Neonatology Practice Questions

Q: Lifespan of the fetal red blood cell is approximately:

80 days. **Explanation:** The lifespan of a red blood cell (RBC) is determined by its metabolic rate and the stability of its membrane. In a term neonate, the fetal RBC lifespan is approximately **80 to 90 days**, significantly shorter than the adult RBC lifespan. **Why 80 days is correct:** Fetal RBCs have a shorter survival time due to several physiological factors: 1. **Lower Enzyme Activity:** They have reduced levels of enzymes like phosphofructokinase, making them more prone to oxidative stress. 2. **Membrane Characteristics:** Fetal RBC membranes are more fragile and have different lipid compositions compared to adults. 3. **Metabolic Demand:** The rapid growth and transition in the neonatal period necessitate a higher turnover of cells. *Note: In preterm infants, the lifespan is even shorter, ranging from 40 to 60 days.* **Analysis of Incorrect Options:** * **A. 50 days:** This is characteristic of a **preterm neonate's** RBC lifespan (approx. 40–60 days), but not a term neonate. * **C. 100 days:** This is an intermediate value and does not represent the standard physiological average for any specific age group. * **D. 120 days:** This is the standard lifespan of an **adult RBC**. Adult cells have more robust enzymatic pathways and membrane stability. **NEET-PG High-Yield Pearls:** * **Polycythemia:** Neonates have a higher hematocrit (50–60%) at birth to compensate for the lower oxygen tension in utero. * **Physiological Jaundice:** The combination of a shorter RBC lifespan (80 days) and an immature liver (low glucuronosyltransferase activity) is the primary cause of physiological jaundice in newborns. * **Fetal Hemoglobin (HbF):** Composed of $\alpha_2\gamma_2$ chains. It has a higher affinity for oxygen but shifts the dissociation curve to the left.

Q: Which of the following findings is commonly seen in an infant of a diabetic mother?

Hypocalcemia. **Explanation:** Infants of Diabetic Mothers (IDM) face a unique set of metabolic challenges due to the intrauterine environment. **Why Hypocalcemia is correct:** Hypocalcemia (defined as serum calcium <7 mg/dL) occurs in up to 50% of IDMs. The primary mechanism is **delayed parathyroid hormone (PTH) secretion**. During pregnancy, maternal hypercalcemia (secondary to bone resorption) suppresses the fetal parathyroid glands. Additionally, maternal diabetes is often associated with **hypomagnesemia**, which further impairs PTH secretion and induces end-organ resistance to PTH in the neonate, leading to low calcium levels in the first 24–72 hours of life. **Analysis of Incorrect Options:** * **A. Hyperglycemia:** IDMs experience **Hypoglycemia**. Chronic fetal hyperinsulinism (in response to maternal hyperglycemia) persists after birth. Once the umbilical cord is cut, the glucose supply stops, but high insulin levels remain, causing a rapid drop in blood glucose. * **B. Anemia:** IDMs are prone to **Polycythemia** (increased hematocrit). Chronic fetal hypoxia (due to increased metabolic rate and oxygen demand) stimulates erythropoietin production, leading to an overproduction of red blood cells. * **C. Hypermagnesemia:** IDMs typically present with **Hypomagnesemia**. This is due to maternal magnesium loss through osmotic diuresis (glycosuria), which leads to fetal magnesium deficiency. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cardiac anomaly:** Ventricular Septal Defect (VSD). * **Most specific cardiac anomaly:** Transposition of the Great Arteries (TGA). * **Most specific malformation:** Caudal Regression Syndrome (Sacral Agenesis). * **Other common findings:** Hyperbilirubinemia, Respiratory Distress Syndrome (delayed surfactant production), and Hypertrophic Cardiomyopathy (septal hypertrophy).

Q: Moderate hypothermia in a neonate is defined as an axillary temperature?

32-35.9°C. The normal axillary temperature of a neonate is **36.5°C to 37.5°C**. Hypothermia occurs when the temperature drops below 36.5°C. The World Health Organization (WHO) classifies neonatal hypothermia into three distinct stages based on severity: * **Mild Hypothermia (Cold Stress):** 36.0°C to 36.4°C. This is a warning sign to initiate warming. * **Moderate Hypothermia:** **32.0°C to 35.9°C.** This requires immediate intervention to prevent metabolic complications. * **Severe Hypothermia:** < 32.0°C. This is a medical emergency associated with high mortality. **Analysis of Options:** * **Option D (32-35.9°C):** Correct. This aligns with the WHO classification for moderate hypothermia. * **Option A (< 34°C) & B (31-34°C):** Incorrect. These ranges do not align with standardized WHO definitions and overlap between moderate and severe categories. * **Option C (< 32°C):** Incorrect. This defines **Severe Hypothermia**, not moderate. **High-Yield Clinical Pearls for NEET-PG:** 1. **Brown Fat:** Neonates generate heat via **non-shivering thermogenesis** by metabolizing brown fat (located in the interscapular region, neck, and axilla). 2. **The Warm Chain:** A set of 10 interlinked procedures (e.g., warm delivery room, immediate drying, skin-to-skin contact) to prevent heat loss. 3. **Kangaroo Mother Care (KMC):** The gold standard for managing stable low-birth-weight infants with hypothermia. 4. **Complications:** Prolonged hypothermia leads to metabolic acidosis, hypoglycemia, and pulmonary hemorrhage.

Q: A 4.2 kg baby born to a diabetic mother develops seizures at 16 hours of age. What is the most likely cause?

