patient with atopy)
- Subcutaneous epinephrine –> Anaphylactic shock (pronounced hypotension and urticarial rash following exposure)
15) A 3-year-old girl is brought to the physician because of a 2-week history of cough and nasal congestion. Her parents say that…
Adenoidectomy and tonsillectomy
- Young child who is excessively tired and irritable who also snores and is found to have enlarged tonsils/adenoids found on work-up to have signs of cor pulmonale (pulmonary hypertension in the setting of lung disease) who therefore needs treatment through removal of the tonsils/adenoids to avoid long-term complications
- Key idea: Most common cause of OSA in children is tonsillar/adenoid hypertrophy, whereas in adults most common cause is excessive soft tissue in setting of obesity
- Pathophysiological concept: Most of the capillary beds in the body will respond to hypoxia through vasodilation to increase blood flow to those areas; the one exception is the lungs which will vasoconstrict in setting of hypoxia to divert blood flow to more well-oxygenated portions of the lung, but this becomes a problem if oxygen tension is low throughout the lungs –> Diffuse vasoconstriction –> Increased pulmonary vascular resistance –> Increased RV afterload –> Pulmonary hypertension
- Pulmonary vasodilator therapy –> Useful in pulmonary ARTERIAL hypertension (genetic disease that commonly presents as a young woman with worsening shortness of breathe found to have an RV heave and a loud S2)
16) A 1-month-old girl is brought to the physician because of a 1-day history of decreased oral intake. Her mother says that the child…
Decreased T-lymphocyte activity
- Young baby with thrush and a candidal diaper rash concerning for Chronic mucocutaneous candidiasis (impaired cell-mediated (T cell) immunity in response to Candida)
- Key idea: Even if you could not remember the rare immunodeficiency syndrome being presented, you could guess that patient has decreased T-lymphocyte activity because thrush is classically seen in patients with HIV/AIDS, and those patients have decreased T-lymphocyte activity
- B-cell immunodeficiency –> Recurrent sinopulmonary infections (loss of IgA mucosal immunity), including both encapsulated bacteria (loss of IgG opsonization) and parasites (loss of IgE)
- T-cell immunodeficiency –> Recurrent viral and fungal infections
17) A 15-year-old girl is brought to the physician because of a 2-week history of a facial rash and fatigue. She has a 9-day history of…
Renal biopsy
- Adolescent girl presenting with non-specific systemic symptoms + inflammatory arthritis + malar rash + pleuritis + oral ulcers concerning for lupus who is also found to have blood and protein in her urine concerning for diffuse proliferative glomerulonephritis and should have a kidney biopsy performed to work up that possibility
- Lupus patient with nephrotic syndrome (lots of urine protein and no blood) –> Membranous nephropathy
- Lupus patient with nephritic syndrome (urine protein AND blood) –> Diffuse proliferative glomerulonephritis
- Differential for oral ulcers (on the NBME) includes:
- Lupus
- HIV
- Inflammatory bowel disease (primarily Crohn’s)
- Behcet’s disease
- Infectious mononucleosis
18) A previously healthy 6-year-old girl is brought to the emergency department because of severe abdominal pain, nausea, and vomiting…
Staphylococcus aureus
- Key idea: Rapid-onset food poisoning (<24 hours after exposure) are due to toxin-mediated processes and are primarily caused by Staph aureus (fatty, creamy foods left out in the sun) and Bacillus cereus (reheated rice syndrome)
- Key idea: These causes of food poisoning both begin quickly AND end quickly and therefore they are managed solely with supportive care
19) A previously healthy 10-year-old girl is brought to the physician because of a rash over the eyelids and fingers for 1 week…
Dermatomyositis
- Young girl with proximal muscle weakness + heliotrope rash (violaceous eyelid rash) + Gottron papules (scaly rash over dorsal aspect of knuckles) –> Dermatomyositis
- Key idea: Patients with dermatomyositis can also have a malar rash, so if you see a patient with a malar rash DO NOT IMMEDIATELY JUMP TO LUPUS!
- Mixed connective tissue disease –> Patient with features of SLE, systemic sclerosis and polymyositive
- Scleroderma –> Tight skin on fingers/face, esophageal dysmotility, Raynaud’s phenomenon, telangiectasias, pulmonary disease, etc.
