12.2 Neonatal Hyperbilirubinemia & Hematologic Complications

12.2 Neonatal Hyperbilirubinemia & Hematologic Complications

Core Focus: Bilirubin care is threshold-based and individualized. Hematologic disorders can produce jaundice, bleeding, thrombosis, hypoxia, or shock, so assess the infant rather than treating color alone.

Bilirubin surveillance

Visually assess jaundice regularly, but estimate neither level nor treatment need from skin color alone. Obtain a transcutaneous or serum bilirubin at least once between 24 and 48 hours or before an earlier discharge. Jaundice during the first 24 hours requires prompt TcB/TSB measurement and evaluation.

Obtain a confirmatory TSB when TcB is within 3 mg/dL of the phototherapy threshold or TcB is at least 15 mg/dL. Treatment decisions use TSB. Plot the value by age in hours, gestational age, and hyperbilirubinemia neurotoxicity risk factors on the current AAP phototherapy and exchange-transfusion curves. Do not use the retired Bhutani “low/intermediate/high-risk zone” nomogram to decide treatment or follow-up.

A rise >=0.3 mg/dL/hour in the first 24 hours or >=0.2 mg/dL/hour thereafter suggests hemolysis. Evaluate blood type/DAT when indicated, CBC/hematocrit, reticulocytes and smear, G6PD testing when risk or unexplained course warrants, feeding, weight, stool/urine, bruising/hematoma, infection, and family history.

Patterns and causes

Physiologic bilirubin production rises after 24 hours because newborn red-cell turnover is high and hepatic conjugation is immature. Suboptimal-intake hyperbilirubinemia occurs in the first week with ineffective transfer, excess weight loss, low output, and delayed stooling; correct feeding and supplement when medically indicated. Human-milk jaundice can persist in a thriving infant after adequate intake is established, but other causes must be excluded.

ABO or Rh isoimmune hemolysis, G6PD deficiency, hereditary spherocytosis, sepsis, cephalohematoma/subgaleal blood, and polycythemia increase bilirubin load. Direct/conjugated bilirubin above 1 mg/dL is abnormal and prompts cholestasis evaluation, especially with dark urine, pale stool, poor growth, or hepatomegaly. Phototherapy removes unconjugated bilirubin; a cholestatic infant may still need phototherapy for a dangerous unconjugated component, so “never phototherapy” is incorrect.

Treatment and follow-up

Intensive phototherapy uses blue-green light with irradiance and exposed surface area meeting device/protocol standards. Protect eyes, maintain thermoregulation, support feeding/hydration, monitor TSB and output, and avoid routine water or dextrose-water supplements. Escalation-of-care and exchange thresholds are lower when neurotoxicity risks are present. Signs of acute bilirubin encephalopathy—poor suck, lethargy/hypotonia progressing to hypertonia, retrocollis/opisthotonus, high-pitched cry, apnea, or seizure—are an emergency.

Before discharge, calculate how far the TSB is below the applicable phototherapy threshold. A smaller margin requires earlier follow-up. Include gestational age, feeding adequacy, weight trajectory, hemolysis risk, family support, and ability to obtain a bilirubin. Give explicit return precautions.

Anemia and hemolytic disease

Anemia may reflect blood loss, fetomaternal or twin-to-twin transfusion, occult hemorrhage, hemolysis, infection, or reduced production. Pallor, tachycardia, weak pulses, poor feeding, tachypnea, or shock requires CBC/reticulocyte assessment and source evaluation. Treat physiology and cause; transfusion decisions depend on symptoms, level, age, and disease context.

Isoimmune hemolytic disease can cause early jaundice and anemia. A positive DAT supports antibody coating but does not by itself predict severity. G6PD deficiency can cause severe, sometimes sudden hemolysis; avoid known oxidant exposures and arrange family education/testing under the care plan.

Polycythemia and hyperviscosity

Confirm a high capillary hematocrit with a venous sample; venous hematocrit >=65% defines neonatal polycythemia. Hyperviscosity can cause ruddy color, lethargy, poor feeding, hypoglycemia, respiratory distress, cyanosis, thrombosis, or neurologic findings. Management depends on symptoms and venous value; ensure appropriate hydration/glucose evaluation and follow neonatal orders rather than treating a capillary number alone.

Thrombocytopenia and VKDB

Platelets below 150,000/µL define thrombocytopenia, but bleeding risk and treatment depend on count, trend, gestational age, clinical illness, and cause. Early causes include placental insufficiency and maternal immune thrombocytopenia; severe illness/sepsis, NEC, congenital infection, alloimmune thrombocytopenia, and genetic disease are important differentials. Petechiae, mucosal bleeding, or neurologic change requires urgent evaluation; suspected neonatal alloimmune thrombocytopenia carries intracranial-hemorrhage risk.

Vitamin K deficiency bleeding can occur early with maternal drug effects, classically in the first week, or late—often 2 to 12 weeks—in infants who did not receive reliable prophylaxis, especially when exclusively human-milk fed or cholestatic. Bleeding from the cord/circumcision, GI bleeding, bruising, pallor, bulging fontanelle, seizure, or shock demands emergency coagulation studies and treatment. IM vitamin K after birth is the most reliable prevention.

Safe transitions across settings

Communicate the last bilirubin value, exact collection age, applicable treatment threshold, rate of rise, feeding plan, weight change, hemolysis results, phototherapy history, and scheduled follow-up to both family and receiving clinician. Home phototherapy is appropriate only for carefully selected infants who meet current criteria and have reliable equipment, daily bilirubin measurement, adequate feeding, and rapid access to care. Readmission is safer when neurotoxicity risk, rapid rise, illness, or unreliable follow-up is present.

After phototherapy, obtain rebound testing when the infant's age at treatment, hemolysis, gestational age, or treatment course creates meaningful risk. Teach that visual improvement does not prove the bilirubin is safe and that sunlight is not a controlled substitute for medical phototherapy.