What Are the Characteristics of Pathological Jaundice?

Generally speaking, first, jaundice appears unusually early—within 24 hours after birth in term infants and within 48 hours in preterm infants—indicating premature onset.

Second, the jaundice is severe: serum bilirubin levels exceed the average for age-matched healthy infants—i.e., ≥220 μmol/L (≥12.9 mg/dL) in term infants or ≥256 μmol/L (≥15 mg/dL) in preterm infants. In addition to facial and trunk involvement, jaundice becomes visibly apparent on the lower legs, forearms, palms, and soles—indicating a high degree of severity.

Third, jaundice persists abnormally long—typically beyond two weeks in term infants or four weeks in preterm infants—or reappears and worsens after initial resolution—both considered hallmarks of pathological jaundice.

Fourth, jaundice progresses rapidly—i.e., deepens markedly within 24 hours or increases by more than 85.5 μmol/L (5 mg/dL) per day.

Fifth, late-onset jaundice—i.e., appearing one week to several weeks after birth—is also classified as pathological.

Sixth, a serum direct (conjugated) bilirubin level exceeding 25 μmol/L (1.5 mg/dL) is likewise indicative of pathological jaundice.