Neonatology and Perinatology Practice Questions

Q: Erythroblastosis fetalis can be prevented if the mother is injected with an antibody called?

Rh (D) immunoglobulin. **Explanation:** **Erythroblastosis fetalis** (Hemolytic Disease of the Newborn) occurs when an Rh-negative mother is sensitized to Rh-positive fetal red blood cells (RBCs), leading to the production of maternal IgG antibodies that cross the placenta and destroy fetal erythrocytes. **Why Rh (D) Immunoglobulin is correct:** The administration of **Rh (D) immunoglobulin (Anti-D)** is the standard preventive measure. It contains high titers of antibodies against the Rh(D) antigen. When injected into the mother, these antibodies bind to and neutralize any fetal Rh-positive RBCs in the maternal circulation before her immune system can recognize them and initiate an active immune response (isoimmunization). This is a form of **passive immunization**. **Why the other options are incorrect:** * **A. Blocking antibody:** While Anti-D acts by "blocking" the antigen sites, the term is non-specific. In immunology, blocking antibodies usually refer to IgG antibodies that compete with IgE in allergic reactions. * **C & D. Antilymphocyte globulin (ALG) and Antithymocyte serum (ATS):** These are potent immunosuppressants used primarily in organ transplantation and aplastic anemia to prevent graft rejection by depleting T-cells. They play no role in preventing Rh isoimmunization. **High-Yield Clinical Pearls for NEET-PG:** * **Standard Dose:** 300 mcg (1500 IU) of Anti-D can neutralize **30 ml of fetal whole blood** or 15 ml of packed RBCs. * **Timing:** Administered routinely at **28 weeks gestation** and within **72 hours of delivery** (if the neonate is Rh-positive). * **Kleihauer-Betke Test:** Used to quantify the volume of fetomaternal hemorrhage to determine if additional doses of Anti-D are required. * **Indirect Coombs Test (ICT):** Used to screen the mother for sensitization. Anti-D is only effective if the mother is **not** already sensitized (ICT negative).

Q: Hypoxia induced metabolic acidemia is when?

Umbilical artery blood pH < 7.00. **Explanation:** The diagnosis of **hypoxia-induced metabolic acidemia** (often termed "pathological acidemia") is a critical marker in neonatology used to define birth asphyxia and predict potential neurological sequelae like Hypoxic-Ischemic Encephalopathy (HIE). **1. Why Option A is Correct:** According to the American College of Obstetricians and Gynecologists (ACOG) and the American Academy of Pediatrics (AAP), the threshold for clinically significant metabolic acidemia is an **umbilical artery blood pH 17.7 mmol/L is relatively normal; pathological acidemia typically involves significantly lower levels as bicarbonate is consumed to buffer the excess lactic acid. * **Option C:** The criteria for metabolic acidemia require a **Base Deficit ≥ 12 mmol/L**. A base deficit *less* than 12 mmol/L (e.g., 8 or 10) indicates a milder state that does not meet the formal definition of severe metabolic acidemia. **Clinical Pearls for NEET-PG:** * **Gold Standard:** Umbilical **arterial** blood gas (ABG) is more reflective of fetal status than venous blood. * **The "Rule of 7 & 12":** For a diagnosis of birth asphyxia, you need a pH ** 6 mmol/L) are also used as an early indicator of anaerobic metabolism due to hypoxia. * **Associated Findings:** To label a case as "Birth Asphyxia," the acidemia must be accompanied by an Apgar score of 0–3 for > 5 minutes and evidence of multisystem organ dysfunction.

Q: A 26-year-old primigravida develops gestational diabetes and remains hyperglycemic during the remainder of her pregnancy. Which of the following abnormalities in the newborn child is likely related to the maternal hyperglycemia?

Increased birth weight. **Explanation:** The correct answer is **C. Increased birth weight (Macrosomia).** **Pathophysiology:** The underlying mechanism is explained by the **Pedersen Hypothesis**. Maternal hyperglycemia leads to fetal hyperglycemia because glucose crosses the placenta via facilitated diffusion. In response, the fetal pancreas undergoes islet cell hyperplasia and secretes excess insulin (fetal hyperinsulinemia). Since insulin is a potent anabolic hormone and a structural analogue of Insulin-like Growth Factor (IGF-1), it promotes excessive deposition of fat and glycogen in fetal tissues, leading to **macrosomia** (birth weight >4000g or >90th percentile). **Analysis of Incorrect Options:** * **A. Ambiguous genitalia:** This is typically caused by Congenital Adrenal Hyperplasia (CAH) or chromosomal abnormalities, not maternal glucose levels. * **B. Cretinism:** This results from untreated congenital hypothyroidism (iodine deficiency or thyroid dysgenesis), not maternal diabetes. * **D. Sheehan syndrome:** This is a maternal complication involving postpartum pituitary necrosis due to severe obstetric hemorrhage; it does not occur in the newborn. **NEET-PG High-Yield Pearls:** * **Most common cardiac anomaly** in infants of diabetic mothers (IDM): Hypertrophic Cardiomyopathy (specifically asymmetric septal hypertrophy). * **Most specific anomaly:** Caudal Regression Syndrome (Sacral agenesis). * **Metabolic complications in IDM:** Hypoglycemia (due to persistent hyperinsulinemia after cord clamping), Hypocalcemia, Hypomagnesemia, and Polycythemia. * **Respiratory:** Increased risk of Respiratory Distress Syndrome (RDS) because hyperinsulinemia inhibits surfactant production by type II pneumocytes.

