Assess phototherapy and exchange transfusion thresholds for newborns ≥ 35 weeks gestation using the AAP 2022 clinical practice guidelines.
Check any that apply — these lower the treatment threshold.
Neonatal jaundice (newborn jaundice) is a yellowing of the skin and eyes caused by elevated bilirubin levels in the blood. Bilirubin is produced when red blood cells break down. Newborns produce more bilirubin than adults because of higher red blood cell turnover, and their immature livers are slower to process and excrete it.
Common causes include physiologic jaundice (normal and self-limiting), breastfeeding jaundice (inadequate milk intake), breast milk jaundice (substances in breast milk affecting bilirubin metabolism), ABO/Rh incompatibility (hemolytic disease), and G6PD deficiency. Risk factors include prematurity, bruising from delivery, East Asian ethnicity, and a sibling who required phototherapy.
The AAP 2022 Clinical Practice Guideline updated the thresholds for initiating phototherapy in newborns ≥ 35 weeks gestational age. Thresholds are based on the infant's gestational age, postnatal age in hours, and the presence of neurotoxicity risk factors (isoimmune hemolytic disease, G6PD deficiency, asphyxia, sepsis, acidosis, or albumin < 3.0 g/dL).
For a term infant (38+ weeks) with no risk factors, phototherapy is typically indicated when total serum bilirubin (TSB) reaches approximately 18 mg/dL at 24 hours or 21 mg/dL at 48+ hours. With risk factors, thresholds are 2-4 mg/dL lower. Lower gestational ages (35-37 weeks) have progressively lower thresholds.
Exchange transfusion is a procedure where the newborn's blood is gradually replaced to rapidly lower dangerously high bilirubin levels and prevent kernicterus (bilirubin-induced brain damage). AAP 2022 guidelines specify exchange transfusion thresholds that are generally 5-7 mg/dL above the phototherapy threshold.
Exchange transfusion is considered a medical emergency and is indicated when: (1) TSB exceeds the exchange threshold despite intensive phototherapy, (2) TSB continues to rise rapidly despite phototherapy, or (3) there are signs of acute bilirubin encephalopathy (lethargy, hypotonia, high-pitched cry, retrocollis/opisthotonus).
Phototherapy uses blue-green light (wavelength 460-490 nm) to convert unconjugated bilirubin in the skin into water-soluble isomers that can be excreted without liver conjugation. The process involves photo-isomerization and photo-oxidation of bilirubin molecules.
Effective phototherapy requires: maximum skin surface area exposure (infant undressed except diaper), light source as close as safely possible (to maximize irradiance), and eye protection. Intensive phototherapy delivers ≥ 30 µW/cm²/nm using LED or fiber-optic devices. Response is typically seen within 4-6 hours, and TSB should decrease by 1-2 mg/dL within 4-6 hours of starting treatment.
Kernicterus (chronic bilirubin encephalopathy) is a permanent form of brain damage caused by very high unconjugated bilirubin levels crossing the blood-brain barrier. It can cause cerebral palsy, hearing loss, gaze abnormalities, and intellectual disability. It is almost entirely preventable with proper monitoring and treatment.
Prevention includes: universal bilirubin screening before hospital discharge, use of hour-specific bilirubin nomograms to assess risk, appropriate follow-up within 1-2 days after discharge for at-risk infants, timely initiation of phototherapy, and awareness of neurotoxicity risk factors.
The AAP 2022 guideline identifies specific neurotoxicity risk factors that lower the threshold for phototherapy and exchange transfusion. These factors increase the risk that bilirubin will cross the blood-brain barrier or cause damage at lower levels.
Risk factors include: Isoimmune hemolytic disease (Rh or ABO incompatibility with positive DAT), G6PD deficiency, perinatal asphyxia, sepsis, clinically significant acidosis (pH < 7.1), and low serum albumin (< 3.0 g/dL). When any of these factors are present, treatment is initiated at a lower bilirubin level.