20) A 2 1/2-year old boy is brought to the physician by his mother because she is concerned about his language development…
Audiometry
- Young child with normal motor (fine and gross) and social development with slightly delayed language development –> First step in work-up is audiometry to screen for hearing problems –> delayed language acquisition
- Key idea: By age 2, kids should use at least 200 words and speak in 2-word phrases/sentences
- Key idea: Hearing problems –> delayed language acquisition should be particularly suspected in a child with a history of recurrent ear infections or bacterial meningitis
- Note: All patients with bacterial meningitis should undergo audiologic testing preferably before hospital discharge
21) A 3-year-old boy is brought to the physician because of increasing lethargy and jaundice over the past week. At birth, he had jaundice…
Normocytic and normochromic
- Young boy with a father who needed a splenectomy for unspecified reason with a history of jaundice who presents with scleral icterus and splenomegaly found to have anemia with a normal reticulocyte count and negative Coombs test most concerning for a hemolytic anemia and most specifically for hereditary spherocytosis –> Normocytic anemia (as is the case with most types of hemolytic anemia)
- Key idea: Hereditary spherocytosis is inherited in an autosomal dominant fashion, with classic laboratory findings being an increased mean corpuscular hemoglobin concentration (MCHC), negative Coombs test and increased osmotic fragility test
- Key idea: Hereditary spherocytosis often managed with folate + blood transfusions but can be fully treated through splenectomy so patients with this condition often have relatives with a history of splenectomy for unknown reason
- Key idea: Both hereditary spherocytosis AND autoimmune hemolytic anemia lead to spherocytes on peripheral smear and the main way to differentiate between the conditions is the Coombs test (negative in HS, positive in AIHA)
22) A 16-year-old girl is brought to the physician because she has not had a menstrual period for 4 months. Menarche was at the age of 12 years…
Ovary
- Adolescent obese girl with signs of hyperandrogenism (hirsutism [hair growth in androgen-sensitive areas], acne) and menstrual irregularity most concerning for PCOS, with the pathology occurring in the ovary (polycystic OVARIAN syndrome due to anovulation in the OVARY)
- Diagnosis of PCOS requires at least 2 of the 3 following criteria:
- Irregular menses (anovulation)
- Polycystic ovaries on ultrasound
- Clinical (acne, hirsutism) or laboratory (elevated testosterone) signs of hyperandrogenism
- Key idea: While insulin resistance is often a component of PCOS, it is NOT part of the diagnostic criteria
- Key idea: Patients with PCOS at increased risk for endometrial hyperplasia/carcinoma because they have high levels of androgens that is readily aromatized to estrogen due to elevated fat levels (aromatization primarily takes place in fat cells)
- Key idea: Secondary amenorrhea defined as amenorrhea for >3 months among women with previously regular menses OR amenorrhea for >6 months among women with previously irregular menses
- Key idea: First step in work-up of secondary amenorrhea is a pregnancy test, and if that is negative then next best steps depending on patient’s presentation and your clinical suspicion would be prolactin, testosterone, FSH and TSH, with primary consideration for the following disorders:
- PCOS –> Heavy girl with signs of hyperandrogenism and/or insulin resistance found to have an elevated LH:FSH ratio
- Primary ovarian insufficiency –> Signs of menopause before 40 (hot flashes, mood swings, increased FSH) often in setting of autoimmune disease or prior radiation therapy
- Prolactinoma –> Infertility, galactorrhea, bitemporal hemianopsia
- Asherman syndrome –> History of D&C with normal hormonal profile but with cyclical painful abdominal pain
- Hypothyroidism –> Weight gain, bradycardia, cold intolerance, delayed deep tendon reflex relaxation, etc.
