Examkin

All practice questions

1849 questions

All types8,270Multiple choice4,249Multiple select325Numeric160Matching1,849Ordering1,687
Question 641Question →

Match each clinical scenario describing a high-risk infectious disease exposure with the most appropriate post-exposure prophylaxis (PEP) regimen.

Click a left item, then click its matching right item

Items

An unvaccinated healthcare worker sustains a needlestick injury from a patient who is positive for hepatitis B surface antigen.
A 20-year-old college student shares a small dormitory room with a classmate who was just hospitalized with confirmed Neisseria meningitidis infection.
A 45-year-old camper awakens in a tent to find a bat flying nearby; upon closer inspection, a small, unexplained scratch is found on his arm.
A surgical resident suffers a deep scalpel laceration while operating on a patient with an unsuppressed, highly viremic HIV infection.

Matches

Show answer & explanation

Answer

Match the specific exposure to its guideline-directed prophylaxis: Unvaccinated HBV exposure requires HBIG and vaccine; meningococcal close contact requires ceftriaxone, ciprofloxacin, or rifampin; potential bat exposure requires RIG and rabies vaccine; and high-risk occupational HIV exposure requires a 3-drug antiretroviral regimen.
Appropriate post-exposure prophylaxis depends entirely on the specific pathogen, the nature of the exposure, and the host's prior immunity. Bacterial exposures like Neisseria meningitidis require short-course antibiotics to eliminate carriage. Viral exposures like HIV require multi-drug antiretroviral therapy to prevent viral replication and integration. Pathogens with potentially lethal outcomes in naive hosts (Rabies, HBV) require a combination of immune globulin (for immediate passive protection) and vaccination (for lasting active immunity).

Step-by-Step Solution

1
Evaluate the source patient and the type of exposure.
Identify the specific pathogen risk (HBV, Neisseria meningitidis, Rabies virus, HIV).
Post-exposure prophylaxis regimens are highly pathogen-specific.
2
Assess the immune status of the exposed individual.
Determine if passive immunity, active immunity, or both are required.
Vaccinated individuals may need different interventions compared to naive individuals (e.g., an unvaccinated person exposed to HBV needs both HBIG and the vaccine).
3
Select the appropriate pharmacologic or immunologic intervention.
Match the exposure to the current guideline-directed prophylaxis regimen.
Timely administration of the correct regimen prevents disease transmission and progression.

Key Concept

Post-exposure prophylaxis (PEP) guidelines for high-risk infectious exposures
Question 642Question →

Match each of the following benign neonatal skin findings with its most likely clinical diagnosis.

Click a left item, then click its matching right item

Items

Blotchy erythematous macules with central tiny papules and pustules appearing on the trunk and face of a 48-hour-old neonate; Wright stain of the exudate shows a predominance of eosinophils.
Superficial pustules lacking surrounding erythema present at delivery, which rapidly rupture to leave hyperpigmented macules with a collarette of scale; microscopic examination shows abundant neutrophils.
Firm, 1- to 2-millimeter pearly white papules concentrated on the nose, cheeks, and chin of a newborn, representing benign retention of keratin within the pilosebaceous units.
A flat, homogeneous, blue-gray patch with indistinct borders located on the sacrum and buttocks of a healthy newborn, caused by delayed disappearance of dermal melanocytes.

Matches

Show answer & explanation

Answer

The presentation with eosinophils at 48 hours matches Erythema toxicum neonatorum. The presentation with neutrophils at birth matches Transient neonatal pustular melanosis. The pearly white facial papules match Milia. The blue-gray sacral patch matches Congenital dermal melanocytosis.
Each benign neonatal skin finding has a distinct clinical presentation, cellular composition, and temporal onset. Erythema toxicum neonatorum typically appears on days 2-3 of life with eosinophil-filled pustules. Transient neonatal pustular melanosis is present at birth, lacks surrounding erythema, leaves hyperpigmented macules, and contains neutrophils. Milia are benign keratin-filled cysts presenting as firm white papules on the face. Congenital dermal melanocytosis presents as blue-gray patches over the lower back and buttocks due to deep dermal melanocytes.

Step-by-Step Solution

1
Analyze the first clinical description emphasizing the timeline (48 hours) and cellular makeup (eosinophils).
Identify this as erythema toxicum neonatorum.
Erythema toxicum neonatorum rarely appears at birth and is characterized by eosinophil-filled pustules on an erythematous base.
2
Analyze the second clinical description emphasizing the timeline (present at birth) and cellular makeup (neutrophils).
Identify this as transient neonatal pustular melanosis.
This condition is present at delivery, leaves hyperpigmented macules, and contains neutrophils rather than eosinophils.
3
Evaluate the third description detailing firm white papules on the face.
Identify this as milia.
Milia are common epidermal inclusion cysts containing keratin that spontaneously resolve.
4
Assess the final description of a blue-gray macular lesion on the sacrum.
Identify this as congenital dermal melanocytosis.
These lesions are benign collections of melanocytes in the deeper layers of the dermis, most commonly seen in infants of African or Asian descent.

Key Concept

Differentiation of benign neonatal dermatologic findings
Question 643Question →

Match each clinical and laboratory presentation with the most likely underlying hematologic diagnosis.

Click a left item, then click its matching right item

Items

A 45-year-old woman with confusion, fever, petechiae, and acute kidney injury. Labs show hemoglobin 8.2 g/dL, platelets 18,000/mm³, normal PT/PTT, and numerous schistocytes.
A 62-year-old man with aquagenic pruritus and erythromelalgia. Labs show hematocrit 58%, WBC 14,000/mm³, platelets 450,000/mm³, and decreased serum erythropoietin.
A 35-year-old woman with epistaxis and ecchymoses. Labs show isolated thrombocytopenia of 22,000/mm³ with normal hemoglobin, WBC count, and coagulation studies. Smear shows megathrombocytes.
A 55-year-old man with fatigue, night sweats, and massive splenomegaly. Labs show WBC 85,000/mm³ with a left shift including basophilia and a low leukocyte alkaline phosphatase score.

