Medical problems – the neonate

The Apgar Score

 

• Assists in the recognition of an infant who is failing to make a successful transition to extrauterine life
• The original Apgar score includes an item called grimace that reports the infants reponse to a suction catheter- frequent deep suction of the oropharynx can cause bradycardia and therefore this item carries less weight than the other parameters.

 

 

Examination of the newborn

 

• Introduce yourself to mother, ask about any problems during pregnancy or any family problems e.g. deafness. Check for risk factors that predispose to neonatal sepsis such as pyrexia in labour
• Remove baby’s clothing, look at the skin
• Feel anterior fontenella for tension, palpate sutures (craniosynostosis when the suctures prematurely fuse). Feel the scalp for swelling
• Measure head circumference
• Look at face for colour – jaundice/cyanosis/pallor
• Listen to heart and estimate rate
• Count respiratory rate – normally <60 bpm              
• Palpate abdomen feeling for any masses including large bladder and kidney
• Examine eyes –particularly looking for a red reflex
• Examine ears, nose and mouth
• Examine neck including clavicles
• Examine arms, hands, legs and feet
• Remove nappy
• Check for femoral pulses
• Examine genitalia and anus
• Turn baby onto prone position and examine spine and evaluate CNS
• Examine hips

 

Danger signs

• Temperature instability
• Change in activity including refusal to feed
• Unusual skin mottling
• Abnormal heart or respiratory rate including grunt or fast breathing
• Apnoea
• Excessive jitteriness or abnormal stereotyped repetitive movement patterns
• Delayed stooling or dry nappies
• Abdominal distension, green vomit
• Odd lumps, swellings
• Lethergy, floppiness, excessive sleeping

 

Conditions which can cause a dramatic deterioration are;

• Congenital heart disease (coarctation or hypoplastic left heart syndrome)
• Inborn error of metabolism
• Necrotizing enterocolitis
• Gut volvulususing
• Intracranial haemorrhage

 

Screening for important neonatal conditions

 

Developmental dysplasia of the hip

 

• Incidence 1-2 per 1000 births
• Girls more affected than boys (5:1)
• Clinical examination using Ortolani-Barlow manoeuvres
• Not all dislocated hips are detectable using this method and some dislocate later
• Commoner in;
• Breech presentation
• Oligohydramnios
• Family history
• Females

 

 

Hypoglycaemia

 

• Healthy term, breast fed babies have lower blood sugars than formula fed infants in the first 2-3 days
• They may also have raised ketone bodies and the neonatal brain can use ketone as an alternative fuel
• Infants who are at high risk of developing symptomatic hypoglycaemia
  • Infants with intrauterine growth restriction
  • Infants of diabetic mothers
  • Preterm infants
  • Infants who have suffered fetal distress in labour
  • Infants who are ‘large for dates’- possibility of undiagnosed maternal gestational diabetes
• Other rarer causes include;                               
  • Idiopathic hyperinsulinaemic hypoglycaemia of infancy
  • Medium chain acyl coenzyme A dehydrogenase (MCAD) deficiency
  • Breast milk insufficiency
• Signs of hypoglycaemia
  • Apathy/floppiness
  • Apnoea
  • Excessive jitteriness
• These non specific signs can also be due to sepsis
• If a diagnosis of symptomatic hypoglycaemia, i.v. glucose must be given stat
• Blood samples for true glucose, insulin and ketones should be taken prior to a 0% dextrose drip being commenced

 

Phenylketonuria

 

• Screened for using Gurthrie test – dried blood spots collected onto filter paper
• Mil feeds need to be established first

 

Hypothyroidism

 

• Also screened for at 5-8 days of age
• Virtually all infants with congenital hypothyroidism who start treatment by 28 days of age achieve a normal IQ

 

Prophylaxis and prevention of disease in the well newborn

 

Prevention of vitamin K deficiency bleeding (VKDB)

 

