Newborn Screening US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Newborn Screening. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Newborn Screening US Medical PG Question 1: The following cost-effective investigations are routinely recommended in the screening of antenatal mothers, EXCEPT:
- A. Blood sugar levels for GDM
- B. VDRL for syphilis
- C. Urine analysis for bacteriuria
- D. Echocardiography for cardiac disease (Correct Answer)
Newborn Screening Explanation: ***Echocardiography for cardiac disease***
- **Echocardiography** is not a *routinely recommended* screening investigation for all antenatal mothers due to its cost and the relatively low prevalence of significant congenital heart disease requiring universal screening.
- It is typically performed only if there are **specific risk factors** or suspicious findings suggesting cardiac pathology.
*Blood sugar levels for GDM*
- Screening for **gestational diabetes mellitus (GDM)** with blood sugar levels (e.g., glucose challenge test) is routinely recommended due to the potential maternal and fetal complications if untreated.
- GDM is a common condition that can be effectively managed with early diagnosis, making screening a **cost-effective** preventive measure.
*VDRL for syphilis*
- Screening for **syphilis** using tests like VDRL (Venereal Disease Research Laboratory) is a standard and *routinely recommended* antenatal investigation.
- Early detection and treatment of syphilis in pregnant women prevent serious adverse outcomes such as **congenital syphilis**, which can cause severe fetal morbidity and mortality.
*Urine analysis for bacteriuria*
- **Urine analysis** for **asymptomatic bacteriuria** is routinely recommended during pregnancy because untreated bacteriuria can lead to pyelonephritis, preterm labor, and low birth weight.
- It is a simple, **cost-effective** test with significant benefits for maternal and fetal health.
Newborn Screening US Medical PG Question 2: Which diagnostic tool is preferred for metabolic disease screening in children?
- A. Urinalysis
- B. Genetic testing
- C. Complete Blood count
- D. Tandem mass spectrometry (Correct Answer)
- E. Plasma amino acid analysis
Newborn Screening Explanation: ***Tandem mass spectrometry***
- **Tandem mass spectrometry (TMS)** is the preferred method for newborn screening of many **inborn errors of metabolism** because it can simultaneously detect a wide range of metabolites from a single dried blood spot.
- This technique rapidly identifies multiple **amino acid disorders**, **fatty acid oxidation disorders**, and **organic acidemias**, allowing for early intervention.
*Urinalysis*
- While urinalysis can detect some metabolic abnormalities (e.g., **ketones**, **glucose**), it is not a comprehensive screening tool for the broad spectrum of inherited metabolic diseases.
- It primarily identifies end-products of metabolism rather than specific enzyme deficiencies or precursor compounds.
*Genetic testing*
- **Genetic testing** is highly specific for known genetic mutations, but it is typically used for confirmatory diagnosis or targeted screening when a specific condition is suspected, not for broad, universal newborn metabolic screening.
- It can be expensive and time-consuming for population-wide screening of hundreds of potential metabolic disorders.
*Complete Blood count*
- A **complete blood count (CBC)** assesses cellular components of the blood (e.g., **red blood cells**, **white blood cells**, **platelets**) and is useful for detecting hematological disorders.
- It does not directly screen for metabolic diseases, although some metabolic disorders can secondarily affect blood cell counts.
*Plasma amino acid analysis*
- **Plasma amino acid analysis** can detect specific aminoacidopathies (e.g., **phenylketonuria**, **maple syrup urine disease**), but it is limited to amino acid disorders only.
- Unlike tandem mass spectrometry, it cannot simultaneously screen for fatty acid oxidation disorders and organic acidemias, making it less comprehensive for broad metabolic screening.
Newborn Screening US Medical PG Question 3: An infant presented with vomiting, malnutrition, blue eyes, blonde hair & fair skin. On investigation, Guthrie test was positive. All are true regarding this disease EXCEPT:
- A. Phenyl acetate positive in urine
- B. Mental retardation is present
- C. Hypopigmentation due to tryptophan deficiency (Correct Answer)
- D. Due to PAH enzyme defect
Newborn Screening Explanation: ***Hypopigmentation due to tryptophan deficiency***
- The characteristic **hypopigmentation** (fair skin, blonde hair, blue eyes) in **phenylketonuria (PKU)** is due to **tyrosine deficiency**, not tryptophan deficiency.
- **Phenylalanine hydroxylase (PAH)** deficiency leads to accumulation of phenylalanine, which cannot be converted to **tyrosine**.
