Neonatology Practice Questions

Q: Dried blood drops from an infant can be used to screen for which of the following?

Inborn errors of metabolism. **Explanation:** The correct answer is **Inborn Errors of Metabolism (IEM)**. This screening method is known as the **Guthrie Test** or **Newborn Screening (NBS)** using **Dried Blood Spots (DBS)**. 1. **Why it is correct:** Dried blood spots are collected by pricking the infant's heel (Heel-prick test) and dropping the blood onto specialized filter paper (Whatman 903). This method is ideal for screening IEMs because the samples are stable, easy to transport, and can be analyzed using **Tandem Mass Spectrometry (TMS)**. Common conditions screened include Phenylketonuria (PKU), Congenital Hypothyroidism, Galactosemia, and G6PD deficiency. 2. **Why other options are incorrect:** * **Blood sugar levels:** These require immediate analysis of fresh whole blood (usually via glucometer or venous sample) to manage acute hypoglycemia; dried spots are not suitable for real-time monitoring. * **Hepatitis infection:** Screening for Hepatitis B or C in neonates typically involves serological markers (HBsAg) or PCR from fresh serum/plasma, not routine dried blood spots. * **Congenital cataracts:** This is a clinical diagnosis made via the **Red Reflex Test** (Bruckner test) using an ophthalmoscope, not a laboratory blood test. **High-Yield Clinical Pearls for NEET-PG:** * **Timing:** NBS should ideally be performed **48–72 hours after birth** to ensure the infant has ingested sufficient protein (for PKU) and to avoid the physiological TSH surge. * **Most common IEM in India:** Congenital Hypothyroidism (CH) followed by G6PD deficiency. * **The "Guthrie Test"** specifically refers to the original bacterial inhibition assay for Phenylketonuria. * **Storage:** DBS samples can be stored at room temperature for long periods, making them excellent for large-scale epidemiological studies.

Q: A mother reports that her 2-week-old infant sleeps most of the day and needs to be awakened every 4 hours for feeding, taking only one ounce of formula at a time. She is also concerned about the infant's persistently hard, pellet-like stools. Examination reveals an infant with normal weight and length, but with an enlarged head, a heart rate of 75 beats per minute, a temperature of 35°C (95°F), persistent jaundice, large anterior and posterior fontanelles, a distended abdomen, and an umbilical hernia. This clinical presentation is likely a result of which of the following?

Congenital hypothyroidism. ### Explanation **Correct Answer: A. Congenital Hypothyroidism** This infant presents with the classic "quiet baby" syndrome of **Congenital Hypothyroidism (CH)**. Thyroid hormones are essential for metabolic processes and neurological development. A deficiency leads to a generalized slowing of body functions, manifesting as: * **Metabolic slowing:** Hypothermia (35°C), bradycardia (75 bpm), and lethargy (sleeping most of the day). * **Gastrointestinal:** Decreased motility leads to constipation (hard, pellet-like stools), poor feeding, and abdominal distension. * **Structural signs:** Large anterior and posterior fontanelles (delayed bone age), umbilical hernia, and macroglossia (often causing feeding issues). * **Jaundice:** Prolonged unconjugated hyperbilirubinemia due to delayed glucuronyl transferase activity. **Why other options are incorrect:** * **B. Hirschsprung Disease:** While it causes constipation, abdominal distension, and potentially an umbilical hernia, it does **not** explain the bradycardia, hypothermia, large fontanelles, or prolonged jaundice. * **C. Sepsis:** Can cause lethargy, poor feeding, and temperature instability, but it is an acute presentation. It would not explain the large fontanelles or umbilical hernia. * **D. Infantile Botulism:** Presents with "floppy baby" syndrome (hypotonia) and constipation, but typically occurs in slightly older infants (after honey ingestion) and does not feature the structural/metabolic signs of CH. **NEET-PG High-Yield Pearls:** * **Most common cause:** Dysgenesis (Agenesis/Ectopy) of the thyroid gland. * **Most sensitive screening test:** Serum TSH (usually performed via heel prick on day 3–5). * **Clinical Clue:** A posterior fontanelle >0.5 cm in a term neonate is highly suggestive of CH. * **Treatment:** Levothyroxine (10–15 μg/kg/day). Early treatment (within 2 weeks) is critical to prevent permanent intellectual disability (Cretinism).