Matches

Show answer & explanation

Answer

Properly align each clinical vignette with its corresponding hematologic malignancy or disorder based on unique laboratory and symptomatic clues.
Each diagnosis uniquely matches a constellation of symptoms and lab findings. TTP is defined by MAHA and thrombocytopenia with normal coagulation parameters. Polycythemia vera presents with primary erythrocytosis (low EPO) and aquagenic pruritus. ITP presents with isolated thrombocytopenia in the absence of other systemic illnesses. CML is a myeloproliferative disorder characterized by massive splenomegaly, prominent basophilia, and a low LAP score.

Step-by-Step Solution

1
Analyze the first vignette for the classic pentad.
Identified microangiopathic hemolytic anemia (MAHA), thrombocytopenia, renal failure, neurologic changes, and fever.
These concurrent findings represent Thrombotic thrombocytopenic purpura (TTP).
2
Evaluate the second vignette for signs of myeloproliferation and specific symptoms.
Elevated hematocrit, WBCs, and platelets with low EPO and aquagenic pruritus.
These are hallmark features of Polycythemia vera, caused by autonomous marrow proliferation.
3
Assess the third vignette for isolated lab abnormalities.
Isolated thrombocytopenia with normal coagulation studies and no other cytopenias.
This presentation strongly suggests Immune thrombocytopenia (ITP), a diagnosis of exclusion.
4
Review the fourth vignette for leukocytosis and splenomegaly.
High WBC count with left shift, basophilia, and low LAP score.
A low LAP score and the presence of basophilia differentiate Chronic myeloid leukemia (CML) from severe infection (leukemoid reaction).

Key Concept

Accurate diagnosis of hematologic disorders relies on recognizing pathognomonic clinical features paired with specific laboratory abnormalities, such as smear findings (schistocytes, megathrombocytes) or functional assays (LAP score, EPO levels).
Question 644Question →

Match the following neonatal dermatologic conditions with their characteristic clinical and cytological findings.

Click a left item, then click its matching right item

Items

Erythema toxicum neonatorum
Transient neonatal pustular melanosis
Neonatal cephalic pustulosis
Neonatal herpes simplex virus infection

Matches

Show answer & explanation

Answer

Erythema toxicum neonatorum matches with eosinophil-predominant pustules; Transient neonatal pustular melanosis matches with neutrophil-predominant pustules lacking erythema; Neonatal cephalic pustulosis matches with Malassezia-associated facial papules; Neonatal herpes simplex virus infection matches with coalescing vesicles requiring immediate antiviral therapy.
Each dermatologic condition has highly specific defining features: Erythema toxicum neonatorum presents with eosinophils and an erythematous base; transient neonatal pustular melanosis has neutrophils and leaves hyperpigmented macules; neonatal cephalic pustulosis is Malassezia-associated and appears at approximately three weeks; neonatal herpes simplex virus presents with clustered vesicles and requires immediate evaluation and treatment.

Step-by-Step Solution

1
Analyze the cytological findings of the vesicular and pustular rashes.
Identify eosinophils as characteristic of erythema toxicum neonatorum and neutrophils as characteristic of transient neonatal pustular melanosis.
Differentiating common benign neonatal pustular eruptions relies heavily on the predominant inflammatory cell type seen on a Wright stain.
2
Evaluate the clinical presentation and timing of the facial rashes.
Distinguish neonatal cephalic pustulosis (presenting around three weeks, lacking comedones, caused by Malassezia) from true infantile acne or other entities.
Clinical timing and lesion morphology help separate benign neonatal cephalic pustulosis from more severe infectious etiologies or endocrinologic abnormalities.
3
Identify the infectious, potentially life-threatening rash.
Match the clustered vesicles on an erythematous base (especially on presenting parts like the scalp) with neonatal herpes simplex virus infection.
HSV is a critical 'must-not-miss' diagnosis that requires urgent systemic antiviral therapy to prevent severe morbidity or mortality.

Key Concept

Differentiation of neonatal vesiculopustular eruptions based on clinical presentation, timing, and cytological findings.
Question 645Question →

Match the following pediatric endocrine conditions to their most characteristic clinical or laboratory presentation.

Click a left item, then click its matching right item

Items

21-hydroxylase deficiency
Central precocious puberty
Constitutional delay of growth and puberty
Hashimoto thyroiditis

Matches

Show answer & explanation

Answer

The correct matches are: 21-hydroxylase deficiency with elevated 17-hydroxyprogesterone; Central precocious puberty with advanced bone age and pubertal LH; Constitutional delay with delayed bone age; and Hashimoto thyroiditis with elevated TSH and anti-TPO antibodies.
Each listed condition has a highly specific diagnostic presentation. 21-hydroxylase deficiency is confirmed by elevated 17-hydroxyprogesterone. Central precocious puberty requires evidence of hypothalamic-pituitary activation via elevated LH. Constitutional delay is recognized by a delayed bone age without other pathology. Hashimoto thyroiditis is defined by autoimmune primary hypothyroidism with elevated TSH and anti-TPO antibodies.

Step-by-Step Solution

1
Analyze the characteristic presentation of 21-hydroxylase deficiency.
Identified as the classic cause of congenital adrenal hyperplasia, presenting with elevated 17-hydroxyprogesterone.
To correctly map the enzymatic defect to its biochemical marker.
2
Evaluate the clinical features of central precocious puberty.
Identified as true puberty occurring early, driven by gonadotropins (LH).
To distinguish central (gonadotropin-dependent) from peripheral causes.
3
Determine the diagnostic hallmark of constitutional delay of growth and puberty.
Identified that bone age is delayed and correlates with height age.
To differentiate from pathologic causes of short stature or delayed puberty.
4
Identify the primary markers for Hashimoto thyroiditis.
Matched with elevated TSH and positive anti-thyroid peroxidase antibodies.
To confirm the autoimmune etiology of primary hypothyroidism.

Key Concept

Diagnosis of common pediatric endocrine disorders relies on identifying specific hormonal and radiologic patterns, such as characteristic hormone accumulations, gonadotropin levels, and bone age assessments.
Question 646Question →

Match each clinical presentation of third-trimester or intrapartum vaginal bleeding with its most likely diagnosis.

Click a left item, then click its matching right item

Items

A 32-year-old G2P1 at 36 weeks gestation presents with sudden-onset, severe abdominal pain, dark red vaginal bleeding, and a rigid, tender uterus.
A 29-year-old G3P2 at 34 weeks gestation experiences a sudden episode of painless, bright red vaginal bleeding. Her abdomen is soft and non-tender.
A 26-year-old G1P0 at 38 weeks gestation in active labor undergoes artificial rupture of membranes, immediately followed by moderate vaginal bleeding and sudden fetal bradycardia.
A 24-year-old G1P0 at 39 weeks gestation reports a small amount of blood-tinged mucous discharge associated with irregular contractions and cervical dilation.

