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Neonatal Cyanosis: Differential Diagnoses

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Overview

Central cyanosis

Central cyanosis describes this appearance throughout the body and when it includes the tongue and mucous membranes. This is due to inadequate oxygenation of the blood due to problems with ventilation, shunting of blood in the heart, impaired gas exchange, or inadequate transport of oxygen by haemoglobin in the blood.

Acrocyanosis

Acrocyanosis (a form of peripheral cyanosis) describes a blue-tinge of the distal extremities (e.g. the fingers and toes) which is common in the first 24 hours of life. This is usually benign if present immediately after birth (as other causes such as infection tend to develop later) and may last up to 48 hours. It is due to initial peripheral vasoconstriction in response to stimuli such as a cold environment after delivery.

Causes

Cardiac causes

  • Tetralogy of Fallot (TOF)
  • Transposition of the great arteries (TGA)
  • Ebstein’s anomaly
  • Eisenmenger syndrome

Pulmonary causes

Other causes

Differential Diagnoses: Cardiac

Transposition of the great arteries

  • Cyanosis within the first week of life (sometimes within the first day)
  • Tachypnoea, tachycardia, poor feeding, irritability
  • A single heart sound is present, a loud S2
  • Prominent right ventricular heaves may be felt

Tetralogy of Fallot

  • Severity depends on the degree of right ventricular outflow tract obstruction
  • Hypercyanotic ‘tet spells’ – episodic cyanosis, shortness of breath, irritability, reduced consciousness – often triggered by pain, dehydration, or anxiety
  • Ejection systolic murmur – due to pulmonary stenosis
  • Prominent right ventricular heaves may be felt
  • Some investigations include:
    • ECG:
      • May show right ventricular hypertrophy
    • Chest X-ray:
      • May show ‘egg on string’ or ‘egg on side’ appearance of the heart
    • Echocardiography:
      • Diagnostic

Ebstein’s anomaly

  • Associated with maternal lithium use during pregnancy
  • Cyanosis, shortness of breath, tachypnoea, poor feeding
  • Features of heart failure may be present – peripheral oedema, hepatomegaly, ascites
  • Widely split S1 and S2 heart sounds
  • Tricuspid regurgitation: a pansystolic murmur is heard at the lower left sternal edge
  • Some investigations include:
    • ECG:
    • Chest X-ray:
      • May show cardiomegaly, large right atrium
    • Echocardiography:
      • Diagnostic

Differential Diagnoses: Respiratory

Transient tachypnoea of the newborn (TTN)

  • Self-limiting and benign, symptoms occur within minutes after birth and resolve after around 48 hours
  • TTN is a diagnosis of exclusion, as infant respiratory distress syndrome can present similarly
  • More common in neonates born by caesarean section
  • Features of respiratory distress: tachypnoea, nasal flaring, grunting, chest recessions, crackles on auscultation, cyanosis
  • Some investigations may show:
    • Chest X-ray:
      • Hyperinflation of the lungs and fluid in lung fissures, no other abnormalities

Infant respiratory distress syndrome (IRDS)

  • Due to surfactant deficiency, more common in preterm infants, infants with low birth weight, maternal diabetes
  • Features are seen within seconds-minutes after birth: tachypnoea, nasal flaring, grunting, chest recessions, crackles on auscultation, cyanosis
  • As time goes on, IRDS worsens with fatigue, hypoxia, and apnoea
  • Some investigations include:
    • Chest X-ray:
      • May show a ground-glass appearance
    • Blood gases:
      • May show hypoxia and hypercapnia

Aspiration (such as meconium aspiration syndrome)

  • More common in neonates born after 42 weeks’ gestation maternal hypertension/pre-eclampsia, maternal smoking, maternal cocaine use
  • Aspiration can be due to meconium aspiration syndrome (MAS), amniotic fluid, blood, or breastmilk
  • In MAS, there may be meconium-stained amniotic fluid and respiratory distress in the absence of another condition
  • Features of respiratory distress: tachypnoea, nasal flaring, grunting, chest recessions, crackles on auscultation, cyanosis
  • Features of post-maturity: vernix, peeling skin, long fingernails
  • Some investigations include:
    • Chest X-ray:
      • May show hyperinflation and diaphragm flattening, patchy infiltrates, coarse streaking of lungs
    • Blood gases:
      • May show hypoxia and hypercapnia

Pneumothorax

  • May be spontaneous or can occur post-mechanical ventilation
  • Risk is higher if causes of respiratory distress are present
  • Features of respiratory distress: tachypnoea, nasal flaring, grunting, chest recessions, crackles on auscultation, cyanosis
  • Absent/reduced lung sounds unilaterally may be present
  • Some investigations include:
    • Chest X-ray:
      • Absent lung markings

