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Difficulty: HardNeonatal Disorders

A male infant is born at 39 weeks gestation via spontaneous vaginal delivery to a 28-year-old primigravida. The pregnancy was complicated by maternal preeclampsia and intrauterine growth restriction. Birth weight is 2100 g. APGAR scores are 8 and 9 at 1 and 5 minutes.

At 14 hours of life, the infant is evaluated for lethargy, jitteriness, and poor feeding. Vital signs show a temperature of 36.8°C (98.2°F), heart rate of 150/min, and respiratory rate of 64/min. Physical examination reveals a plethoric appearance, sluggish capillary refill, and scattered erythematous macules with central yellow-white papules on the infant's trunk.

Laboratory TestResult
Capillary blood glucose58 mg/dL
Serum calcium9.4 mg/dL
Peripheral venous hematocrit72%
White blood cell count14,500/mm³

Which of the following is the most appropriate next step in management?

  1. Partial exchange transfusion with normal salineAnswer
  2. B
    Intravenous broad-spectrum antibiotic therapy
  3. C
    Isolation and initiation of intravenous acyclovir
  4. D
    Administration of a 10% dextrose intravenous bolus
  5. E
    Reassurance and continuation of routine newborn care

Answer

Partial exchange transfusion with normal saline
The correct answer is partial exchange transfusion with normal saline. This infant has neonatal polycythemia, defined as a peripheral venous hematocrit of 65% or greater. Intrauterine growth restriction (IUGR) secondary to maternal preeclampsia causes chronic fetal hypoxia, which stimulates fetal erythropoietin production and leads to an increased red blood cell mass. The resulting hyperviscosity decreases tissue perfusion, presenting clinically with plethora, lethargy, poor feeding, jitteriness, and respiratory distress. Because this infant is symptomatic with a venous hematocrit of 72%, immediate intervention is required to reduce blood viscosity while maintaining intravascular volume. This is achieved via a partial exchange transfusion, where a portion of the infant's blood is removed and replaced with an equal volume of normal saline. The skin findings described represent erythema toxicum neonatorum, a benign condition requiring no treatment.

Step-by-Step Solution

1
Analyze the patient's risk factors and clinical presentation.
The patient is an IUGR infant presenting with lethargy, jitteriness, plethora, and a benign rash (erythema toxicum neonatorum) at 14 hours of life.
Identifying the constellation of risk factors (IUGR/hypoxia) and signs (plethora/neurologic symptoms) points toward hyperviscosity syndrome.
2
Interpret the provided laboratory findings to establish a diagnosis.
Capillary glucose and serum calcium are normal, ruling out common metabolic causes of jitteriness. A peripheral venous hematocrit of 72% confirms the diagnosis of neonatal polycythemia.
Symptoms like jitteriness overlap with hypoglycemia and hypocalcemia, which must be excluded before attributing symptoms solely to polycythemia.
3
Determine the definitive treatment for symptomatic neonatal polycythemia.
Partial exchange transfusion using normal saline is the standard of care.
This procedure safely lowers the hematocrit and reduces blood viscosity without causing dangerous hypovolemia.

Key Concept

Diagnosis and management of symptomatic neonatal polycythemia
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Topics

Neonatal Disorders

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