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: Which layer of the epidermis is underdeveloped in very low birth weight (VLBW) infants during the initial 7 days of life?

Stratum corneum. The correct answer is **Stratum corneum**. **1. Why Stratum corneum is correct:** The stratum corneum is the outermost layer of the epidermis, consisting of dead, keratinized cells (corneocytes) that provide the primary barrier against water loss and infection. In Very Low Birth Weight (VLBW) infants (typically those born before 30 weeks of gestation), the skin is structurally immature [1]. The process of keratinization is incomplete, resulting in a **thin or virtually absent stratum corneum** during the first week of life [1]. This leads to high transepidermal water loss (TEWL), electrolyte imbalances, and increased permeability to topical agents and pathogens. **2. Why other options are incorrect:** * **Stratum germinativum (Basale):** This is the deepest, proliferating layer. It is present and active early in fetal life to ensure the upward migration of cells; if this were underdeveloped, the entire epidermis would be absent. * **Stratum granulosum:** While this layer (responsible for producing keratohyalin granules) may be thin, it is the functional failure of the final cornified layer (stratum corneum) that defines the clinical vulnerability of VLBW infants. * **Stratum lucidum:** This is a translucent layer found only in thick skin (palms and soles). Its absence is a regional anatomical feature, not a systemic developmental deficiency related to VLBW status. **3. Clinical Pearls for NEET-PG:** * **Post-natal Maturation:** In VLBW infants, the stratum corneum undergoes rapid "accelerated maturation" upon exposure to a dry environment, usually becoming functionally effective by **2–3 weeks** of life. * **Clinical Consequence:** The lack of stratum corneum in preterms is the primary reason for using **humidified incubators** to prevent dehydration. * **Skin Layers (Deep to Superficial):** Remember the mnemonic **"B**ut **S**ome **G**uys **L**ove **C**orn" (**B**asale, **S**pinosum, **G**ranulosum, **L**ucidum, **C**orneum).

Q: A term baby girl has two episodes of bile-stained emesis at 24 hours after birth. There is a history of excessive amniotic fluid volume. What is the most appropriate diagnostic test?

Barium swallow and Gastrointestinal X-rays. **Explanation:** The clinical presentation of **bilious emesis** in a neonate is a surgical emergency until proven otherwise. In this case, the presence of **polyhydramnios** (excessive amniotic fluid) suggests a high intestinal obstruction, as the fetus was unable to swallow and process amniotic fluid in utero. **Why Barium Swallow and Gastrointestinal X-rays are correct:** The primary goal is to differentiate between life-threatening conditions like **Malrotation with Midgut Volvulus** and anatomical obstructions like **Duodenal Atresia**. * An initial **Plain X-ray (Abdomen)** may show a "Double Bubble" sign (pathognomonic for duodenal atresia). * If the X-ray is inconclusive or suggests malrotation, an **Upper GI Contrast Study (Barium/Gastrografin swallow)** is the gold standard to visualize the position of the Ligament of Treitz or a "corkscrew" appearance of the bowel. **Why other options are incorrect:** * **A. Blood Culture:** While sepsis can cause vomiting, bilious emesis specifically points to a mechanical obstruction. Sepsis workup is secondary to ruling out surgical emergencies. * **C & D. CT Head / Neurosonogram:** These are used to rule out increased intracranial pressure or intracranial hemorrhage as causes of vomiting. However, vomiting due to neurological causes is typically non-bilious. **NEET-PG High-Yield Pearls:** 1. **Bilious vomiting** in a newborn = **Midgut Volvulus** until proven otherwise. 2. **Duodenal Atresia** is strongly associated with **Down Syndrome** (Trisomy 21) and presents with a **Double Bubble sign**. 3. **Polyhydramnios** is a common maternal finding in high GI obstructions (Esophageal or Duodenal atresia). 4. The most common cause of lower GI obstruction in neonates is **Hirschsprung disease** (presents with delayed passage of meconium).

Q: A 2-day-old newborn male develops mild cyanosis. An ultrasound examination reveals a patent ductus arteriosus. Which of the following infections will most likely lead to this congenital anomaly?