Matches

Show answer & explanation

Answer

Painful bleeding with rigid uterus matches Placental abruption. Painless bleeding with soft abdomen matches Placenta previa. Bleeding with bradycardia post-rupture of membranes matches Vasa previa. Blood-tinged mucus with contractions matches Bloody show.
The correct matches rely on hallmark clinical signs. Placental abruption involves premature placental separation, causing painful bleeding and a hypertonic uterus. Placenta previa involves abnormal placentation over the cervical os, causing painless bleeding. Vasa previa involves fetal vessels overlying the cervix, which tear upon membrane rupture, causing immediate fetal hemorrhage and bradycardia. Bloody show is a normal sign of cervical dilation involving blood-tinged mucus.

Step-by-Step Solution

1
Analyze the clinical features of each vignette, focusing on the presence or absence of abdominal pain, uterine tone, and the timing of bleeding relative to membrane rupture.
The vignettes can be categorized as: painful/rigid uterus, painless/soft uterus, post-membrane rupture with fetal distress, and blood-tinged mucus in early labor.
These key clinical features help differentiate the major causes of late-pregnancy bleeding.
2
Correlate each distinct clinical presentation with its underlying pathophysiological etiology.
Pain and rigidity correlate with placental abruption; painless bleeding correlates with placenta previa; tearing of fetal vessels at amniotomy correlates with vasa previa; physiologic cervical change correlates with bloody show.
Matching the clinical signs to the underlying disease process ensures the correct diagnosis is selected.

Key Concept

Differentiating the etiologies of third-trimester and intrapartum vaginal bleeding based on pain, uterine tone, and fetal status.
Question 647Question →

Match each of the following pediatric congenital heart defects with its classic clinical or auscultatory finding.

Click a left item, then click its matching right item

Items

Ventricular septal defect
Atrial septal defect
Patent ductus arteriosus
Tetralogy of Fallot

Matches

Show answer & explanation

Answer

Ventricular septal defect matches with a harsh holosystolic murmur. Atrial septal defect matches with a wide, fixed split S2. Patent ductus arteriosus matches with a continuous machine-like murmur. Tetralogy of Fallot matches with cyanotic episodes that improve with knee-chest positioning.
Each congenital heart defect alters hemodynamics in a specific way that leads to classic, identifiable clinical signs. VSD produces a holosystolic murmur due to continuous systolic left-to-right shunting. ASD causes delayed pulmonic valve closure due to increased right-sided volume, creating a wide, fixed split S2. PDA produces a continuous machine-like murmur because aortic pressure exceeds pulmonary artery pressure in both systole and diastole. Tetralogy of Fallot features hypercyanotic spells caused by right-to-left shunting, which are relieved by increasing systemic vascular resistance (such as assuming a knee-chest position).

Step-by-Step Solution

1
Identify the hallmark finding of a ventricular septal defect.
Matches with harsh, holosystolic murmur at the left lower sternal border.
Blood flows continuously across the defect during ventricular contraction.
2
Identify the hallmark finding of an atrial septal defect.
Matches with wide, fixed splitting of the second heart sound (S2).
Increased right heart volume constantly delays pulmonic valve closure.
3
Identify the hallmark finding of a patent ductus arteriosus.
Matches with continuous, machine-like murmur at the left infraclavicular area.
Flow from the aorta to the pulmonary artery occurs throughout the entire cardiac cycle.
4
Identify the clinical hallmark of Tetralogy of Fallot.
Matches with episodes of severe cyanosis that improve with knee-chest positioning.
Increasing systemic vascular resistance reduces the right-to-left shunt, temporarily improving oxygenation.

Key Concept

Hallmark clinical presentations of common congenital heart defects
Estimated Time:1m 0s
Question 648Question →

Match the following clinical vignettes of neonatal cyanotic heart disease with the most likely underlying congenital cardiac defect.

Click a left item, then click its matching right item

Items

Cyanosis, left axis deviation, and absent R waves in V1 with tall R waves in V6 on ECG, alongside decreased pulmonary vascularity.
Severe respiratory distress and cyanosis at birth, prominent parasternal heave, no audible murmur, and severe pulmonary edema on chest radiograph.
Mild cyanosis, hyperactive precordium, single S2, bounding peripheral pulses, and a serum calcium level of 6.8 mg/dL.
Cyanosis, massive cardiomegaly on chest radiograph, and right atrial enlargement with a short PR interval and slurred QRS upstroke on ECG.

Matches

Show answer & explanation

Answer

Tricuspid atresia matches with left axis deviation; obstructed TAPVR matches with severe pulmonary edema and no murmur; truncus arteriosus matches with bounding pulses and hypocalcemia; Ebstein anomaly matches with massive cardiomegaly and Wolff-Parkinson-White syndrome changes.
Each congenital heart defect possesses a unique constellation of findings. Tricuspid atresia is distinctively associated with left ventricular hypertrophy in a cyanotic neonate. Obstructed TAPVR uniquely causes severe pulmonary venous congestion without an audible murmur. Truncus arteriosus combines wide pulse pressures with DiGeorge syndrome features. Ebstein anomaly uniquely presents with extreme right atrial enlargement and Wolff-Parkinson-White syndrome.

Step-by-Step Solution

1
Analyze the ECG findings in cyanotic neonates to distinguish right versus left ventricular dominance.
Left axis deviation and left ventricular hypertrophy in a cyanotic newborn strongly point to tricuspid atresia.
Neonatal ECGs typically show right axis deviation; deviation to the left indicates an underdeveloped right ventricle.
2
Assess the presence or absence of a murmur combined with chest radiograph findings.
Profound cyanosis with pulmonary edema and no murmur indicates a venous obstruction, characteristic of obstructed total anomalous pulmonary venous return (TAPVR).
The lack of a murmur rules out major valvular stenoses or significant septal defects, pointing towards a venous return anomaly.
3
Evaluate systemic findings, such as pulse quality and metabolic derangements.
Bounding pulses combined with a single S2 and hypocalcemia suggest truncus arteriosus.
The common arterial trunk creates a wide pulse pressure, and the embryological neural crest defect associates with thymic and parathyroid hypoplasia (DiGeorge syndrome).
4
Identify characteristic radiographic and electrophysiologic syndromes.
Massive cardiomegaly with pre-excitation (short PR, slurred upstroke) indicates Ebstein anomaly.
Tricuspid valve displacement massively dilates the right atrium, and accessory electrical pathways are a well-known comorbidity.