Q: Respiratory distress syndrome (RDS) in a neonate is primarily due to deficiency of which substance?

Dipalmitoyl lecithin. **Explanation:** **Respiratory Distress Syndrome (RDS)**, also known as Hyaline Membrane Disease, is caused by a deficiency of **pulmonary surfactant**. Surfactant is a complex mixture of lipids and proteins synthesized by **Type II pneumocytes**. Its primary function is to reduce surface tension at the air-liquid interface of the alveoli, preventing alveolar collapse (atelectasis) during expiration. **Why Option C is correct:** The most abundant and active component of pulmonary surfactant (accounting for approximately 50-60% of its composition) is **Dipalmitoylphosphatidylcholine (DPPC)**, commonly known as **Dipalmitoyl lecithin**. It is the specific molecule responsible for the surface-tension-lowering properties of surfactant. **Why other options are incorrect:** * **A. Sphingomyelin:** This is a membrane phospholipid. While it is measured alongside lecithin to determine fetal lung maturity (L/S ratio), its concentration remains relatively constant during gestation and it does not possess the surfactant properties required to prevent RDS. * **B. Ceramide:** This is a precursor for sphingolipids and a signaling molecule involved in cell apoptosis and skin barrier function, but it plays no role in reducing alveolar surface tension. **High-Yield Clinical Pearls for NEET-PG:** * **L/S Ratio:** A Lecithin/Sphingomyelin ratio of **>2:1** in amniotic fluid indicates fetal lung maturity. * **Risk Factors:** Prematurity (most common), maternal diabetes, and Cesarean section without labor. * **Chest X-ray Findings:** Characterized by a diffuse **"ground-glass appearance"** and prominent air bronchograms. * **Management:** Antenatal corticosteroids (e.g., Betamethasone) given to the mother accelerate surfactant production; exogenous surfactant is the treatment of choice for the neonate.

Q: A newborn has a fever of 103°F. Blood culture grows gram-positive cocci in chains. This is most likely to be which of the following?

Group B Streptococci (Streptococcus agalactiae). **Explanation:** The correct answer is **Group B Streptococci (GBS)**, also known as *Streptococcus agalactiae*. **Why Group B Streptococci is correct:** In the neonatal period (0–28 days), GBS is the **most common cause** of neonatal sepsis and meningitis worldwide. Microbiologically, GBS are **Gram-positive cocci in chains** and are typically β-hemolytic. They colonize the maternal vaginal tract, and the newborn acquires the infection during passage through the birth canal (vertical transmission). A high-grade fever (103°F) in a neonate with these Gram stain findings is a classic presentation of GBS sepsis. **Why the other options are incorrect:** * **Group A Streptococci (S. pyogenes):** While these are also Gram-positive cocci in chains, they are a rare cause of neonatal sepsis. They more commonly cause skin infections (impetigo) or pharyngitis in older children. * **Salmonella species:** These are **Gram-negative bacilli**. While they can cause sepsis in infants (especially in developing countries), they do not match the Gram stain description provided. * **Streptococcus pneumoniae:** These are **Gram-positive cocci in pairs (diplococci)** and are lancet-shaped. While a cause of sepsis, they are much less common than GBS in the immediate neonatal period. **Clinical Pearls for NEET-PG:** * **Top 3 causes of Neonatal Sepsis:** 1. Group B Streptococcus, 2. *E. coli*, 3. *Listeria monocytogenes*. * **Early-onset Sepsis ( 72 hours):** Often due to environmental or nosocomial pathogens (CONS, *Staph aureus*). * **Drug of Choice:** For suspected neonatal sepsis, the empirical treatment is **Ampicillin + Gentamicin**.

Q: Macrosomia is seen in all of the following conditions EXCEPT:

Hydrocephalus. **Explanation:** **Macrosomia** is defined as a birth weight >4000g or >4500g (regardless of gestational age) or a birth weight above the 90th percentile for gestational age. It refers to a generalized increase in body size and fat deposition. **Why Hydrocephalus is the Correct Answer:** Hydrocephalus involves an abnormal accumulation of cerebrospinal fluid (CSF) within the brain's ventricles, leading to an **enlarged head circumference (macrocephaly)**. While the head is disproportionately large, the overall body weight does not necessarily exceed the 90th percentile. Therefore, hydrocephalus causes macrocephaly, not true macrosomia. **Analysis of Incorrect Options:** * **Diabetes Mellitus:** Maternal hyperglycemia leads to fetal hyperglycemia, which stimulates the fetal pancreas to produce excess **insulin**. Since insulin is a potent anabolic hormone (fetal growth factor), it causes excessive deposition of fat and glycogen, leading to macrosomia. * **Obesity:** Maternal obesity is one of the most common risk factors for macrosomia due to increased nutrient availability and insulin resistance. * **Post-maturity:** Pregnancies exceeding 42 weeks allow for a longer period of intrauterine growth. If the placenta remains functional, the fetus continues to gain weight, often resulting in macrosomia. **High-Yield Clinical Pearls for NEET-PG:** * **Beckwith-Wiedemann Syndrome:** A classic high-yield cause of macrosomia characterized by the triad of macrosomia, macroglossia, and omphalocele. * **Infant of Diabetic Mother (IDM):** These infants are "large and plump" but have small brains (except for the heart and adrenals, most organs are enlarged). * **Complications:** Macrosomia increases the risk of shoulder dystocia, Erb’s palsy, and neonatal hypoglycemia.

Question 1

Dried blood drops from an infant can be used to screen for which of the following?

Accepted Answer

Inborn errors of metabolism

Answer

Blood sugar levels

Answer

Hepatitis infection

Answer

Congenital cataracts

Question 2

A mother reports that her 2-week-old infant sleeps most of the day and needs to be awakened every 4 hours for feeding, taking only one ounce of formula at a time. She is also concerned about the infant's persistently hard, pellet-like stools. Examination reveals an infant with normal weight and length, but with an enlarged head, a heart rate of 75 beats per minute, a temperature of 35°C (95°F), persistent jaundice, large anterior and posterior fontanelles, a distended abdomen, and an umbilical hernia. This clinical presentation is likely a result of which of the following?

Accepted Answer

Congenital hypothyroidism

Answer

Congenital megacolon (Hirschsprung disease)

Answer

Sepsis

Answer

Infantile botulism

Question 3

In Rh isoimmunization, exchange transfusion is indicated in all of the following situations EXCEPT:

Accepted Answer

Hydrops fetalis

Answer

Cord blood hemoglobin < 10 g/dL

Answer

Cord bilirubin > 5 mg/dL

Answer

Direct Coombs Test (DCT) positive with a history of a previously affected sibling

Question 4

A neonate presents with a warm abdomen but cold extremities. What is the likely condition?

Accepted Answer

Cold stress

Answer

Normal body temperature

Answer

Severe hypothermia

Answer

Shock

Question 5

Respiratory distress syndrome (RDS) in a neonate is primarily due to deficiency of which substance?

Accepted Answer

Dipalmitoyl lecithin

Answer

Sphingomyelin

Answer

Ceramide

Answer

All of the above

Question 6

What is the common cause of neonatal hypoglycemia?

Accepted Answer

Infant of diabetic mother

Answer

Deficiency of glucagon

Answer

Glycogen storage diseases

Answer

Maple syrup urine disease

Question 7

A newborn has a fever of 103°F. Blood culture grows gram-positive cocci in chains. This is most likely to be which of the following?

Accepted Answer

Group B Streptococci (Streptococcus agalactiae)

Answer

Group A Streptococci (Streptococcus pyogenes)

Answer

Salmonella species

Answer

Streptococcus pneumoniae

Question 8

A neonate delivered at 38 weeks of gestation with a birth weight of 2.2 kg develops intolerance to feeds and abdominal distension on the second day of life. Physical examination is unremarkable. Sepsis screen is negative. PCV is observed to be 72%. What is the best management option?

Accepted Answer

Partial Exchange Transfusion

Answer

Hydration with IV Fluids

Answer

Presumptive treatment for sepsis

Answer

Medical Management for intestinal obstruction

Question 9

Hypoglycemia in a newborn is seen in which of the following conditions?

Accepted Answer

Intrauterine growth restriction and Macrosomia

Answer

Maternal hypothyroidism

Answer

Maternal hypothyroidism and Rh incompatibility

Answer

Intrauterine growth restriction and Rh incompatibility

Question 10

Macrosomia is seen in all of the following conditions EXCEPT:

Accepted Answer

Hydrocephalus

Answer

Diabetes mellitus

Answer

Obesity

Answer

Post maturity

Neonatology — MCQs

Neonatology — MCQs

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