Q: At the time of delivery, a growth-restricted fetus would be prone to all of the following neonatal complications except?

Hyperglycemia. **Explanation:** The correct answer is **C. Hyperglycemia**. In fact, growth-restricted fetuses (Fetal Growth Restriction - FGR/IUGR) are prone to **Hypoglycemia**, not hyperglycemia. **Why Hyperglycemia is incorrect (The Medical Concept):** Growth-restricted fetuses have chronic placental insufficiency, leading to poor nutrient transfer. Consequently, they have **depleted glycogen stores** in the liver and heart, and diminished subcutaneous fat (reduced glycerol for gluconeogenesis). Post-delivery, they cannot maintain blood glucose levels, making hypoglycemia a hallmark neonatal complication. **Analysis of other options:** * **Meconium Aspiration (A):** Chronic hypoxia in utero triggers vagal stimulation, leading to the passage of meconium. Combined with reduced amniotic fluid (oligohydramnios), the risk of thick meconium aspiration syndrome (MAS) is high. * **Hypothermia (B):** These neonates have a high surface-area-to-body-mass ratio and lack **brown fat** and subcutaneous adipose tissue, which are essential for non-shivering thermogenesis. * **Polycythemia (D):** Chronic intrauterine hypoxia stimulates fetal **erythropoietin** production, leading to an increased red cell mass (polycythemia) to compensate for low oxygen levels. This can result in hyperviscosity syndrome. **NEET-PG High-Yield Pearls:** * **Ponderal Index:** Used to differentiate between Symmetrical and Asymmetrical IUGR. * **Commonest cause of Asymmetrical IUGR:** Placental insufficiency (e.g., Preeclampsia). * **Other complications:** Hypocalcemia (due to relative hypoparathyroidism) and Pulmonary Hemorrhage. * **Rule of thumb:** IUGR babies are "Small but Mature," meaning they often have accelerated lung maturity due to chronic stress (increased steroids), reducing the risk of RDS compared to preterm infants of the same weight.

Q: Which component is NOT included in the standard APGAR score, considering its historical 'A/E' (Appearance/Color) interpretation?

Respiratory rate. The APGAR score, developed by Dr. Virginia Apgar in 1952, is a rapid method for assessing the clinical status of a newborn at 1 and 5 minutes after birth. **Explanation of the Correct Answer:** The correct answer is **Respiratory Rate (Option B)**. While the APGAR score assesses the respiratory system, it specifically evaluates **Respiratory Effort** (the quality of crying and breathing patterns), not the numerical respiratory rate. A baby can have a high respiratory rate (tachypnea) but still receive a low score if the effort is gasping or weak. **Analysis of Incorrect Options:** * **Appearance (Option A):** This refers to skin color. A score of 0 is given for central cyanosis/pallor, 1 for acrocyanosis (blue extremities, pink body), and 2 for a completely pink baby. * **Muscle Tone (Option C):** Also known as **Activity**. It assesses the degree of flexion and resistance to extension of the limbs. * **Reflex Irritability (Option D):** Also known as **Grimace**. It measures the newborn's response to stimulation (e.g., suctioning the oropharynx or flicking the soles). **NEET-PG High-Yield Pearls:** * **The Mnemonic:** **A**ppearance (Color), **P**ulse (Heart Rate), **G**rimace (Reflex Irritability), **A**ctivity (Muscle Tone), **R**espiration (Effort). * **Heart Rate Scoring:** This is the most important prognostic component. 0 = Absent; 1 = 100 bpm. * **Clinical Significance:** A score of 7–10 is normal; 4–6 is moderately depressed; 0–3 is severely depressed. * **Important Note:** The APGAR score is used to assess the need for continued resuscitation but is **NOT** used to decide whether to *initiate* resuscitation (which is based on initial assessment of gestation, tone, and breathing).

Question 1

Erythroblastosis fetalis can be prevented if the mother is injected with an antibody called?

Accepted Answer

Rh (D) immunoglobulin

Answer

Blocking antibody

Answer

Antilymphocyte globulin

Answer

Antithymocyte serum

Question 2

Hypoxia induced metabolic acidemia is when?

Accepted Answer

Umbilical artery blood pH < 7.00

Answer

HCO3 - concentration > 17.7 mmol/L

Answer

Base deficit < 12 mmol/L

Answer

None of the above

Question 3

A 26-year-old primigravida develops gestational diabetes and remains hyperglycemic during the remainder of her pregnancy. Which of the following abnormalities in the newborn child is likely related to the maternal hyperglycemia?

Accepted Answer

Increased birth weight

Answer

Ambiguous genitalia

Answer

Cretinism

Answer

Sheehan syndrome

Question 4

At the time of delivery, a growth-restricted fetus would be prone to all of the following neonatal complications except?

Accepted Answer

Hyperglycemia

Answer

Meconium aspiration

Answer

Hypothermia

Answer

Polycythemia

Question 5

Which component is NOT included in the standard APGAR score, considering its historical 'A/E' (Appearance/Color) interpretation?

Accepted Answer

Respiratory rate

Answer

Appearance (Color)

Answer

Muscle tone

Answer

reflex irritability

Neonatology and Perinatology — MCQs

Neonatology and Perinatology — MCQs

On this page

Practice by Chapter

Want unlimited practice?