Key Concept

Diagnostic differentiation of neonatal cyanotic congenital heart defects based on unique physical examination, ECG, and radiographic findings.
Question 649Question →

Match each patient's clinical presentation to the most likely underlying cardiovascular anomaly.

Click a left item, then click its matching right item

Items

A 4-year-old boy with elfin facial features, developmental delay, hypercalcemia, and a systolic ejection murmur heard best at the right upper sternal border.
A 15-year-old girl with primary amenorrhea, short stature, a webbed neck, and diminished femoral pulses compared to brachial pulses.
A 3-day-old cyanotic neonate with hypocalcemic seizures, a cleft palate, and echocardiography showing a single large vessel arising from the heart.
A 2-month-old infant with hypotonia, upslanting palpebral fissures, a single palmar crease, and a loud S1 with a hyperdynamic precordium.
A newborn infant presenting with severe bradycardia (heart rate of 45/min) born to a mother with a history of recurrent miscarriages and joint pains.

Matches

Show answer & explanation

Answer

Williams syndrome pairs with supravalvular aortic stenosis; Turner syndrome pairs with coarctation of the aorta; DiGeorge syndrome pairs with truncus arteriosus; Down syndrome pairs with complete atrioventricular septal defect; and Neonatal lupus pairs with congenital complete heart block.
Each clinical vignette provides classic physical exam and historical clues for a specific syndrome. Williams syndrome (elfin facies, hypercalcemia) causes supravalvular aortic stenosis. Turner syndrome (short stature, webbed neck, amenorrhea) is linked to coarctation of the aorta. DiGeorge syndrome (hypocalcemia, cleft palate, conotruncal defects) is linked to truncus arteriosus. Down syndrome (hypotonia, typical facies) is linked to complete atrioventricular septal defect. Maternal SLE (recurrent miscarriages, joint pain) with anti-Ro antibodies causes congenital complete heart block in the neonate.

Step-by-Step Solution

1
Analyze each clinical vignette to identify the underlying genetic syndrome or maternal condition based on physical exam findings and history.
Identified Williams syndrome, Turner syndrome, DiGeorge syndrome, Down syndrome, and Neonatal lupus.
Recognizing the syndromic presentation is a necessary prerequisite before determining the associated cardiac defect.
2
Recall the most characteristic cardiovascular anomaly associated with each identified syndrome.
Williams links to supravalvular aortic stenosis, Turner to coarctation, DiGeorge to conotruncal defects, Down to AV septal defect, and Neonatal lupus to heart block.
This tests core competency regarding syndromic associations in pediatric cardiology.
3
Map the specific cardiovascular anomalies to their corresponding clinical presentations.
Successfully paired all five items correctly.
Completes the requirements for the matching evaluation.

Key Concept

Many pediatric cardiovascular disorders are strongly associated with specific genetic syndromes or maternal autoimmune conditions. Recognizing the syndromic phenotype is critical for targeted screening, accurate diagnosis, and appropriate management of the underlying cardiac defect.
Question 650Question →

Correlate each distinct clinical and laboratory vignette with its most accurate diagnosis.

Click a left item, then click its matching right item

Items

A 2-week-old female newborn with ambiguous genitalia, hyponatremia, hyperkalemia, and markedly elevated 17-hydroxyprogesterone.
A 6-month-old infant with failure to thrive, severe polyuria, hypernatremia, and dilute urine that remains dilute following desmopressin administration.
A 14-year-old male with delayed puberty, lack of sense of smell, prepubertal testicular volume, and inappropriately low luteinizing and follicle-stimulating hormones.
A 7-year-old female with rapid linear growth, isolated breast development, advanced bone age, and luteinizing hormone levels that rise significantly after gonadotropin-releasing hormone (GnRH) stimulation.

Matches

Show answer & explanation

Answer

The presentations match as follows: The virilized neonate with salt wasting has 21-hydroxylase deficiency; the infant with vasopressin-resistant polyuria has nephrogenic diabetes insipidus; the anosmic teen with delayed puberty has Kallmann syndrome; and the child with early maturation and robust GnRH response has central precocious puberty.
Each vignette provides pathognomonic clinical features and laboratory findings that map specifically to a single pediatric endocrine disorder, differentiating it from similar conditions based on distinct physiological principles.

Step-by-Step Solution

1
Analyze the neonatal presentation involving virilization and electrolyte abnormalities.
Identified as 21-hydroxylase deficiency.
The combination of elevated 17-hydroxyprogesterone and salt-wasting is specific to this form of congenital adrenal hyperplasia.
2
Evaluate the infant with polyuria and a failed desmopressin response.
Identified as nephrogenic diabetes insipidus.
Lack of urine concentration following desmopressin rules out central diabetes insipidus.
3
Assess the teenager with delayed puberty and anosmia.
Identified as Kallmann syndrome.
Anosmia paired with low gonadotropins (hypogonadotropic hypogonadism) points directly to a failure of GnRH neuron migration.
4
Review the child with early puberty and a positive GnRH stimulation test.
Identified as central precocious puberty.
A robust luteinizing hormone increase post-GnRH confirms central activation of the hypothalamic-pituitary-gonadal axis.

Key Concept

Clinical presentation and diagnostic testing in pediatric endocrine disorders
Estimated Time:1m 30s
Question 651Question →

A pediatrics clerkship director is reviewing classic presentations of congenital heart diseases with medical students. Match each congenital heart defect to its most characteristic clinical or radiographic finding.

