Fetal and neonatal Flashcards
Newborn blood spot test / Guthrie card
Screening for conditions in which early treatment can improve health and prevent severe disability or death
>20 rare but potentially serious conditions
Usually at 48h of age
Conditions screened for:
- amino acid disorders (eg, phenylketonuria (PKU) and maple syrup urine disease)
- fatty acid oxidation disorders (eg, MCAD)
- congenital hypothyroidism
- cystic fibrosis
- congenital adrenal hyperplasia
- galactosaemia
- biotinidase deficiency
- severe combined immunodeficiency (SCID)
Apgar score
0-2
Activity = muscle tone
Pulse
Grimace = reflex irritability
Appearance = skin colour
Respirations
Incidence and risk factors for birth injuries
6-8 injuries per 1000 live births
Factors predisposing to birth injury:
- Prima gravida - CPD, small maternal stature, maternal pelvic anomalies - Prolonged or rapid labour - Deep transverse arrest - Oligohydramnios - Abnormal presentation - Midcavity forceps or vacuum - Very low BW or extreme prematurity - Macrosomia - Large fetal head - Fetal anomalies
Why newborns are susceptible to hypothermia
Increased body surface area to weight ratio –> augmenting heart loss
Thin skin
Little subcut fat
Rely on non-shivering thermogenesis, therefore limited capacity to generate heat
Preterm infants - have less brown fat
Incidence of neonatal jaundice
~60% of term babies, 80% of preterm babies develop jaundice in the first week of life
10% of breastfed babies are still jaundiced at 1 month
Pathophysiology of jaundice
Breakdown of RBC and Hb –> accumulation of unconjugated bilirubin
Unconjugated bilirubin binds to albumin –> transported to the liver –> converted to conjugated bilirubin
Conjugated bilirubin is water soluble –> eliminated via urine and faeces
Unconjugated bilirubin is lipid soluble
- Can cross the blood-brain barrier
Bilirubin acts as a scavenger of free radicals which are high after birth
More common in SGA and IUGR babies
- Because they frequently have a degree to polycythaemia
In young babies
- Lifespan of RBCs is shorter
- Hb concentration is higher at birth and falls rapidly during the first few days of life
- Immaturity of enzymes in the liver impairs bilirubin conjugation and excretion
Jaundice within first 24h
Always pathological
Haemolytic disease of the newborn Rhesus disease ABO incompatibility Minor blood group incompatibility G6PD deficiency Hereditary spherocytosis Congenital infections
Causes of jaundice presenting 24h to 2 weeks
Physiological Breast milk jaundice Haemolytic Infection Bruising GI obstruction Polycythaemia Metabolic disorders Liver enzyme defects
Late onset (>7-10 days) should be evaluated - Unlikely to be physiological
> 3 weeks old - prolonged jaundice - causes
Unconjugated
- Breast milk
- Hypothyroidism
Conjugated (>20%)
- Neonatal hepatitis syndrome
- Biliary atresia
Treatment of jaundice
Most do not need treatment
Phototherapy (blue-green light)
Exchange transfusion
PERSISTENT DUCTUS ARTERIOSUS (PDA)
Persistent communication between the descending thoracic aorta and the pulmonary artery
Functional closure usually occurs in the first few hours of life in infants born at term
Contributing factors to PDA in preterm infants:
- Immaturity of the smooth muscle structure
- Inability of the immature lungs to clear circulating prostaglandins
Treatment:
- Prostaglandin inhibitors (ibuprofen, indomethacin, paracetamol)
- Surgical ligation
Definition of hydrops fetalis
Abnormal fluid collections in at least 2 fetal serous cavities
- Ascites - Pleural effusions - Pericardial effusions - Skin oedema (>5mm)
May be associated with polyhydramnios and placental thickening
Pathophysiology of hydrops fetalis
Obstructed lymphatic drainage in the thoracic and abdominal cavities
Increased capillary permeability
Increased central venous pressure
Decreased osmotic pressure
Causes of hydrops
Cardiovascular abnormalities - Up to 40% of NIHF -Structural anomalies - Arrhythmias - Thoracic or Vascular abnormalities Aneuploidy - Turner syndrome - Trisomy 21, 13, 18 and 12 - Mortality rate approaching 100%
Anaemia
Infection
- Parvovirus B19
- CMV
- Toxoplasmosis
- Syphilis
Twins
Placental and umbilical cord lesions
Hx / Investigations for hydrops
Detailed fetal USS and ECHO MCA-PSV Detailed FHx (three generations) - Consanguinity PMHx - SLE (anti-Ro), Graves, meds Infection exposure
Bloods
- G&H, Antibody screen
- FBC and film screen for thalassaemia
- Kleihauer
- TORCH (parvo, CMV, toxo, syph)
Amnio
- Karyotype
- Testing for infection
Baseline BP and urine for mirror syndrome
Management of hydrops
Overall perinatal mortality rate 50-98% with NIHF
- Depends upon the aetiology, gestational age at onset and delivery, whether pleural effusions are present
Management depends on the condition, as does recurrence risk
Severe anaemia can be treated with in utero blood transfusion
Expedite delivery if appropriate gestation
Offer TOP
Consider CS
Monitor for PET, mirror syndrome
Recommend autopsy and genetics
Mirror syndrome definition
Condition of generalised maternal oedema, often with pulmonary involvement
Mirrors the oedema of the hydropic fetus and placenta
Usually a/w NIHF
Presentation and investigations of mirror syndrome
Rapid weight gain, increasing peripheral oedema, progressive SOB
May present like PET
Hct often low
Polyhydramnios
Fetal shows signs of hydrops
Overall rate of fetal death 56%
Management of mirror syndrome
Delivery to induce remission of maternal symptoms
- Prompt delivery usually required because women with severe features of PET can deteriorate rapidly
Interventions to reverse fetal hydrops