Hypoglycemia. **Explanation:** **1. Why Hypoglycemia is the correct answer:** Infants of Diabetic Mothers (IDM) are prone to **hyperinsulinism** due to chronic exposure to maternal hyperglycemia in utero. After birth, the glucose supply is cut off, but the baby’s pancreas continues to secrete high levels of insulin, leading to rapid glucose consumption. **Hypoglycemia** is the most common metabolic complication in IDMs, typically occurring within the first 6–24 hours of life. In this scenario, the combination of macrosomia (4.2 kg) and the timing (16 hours) makes hypoglycemia the most probable cause of seizures. **2. Why other options are incorrect:** * **Hypoxia/RDS:** While IDMs are at risk for RDS due to delayed surfactant synthesis (insulin inhibits cortisol), seizures are not a primary presentation of RDS unless there is severe secondary birth asphyxia. * **Hypocalcemia:** This is common in IDMs but usually presents between **24 to 72 hours** of life. It is often associated with functional hypoparathyroidism. * **Hypomagnesemia:** This often co-exists with hypocalcemia and can cause jitteriness or seizures, but it is less common than hypoglycemia as an isolated cause in the first 24 hours. **Clinical Pearls for NEET-PG:** * **Most common complication in IDM:** Hypoglycemia. * **Most common malformation in IDM:** Cardiac defects (specifically VSD; though **Transposition of Great Arteries** is highly associated). * **Most specific malformation:** Caudal Regression Syndrome (Sacral Agenesis). * **Management:** If the baby is symptomatic (seizures), the immediate treatment is a **2 ml/kg bolus of 10% Dextrose (D10W)** followed by a continuous glucose infusion (GIR 6-8 mg/kg/min).

Q: Which of the following vaccines is recommended for newborns?

BCG. **Explanation:** In accordance with the National Immunization Schedule (NIS) in India, the vaccines administered at birth (birth dose) are **BCG, Oral Polio Vaccine (OPV-0), and Hepatitis B**. **Why BCG is the correct answer:** BCG (Bacillus Calmette-Guérin) is a live attenuated vaccine derived from *Mycobacterium bovis*. It is administered intradermally (0.05 ml for newborns) to protect against severe forms of childhood tuberculosis, such as TB meningitis and disseminated (miliary) TB. It is recommended as soon as possible after birth. **Why the other options are incorrect:** * **MMR (Measles, Mumps, Rubella):** This is a live vaccine typically administered at 9 months (as MR) or 12–15 months. It is not given at birth due to the presence of maternal antibodies, which can interfere with the immune response. * **DPT (Diphtheria, Pertussis, Tetanus):** The primary series for DPT (usually as part of the Pentavalent vaccine) starts at 6 weeks of age, followed by doses at 10 and 14 weeks. * **HiB (Haemophilus influenzae type b):** This is also part of the Pentavalent vaccine and is initiated at 6 weeks of age, not at birth. **High-Yield Clinical Pearls for NEET-PG:** * **BCG Site:** Left upper arm (deltoid) to maintain uniformity for scar inspection. * **BCG Evolution:** Papule (2-3 weeks) → Pustule → Shallow Ulcer → Permanent depressed scar (6-12 weeks). * **Dose Change:** If not given at birth, the dose is 0.1 ml after 1 month of age. It can be given up to 1 year of age. * **Hepatitis B:** The birth dose must be given within 24 hours to prevent vertical transmission.

Question 1

Lifespan of the fetal red blood cell is approximately:

Accepted Answer

80 days

Answer

50 days

Answer

100 days

Answer

120 days

Question 2

Which of the following findings is commonly seen in an infant of a diabetic mother?

Accepted Answer

Hypocalcemia

Answer

Hyperglycemia

Answer

Anemia

Answer

Hypermagnesemia

Question 3

In hyaline membrane disease, what is the primary pathological feature in the lung?

Accepted Answer

Fibrin deposition

Answer

Albumin and complement deposition

Answer

Precipitated surfactant

Answer

Mucus accumulation

Question 4

A female newborn presents with vaginal bleeding 4 days after birth. What is the recommended course of action?

Accepted Answer

Rule out clotting factor deficiency

Answer

Wait and watch

Answer

Perform bleeding time test

Answer

Administer blood transfusion

Question 5

Moderate hypothermia in a neonate is defined as an axillary temperature?

Accepted Answer

32-35.9°C

Answer

< 34°C

Answer

31-34°C

Answer

< 32°C

Question 6

Which of the following is a contraindication for bag and mask ventilation?

Accepted Answer

Meconium aspiration

Answer

Tracheoesophageal fistula

Answer

Congenital lung cyst

Answer

Birth asphyxia

Question 7

A 4.2 kg baby born to a diabetic mother develops seizures at 16 hours of age. What is the most likely cause?

Accepted Answer

Hypoglycemia

Answer

Hypoxia/Respiratory distress syndrome

Answer

Hypomagnesemia

Answer

Hypocalcemia

Question 8

A term neonate presents to the pediatric emergency with poor feeding for the last 6 hours. The mother had a history of chorioamnionitis and premature rupture of membranes. What is the best initial management approach for this neonate?

Accepted Answer

Start intravenous antibiotics immediately after obtaining a blood culture sample.

Answer

Start oral antibiotics and monitor for clinical deterioration.

Answer

Reassure the parents and provide supportive care only.

Answer

Monitor the neonate and start intravenous fluids only.

Question 9

A 3-day-old neonate born after a 32-week gestation develops yellow skin. Physical examination of the infant is unremarkable. Which of the following is most likely to be increased in this neonate's serum?

Accepted Answer

Unconjugated bilirubin

Answer

Alanine aminotransferase

Answer

Carotene

Answer

Conjugated bilirubin

Question 10

Which of the following vaccines is recommended for newborns?

Accepted Answer

BCG

Answer

MMR

Answer

DPT

Answer

HiB

Neonatology — MCQs

Neonatology — MCQs

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