Neonatal Emergencies
Question 28 of 300
A 3 day old boy is brought to the Emergency Department by his mother. She has noticed that he has become jaundiced. He is otherwise well and feeding well. What is the most common cause of jaundice in the neonate?
Answer:
Although each of these may be a cause of hyperbilirubinemia in the newborn, the most common cause of jaundice is physiological jaundice of the newborn. Physiological jaundice can occur in breastfed and formula-fed babies and results from increased bilirubin load, decreased uptake by the liver, decreased conjugation in the liver, and decreased excretion into bile. Physiological jaundice usually appears at 2 days of age, peaks on days 3 to 5, and then decreases, usually by around day 10.Neonatal Jaundice
Neonatal Emergencies
Last Updated: 12th February 2021
Approximately 60% of term and 80% of preterm babies develop jaundice in the first week of life, and about 10% of breastfed babies are still jaundiced at 1 month.
Jaundice is a yellow colouration of the skin and sclerae caused by the accumulation of bilirubin, a bile pigment which is mainly produced from the breakdown of red blood cells. Bilirubin levels are higher in neonates than in adults because newborn babies have a higher concentration of red blood cells, which also have a shorter lifespan. Red blood cell breakdown creates unconjugated bilirubin which circulates mostly bound to albumin. Unconjugated bilirubin is metabolised by the liver to produce conjugated bilirubin which is excreted in the stool.
Causes
- Physiological jaundice
- Physiological jaundice can occur in breastfed and formula-fed babies and results from increased bilirubin load, decreased uptake by the liver, decreased conjugation in the liver, and decreased excretion into bile. Physiological jaundice usually appears at 2 days of age, peaks on days 3 to 5, and then decreases, usually by around day 10.
- Breastmilk jaundice
- Breastmilk jaundice is a prolongation of physiological jaundice in breastfed babies; it is common in healthy, term, breastfed babies. Weight gain, stools, urine output, and examination are normal and the neonate is well. Breastmilk jaundice usually presents within the first week of life (day 2-4) and peaks on day 7 to 15. In some cases, it can persist for up to 12 weeks. It is important to note that prolonged jaundice may also be caused by serious underlying disease.
- Pathological neonatal jaundice can be caused by a number of factors, including:
- Blood group incompatibility (most commonly Rhesus or ABO incompatibility)
- Other causes of haemolysis
- Sepsis
- Bruising
- Metabolic disorders (for example galactosaemia, hereditary fructose intolerance, alpha-1 antitrypsin deficiency, hypothyroidism)
- Gilbert's syndrome and Crigler-Najjar syndrome — rare causes of neonatal jaundice that are caused by liver enzyme problems
- Glucose-6-phosphate-dehydrogenase deficiency — a familial enzyme deficiency more common in Mediterranean, Middle Eastern, South East Asian, and African populations
- Congenital obstruction and malformations of the biliary system, such as biliary atresia — cause obstructive jaundice with conjugated hyperbilirubinaemia
Risk factors
Babies more likely to develop significant hyperbilirubinaemia include those with the following factors:
- Gestational age under 38 weeks
- A previous sibling with neonatal jaundice requiring phototherapy
- Visible jaundice in the first 24 hours of life
- A mother's intention to breastfeed exclusively
- Visible bruising
- Cephalhaematoma
- Male sex
- Maternal age older than 25 years of age
- Maternal diabetes mellitus
- Asian, European, or native American ethnicity
- Dehydration
Complications
- Neurological complications in neonates with jaundice are rare.
- Unconjugated bilirubin is able to penetrate the blood-brain barrier, a membrane between the brain and the blood. The level at which bilirubin is likely to cause neurotoxicity is variable and may be affected by a number of factors, such as prematurity, postnatal age, the rate of serum bilirubin increase, and co-existing illnesses (particularly if associated with sepsis, acidosis, and hypoxia).
- A number of terms are used to describe the neurological consequences of hyperbilirubinaemia:
- Acute bilirubin encephalopathy — the clinical syndrome which occurs when there is severe hyperbilirubinaemia. Features include lethargy, irritability, poor suck, abnormal muscle tone and posture (opisthotonus), high-pitched cry, apnoea, and eventually seizures and coma.
- Chronic bilirubin encephalopathy — the clinical features resulting from acute encephalopathy. These include athetoid cerebral palsy, seizures, developmental delay, learning difficulties, vision and hearing problems, and dental dysplasia.
- Kernicterus — a term used to describe the clinical features of acute or chronic bilirubin encephalopathy and the pathological findings of deep yellow staining in the brain. Babies with hyperbilirubinaemia are at increased risk of developing kernicterus if they have any of the following: a serum bilirubin level greater than 340 micromol/litre in babies with a gestational age of 37 weeks or more, a rapidly rising bilirubin level of greater than 8.5 micromol/litre per hour or clinical features of acute bilirubin encephalopathy.
Investigations
- Serum bilirubin levels should be measured in order to confirm the diagnosis and guide treatment.
- Neonates with significant jaundice should have investigations to determine any underlying causes, which may include:
- Full blood count and blood film — a high or low white blood cell count or thrombocytopaenia can suggest sepsis; a haematocrit of less than 45% can suggest haemolytic anaemia; an increased reticulocyte count suggests haemolysis; a peripheral blood film may show evidence of haemolysis.
- Blood group (mother and baby) — ABO incompatibility is suggested by a mother with blood group O and a baby with group A or B. Rhesus incompatibility is suggested if the mother is Rhesus negative and her baby is Rhesus positive.
- DAT (Coombs' test) — used to diagnose ABO or Rhesus isoimmunisation.
- Liver function tests — in congenital infection, liver enzymes may be increased.
- Blood glucose-6-phosphate-dehydrogenase (G6PD) levels, taking into account ethnic origin — to check for G6PD deficiency.
- Microbiological cultures of blood, urine, and/or cerebrospinal fluid — to look for a source of sepsis if infection is suspected.
Management
Refer urgently to a neonatal or paediatric unit if:
- Jaundice first appears at less than 24 hours of age
- Jaundice first appears at more than 7 days of age
- The neonate is unwell (for example, lethargy, fever, vomiting, irritability)
- Gestational age of less than 35 weeks
- Prolonged jaundice is suspected — that is a gestational age of less than 37 weeks with more than 21 days of jaundice; or a gestational age of 37 weeks or more with more than 14 days of jaundice
- Poor feeding and/or concerns about weight, particularly in breastfed infants
- Pale stools and dark urine
The choice of specialist treatment will depend on a number of factors, including the underlying cause of the jaundice. Bilirubin levels should be interpreted according to the baby's postnatal age in hours and hyperbilirubinaemia managed according to the threshold table and the treatment threshold graphs.
Treatment options include:
- No treatment — this may be appropriate for well neonates with physiological or breastmilk jaundice and a bilirubin level below the treatment threshold.
- Treatment of any underlying illness (such as infection).
- Phototherapy — absorption of light through the skin converts unconjugated bilirubin into products that are more easily excretable in the stool and urine.
- Intravenous immunoglobulin (IVIG) - indicated as an adjunct to phototherapy in some cases of rhesus haemolytic disease or ABO haemolytic disease.
- Exchange transfusion — indicated if the baby has signs of bilirubin encephalopathy and considered if the risk of kernicterus is high or jaundice is not responding to phototherapy.
- Early surgical treatment — required for conditions such as biliary atresia.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
