NNP Hematology and Hyperbilirubinemia 2 — Questions and Answers
Question 1: A neonate is being evaluated for exchange transfusion. Which of the following is an absolute indication for emergency exchange transfusion?
- TSB at phototherapy threshold on the Bhutani nomogram
- Signs of acute bilirubin encephalopathy (ABE) with rapidly rising TSB (Correct answer)
- TSB 2 mg/dL above the phototherapy line in a term infant
- Positive direct Coombs test with TSB of 10 mg/dL at 48 hours
Correct answer: Signs of acute bilirubin encephalopathy (ABE) with rapidly rising TSB
Signs of acute bilirubin encephalopathy (lethargy, hypotonia, high-pitched cry, arching) with a rapidly rising TSB are an absolute indication for emergency double-volume exchange transfusion.
Question 2: What volume of blood is used for a double-volume exchange transfusion in a neonate?
- 40 mL/kg
- 80 mL/kg
- 160 mL/kg (Correct answer)
- 200 mL/kg
Correct answer: 160 mL/kg
A double-volume exchange transfusion uses approximately 160 mL/kg (2 × 80 mL/kg blood volume), which exchanges roughly 85–90% of the neonate's red blood cells.
Question 3: Which type of blood product is MOST appropriate for exchange transfusion in a neonate with Rh hemolytic disease?
- O-negative irradiated CMV-negative red blood cells reconstituted with AB plasma (Correct answer)
- Type-specific irradiated packed red blood cells reconstituted with fresh frozen plasma
- Leukoreduced type-specific whole blood less than 7 days old
- O-positive washed packed red blood cells
Correct answer: O-negative irradiated CMV-negative red blood cells reconstituted with AB plasma
O-negative (Rh-negative) irradiated CMV-negative red blood cells reconstituted with AB plasma avoids further hemolysis from maternal anti-D antibodies and is safe for all neonates regardless of blood type.
Question 4: A neonate receiving intensive phototherapy has a TSB that rises by 1 mg/dL in 6 hours despite treatment. What is the MOST appropriate next action?
- Add a second phototherapy unit and reassess in 4–6 hours
- Discontinue phototherapy and perform exchange transfusion immediately
- Begin intravenous immunoglobulin (IVIG) therapy (Correct answer)
- Increase the neonate's fluid intake by 10% and continue phototherapy
Correct answer: Begin intravenous immunoglobulin (IVIG) therapy
IVIG (0.5–1 g/kg) is recommended for isoimmune hemolytic disease (Rh or ABO) when the TSB is rising despite intensive phototherapy, as it reduces hemolysis by blocking Fc receptors on macrophages.
Question 5: Which complication is MOST commonly associated with exchange transfusion in neonates?
- Hypercalcemia
- Thrombocytopenia and metabolic acidosis (Correct answer)
- Hypermagnesemia
- Polycythemia
Correct answer: Thrombocytopenia and metabolic acidosis
Exchange transfusion commonly causes thrombocytopenia (platelet dilution), metabolic acidosis (citrate in donor blood), as well as hypocalcemia, hypoglycemia, and electrolyte disturbances.
Question 6: A 28-week preterm neonate has a bilirubin level of 8 mg/dL on day 3. Which factor MOST lowers the threshold for phototherapy in this infant compared to a term neonate?
- Immature hepatic glucuronidation only
- Increased risk of bilirubin neurotoxicity at lower TSB levels due to prematurity and low albumin (Correct answer)
- Higher hematocrit leading to more bilirubin production
- Greater skin surface area per kilogram
Correct answer: Increased risk of bilirubin neurotoxicity at lower TSB levels due to prematurity and low albumin
Preterm infants are at higher risk for bilirubin neurotoxicity at lower TSB levels due to immature blood-brain barrier, lower albumin levels (less bilirubin binding), and concurrent illness, warranting lower phototherapy thresholds.
Question 7: Which condition is associated with elevated DIRECT (conjugated) bilirubin in a neonate and requires further workup for cholestasis?
- Rh hemolytic disease
- Biliary atresia (Correct answer)
- Physiologic jaundice
- ABO incompatibility
Correct answer: Biliary atresia
Biliary atresia causes elevation of conjugated (direct) bilirubin due to obstruction of bile flow and requires urgent evaluation (hepatobiliary scan, liver biopsy) and Kasai portoenterostomy before 60 days of life.
NNP Hematology and Hyperbilirubinemia 2
A neonate is being evaluated for exchange transfusion.
Which of the following is an absolute indication for emergency exchange transfusion?