Click a left item, then click its matching right item

Items

Tetralogy of Fallot
Transposition of the Great Arteries
Ventricular Septal Defect
Coarctation of the Aorta
Patent Ductus Arteriosus

Matches

Show answer & explanation

Answer

Tetralogy of Fallot matches the boot-shaped heart. Transposition of the Great Arteries matches the egg-on-a-string X-ray. Ventricular Septal Defect matches the harsh holosystolic murmur. Coarctation of the Aorta matches the brachial-femoral pulse delay. Patent Ductus Arteriosus matches the continuous machine-like murmur.
Each congenital heart defect has distinct pathophysiologic consequences that lead to classic physical exam and radiographic findings. Recognizing these associations is crucial for rapid clinical identification and determining the next best step in management.

Step-by-Step Solution

1
Identify the characteristic radiographic and auscultatory findings for Tetralogy of Fallot.
Matches with 'boot-shaped' heart and harsh systolic ejection murmur.
The boot shape on X-ray is caused by right ventricular hypertrophy, and the murmur is caused by pulmonary stenosis.
2
Identify the hallmark presentation of Transposition of the Great Arteries.
Matches with narrow mediastinum ('egg-on-a-string') and a single S2.
The anterior location of the aorta narrows the mediastinal shadow and obscures the pulmonary component of the second heart sound.
3
Correlate the physical exam findings for a Ventricular Septal Defect.
Matches with a harsh holosystolic murmur at the left lower sternal border.
Blood flows continuously from the high-pressure left ventricle to the lower-pressure right ventricle throughout systole.
4
Recognize the vascular exam findings specific to Coarctation of the Aorta.
Matches with brachial-femoral pulse delay and interscapular murmur.
The narrowing of the descending aorta restricts distal blood flow, causing delayed or weak femoral pulses and a murmur audible over the back.
5
Identify the classic auscultatory signature of a Patent Ductus Arteriosus.
Matches with a continuous machine-like murmur and bounding pulses.
Continuous flow from the aorta to the pulmonary artery occurs in both systole and diastole, while rapid aortic runoff into the pulmonary circulation causes wide pulse pressure.

Key Concept

Clinical and radiographic hallmarks of congenital heart diseases
Question 652Question →

Match the following rare congenital adrenal hyperplasia variants and related steroidogenesis defects with their most characteristic clinical and laboratory presentations in neonates.

Click a left item, then click its matching right item

Items

11-beta-hydroxylase deficiency
17-alpha-hydroxylase deficiency
3-beta-hydroxysteroid dehydrogenase deficiency
Cytochrome P450 oxidoreductase deficiency

Matches

Show answer & explanation

Answer

11-beta-hydroxylase deficiency matches the hypertensive, virilized 46,XX infant. 17-alpha-hydroxylase deficiency matches the hypertensive, undervirilized 46,XY infant. 3-beta-hydroxysteroid dehydrogenase deficiency matches the salt-wasting infant with elevated 17-hydroxypregnenolone. Cytochrome P450 oxidoreductase deficiency matches the infant with skeletal anomalies and a history of maternal virilization.
Each specific steroidogenesis defect results in a unique clinical signature based on deficient hormones and accumulated precursors. 11-beta-hydroxylase deficiency uniquely combines hypertension with virilization due to DOC and androgen accumulation. 17-alpha-hydroxylase deficiency combines hypertension with undervirilization due to blocked sex steroid synthesis. 3-beta-hydroxysteroid dehydrogenase deficiency impairs all three pathways, elevating delta-5 steroids. Cytochrome P450 oxidoreductase deficiency affects multiple P450 enzymes, uniquely presenting with Antley-Bixler skeletal anomalies and maternal virilization.

Step-by-Step Solution

1
Evaluate each clinical presentation for markers of mineralocorticoid activity and sex steroid production.
Identified two hypertensive profiles (mineralocorticoid excess), one salt-wasting profile (mineralocorticoid deficiency), and one dysmorphic profile with maternal virilization.
Blood pressure and potassium levels indicate the state of the mineralocorticoid pathway, while external genitalia in relation to the karyotype indicates the state of the sex steroid pathway.
2
Differentiate the two hypertensive profiles.
The virilized 46,XX infant with hypertension corresponds to 11-beta-hydroxylase deficiency. The undervirilized 46,XY infant with hypertension corresponds to 17-alpha-hydroxylase deficiency.
Both conditions cause DOC accumulation (hypertension). However, 11-beta-hydroxylase deficiency shunts precursors to androgens (causing virilization), whereas 17-alpha-hydroxylase deficiency blocks androgen synthesis entirely (causing undervirilization).
3
Assign the remaining unique presentations to their corresponding complex enzymatic defects.
The salt-wasting infant with high 17-hydroxypregnenolone matches 3-beta-hydroxysteroid dehydrogenase deficiency. The infant with skeletal anomalies and maternal virilization matches Cytochrome P450 oxidoreductase deficiency.
3-beta-HSD deficiency characteristically elevates delta-5 steroids like 17-hydroxypregnenolone. POR deficiency uniquely causes Antley-Bixler syndrome and placental aromatase deficiency (leading to maternal virilization).

Key Concept

Differential diagnosis of rare congenital adrenal hyperplasia variants and steroidogenesis defects based on specific hormonal and clinical phenotypes.
Question 653Question →

Match each classic clinical presentation with its most likely pediatric musculoskeletal diagnosis.

Click a left item, then click its matching right item

Items

An obese 13-year-old boy presents with a dull ache in his anterior thigh and an altered, waddling gait.
A 6-year-old boy presents with an insidious onset of a painless limp and restricted hip internal rotation and abduction.
A 2-year-old girl holds her right arm pronated against her body after her father playfully swung her by the hands.
A 14-year-old active female soccer player presents with anterior knee pain that worsens with jumping and climbing stairs.

Matches

Show answer & explanation

Answer

The correct matches align the obese adolescent with Slipped capital femoral epiphysis, the 6-year-old with an insidious limp to Legg-Calvé-Perthes disease, the toddler with a traction injury to Radial head subluxation, and the active adolescent to Osgood-Schlatter disease.
Each clinical vignette provides classic demographic and symptomatic clues that point to a single highly specific diagnosis. Recognizing these age-dependent patterns is essential for appropriate orthopedic management.

Step-by-Step Solution

1
Analyze the age profile for each patient.
Identified age cohorts: Toddler (2), Young child (6), Adolescent (13), and Adolescent (14).
Pediatric orthopedic conditions are highly age-stratified, making age the primary discriminator.
2
Evaluate the mechanism of injury or symptom onset.
Identified axial traction (toddler), insidious necrosis (young boy), structural shear stress from obesity (adolescent boy), and overuse (active adolescent girl).
The mechanism differentiates traumatic, developmental, and overuse etiologies.
3
Pair the clinical picture to the corresponding specific pathophysiology.
The pairings are confirmed based on classic textbook presentations.
Ensures the correct diagnosis is assigned to each pathognomonic vignette.