- **Tyrosine** is the precursor for **melanin synthesis** via the enzyme **tyrosinase**, so tyrosine deficiency results in decreased melanin production and hypopigmentation.
*Phenyl acetate positive in urine*
- In **phenylketonuria (PKU)**, **phenylalanine** accumulates and is shunted to alternative metabolic pathways, leading to the production and excretion of **phenylacetate, phenylpyruvate, and phenyllactate** in the urine.
- The presence of these metabolites gives the urine a characteristic **mousey or musty odor**.
*Mental retardation is present*
- If **phenylketonuria (PKU)** is left untreated, the accumulation of **phenylalanine** is neurotoxic and leads to severe, **irreversible intellectual disability** and **developmental delay**.
- Early detection through newborn screening (the **Guthrie test** detects elevated blood phenylalanine) and dietary phenylalanine restriction are crucial to prevent this outcome.
*Due to PAH enzyme defect*
- **Phenylketonuria (PKU)** is primarily caused by a deficiency in the enzyme **phenylalanine hydroxylase (PAH)**, which is responsible for converting phenylalanine to tyrosine.
- This **autosomal recessive genetic disorder** leads to the accumulation of phenylalanine in the blood and tissues, causing the clinical manifestations.
Newborn Screening US Medical PG Question 4: Screening for colorectal cancer is recommended when?
- A. The condition has a low case fatality rate.
- B. Diagnostic tools are not available.
- C. There is no effective treatment available.
- D. Early diagnosis can change the disease course due to effective treatment. (Correct Answer)
Newborn Screening Explanation: ***Early diagnosis can change the disease course due to effective treatment.***
- Screening is primarily recommended when **early detection** allows for interventions that effectively alter the natural history of the disease, improving prognosis or preventing progression.
- For colorectal cancer, early diagnosis through screening allows for timely removal of **precancerous polyps** or early-stage cancers, significantly increasing survival rates.
*The condition has a low case fatality rate.*
- Conditions with low case fatality rates generally do not warrant extensive screening programs, as the **benefit-to-harm ratio** is often unfavorable.
- Colorectal cancer, if undiagnosed and untreated, has a significant **case fatality rate**, making screening beneficial.
*Diagnostic tools are not available.*
- Screening is only conducted when **reliable, accurate, and cost-effective diagnostic tools** are available to detect the disease or its precursors in asymptomatic individuals.
- If diagnostic tools are unavailable, screening would be impossible or ineffective, as there would be no way to identify those with the condition.
*There is no effective treatment available.*
- Screening is not typically recommended for diseases for which there is **no effective treatment**, as early detection would not improve patient outcomes.
- The primary purpose of screening is to identify individuals who can benefit from **early intervention** and treatment to prevent serious morbidity or mortality.
Newborn Screening US Medical PG Question 5: Which of the following is used for initial screening of auditory function in a neonate?
- A. Otoacoustic emission (OAE) (Correct Answer)
- B. Auditory brainstem response (ABR)
- C. Pure tone audiometry (PTA)
- D. Free field audiometry
Newborn Screening Explanation: ***Otoacoustic emission (OAE)***
- **OAE** is the **gold standard for universal newborn hearing screening (UNHS)** programs worldwide due to its **non-invasive nature**, speed, and cost-effectiveness.
- The test measures **sound waves produced by the outer hair cells of the cochlea** in response to auditory stimuli, indicating normal cochlear function.
- **Quick to perform (2-3 minutes)**, requires minimal cooperation, and can be done while the infant is sleeping.
*Auditory brainstem response (ABR)*
- While **ABR** is a definitive diagnostic test for hearing loss, it is typically used as a **second-stage test** if an OAE screening fails, rather than the initial screening tool.
- ABR measures the **brain's response to sound**, providing information about the neural pathway from the cochlea to the brainstem.
- More **time-consuming and expensive** than OAE, making it less suitable for mass screening.
*Pure tone audiometry (PTA)*
- **PTA** requires active participation and understanding of instructions, making it **unsuitable for neonates** and young children.
- This test is primarily used for **older children (typically >4 years) and adults** to determine hearing thresholds across various frequencies.
*Free field audiometry*
- **Free field audiometry** involves presenting sounds through loudspeakers to assess hearing, but it is **not suitable for precise threshold determination** in neonates due to their inability to localize sounds reliably or respond consistently.
- It's mainly used for behavioral observation audiometry in older infants (6-24 months), but **not as a primary screening method** for neonates.