23) A 3-year-old boy is brought to the physician because of eye swelling for 1 week. His blood pressure is 120/60 mm Hg. Examination shows…
Minimal change nephrotic syndrome
- Key idea: Most common cause of nephrotic syndrome (significant proteinuria WITHOUT hematuria) in children is minimal change disease and it often follows a viral illness
- Focal segmental glomerulonephritis –> Often seen in adults who are African-American, hispanic, HIV-positive or IV drug abusers
- Hemolytic-uremic syndrome –> Patient with bout of bloody diarrhea followed by Brain FART (Neuro symptoms, Fever, Anemia (hemolytic), Renal problems, Thrombocytopenia)
- Henoch-Schonlein purpura –> Palpable purpura on buttocks + IgA vasculitis + GI symptoms (increased risk of intussusception) + arthralgias
- Acute PSGN –> Patient with proteinuria AND hematuria occurring weeks after a Group A Strep skin or pharyngeal infection
24) A 5-month-old girl is brought to the physician because of daily episodes of vomiting after feedings. Her mother reports that the episodes began shortly…
Intestinal malrotation
- Young girl with intermittent bilious vomiting with an upper GI series with oral contrast showing lots of contrast in the stomach and an unusual amount of bowel loops on the right side most consistent with intestinal malrotation
- Key idea: Common causes of bilious vomiting in a newborn would include intestinal malrotation, duodenal atresia or etiologies of failure to pass meconium (meconium ileus, Hirschsprung disease), but the fact that the patient was normal in the first week of life means duodenal atresia and etiologies of failure to pass meconium are HIGHLY UNLIKELY
- Imaging findings of malrotation: https://radiopaedia.org/articles/intestinal-malrotation?lang=gb
- Pyloric stenosis –> Non-bilious projectile vomiting in a 2-6 week old child +/- palpable olive-shaped mass in the epigastric region
25) A 3-year-old boy is brought to the emergency department because of a 2-day history of watery diarrhea and vomiting. During this period…
Inadequate caloric intake
- Young boy with acute diarrhea and vomiting complicated by poor oral intake found to have metabolic acidosis (likely due to diarrhea) and hypoglycemia most likely due to decreased caloric intake
- Adrenal insufficiency (primary) –> History of autoimmune disease, hyponatremia, hypoglycemia, hyperkalemia, metabolic acidosis, hyperpigmented gums/skin
- Insulin deficiency –> Type 1 diabetes –> HYPERglycemia
- Fructose 1-phosphate aldolase deficiency –> Consumption of fructose (juice, honey, etc.) –> Hypoglycemia, vomiting, jaundice, cirrhosis
- Note: Aspartame (artificial sweetener in sugar-free soda) known to worsen phenylketonuria (light complexion, eczema, musty body odor, seizures, intellectual disability)
26) A previously healthy 17-year-old girl comes to the physician for a follow-up examination after a PPD test produced 17 mm…
Volunteering at a skilled nursing facility
- Key idea: Common risk factors for tuberculosis include living/visiting crowded living spaces (prisons, homeless shelter, nursing homes), traveling to countries in which TB is endemic (NOT IRELAND), IVDU, etc.
- Key idea: PPD induration (NOT erythema) required for positivity depends upon patient risk factors with >5 mm being positive in patients with significant immunosuppression (HIV, organ transplant, immunosuppressant meds), recent contact with patient with active TB or patients with CXR findings consistent with TB // >10 mm being positive for patients from Tb endemic countries, IVDU, residents of high-risk settings (prisons, nursing homes, homeless shelters, etc.), children < 4 years old and patients working in mycobacterial labs // >15 mm in all patients
- Note: 3 treatment options for latent tuberculosis include (1) Isoniazid and rifapentine +/- pyridoxine (2) Isoniazid +/- pyridoxine (3) Rifampin
27) A 4-year-old African American girl has pallor and progressive malaise 6 weeks after being diagnosed with severe hepatitis A…
Anemia, aplastic
- Young girl with recent infection who presents with clinical and/or laboratory findings of leukopenia (low WBCs), anemia (low RBCs) and thrombocytopenia (low platelets) consistent with aplastic anemia
