Introduction To Neonatal Jaundice

Neonatal jaundice is the yellowing of the skin, sclerae, and/or mucous membranes caused by bilirubin deposition.

It occurs when total serum bilirubin is in excess of 5 mg/dL and progresses in a head-to-toe fashion as levels increase. Most cases of physiologic (<12 mg/dL) jaundice are self-limited without sequelae, and appear on the second or third day of life peaking between the third and fifth day. Preterm infants may peak later.

Pathophysiology: The increased bilirubin production in newborns is a result of turnover of fetal red blood cells, a temporary decrease in conjugation and clearance by the immature newborn liver, and increased enterohepatic circulation.

Risk factors for indirect hyperbilirubinemia include

• maternal diabetes,
• prematurity, 
• drugs, 
• polycythemia, 
• traumatic delivery with cutaneous bruising or hematoma, 
• breastfeeding, and 
• ABO (O mother and A/B infant) or Rh(D) incompatibility (Rh(D) negative mother and Rh(D) positive infant). 

Clinical Features: Most infants with jaundice have no “disease” per se, but a careful history and organized approach is necessary to identify potentially pathologic causes.

Kernicterus manifests in a multitude of irreversible neurologic abnormalities and is the long-term
result of bilirubin-induced neurologic dysfunction secondary to extreme unconjugated hyperbilirubinemia which leads to neuronal death and pigment deposition in the basal ganglia and cerebellum.

Management
Initial laboratory workup should include

• blood type, 
• Coombs test, 
• complete blood count (CBC) with smear for red cell morphology,
• reticulocyte count, and 
• indirect and direct bilirubin levels. 

Although transcutaneous bilirubin measurement devices are widespread, they can underestimate total bilirubin at levels >15 mg/dL; therefore, a serum measurement is recommended for severely jaundiced newborns.

Initial management should ensure adequate hydration and treatment of the underlying condition. The level of serum bilirubin at which to start phototherapy can be obtained from a standardized nomogram and is dependent upon the infant’s postnatal age in hours, gestational age, and an assessment of risk factors. In general, the goal of phototherapy is to maintain the bilirubin level below 20 mg/dL.

Exchange transfusion is considered if the serum level remains elevated (22-25 mg/dL) despite appropriate phototherapy.

Points To Remember
1. Onset of clinical jaundice in the first 24 hours of life strongly suggests the presence of a pathologic process.
2. Direct serum bilirubin concentration exceeding 10% of total serum bilirubin or 2 mg/dL suggests hepatobiliary disease or a metabolic disorder.
3. Bilirubin levels at which to initiate phototherapy or exchange transfusion should be modified for prematurity, sepsis, low birth weight, and other risk factors.