Final answer:
Pathologic jaundice in newborns is determined by significant bilirubin levels and may suggest Rh or ABO incompatibility if the Coombs' test is positive. A negative Coombs' test indicates other possible causes like twin-to-twin transfusion or maternal-fetal transfusion. Understanding the type of jaundice—hemolytic, hepatic, or obstructive—is critical for management.
Step-by-step explanation:
Pathologic jaundice in newborns is characterized by elevated levels of bilirubin in the blood, which can cause the skin and eyes to appear yellow. This condition is often assessed on the first day of life (DOL) with specific diagnostic levels indicating concern: bilirubin (bili) greater than 12 mg/dl, direct bilirubin (d-bili) higher than 2 mg/dl, and a rate of rise of more than 5 mg/dl per day.
One important diagnostic tool used in this context is the Coombs' test, which detects whether antibodies in the mother's blood have begun attacking the child's red blood cells, potentially leading to hemolysis (rupture of red blood cells) and increased bilirubin production. A positive Coombs' test can be suggestive of Rh or ABO incompatibility, whereas a negative result might be associated with conditions such as twin-to-twin transfusion, maternal-fetal transfusion, infant of a diabetic mother (IDM), spherocytosis, or G6PD deficiency.
Classification of jaundice is essential to understand the underlying cause and treatment options. Jaundice can be classified into three types:
- Haemolytic or prehepatic jaundice: Excessive breakdown of red blood cells leads to increased levels of unconjugated bilirubin in the blood.
- Infective or hepatic jaundice: Liver damage prevents normal excretion of bilirubin, causing an increase in both conjugated and unconjugated bilirubin.
- Obstructive or posthepatic jaundice: Bile duct obstruction results in elevated levels of conjugated bilirubin.
It is important to correctly identify the type of hyperbilirubinemia—whether it is unconjugated or conjugated—as this influences the management strategy. Conditions like unconjugated hyperbilirubinemia may occur in infants due to immature liver enzyme systems, whereas obstructive causes involve an increase in conjugated bilirubin.