- Key idea: Aplastic anemia is the only one of the answer choices listed that would lead to low levels of all three blood cell lines
28) A previously healthy 14-month-old girl is brought to the physician by her mother because of a 2-month history of the left eye wandering…
Retinoblastoma
- Key idea: Normally eyes should have a Red reflex when light is shown into them due to light reflecting off the retina, so if there is no red reflex and the eye appears white, that means that there is a retinoblastoma or opacity of the lens (cataracts)
- Key idea: Retinoblastoma tends to be unilateral, whereas cataracts tends to be bilateral and can be associated with disorders of lactose metabolism and congenital Rubella, among other disorders
29) A previously healthy 8-year-old boy is brought to the emergency department because of fever, abdominal pain, and bloody…
Entamoeba histolytica
- Young immigrant boy presenting with fever, GI pain and bloody diarrhea found to have RUQ tenderness w/ hepatomegaly and colonic flask-shaped ulcers (VERY SPECIFIC FINDING!) most consistent with Entamoeba histolytica infection
- Key idea: While in reality ~90% of patients with this infection are asymptomatic, on the NBME exam the patient will classically have signs related to colitis (GI pain, bloody stool, etc.) and liver abscess (RUQ pain, fevers, “anchovy paste”-filled abscess)
- Key idea: Patients with colitis can be diagnosed via stool ova and parasites testing, whereas patients with an abscess can be diagnosed via Entamoeba serology
- Key idea: Treatment involves Metronidazole + Intraluminal paromomycin (for RUQ liver abscess)
- Giardia –> Patient who went camping and now has fatty stools
- Salmonella and Shigella would also have bloody diarrhea, but wouldn’t involve the liver
30) A 10-day-old male newborn is brought to the emergency department because of poor feeding and drowsiness for the past day…
Na+: Decreased // K+: Increased // Glucose: Decreased
- Newborn with GI symptoms (vomiting, poor feeding) found to be hypotensive with skin/mucosal hyperpigmentation concerning for primary adrenal insufficiency
- Key idea: Primary adrenal insufficiency means that the entire adrenal gland is dysfunctional such that patients will have decreased levels of cortisol, aldosterone and androgens
- Low cortisol (glucocorticoids) –> Hypoglycemia (decreased gluconeogenesis, decreased lipolysis) and Hypotension (decreased sensitivity of alpha-1 receptors to epinephrine)
- Low aldosterone (mineralocorticoids) –> NO reabsorption of Na+ in exchange for secretion of K+ and H+ in collecting duct –> Salt wasting (hyponatremia) along with retention of potassium (hyperkalemia) and protons (metabolic acidosis)
- Low cortisol –> Decreased negative feedback on anterior pituitary –> Increased ACTH production which also leads to increased melanocyte stimulating hormone production because ACTH and MSH are both derived from POMC –> hyperpigmentation
- Key idea: Hyperkalemia and skin hyperpigmentation are the two unique features present in primary adrenal insufficiency but absent in secondary adrenal insufficiency
- In-depth video about the HPA axis (including adrenal insufficiency) can be found here:
- https://www.youtube.com/watch?v=8VF719Jp34M&t=1470s
31) A 1-month-old girl is brought to the emergency department because of increasing irritability and difficulty breathing over the past 6 hours…
Supraventricular tachycardia
- Key idea: We can see that there is only slightly more than 1 big box between each QRS complex, telling us that the patient’s heart rate is only slightly less than 300 beats/min (1 big box = 0.2 seconds); since sinus tachycardia maxes out at approximately 220 – age, we know that this patient does not simply have sinus tachycardia
- Key idea: Children under 5-6 should NOT receive over the counter cough/cold medication because of the significant side effects, including tachycardia (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3461939/)
- We can see p-waves in leads I and aVL, so that rules out atrial fibrillation and VTach
32) A 2-year-old child with sickle cell hemoglobinopathy has a 2-week history of paroxysmal cough followed by vomiting…
Diphtheria-tetanus-acellular pertussis
- Young child with bouts of coughing with post-tussive vomiting and significant lymphocytosis most consistent with B. pertussis infection