Newborn Screening US Medical PG Question 6: 18 weeks pregnant female presents with no high risk of NTD and low risk of trisomy 21 on quad test. What is the most appropriate next step in management?
- A. Repeat non-invasive screening test.
- B. Perform invasive diagnostic testing.
- C. Perform amniotic fluid analysis.
- D. Perform a detailed fetal ultrasound. (Correct Answer)
Newborn Screening Explanation: ***Perform a detailed fetal ultrasound.***
- A **detailed fetal ultrasound** (often referred to as an **anatomy scan**) at around 18-22 weeks is a standard component of prenatal care for all pregnant women, regardless of screening test results.
- This ultrasound evaluates fetal anatomy for structural anomalies, assesses fetal growth, and confirms gestational age, providing crucial information even with low-risk screening.
*Repeat non-invasive screening test.*
- Repeating a non-invasive screening test (like another quad screen or NIPT) is generally **not indicated** when initial results show a low risk and there are no other clinical concerns.
- Such tests are primarily for screening purposes, and a second low-risk result would offer little additional actionable information, as their positive predictive value is low.
*Perform invasive diagnostic testing.*
- **Invasive diagnostic testing**, such as **amniocentesis** or **chorionic villus sampling (CVS)**, carries a risk of miscarriage and is reserved for situations with a high risk of chromosomal abnormalities or genetic conditions.
- Given the low-risk quad screen results for trisomy 21 and no high risk for NTDs, invasive testing is **not warranted** at this stage.
*Perform amniotic fluid analysis.*
- **Amniotic fluid analysis** is part of an amniocentesis, an **invasive diagnostic procedure** designed to detect chromosomal abnormalities or genetic disorders.
- This procedure is typically reserved for cases where screening tests indicate a high risk or there is a clinical suspicion of a genetic condition; it's **not a routine step** after a low-risk quad screen.
Newborn Screening US Medical PG Question 7: A neonate presents with the clinical features shown in the image below. What is the most likely diagnosis?
- A. Down syndrome
- B. Congenital hypothyroidism (Correct Answer)
- C. Ellis-Van Creveld syndrome
- D. Turner syndrome
Newborn Screening Explanation: ***Congenital hypothyroidism***
- The image shows a neonate with **macroglossia** (large tongue), **umbilical hernia**, and possibly **puffy eyelids** and **dull facies**, all characteristic signs of congenital hypothyroidism.
- Other features often include **hypotonia**, **feeding difficulties**, **prolonged jaundice**, and **constipation**.
*Down syndrome*
- While Down syndrome can present with **hypotonia** and some shared features, the characteristic **epicanthal folds**, **simian crease**, **brushfield spots**, and flattened facial profile are not clearly evident.
- Macroglossia is common but other features like an umbilical hernia would be less specific.
*Ellis-Van Creveld syndrome*
- This syndrome is characterized by **chondroectodermal dysplasia**, typically presenting with **polydactyly**, **short-limbed dwarfism**, **nail dysplasia**, and **cardiac defects**.
- These distinct skeletal and ectodermal abnormalities are not visible in the presented image.
*Turner syndrome*
- Turner syndrome (XO karyotype) primarily affects females and is characterized by **short stature**, **webbed neck**, **lymphedema of hands and feet**, and **cardiac anomalies** (e.g., coarctation of the aorta).
- The features shown in the image, such as macroglossia and umbilical hernia, are not typical of Turner syndrome.
Newborn Screening US Medical PG Question 8: Consider the following disorders :
1. Delayed motor milestones
2. Spastic diplegia
3. Nyctalopia
4. Hearing defects
Which of the above disorders occur as part of the spectrum of iodine deficiency disorders ?
- A. 2, 3 and 4
- B. 1, 2 and 3
- C. 1 and 3 only
- D. 1, 2 and 4 (Correct Answer)
Newborn Screening Explanation: ***1, 2 and 4***
- **Delayed motor milestones** and **spastic diplegia** are hallmark neurological symptoms of **cretinism**, caused by severe congenital iodine deficiency. The spasticity results from pyramidal tract involvement affecting motor development.
- **Hearing defects** (sensorineural deafness) are frequently observed in individuals with iodine deficiency disorders due to impaired thyroid hormone synthesis affecting inner ear development during critical developmental periods.
*2, 3 and 4*
- **Nyctalopia (night blindness)** is primarily associated with **Vitamin A deficiency**, not iodine deficiency.