• Occurs in three forms
  • Very early VKDB – limited to babies whose mothers have taken drugs that interfere with the manufacture of Vit-K dependant clotting factors such as antituberculous or anticonvulsant drugs. These mothers should be given extra Vit K in the last month of pregnancy and the babies should be given i.m. Vit K prophylaxis
  • Classical VKDB – presents on days 2-7 of life, with bleeding of the umbilical stump, bruising or melaena. Mortality low. Can be prevented by single does of Vit K
  • Late VKDB – occurs virtually exclusively in babies who are breastfed, unless they have liver disease. Small bleeds from the gum can be a feature. There is a risk of intracranial haemorrhage. Can be prevented with a single dose of Vit K
• Confirmation of VKDB is obtained via coagulation tests, which show a normal platelet count and prolonged thrombin and prothrombin time.
• Treatment is with i.v. Vit K and fresh frozen plasma

Group B Streptococcus

 

• Most frequent cause of severe early onset infection in the newborn
• 10% mortality and risk of deafness and cerebral palsy in survivors
• Intrapartum antibiotic prophylaxis is offered to women identified as GBS carriers – penicillin
• Also to women who rupture their membranes early

 

Jaundice and prevention of kernicterus

 

• At least 2/3 of babies develop jaundice in the first week of life but normally this is not seen on the first day of life
• Any jaundice present on the first day should be investigated and assumed to be due to haemolysis (rhesus incompatibility, glucose-6-phosphate dehydrogenase deficiency, ABO incompatibility)
• Kernicterus can result due to elevated levels of bilirubin – which can damage the basal ganglia
• Survivors can be extremely handicapped
• The level of unconjugated bilirubin must reach 425umol/L for kernicterus to occur
• Treatment is via phototherapy

 

Cardiac disease

 

• Screening begins in the antenatal period using ultrasound to view four chambers of the heart
• Heart disease may present as;
• Cyanosis
• Shock
• Heart failure – suggested by slow feeding, grunting, sweatiness and poor weight gain
• Finding of a murmur
• Absent femoral pulses

 

Care of the Ill term newborn

 

Birth trauma

 

Erb’s palsy

• Particularly associated when birth is complicated by shoulder dytocia
• Upper root palsy – C5, C6 and C7 – waiter’s tip
• In a complete palsy of upper and lower roots, the arm is flail and is accompanied by Horner’s syndrome and ptosis due to damage to the stellate ganglion next to C8 T1

 

Subgaleal (subaponeurotic) haemorrhage

• Subaponeurotic space lies between the skull and the scalp
• Babies who bleed into this space can become shocked
• Mortality rate of 20%
• Associated with delivery by ventouse
• Presents as a boggy swelling of the scalp that crosses suture lines
• Also shows as an increase in baby’s head circumference

 

Transient tachpnoea of the newborn (TTN)

• Commonist respiratory disease of the newborn occurs 4 in 1000
• Due to delayed clearance of lung fluid and is more common after a Caesarean particularly without labour
• Usually mild but may require ventilation and intubation

 

Meconium Aspiration syndrome

 

• Disease of post term infants
• Meconium aspirated before or after birth
• Co-exists with asphyxia which is associated with the development of pulmonary hypertension

 

Persistent pulmonary hypertension

 

• Baby is cyanosed because there is a failure of the usually rapid fall in pulmonary vascular resistance
• Is a complication of;
• Asphyxia
• Infection
• Pulmonary hypoplasia
• Diagnosis should be suspected in an infant who remains hypoxic on 100% oxygen with a normal CXR
• Nitric oxide may be used if warmth, artificial ventilation, oxygen or alkali therapy do not succeed in correcting acidosis

 

Hypoxic-ischaemic encephalopathy

 

• Hallmark of disease is seizures
• Other causes of neonatal seizures are;
  • Meningitis
  • Stroke
  • Hypoglycaemia
• Diagnosis should be considered if there is;
  • Fetal distress
  • Low Apgar score
  • Metabolic acidosis of cord pH
  • Seizures
  • Renal impairment
  • Alternation of CNS state

 

Management of the preterm infant

 

• Main problems of prematurity
  • Respiratory distress syndrome
  • Chronic lung disease
  • Intraventricular haemorrhage
  • Periventricular leukomalacia
  • Infection
  • Hypoglycaemia
  • Necrotizing enterocolitis
  • Patent ductus arteriosus
  • Jaundice

 

Respiratory distress syndrome

 

• Occurs in virtually all infants delivered at 26 weeks
• Due in part to insufficiency in pulmonary surfactant
• RDS is manifest by respiratory distress;
• Cyanosis
• Tachypnoea
• Grunting
• Recession
• Diagnosed by blood gas analysis
• Antenatal steroids and postnatal surfactant are beneficial
• Requires artificial ventilation