Key Concept

Age-stratified clinical presentations of pediatric musculoskeletal disorders
Question 654Question →

Match each clinical description of a pregnant patient after 20 weeks gestation to the most accurate hypertensive disorder of pregnancy.

Click a left item, then click its matching right item

Items

Blood pressure of 152/96 mm Hg, normal laboratory values, and negative urine protein.
Blood pressure of 165/110 mm Hg accompanied by greater than 300 mg of protein in a 24-hour urine collection.
New-onset, unprovoked tonic-clonic seizures in a patient with a blood pressure of 155/100 mm Hg.
Blood pressure of 148/94 mm Hg, schistocytes on peripheral smear, AST of 120 U/L, and platelets of 85,000/mm³.

Matches

Show answer & explanation

Answer

The presentations are matched to their respective hypertensive disorders based on the presence or absence of proteinuria, systemic end-organ damage, hemolysis, and seizures.
Each hypertensive disorder of pregnancy has distinct, non-overlapping diagnostic criteria that must be rapidly identified for appropriate maternal and fetal triage.

Step-by-Step Solution

1
Evaluate the patient's blood pressure and gestational age.
All patients exhibit hypertension (>140/90 mm Hg) after 20 weeks gestation, indicating a hypertensive disorder of pregnancy.
Establishing the baseline category of disease is the first diagnostic requirement.
2
Check for the presence of proteinuria or severe features.
Absence of both points to gestational hypertension; presence of proteinuria points to preeclampsia.
Proteinuria or end-organ damage differentiates simple gestational hypertension from preeclampsia.
3
Assess for life-threatening complications or specific severe variants.
Seizures indicate eclampsia. The specific triad of microangiopathic hemolysis, transaminitis, and thrombocytopenia identifies HELLP syndrome.
Identifying these severe manifestations dictates immediate management, such as magnesium sulfate administration and prompt delivery.

Key Concept

Diagnostic criteria for hypertensive disorders of pregnancy
Estimated Time:45s
Question 655Question →

Carefully evaluate the following pediatric musculoskeletal case summaries. Pair each specific clinical profile with the most accurate underlying pathologic diagnosis.

Click a left item, then click its matching right item

Items

Evaluation of a male in early childhood reveals unilateral proximal muscle atrophy, a positive Trendelenburg sign, and limited hip internal rotation and abduction after several weeks of an altered gait without systemic symptoms.
An early adolescent with a high body mass index and known endocrine dysfunction complains of chronic distal anterior thigh discomfort, demonstrating obligatory outward rotation of the leg during passive hip flexion.
A toddler is evaluated for acute failure to ambulate, presenting with significantly elevated acute phase reactants, pyrexia, and the affected joint rigidly maintained in flexion, abduction, and external rotation.
A young athlete experiences nocturnal lower extremity pain that is exquisitely sensitive to prostaglandin synthesis inhibitors, accompanied by a diaphyseal cortical lesion with a central radiolucency on imaging.

Matches

Show answer & explanation

Answer

The clinical profiles map to their respective diagnoses based on distinct combinations of patient age, chronicity, inflammatory status, and pathognomonic physical exam or imaging findings.
Each pairing accurately reflects the core pathophysiology and hallmark clinical presentation of the specific disease. Avascular necrosis (Legg-Calvé-Perthes) is insidious and occurs in younger children. Slipped capital femoral epiphysis is an adolescent condition characterized by altered hip mechanics (obligatory external rotation). Septic arthritis is an acute medical emergency presenting with systemic toxicity. Osteoid osteoma is a benign neoplastic process defined by its prostaglandin-mediated pain and distinct radiologic nidus.

Step-by-Step Solution

1
Analyze the first clinical profile for demographic and chronicity clues.
Identified early childhood onset, chronic insidious course, and lack of systemic symptoms, pointing to an avascular rather than inflammatory process.
Differentiates Legg-Calvé-Perthes disease from acute inflammatory conditions like transient synovitis or septic arthritis.
2
Evaluate the second profile for risk factors and referred pain patterns.
Identified adolescence, high BMI, endocrinopathy, and obligatory external rotation during flexion as classic signs of a displaced epiphysis.
Highlights the crucial USMLE concept that hip pathology often presents as referred distal thigh or knee pain via the obturator nerve.
3
Assess the third profile for urgency and position of comfort.
Acute presentation with pyrexia, elevated inflammatory markers, and a rigid FABER position indicates a purulent joint capsule.
Applying the Kocher criteria confirms the high likelihood of septic arthritis requiring immediate intervention.
4
Review the fourth profile for specific pharmacologic responses and imaging.
Recognized the diagnostic triad of nocturnal pain, exquisite relief with NSAIDs, and a radiolucent nidus as a benign tumor.
Osteoid osteomas secrete abundant prostaglandins, which directly explains the dramatic response to NSAIDs.

Key Concept

Differentiating pediatric musculoskeletal conditions requires synthesizing age demographics, acuity of onset, presence of systemic inflammatory signs, and distinct physical exam maneuvers (e.g., obligatory external rotation vs. rigid capsular positioning).
Estimated Time:2m 0s
Question 656Question →

Match each pediatric patient's clinical presentation with the most likely underlying diagnosis.

Click a left item, then click its matching right item

Items

A 6-year-old girl with declining linear growth velocity, weight gain, cold intolerance, and a firm, symmetrically enlarged thyroid gland.
A 7-year-old girl with early breast bud development, pubic hair, accelerated linear growth, and an advanced bone age.
A 10-year-old boy with new-onset enuresis, excessive thirst, and an unexplained 3-kg (6.6-lb) weight loss over the past month.
A 5-year-old boy whose height has dropped from the 50th to the 5th percentile over two years, with delayed bone age but normal weight gain.