- Key idea: B. pertussis is unique in that it is a bacterial infection but rather than a neutrophilic-predominant leukocytosis it leads to a lymphocyte-predominant leukocytosis due to pertussis toxin (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5761200/)
- Key idea: In addition to an inspiratory whoop, B. pertussis is known to lead to exceedingly forceful coughing which can lead to:
- Post-tussive vomiting
- Facial petechiae
- Subconjunctival hemorrhage
- Key idea: B. pertussis is treated with a macrolide (classically azithromycin)
33) A 7-year-old girl is brought for a follow-up examination 2 days after completing a 10-day course of antibiotics for her second episode…
HIV infection
- Young girl with a mother with a recent infection with non-tuberculous mycobacteria (M. avium-complex) who has had recurrent infections, lymphadenopathy and bilateral serous otitis media concerning for HIV infection
- Key idea: HIV’s clinical expression in kids is highly variable, with some showing signs early in life (recurrent infections, failure to thrive) and others remaining asymptomatic for many years (https://www.ncbi.nlm.nih.gov/books/NBK304129/)
- Key idea: Serous otitis media (fluid behind tympanic membrane WITHOUT inflammatory findings) is the most common middle ear pathology in patients with HIV
- Chronic granulomatous disease –> Boy (X-linked) with recurrent infections with catalase positive organisms (BELCH SPANS: Burkholderia, E coli, Listeria, Candida, H pylori, Staph aureus, Pseudomonas, Aspergillus, Nocardia, Serratia)
- DiGeorge –> CATCH-22 –> Cardiac defects, Abnormal facies, Thymic aplasia, Cleft lip/palate, Hypocalcemia
- X-linked agammaglobulinemia –> Boy (X-linked) with recurrent sinopulmonary bacterial and parasitic infections with scanty lymph nodes and tonsillar tissue (due to lack of germinal centers)
34) A previously healthy 7-year-old girl is brought to the physician by her father because of a 4-month history of bright red blood in her stool…
Colonoscopy
- Young girl with hyperpigmented macules on the lips who presents with a chronic history of intermittent bloody stools most consistent with Peutz-Jeghers syndrome c/b hamartomatous polyps versus colon cancer –> Work-up with colonoscopy to determine which is present
- Key idea: Patients with Peutz-Jeghers syndrome have increased risk of breast and GI cancers (colorectal, stomach, etc.)
- Air contrast enema –> Intussusception –> Toddler with intermittent episodes of abdominal pain that improves with bringing knees to chest +/- bloody stools
- Meckel scan –> Most common cause of bloody stools in a child and can predispose to intussusception (by acting as a lead point)
35) A 3-month-old girl is brought to the emergency department by her parents because of a 1-day history of fever and poor feeding…
Administration of a 0.9% saline
- Young infant brought to the ED with fever, vomiting, poor feeding, altered mental status and petechial/purpuric lesions (non-blanching erythematous lesions) found to have labs compatible with an uncompensated anion gap metabolic acidosis most consistent with sepsis c/b lactic acidosis –> Infants with non-specific presentation should receive thorough evaluation (urine culture, blood culture, usually lumbar puncture) and should be started on empiric antimicrobial therapy + Fluids
- Anion gap = [Na+] – ([HCO3-] + [Cl-]) = 136 – (17 + 100) = 19 > 12 –> Anion gap metabolic acidosis
- Winter’s formula: Predicted CO2 = (1.5 * HCO3) + 8 +/- 2 = (1.5 * 17) + 8 +/- 2 = 25.5 + 8 +/- 2 = (31.5 to 35.5) < 38 –> Uncompensated AG metabolic acidosis
- PAO2 = 150 – (PaCO2 / 0.8) = 150 – (38 / 0.8) = 150 – 47.5 = 102.5
- A-a gradient = 102.5 – 94 = 8.5 –> Normal A-a gradient ~5-10 –> No sign of hypoventilation or V/Q mismatch –> No need for intubation
- Patient’s presentation not severe enough to warrant pressors and acidosis not severe enough to warrant bicarbonate
36) A 15-month-old boy is brought to the physician for an initial exam. According to his mother and previous medical records…
Recommend a diet diary with calorie counts
- Young infant who over the last 3 months has had their weight drop from the 25th percentile –> 10th percentile and should have the patient’s diet and activity levels evaluated