 

Necrotizing enterocolitis

 

• Affects 2-55 of preterm infants
• Those at particular risk have reversed end diastolic flow of the umbilical artery and are growth restricted
• Mortality is 10-20%

 

 

 

 

 

 

 

 

 

 

Jaundice

 

• Jaundice in the newborn is common due to red cell destruction and immature handling of bilirubin by the liver
• Leads to high levels of unconjugated bilirubin
• ‘physiological jaundice’ is defined as mild jaundice not present at birth which develops within the first few days and continues for the first week of life
• Jaundice is common but infants that are born prematurely with low birth weights are particularly likely to be jaundice.
• This may result in high levels of unconjugted bilirubin being deposited in the brain causing kernicterus
• In utero, bilirubin is transported across the placenta and removed by the maternal liver dehydrogenase
• After birth, levels of glucuronyl transferase increase exponentially to reach adult levels by 14 weeks of age
• Jaundice within the first 24 hours is likely to be pathological. Causes include;
  • Maternofetal rhesus or ABO blood group incompatibility
  • Inherited erythrocyte abnormalities associated with haemolysis such as glucose-6-phosphate deficiency or hereditary spherocytosis
  • Intrauterine infections such a syphilis, rubella or toxoplasmosis

Management

• Exchange transfusion may be required if levels a plasma bilirubin get very high
• Phototherapy with ultraviolet light can be used with lesser degrees of unconjugated hyperbilirubinaemia

 

• Conjugated hyperbilirubinaemia (always pathological) may be due to;
  • Congenital biliary atresia (Byler’s disease)
  • Biliary obstruction by pressure on the bile duct e.g. extrabiliary tumour

 

• Other causes of neonatal jaundice;
  • Neonatal hepatitis- generally presents after the first week of life. Associated with intrauterine infection such as CMV and rubella
  • Metabolic causes – galactosaemia and a1-antitrypsin deficiency

 

Initial investigations

• Haemolysis? – FBC, blood group
• Hepatitis? – Liver function (ALP, ALT, albumin, total bilirubin)
• Obstructive jaundice? – conjugated and unconjugated bilirubin
• Other conditions? TSH, T4, urine dipstick

 

Secondary investigations

• Additional liver function tests –clotting, AST, gamma GT
• Unconjugated hyperbilirubinaemia?
  • FBC – persistent haemolysis
  • G6PD in black ,Mediterranean and Asian infants
  • Blood film – spherocytosis/elliptocytosis
• Conjugated hyperbilirubinaemia
  • UTI?
  • TORCH – toxoplasmosis, rubella, CMV, herpes simplex
  • Hepatitis screen – A, B and C

 

Transient familial neonatal hyperbilirubinaemia

 

• A familial tendency to develop jaundice
• Infants can develop kernicterus even after being born at full term
• There is no haemoloysis and jaundice occurs earlier than it does with breast milk jaundice
• Transient, good outcome

 

Breast-milk jaundice

 

• Kernicterus not a complication
• Appears to be due to a factor in the breast milk that is not found in the maternal serum

 

 

 

Inborn errors of metabolism

 

• A group of disorders characterised by defects in metabolism
• Generally due to single gene defects which prevent certain metabolic substrates being broken down into their products
• Mostly problems arise because there are a build up of toxic substrates or there is an inability to synthesis essential compounds
• They are generally categorised as;
  • Disorders of carbohydrate metabolism
  • Disorders of amino acid metabolism
  • Disorders of organic acid metabolism e.g. organic aciduria
  • Disorders of lysosomal function
• Presently we only screen for phenylketonuria and congenital hypothyroidism

 

 

• Organic acidurias are a group of inborn errors of metabolism
• Typically results in inability to properly breakdown certain amino acids
• They generally affect one organ system and vary in the degree of severity
• Some affect the CNS causing developmental retardation
• Some affect growth
• Some may cause episodic illness such as vomiting or metabolic acidosis
• May be precipitated by periods of fasting, viral illness or other catabolic events
• Diagnosis is via an abnormal pattern of organic acid in the urine via mass spectrometry
• Treatment may be via avoiding fasting, giving extra carbohydrates during illness or i.v. fluid and dextrose to reverse catabolism

 

Screening tests for metabolic illness in the newborn