Matches

Show answer & explanation

Answer

The correct pairings match each classic symptom cluster to its corresponding disease: the child with goiter and poor growth has autoimmune thyroiditis; the child with early sexual development has central precocious puberty; the child with enuresis and weight loss has type 1 diabetes mellitus; and the child with isolated growth deceleration has growth hormone deficiency.
Each clinical vignette provides classic, unambiguous hallmark symptoms of a distinct pediatric endocrine disorder, allowing for direct recognition of the underlying pathology based on standard diagnostic criteria.

Step-by-Step Solution

1
Analyze the 6-year-old girl's presentation.
Identified declining growth, weight gain, cold intolerance, and a goiter.
These are the textbook systemic features of acquired hypothyroidism, primarily caused by autoimmune thyroiditis in this age group.
2
Analyze the 7-year-old girl's presentation.
Identified early breast development, accelerated growth, and advanced bone age.
These findings confirm early activation of the hypothalamic-pituitary-gonadal axis, defining central precocious puberty.
3
Analyze the 10-year-old boy's presentation.
Identified new-onset enuresis, extreme thirst, and weight loss.
Enuresis acts as a marker for polyuria; combined with polydipsia and weight loss, this is the classic triad of type 1 diabetes mellitus.
4
Analyze the 5-year-old boy's presentation.
Identified an isolated height drop across major percentiles with delayed bone age.
This specific growth pattern is the hallmark of growth hormone deficiency.

Key Concept

Recognizing the hallmark clinical presentations of common pediatric endocrine disorders.
Question 657Question →

Match each pediatric patient's clinical presentation with the most accurate description of the underlying pathophysiology or anatomic abnormality.

Click a left item, then click its matching right item

Items

A 13-year-old boy with a BMI at the 97th percentile presents with a 3-week history of left knee pain and demonstrates obligatory external rotation when the left hip is passively flexed.
A 6-year-old boy with a normal BMI presents with an insidious onset of a mild, painless limp for 2 months and shows decreased hip abduction and internal rotation on examination.
A 14-year-old boy who plays competitive basketball presents with progressive anterior knee pain and a tender, prominent bony mass distal to the patella.
A 3-year-old girl refuses to use her right arm, holding it pronated and extended against her side after her older sibling abruptly pulled her by the hand.

Matches

Show answer & explanation

Answer

The clinical presentations correctly match with their pathophysiological descriptions as follows: the obese adolescent with referred knee pain matches posterior epiphyseal displacement (SCFE); the 6-year-old with an insidious limp matches avascular necrosis (Legg-Calvé-Perthes); the adolescent athlete with a prominent tibial tubercle matches traction apophysitis (Osgood-Schlatter); and the toddler with a pulled arm matches annular ligament slippage (radial head subluxation).
Each clinical vignette contains pathognomonic demographic details, injury mechanisms, and physical exam findings that uniquely identify a specific pediatric musculoskeletal disorder. Correctly matching them requires translating the clinical diagnosis into its underlying pathophysiological mechanism.

Step-by-Step Solution

1
Analyze the first presentation (13-year-old obese male with knee pain and hip external rotation).
Identify the diagnosis as Slipped Capital Femoral Epiphysis (SCFE), which corresponds to the displacement of the proximal femoral epiphysis.
Obesity, adolescent age, and referred knee pain with restricted hip internal rotation are pathognomonic for SCFE.
2
Analyze the second presentation (6-year-old male with an insidious painless limp).
Identify the diagnosis as Legg-Calvé-Perthes disease, which corresponds to idiopathic avascular necrosis of the femoral head.
The demographic (age 4-8) and the chronic, indolent nature of the limp without systemic symptoms point to avascular necrosis rather than acute inflammatory processes.
3
Analyze the third presentation (14-year-old athlete with tender tibial tubercle).
Identify the diagnosis as Osgood-Schlatter disease, which corresponds to traction apophysitis at the patellar tendon insertion.
Localized pain at the tibial tubercle in an active adolescent undergoing a growth spurt is the hallmark of this condition.
4
Analyze the fourth presentation (3-year-old girl with a pulled, pronated arm).
Identify the diagnosis as radial head subluxation, which corresponds to the slippage of the annular ligament.
The mechanism of injury (axial traction) and the characteristic posture of the arm perfectly describe nursemaid's elbow.

Key Concept

Pathophysiology and clinical presentation of common pediatric musculoskeletal disorders
Question 658Question →

Match each patient's clinical vignette with the most appropriate initial targeted intervention.

Click a left item, then click its matching right item

Items

A 3-week-old premature infant (HR 165/min, SaO2 95%) presents with a widened pulse pressure, bounding peripheral pulses, and a continuous murmur at the left infraclavicular area.
A 2-day-old cyanotic neonate (HR 170/min, SaO2 75%) presents in shock with absent femoral pulses and no audible murmur, shortly after the physiologic closure of the ductus arteriosus.
A 6-month-old infant becomes agitated and profoundly cyanotic (SaO2 65%) while crying. Exam reveals a normal pulse pressure but a suddenly diminished harsh systolic murmur.
A 2-year-old child presents with a 6-day history of 39.5°C fever, heart rate of 150/min, normal pulses, normal SaO2 (99%), and no murmurs, accompanied by a strawberry tongue and bilateral conjunctivitis.
A 10-year-old child presents with fever (38.8°C), migrating joint pain, HR 110/min, normal SaO2 (98%), and a new holosystolic murmur at the apex following an untreated pharyngitis infection.

Matches

Show answer & explanation

Answer

Premature infant with PDA matches indomethacin; Neonate in shock with absent femoral pulses matches prostaglandin E1; Cyanotic infant with 'tet' spell matches knee-to-chest positioning; Toddler with Kawasaki disease matches IVIG and aspirin; Child with acute rheumatic fever matches penicillin.
Each pediatric cardiovascular condition requires a specific targeted intervention. Indomethacin is used to close a PDA, while Prostaglandin E1 is used to keep it open in ductal-dependent congenital heart disease. Tet spells are initially managed by increasing systemic vascular resistance via knee-to-chest positioning. Kawasaki disease requires IVIG and aspirin to prevent coronary aneurysms. Acute rheumatic fever necessitates penicillin to eradicate the triggering streptococcal infection.