Rubella. **Explanation:** The correct answer is **Rubella**. This question tests the association between maternal infections and specific congenital heart defects (CHDs). **Why Rubella is correct:** Congenital Rubella Syndrome (CRS) occurs when a non-immune mother is infected with the Rubella virus during the first trimester [1]. The virus is highly teratogenic and classically presents with a triad of clinical findings [1]: 1. **Cardiac defects:** Most commonly **Patent Ductus Arteriosus (PDA)** and peripheral pulmonary artery stenosis [1], [2]. 2. **Eye abnormalities:** Congenital cataracts and glaucoma. 3. **Sensorineural hearing loss:** The most common manifestation [1]. **Why the other options are incorrect:** * **Toxoplasmosis:** Typically presents with the triad of chorioretinitis, hydrocephalus, and intracranial calcifications. It is not classically associated with PDA. * **Cytomegalovirus (CMV):** The most common congenital infection. It typically presents with periventricular calcifications, microcephaly, and sensorineural hearing loss, but not specific structural cardiac anomalies like PDA. * **Varicella virus:** Congenital Varicella Syndrome is characterized by cicatricial skin scarring, limb hypoplasia, and chorioretinitis, rather than primary cardiac shunts. **High-Yield Clinical Pearls for NEET-PG:** * **PDA Anatomy:** The ductus arteriosus is a remnant of the **6th aortic arch**. It normally closes functionally within 10–15 hours of birth due to increased oxygen tension and decreased prostaglandin E2 (PGE2). * **Murmur:** PDA is characterized by a "machinery-like" continuous murmur heard best at the left infraclavicular area. * **Management:** **Indomethacin** or Ibuprofen (NSAIDs) are used to close a PDA by inhibiting prostaglandin synthesis. **Alprostadil (PGE1)** is used to keep it open in ductal-dependent lesions. * **Mnemonic for CRS:** "I (Eye-Cataract) Heart (PDA) Ruby (Rubella) Earrings (Deafness)."

Q: What are the least likely findings in a preterm baby with a patent ductus arteriosus (PDA)?

CO2 washout. In a preterm neonate, a **Patent Ductus Arteriosus (PDA)** leads to a left-to-right shunt, causing pulmonary over-circulation and systemic "steal." ### **Why "CO2 Washout" is the Least Likely Finding** CO2 washout (hypocapnia) occurs during hyperventilation. However, a significant PDA leads to **pulmonary edema** and increased lung stiffness (decreased compliance). This impairs gas exchange and increases the work of breathing, typically resulting in **CO2 retention (hypercapnia)** rather than washout. Therefore, CO2 washout is not a characteristic finding of PDA. ### **Explanation of Other Options** * **Bounding Pulses:** The "ductal steal" during diastole (blood flowing from the aorta into the pulmonary artery) causes a low diastolic pressure and a wide pulse pressure, manifesting clinically as bounding peripheral pulses. * **Pulmonary Hemorrhage:** Excessive pulmonary blood flow and high pressure can rupture capillary membranes, leading to hemorrhagic edema. PDA is a major risk factor for pulmonary hemorrhage in VLBW infants. * **Necrotizing Enterocolitis (NEC):** The "steal phenomenon" reduces perfusion to the mesenteric arteries (post-ductal systemic circulation). This intestinal ischemia significantly increases the risk of NEC. ### **NEET-PG High-Yield Pearls** * **Clinical Triad:** Tachycardia, bounding pulses, and a continuous "machinery" murmur (though in preterms, it may only be systolic). * **Hyperdynamic Precordium:** Often visible due to volume overload of the left heart. * **Chest X-ray:** Shows cardiomegaly and increased pulmonary vascular markings. * **Management:** First-line medical treatment includes **Indomethacin** or **Ibuprofen** (NSAIDs) which inhibit prostaglandin synthesis. **Paracetamol** is an emerging alternative with fewer side effects.

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

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 3

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 4

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 5

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 6

Which layer of the epidermis is underdeveloped in very low birth weight (VLBW) infants during the initial 7 days of life?

Accepted Answer

Stratum corneum

Answer

Stratum germinativum

Answer

Stratum granulosum

Answer

Stratum lucidum

Question 7

A term baby girl has two episodes of bile-stained emesis at 24 hours after birth. There is a history of excessive amniotic fluid volume. What is the most appropriate diagnostic test?

Accepted Answer

Barium swallow and Gastrointestinal X-rays

Answer

Blood culture

Answer

CT scan of the head

Answer

Neurosonogram

Question 8

A 2-day-old newborn male develops mild cyanosis. An ultrasound examination reveals a patent ductus arteriosus. Which of the following infections will most likely lead to this congenital anomaly?

Accepted Answer

Rubella

Answer

Toxoplasmosis

Answer

Cytomegalovirus

Answer

Varicella virus

Question 9

A newborn is prone to hypothermia due to which of the following reasons?

Accepted Answer

Presence of brown fat

Answer

More body surface area relative to mass

Answer

Less subcutaneous fat

Answer

Larger head size compared to the rest of the body

Question 10

What are the least likely findings in a preterm baby with a patent ductus arteriosus (PDA)?

Accepted Answer

CO2 washout

Answer

Bounding pulses

Answer

Pulmonary hemorrhage

Answer

Necrotizing enterocolitis

Neonatology — MCQs

Neonatology — MCQs

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