Neonatal Jaundice and Hyperbilirubinemia

Clinical Note: The Entero-Hepatic Circulation In newborns, a high level of the enzyme Beta glucuronidase in the intestinal brush border can deconjugate the water-soluble bilirubin back into its fat-soluble form, allowing it to be reabsorbed into the bloodstream. This cycle can exacerbate hyperbilirubinemia.

Categorizing Jaundice: Physiological vs. Pathological

Distinguishing between these two categories is the most critical skill for a neonatal nurse or midwife.

Physiological Jaundice

Physiological jaundice is a normal, transient process in otherwise healthy term infants. It is considered a "diagnosis of exclusion," meaning we only call it physiological once all other causes have been ruled out.

• Onset: Typically appears after the first 24 hours of life (often peaking around day 3).
• Timeline: Usually peaks at day 5 and resolves by day 7–10.
• Presentation: The infant remains well, alert, and is feeding effectively.

Pathological Jaundice

Pathological jaundice is a red flag that requires urgent investigation and treatment. You should be highly suspicious of pathology if:

• Jaundice appears within the first 24 hours of life.
• There is a history of jaundice in previous siblings.
• Maternal blood type suggests incompatibility (e.g., Rhesus negative mother).
• Bilirubin levels rise rapidly.

Haemolytic Jaundice and Risk Factors

Haemolysis refers to the rapid destruction of red blood cells. When this process is excessive, it leads to Haemolytic Disease of the Newborn (HDN), which can begin even before birth.

Key causes of haemolysis include:

• Blood Group Incompatibilities:
  • Rhesus (Rh) Incompatibility: Occurs when a mother is Rh-negative and the baby is Rh-positive.
  • ABO Incompatibility: Most commonly occurs when the mother is blood type O and the baby is type A or B.
• Genetic and Metabolic Conditions:
  • Spherocytosis: A condition affecting the shape of RBCs.
  • G6PD Deficiency: An inborn error of metabolism.
• Infection and Trauma:
  • Neonatal Sepsis: Including Group B Streptococcus or TORCH infections.
  • Physical Trauma: Extensive bruising or a cephalohematoma (bleeding under the scalp) from instrumental delivery.

Prolonged Jaundice and Feeding-Related Issues

If jaundice persists beyond a certain timeframe, it is classified as prolonged jaundice:

• Term infants: $>14$ days.
• Preterm infants: $>21$ days.

Clinicians must investigate metabolic conditions such as hypothyroidism, galactosaemia, or obstructive issues like biliary atresia in these cases.

Additionally, clinicians must differentiate between two types of breastfeeding-related jaundice:

1. Breastfed Jaundice: Linked to inadequate milk supply or delayed passage of meconium. The management focus is on supporting and improving feeding.
2. Breast Milk Jaundice: Occurs in well-fed babies and typically resolves between 1.5–4 months. While the exact cause is not fully understood, it is diagnosed by exclusion and does not require stopping breastfeeding.

Clinical Management and Phototherapy

When a baby's Serum Bilirubin (SBR) level exceeds specific thresholds, intervention is required. In many units, clinicians use age-specific charts (such as NICE guidelines) to plot the SBR against the baby's age in hours to determine the necessary action.

Phototherapy

Phototherapy is the primary treatment used to prevent neurotoxicity. It uses blue light (425–475 nm) to penetrate the skin and rearrange the structure of unconjugated bilirubin into water-soluble photo-isomers that can be excreted without needing conjugation in the liver.

Nursing Care for Phototherapy:

• Skin Exposure: Maximize skin exposure (baby should be in a nappy only).
• Eye Protection: Ensure eyes are covered at all times to prevent damage.
• Thermoregulation: Monitor temperature regularly to maintain a thermoneutral environment.
• Hydration: Monitor wet and dirty nappies closely; ensure the baby is feeding well.
• Safety: Do not apply lotions or oils to the skin, as this can cause burns.

Exam Tip: SBR Monitoring When phototherapy is initiated, SBR levels are typically monitored every 6–12 hours to ensure the treatment is effective and to track the trend. Phototherapy is generally discontinued when the SBR falls $50\ \mu\text{mol/L}$ below the treatment threshold, but a recheck after 24 hours is necessary to watch for a "rebound" rise.