- Key idea; Failure to thrive is repeated weight measurements below the 5th percentile or a drop in weight that crosses two major percentiles, so technically this patient does not qualify as failure to thrive (no need for admission or broad work-up)
- https://www.aafp.org/afp/2011/0401/p829.html
37) A 3-year-old girl is brought to the emergency department because of a 5-day history of increased thirst and urination…
Diabetes insipidus
- Young girl with recent head injury presenting with polydipsia and polyuria found to have low volume status with hypernatremia and dilute urine most consistent with diabetes insipidus (probably central)
- Key idea: Diabetes insipidus can be due to decreased ADH production by the posterior pituitary (often in setting of brain tumor, head trauma, etc.) or due to decreased responsiveness of the kidney to ADH (often due to lithium or hypercalcemia), and to differentiate between these you can give patient vasopressin and evaluate whether there is >50% increase in urine osmolality, which would point to central DI (as is likely the case here given the history of head injury)
- Psychogenic polydipsia and SIADH would lead to HYPOnatremia
38) A 10-year-old girl is brought to the physician because of swelling of the eyelids and feet for 3 days. Over the past week, she has had decreased…
Volume overload
- Young girl with history of possible strep infection 2 weeks ago presenting with diffuse edema and urine labs demonstrating protein, blood and RBC casts consistent with post-strep glomerulonephritis
- Key idea: Renal disease leads to hypertension due to volume overload, which can be remembered by thinking of the AEIOU mnemonic for indications for dialysis because they describe the consequences of poor renal function (Acidosis, Electrolyte abnormalities, Intoxication, Overload (volume), Uremia)
- Key idea: Glomerulonephritis will classically have protein AND blood, with the presence of RBC casts or dysmorphic RBCs being highly specific for glomerulonephritis
- Catecholamine excess –> Pheochromocytoma
- Mineralocorticoid excess –> Hyperaldosteronism, renal artery stenosis (increased RAAS activity)
39) A 16-year-old girl is brought to the emergency department by friends after she passed out at a party. She has a history of substance…
Endotracheal intubation
- Key idea: Patient has rapid, shallow respirations with borderline hypoxia and is exceedingly altered (which elicits concern about the patient’s ability to protect her airway) and therefore should be intubated
- Key idea: For all patients brought to the emergency department, the first consideration is the ABCs (Airway, Breathing, Circulation) as those need to be urgently/immediately addressed before pursuing any other diagnostics/therapy
40) A 3977-g (8-lb 12-oz) male newborn is delivered at term to a 30-year-old primigravid woman. Apgar scores are 8 and 9 at 1 and 5 minutes…
HBIG only if maternal HBsAg is positive and HBV at 2 and 6 months of age
- Key idea: If a mother has hepatitis B, the risk of vertical transmission is 90% without prophylaxis and the majority of vertical transmissions occur during the passage of the fetus through the birth canal –> Therefore, infants born to mothers with Hepatitis B should receive Hep B vaccine and Hep B immunoglobulin within 12 hours of delivery (decreases risk of vertical transmission to <2%)
- Key idea: Vaccinations administered at 2 and 6 months at age can be remembered with the mnemonic B DR. HIP (hepatitis B, DTap, Rotavirus, H influenzae, Inactivated polio, Pneumococcal) –> Note that NONE of these are live attenuated vaccines
41) A 2-year-old boy is brought to the emergency department 30 minutes after he fell approximately 8 feet from a backyard porch…
Urine blood
- Young boy with trauma to the back and unilateral flank tenderness who should be worked up for renal injury which is done primarily by looking for hematuria
- Key idea: Patient with trauma to the back should have evaluation for renal injury both through clinical evaluation (flank tenderness, flank ecchymosis) and lab testing (hematuria) –> If any of these signs are present then patient should receive imaging (often CT scan)
- Note: Abnormalities in all of the other labs listed would not be immediate (within 30 minutes of fall) and would take more time to develop (if they develop at all)