- While spastic diplegia and hearing defects are linked to iodine deficiency, the inclusion of nyctalopia makes this option incorrect.
*1, 2 and 3*
- This option correctly identifies delayed motor milestones and spastic diplegia as symptoms of iodine deficiency, but **nyctalopia** is an incorrect association with iodine deficiency.
- Therefore, the presence of nyctalopia invalidates this choice.
*1 and 3 only*
- This option correctly includes **delayed motor milestones** but incorrectly includes **nyctalopia** as an iodine deficiency disorder.
- It also omits other significant neurological and developmental problems like spastic diplegia and hearing defects that are part of the IDD spectrum.
Newborn Screening US Medical PG Question 9: The image shows a child with virilisation and clitoromegaly. What laboratory finding is typical for this condition, assuming the most common enzyme defect?
- A. Low urinary sodium
- B. Increased plasma cortisol
- C. Increased urinary sodium (Correct Answer)
- D. Increased aldosterone
Newborn Screening Explanation: ***Increased urinary sodium***
- **Congenital adrenal hyperplasia (CAH)** due to **21-hydroxylase deficiency** is the most common cause of virilization and clitoromegaly in female infants, accounting for >90% of CAH cases.
- This enzyme defect blocks the conversion of 17-hydroxyprogesterone to 11-deoxycortisol, impairing both **cortisol and aldosterone synthesis**.
- The lack of **aldosterone** (mineralocorticoid) results in a **salt-wasting crisis** with renal sodium loss, leading to **hyponatremia, hyperkalemia, and inappropriately elevated urinary sodium excretion** despite low serum sodium.
- Among the given options, increased urinary sodium is the characteristic laboratory finding of the salt-wasting form (seen in ~75% of 21-hydroxylase deficiency cases).
*Low urinary sodium*
- Low urinary sodium would suggest effective renal sodium retention with intact aldosterone function.
- This is contrary to the aldosterone deficiency seen in salt-wasting CAH, where the kidneys cannot retain sodium appropriately.
*Increased plasma cortisol*
- In 21-hydroxylase deficiency, the enzyme block **prevents cortisol synthesis**, leading to **decreased plasma cortisol** levels.
- The low cortisol triggers increased ACTH secretion, which drives adrenal androgen overproduction (causing virilization) and accumulation of precursors like 17-hydroxyprogesterone.
*Increased aldosterone*
- **Aldosterone synthesis is severely impaired** in 21-hydroxylase deficiency, leading to **decreased or absent aldosterone** levels.
- Increased aldosterone would cause sodium retention and potassium excretion—the opposite of the salt-wasting crisis observed in this condition.
Newborn Screening US Medical PG Question 10: 4 day old breastfed neonate, otherwise well, term neonate presented with jaundice, on testing the bilirubin level was found to be 18 mg/dl. Which of the following is the best step of management?
- A. Stop breast feeding and do phototherapy
- B. Initiate exchange transfusion
- C. Start iv fluids and give phototherapy
- D. Start phototherapy and continue breast feeding (Correct Answer)
Newborn Screening Explanation: ***Start phototherapy and continue breast feeding***
- For a 4-day-old, otherwise healthy, term neonate with a bilirubin level of 18 mg/dL, **phototherapy** is the recommended initial treatment to lower bilirubin levels and prevent **kernicterus**.
- **Breastfeeding should be continued** as it is crucial for hydration and nutrition, and interruption is generally not needed unless the bilirubin levels are extremely high and unresponsive to phototherapy.
*Stop breast feeding and do phototherapy*
- **Stopping breastfeeding is usually not necessary** for a bilirubin level of 18 mg/dL in a healthy, term neonate, as the benefits of breast milk outweigh the risks associated with this level of jaundice.
- While **phototherapy** is appropriate, discontinuing breastfeeding can lead to complications such as dehydration and decreased milk supply.
*Initiate exchange transfusion*
- **Exchange transfusion** is typically reserved for much higher bilirubin levels (e.g., >25 mg/dL in a term neonate) or when there are signs of **acute bilirubin encephalopathy**, which are not present here.
- It is an invasive procedure with potential risks, making it unsuitable as a first-line treatment for this bilirubin level.
*Start iv fluids and given phototherapy*
- **Intravenous fluids** are generally not indicated for an otherwise well, breastfed neonate unless there are signs of significant dehydration, which is not mentioned in this scenario.
- While **phototherapy** is appropriate, routine IV fluid administration can lead to **fluid overload** and is not standard practice in uncomplicated neonatal jaundice.
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