Upper airway obstruction

  • Stridor present, neurological problems may be present (e.g. laryngeal nerve paralysis), there may be weak cry
  • Cyanosis may not be present initially but emerge as time goes on
  • Problems feeding, regurgitation, choking
  • Some investigations include:
    • Chest X-ray:
      • May identify foreign body
    • Other investigations may include laryngoscopy or bronchoscopy

Differential Diagnoses: Other

Perinatal asphyxia

  • Maternal risk factors – maternal hypoxia (e.g. respiratory failure/infection), maternal shock, placental abruption
  • Intrapartum causes – prolonged labour, shoulder dystocia, umbilical cord compression/knots, uterine rupture, infection, haemorrhage
  • Reduce Apgar score, the neonate may require resuscitation
  • Apnoea, seizures, pupillary abnormalities, reflex abnormalities, and altered consciousness may be present
  • Some investigations include:
    • CT brain:
      • May show cerebral oedema
    • Electroencephalogram:
      • May show seizure activity

Hypoglycaemia

  • More common in preterm infants, small/large for gestational age, maternal diabetes mellitus, maternal hypertension
  • Features of hypoglycaemia include:
    • Adrenergic – jittery, irritability, tachycardia, pallor
    • Neuroglycopenic – lethargy, weak/high-pitched crying, drowsy, apnoea, hypotonia, seizures
    • Hypothermia
  • Some investigations include :
    • Blood glucose:
      • Shows hypoglycaemia

Neonatal sepsis

  • There may be a history of premature rupture of membranes, chorioamnionitis, intrapartum maternal fever, preterm/low birth weight neonate, previous maternal Group B Streptococcus colonisation or a previous infection in a previous child
  • Features are non-specific:
    • Respiratory features (most common): tachypnoea, grunting, nasal flaring, chest recessions
    • Red flags, seizures, apnoea, shock (hypotension, tachycardia, reduced urine output, prolonged capillary refill time, cyanosis, ashen/mottled skin)
    • Poor feeding, vomiting, hypoglycaemia
    • Altered behaviour/responsiveness – lethargy, drowsiness, apathy
  • Some investigations include:
    • Blood cultures – ideally before antibiotics are given but do not delay treatment:
      • If possible, two cultures should be taken to distinguish from contamination
    • Full blood count (FBC):
      • May show neutrophilia or neutropenia
    • C-reactive protein (CRP):
      • Not for diagnosis but measured as a baseline and used to monitor the response to treatment
      • Usually elevated
    • Blood gases:
      • May show metabolic acidosis which suggests severe sepsis, especially if there is a large base deficit (10 mmol/L or greater)
    • Lumbar puncture – if safe to do so and neonatal sepsis is strongly suspected or meningitis is possible:
      • Many places perform a lumbar puncture as part of a septic screen in all babies under 28 days of age
      • Severe sepsis is a contraindication to lumbar punctures, however, they can be performed after the patient is stabilised

Congenital diaphragmatic hernia

  • Most cases diagnosed prenatally via ultrasound scan
  • Features at birth include:
    • Respiratory distress – tachypnoea, cyanosis, tachycardia
    • Chest wall asymmetry
    • Abnormal chest sounds – bowel sounds over chest wall, absent breath sounds on one side (usually the left)
  • Some investigations include:
    • Chest X-ray:
      • May show intestines in the thoracic cavity
    • Echocardiogram:
      • Shows herniation of abdominal contents into the thoracic cavity
    • Arterial blood gases:
      • May show hypoxia and hypercapnia

Polycythaemia

  • More common in maternal diabetes requiring insulin, small for gestational age, twin-to-twin transfusion, maternal hypertension
  • Features of respiratory distress: tachypnoea, nasal flaring, grunting, chest recessions, crackles on auscultation, cyanosis
  • Infants may appear ruddy and plethoric
  • Infants may appear cyanotic but have normal arterial blood gases
  • Some investigations include:
    • Full blood count (FBC):
      • Increased haemoglobin
    • Chest X-ray:
      • Screens for other conditions, may show features consistent with transient tachypnoea of the newborn (e.g. fluid in the lung fissures, lung hyper-expansion)

Initial Management Steps

Overview

If a cyanotic congenital heart disease is suspected management may involve the use of prostaglandin E1 (e.g. alprostadil) alongside supportive treatment:The ductus arteriosus is kept open which can allow shunting of blood to buy time until a definite diagnosis is made and surgery is performed.

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