42) A 1-year-old boy is brought to the physician for a follow-up examination. He completed a 1-week course of intravenous ceftriaxone followed…
Monthly infusion of immune globulin
- Young boy with history of recurrent sinopulmonary infections and a recent infection with an encapsulated bacteria found on lab evaluation to have diffusely low immunoglobulin levels most concerning for Bruton’s agammaglobulinemia –> Treat by replacing immunoglobulins in patient
- Key idea: Patients with B cell disorders tend to have the following types of infections:
- Sinopulmonary (otitis media, pneumonia, etc.): Loss of mucosal IgA
- Encapsulated bacteria (Strep pneumo, H influenzae, etc.): Loss of IgG needed for opsonization
- Parasitic infections (mainly Giardia): Loss of IgE
- Key idea: Disease is X-linked so it will exclusively be seen in boys
- Key idea: These patients have absent B cells –> Poor germinal center development –> Scanty lymph nodes and tonsillar tissue (seen in Bruton’s agammaglobulinemia and Severe combined immunodeficiency)
43) A previously healthy 9-year-old boy is brought to the physician because of moderate groin pain since he participated in a hockey game…
Torsion of the appendix testes
- Key idea: Appendix testis is a remnant of the Mullerian duct that is present in about 90% of XY patients and just like the regular testes, the appendix testis can become twisted
- Key idea: A virtually pathognomonic sign of torsion of the appendix testis is a palpable “blue dot” sign (“3 mm area of bluish discoloration overlays the point of maximal tenderness”)
- Key idea: Just like testicular torsion, torsion of the appendix testis tends to occur in kids-adolescents
- Testicular pain relieved with elevation –> Positive Prehn’s sign –> Epididymitis (also would typically have fever)
- Testicular hematoma –> Would need to be preceded by trauma to the groin
44) A 1-day-old newborn is jittery and irritable. He was born at term to a 25-year-old primigravid woman who received irregular prenatal care…
Hypoglycemia
- Macrosomic 1-day old newborn born to a woman with irregular prenatal care who presents with irritability and jitteriness most concerning for hypoglycemia in setting of a mother with gestational diabetes
- Key idea: Macrosomia is almost always seen in the setting of gestational diabetes, so that was an important clue in this vignette
- Key idea: Glucose can cross the placenta but insulin CANNOT, and therefore when pregnant woman have gestational diabetes the baby will develop islet cell hypertrophy in response to the high levels of glucose they are receiving in utero –> Therefore, newborns of mothers with gestational diabetes are at risk for hypoglycemia because their pancreas will continue to produce large amounts of insulin but they are NO LONGER receiving high levels of glucose from the mother, leading to excessive insulin pushing them to be hypoglycemic
- Note: Newborns of women with gestational diabetes are also at risk for hypocalcemia and hypomagnesemia which can lead to irritability, tremors, twitching, etc. but those tend to present at 48-96 hours of birth (in contrast to hypoglycemia which tends to present within ~24 hours)
- Note: Gestational diabetes also puts the newborn at risk of respiratory distress syndrome because insulin inhibits surfactant production
45) An asymptomatic 15-year-old boy is brought to the physician for a well-child examination. He is concerned because he is the shortest…
Constitutional growth delay
- Adolescent boy who has always been short and has signs of pubertal delay (Tanner Stage 2 although should be Tanner Stage 4) with an otherwise benign exam most consistent with constitutional growth delay
- Key idea: If an adolescent presents with persistent short stature + pubertal delay + delayed bone growth, they have constitutional growth delay
- Key idea: Constitutional growth delay typically characterized by a child being small early in life who will eventually catch up to other kids once they go through puberty at 16-17 or so
- Insufficient caloric intake –> Weight would be decreased
- Adrenal insufficiency –> Hypotension, hypoglycemia, GI symptoms, fatigue, electrolyte abnormalities, etc.