Step-by-Step Solution

1
Analyze the first vignette: a premature infant with bounding pulses and a continuous murmur indicating a symptomatic PDA.
Matches with administration of a cyclooxygenase inhibitor to close the PDA.
Inhibiting prostaglandins facilitates ductal closure.
2
Analyze the second vignette: a cyanotic neonate in shock with absent femoral pulses indicating a ductal-dependent systemic circulation.
Matches with initiation of a prostaglandin E1 infusion to reopen the ductus arteriosus.
Exogenous prostaglandins prevent ductal closure, ensuring critical blood flow.
3
Analyze the third vignette: an agitated infant with severe cyanosis and a disappearing murmur indicating a tetralogy of Fallot hypercyanotic spell.
Matches with placing the patient in a knee-to-chest position to increase systemic vascular resistance.
This position kinks the femoral arteries, increasing systemic vascular resistance and forcing more blood through the pulmonary circulation.
4
Analyze the fourth vignette: a toddler with prolonged fever, conjunctivitis, and mucositis indicating Kawasaki disease.
Matches with administration of intravenous immunoglobulin and high-dose aspirin.
This combination dramatically reduces the risk of coronary artery aneurysms.
5
Analyze the fifth vignette: an older child with migrating arthritis and a new apical murmur indicating acute rheumatic fever.
Matches with administration of intramuscular penicillin G benzathine.
Eradication of group A Streptococcus is essential to prevent ongoing immune-mediated cardiac damage.

Key Concept

Targeted medical and positional interventions for common pediatric cardiovascular conditions.
Question 659Question →

Pair the following pediatric clinical presentations and laboratory findings with their corresponding endocrine diagnoses.

Click a left item, then click its matching right item

Items

A 7-year-old boy with height below the 3rd percentile, normal growth velocity, bone age equal to chronological age, and parents with below-average heights.
A 13-year-old boy with height below the 5th percentile, delayed bone age, normal growth velocity for his bone age, and a father who grew significantly during college.
A 6-year-old girl with bilateral breast development, advanced bone age, and a luteinizing hormone level that surges following gonadotropin-releasing hormone stimulation.
A 9-year-old girl with declining linear growth velocity, increased weight percentiles, delayed bone age, and an elevated thyroid-stimulating hormone level.

Matches

Show answer & explanation

Answer

The correct matches align normal bone age with familial short stature, delayed bone age with constitutional delay, LH surge with central precocious puberty, and growth deceleration with elevated TSH with acquired primary hypothyroidism.
Each clinical profile uniquely aligns with a specific pediatric endocrine disorder by evaluating bone age (normal in familial short stature, delayed in constitutional delay and hypothyroidism, advanced in precocious puberty), growth velocity (normal in normal variants, decreased in hypothyroidism), and hormonal axis activation (LH surge in central precocious puberty).

Step-by-Step Solution

1
Analyze the growth and puberty parameters for the 7-year-old boy.
The patient has short stature but normal growth velocity and normal bone age, with a family history of short stature.
This pattern eliminates systemic diseases or intrinsic endocrine defects, pointing directly to familial short stature.
2
Evaluate the 13-year-old boy's growth pattern and family history.
The patient has delayed bone age with normal growth velocity for that delayed age, plus a family history of delayed puberty.
This classic 'late bloomer' profile is diagnostic of constitutional delay of growth and puberty.
3
Assess the hormonal and skeletal findings of the 6-year-old girl.
Thelarche at age 6 with advanced bone age and an LH surge after GnRH stimulation.
The LH surge confirms central (gonadotropin-dependent) precocious puberty rather than peripheral sources of sex steroids.
4
Interpret the growth deceleration and laboratory findings of the 9-year-old girl.
Declining linear growth, weight gain, delayed bone age, and elevated TSH.
These findings are the classic presentation of acquired primary hypothyroidism, most commonly Hashimoto thyroiditis in this age group.

Key Concept

Differentiating pediatric growth and puberty disorders based on bone age, growth velocity, and targeted hormonal testing.
Estimated Time:1m 30s
Question 660Question →

Match the following classic pediatric clinical presentations and physical examination findings with their most likely underlying congenital heart disorder.

Click a left item, then click its matching right item

Items

Continuous, 'machine-like' murmur best heard at the left infraclavicular area, associated with widened pulse pressure and bounding peripheral pulses.
Harsh, holosystolic murmur best heard at the left lower sternal border, often accompanied by a palpable thrill, in an otherwise acyanotic infant.
Harsh systolic ejection murmur at the left upper sternal border, a single S2, and episodic severe cyanosis relieved by knee-chest positioning.
Decreased and delayed femoral pulses compared to brachial pulses, upper extremity hypertension, and a systolic murmur heard over the left interscapular area.
Profound cyanosis within hours of birth, a single S2, and an 'egg-on-a-string' appearance of the cardiac silhouette on chest radiography.

Matches

Show answer & explanation

Answer

The correct matching aligns Patent ductus arteriosus with a continuous machine-like murmur, Ventricular septal defect with a holosystolic lower sternal border murmur, Tetralogy of Fallot with a systolic ejection murmur and cyanotic spells, Coarctation of the aorta with brachial-femoral pulse delay, and Transposition of the great arteries with neonatal cyanosis and an 'egg-on-a-string' chest X-ray.
Each clinical presentation contains pathognomonic physical examination and imaging findings that correspond to a specific congenital heart defect. Accurate diagnosis relies on identifying key features such as murmur timing (continuous versus holosystolic), location, cyanosis presence, and pulse character.

Step-by-Step Solution

1
Analyze the murmur timing and location for each clinical presentation.
Identified continuous murmur, holosystolic murmur, systolic ejection murmur, and interscapular murmur.
Murmur characteristics are highly specific to underlying structural defects.
2
Evaluate the presence of cyanosis and its onset timing.
Noted episodic cyanosis relieved by squatting (Tetralogy of Fallot) versus profound immediate neonatal cyanosis (Transposition of the great arteries).
Distinguishes between cyanotic heart diseases based on ductal dependency and pathophysiology of right-to-left shunting.
3
Assess peripheral pulse quality and blood pressure discrepancies.
Differentiated bounding pulses (Patent ductus arteriosus) from brachial-femoral pulse delay (Coarctation of the aorta).
Hemodynamic changes in the aorta manifest distinctly in peripheral pulses.

Key Concept

Clinical presentation and pathognomonic physical examination findings of common congenital heart defects.
Estimated Time:1m 30s
PreviousPage 33 / 93Next
All practice questions — USMLE Step 2 CK | Examkin