46) A 5-year-old boy has had pain in the groin and thigh for 2 weeks; 1 week ago, he began limping. There is no history…
Legg-Calve-Perthes disease
- Young boy with groin pain with no other clinical findings and a normal x-ray, but with decreased hip uptake on bone scan most consistent with Legg-Calve-Perthes disease (idiopathic avascular necrosis of the hip in a toddler)
- Key idea: Avascular necrosis of the hip will lead to normal imaging findings early on, with advanced disease leading to a “crescent sign” on MRI –> Therefore, if you are clinically suspecting avascular necrosis but have negative imaging the next step is a bone scan which is helpful in detecting early disease (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5656489/)
- Key idea: Hip pathology (hip osteoarthritis, avascular necrosis of the hip, etc.) will lead to GROIN pain
- Causes of avascular necrosis of the hip can be remembered with mnemonic CAST Bent-LEGS:
- Corticosteroids
- Alcoholism
- Sickle cell disease (RBC clumping –> Vascular occlusion)
- Trauma
- “Bends” (rising too quickly from deep depth)
- LEgg-Calve Perthes (idiopathic in a child ~5 years old) and Lupus
- Gaucher disease (Ashkenazi jew with presentation similar to Sickle cell disease)
- Slipped capital femoral epiphysis (obese adolescent)
47) A 6-year-old girl is brought to the physician by her father because of a 36-hour history of fever and a 1-day history of pain and swelling…
Penicillin
- A young girl with a recent history of sore throat that went untreated (concerning for GAS pharyngitis given the increased ASO titer level) who now presents with arthritis, fever, and a murmur concerning for mitral regurgitation most consistent with Rheumatic fever
- Key idea: Post-strep glomerulonephritis can be seen after a GAS throat OR SKIN infection and penicillin does NOT decrease the risk of PSGN // In contrast, Rheumatic fever is ONLY seen after a GAS throat infection and penicillin DOES decrease the risk of rheumatic fever
- Key idea: Symptoms of rheumatic fever can be remembered by JONES criteria
- Joints (polyarthritis)
- Think of O as being shaped like Heart –> Pancarditis (peri-, myo-, endo-)
- Nodules (subcutaneous)
- Erythema marginatum
- Sydenham chorea (purposeless movements)
- Note: Making a fist –> Increases afterload –> More difficult forward flow of blood through heart –> Forward flowing murmur (AS, MS, HOCM, etc.) become quieter (less blood rushing by messed up valves) and Backward flowing murmur (MR, AR, VSD, etc.) become louder (more blood rushing by messed up valves)
48) A 14-year-old boy is brought to the physician because his parents are concerned that he has had several episodes of tripping and incoordination…
Charcot-Marie-Tooth disease
- Key idea: Charcot-Marie-Tooth is an autosomal dominant disorder (family history) that presents with foot drop, foot deformities and lower extremity weakness and sensory defects
- Duchenne muscular dystrophy –> Male toddler with weakness, calf pseudohypertrophy, Gowers sign, etc.
49) A 1-year-old girl is brought to the emergency department because of a 3-day history of low-grade fever and watery diarrhea…
Lactic acidosis
- Infant with a recent exposure to someone with a URI and diarrhea who presents with acute watery diarrhea containing mucus found to be volume depleted with labs pointing to an anion gap metabolic acidosis (134 – 105 – 8 = 21 > 12) most consistent with lactic acidosis in the setting of hypovolemia
- Causes of an anion-gap metabolic acidosis can be remembered with the mnemonic MUDPILERS:
- Methanol poisoning (blindness and eye symptoms)
- Uremia (kidney disease –> pericarditis, altered mental status, asterixis, etc.)
- DKA (ketonuria, glucose ~300-500, GI symptoms, polyuria, polydipsia)
- Propylene glycol
- Isoniazid or Iron poisoning
- Lactic acidosis (most common –> sepsis, hypovolemia, seizures, etc.)
- Ethylene glycol (kidney stones, acute tubular necrosis)
- Rhabdomyolysis (dark urine, excessive exercise, positive urine blood but negative RBCs on microscopy)
- Salicylates (early respiratory alkalosis followed by late anion gap metabolic acidosis)
- Renal tubular acidosis –> NON-AG metabolic acidosis
- IBD and Celiac disease would lead to chronic symptoms and would often present in somebody a little older
50) A 3-day-old girl with Down syndrome has not had a bowel movement since birth. She feeds poorly but has not vomited…
Absence of ganglion cells in the bowel wall
- Major causes of “Failure to pass meconium”:
- Hirschsprung disease: Due to failed migration of ganglion cells to distal portion of GI tract, associated with down syndrome, obstruction at level of rectosigmoid leading to a positive squirt sign (finger in anus relieves the obstruction and leads to forecful expulsion of backed up meconium/stool)
- Meconium ileus: Due to thick inspissated stool, associated with cystic fibrosis, obstruction at level of terminal ileum, negative squirt sign
- Imperforate anus: Due to lack of an anal opening, abnormal physical exam, sometimes associated with VACTERL syndrome (combination of mesodermal defects affecting muscle, bone, larynx, etc.)
We are not affiliated with the NBME, USMLE or AAMC.
The answer explanations may not be reproduced or distributed, in whole or in part, without written permission of Step Prep.