Selective feticide of hydropic twin
Vulnerable neonates for hypoglycaemia
- Preterm (limited stores, higher metabolic demands due to relatively larger brain size)
- SGA (Decreased hepatic glycogen stores)
- Babies born to diabetic mothers
- Birth asphyxia
- Hypothermia
- Sepsis
- HDFN
- Metabolic diseases
Mosaicism
arises from an error in mitosis that occurs any time after conception
Results in an individual having more than one cell line
This results in some cells having the correct amount of genetic material whereas others will have either an abnormal amount or a defective gene
Somatic mosaicism
- Effect is dependent on the percentage of affected cells and where they are
- As a general rule the phenotype will be milder than that seen with the pure condition
Autosomal dominant
- what is it
- examples
One normal allele and one mutated allele
Features can vary between members of the same family - variable expressivity
Reduced penetrance - some members appear unaffected
Can arise de novo from a new mutation
Key features:
- Condition affects every generation
- Male-to-female and female-to-male inheritance
- Affect both sexes equally
Adult polycystic kidney disease Huntington's disease Marfan's syndrome Neurofibromatosis type 1 and 2 Tuberous sclerosis Myotonic dystrophy Achondroplasia Ehlers-Danlos syndrome vWD BRCA1/2
Autosomal recessive
- what is it
- examples
Only manifest as the full phenotype when the individual is homozygous for the mutant allele
Not possible to trace autosomal recessive conditions through the family tree
Males = females
Cystic fibrosis Phenylketonuria Infantile polycystic kidney disease CAH Glycogen storage diseases Sickle cell anaemia Tay-Sachs disease Wilson's disease
X-linked dominant
- what is it
- examples
Uncommon
Manifest in both male and heterozygote female
Resembles autosomal dominant pattern of inheritance except affected males transmit the condition to all of their daughters but none of their sons
Vitamin D-resistant rickets
Rett syndrome
X-linked recessive
- what is it
- examples
Usually only manifest in males
Females can occasionally exhibit if:
- Homozygous for mutant allele
- Women have a single chromosome (e.g. Turner syndrome)
Becker's muscular dystrophy Haemophilia A and B Duchenne muscular dystrophy Fragile X syndrome Red-green colour blindness
Risk of Down syndrome based on age
also risk of recurrence
20y 1 in 1,500
30y 1 in 800
40 1 in 100
45 1 in 50 (or greater)
Majority arise from non-disjunction in meiosis (>95%)
- becomes more common with AMA
Chance of recurrence 0.5-0.75% above background risk
- Will significantly increase risk in younger, not older, women
Aetiology of Edward syndrome
Majority arise due to maternal non-disjunction in meiosis
Trisomy 18
Incidence at birth 1 in 3000
- Higher at conception, but majority miscarry
Risk increases slightly with each added year of maternal age
Features of Edward syndrome
Omphalocele
Abnormal posturing of the hands
Megacystis
Abnormal four-chamber view of the heart
IUGR
Polyhydramnios
Congenital heart disease (up to 80%)
Majority die within first year (90-95%)
Incidence of Patau syndrome
Trisomy 13
1 in 5000
Associated with increased maternal age
Only 5% survive longer than one year
Fragile X Syndrome
expansion or lengthening of the FMR1 gene on the X chromosome
Most common single gene cause of autism worldwide Causes: - Intellectual disability - Behavioural and learning challenges - Various physical characteristics
Oesophageal atresia
Suspected when no fetal stomach seen and polyhydramnios.
If there is associated fistula then stomach may be seen
2/3 will have other associated abnormalities (part of VACTERL)
Karyotyping should be offered
Duodenal Atresia
Double bubble and polyhydramnios on scan - distended stomach and duodenum
Not usually detected at anatomy but in third trimester
30% chance of T21 and high incidence of other abnormalities
What is gastroschisis
- prognosis
Free floating loops of bowel without a covering membrane
Caused by right paraumbilical defect, thought to be related to vascular compromise during embryonic development
Chromosomal abnormalities are rare
Can be associated with IUGR (20%) and IUFD (10%)
May have high AFP
Good prognosis - 90-100% survival
omphalocele
- what is it
- prognosis
Herniation of abdominal viscera into base of umbilical cord
Covered with membrane
Cord inserts in to the sac
Worse prognosis
Small omphalocele more likely to have chromosomal abnormalities
70-80% survival if isolated abnormality
Management of gastroschisis or omphalocele
Tertiary USS, exclude other anomalies Amnio - Recommended for omphalocele - Risk of chromosome abnormalities is low if isolated gastroschisis Consider discussing TOP for omphalocele
MFM & Paeds Surg input
Serial USS
- More intensive monitoring from 32 weeks for gastroschisis due to increased risk of stillbirth
Intrapartum
- Deliver in tertiary centre
- Aim for vaginal birth
- consider IOL at 37 wks for gastroschisis (due to risk of stillbirth)
- Neither an indication for CS (unless large omphalocele)
Paediatricians present
- cover bowel
- NG
- IV fluids and antibiotics
- NBM
Diagnosis of echogenic fetal bowel
Increased brightness of the fetal bowel on second trimester USS
echogenicity similar to or greater than that of adjacent fetal bone
1% at second tri
Common finding in third
- Reflects normal fetal physiology - meconium is present in the colon and can be echogenic
Causes of echogenic fetal bowel
If isolated finding, prognosis usually good
- 80-90% normal
Some types of aneuploidy - T21 Cystic fibrosis Intra-amniotic bleeding, e.g. post-amniocentesis, placental abruption CMV Toxo IUGR Primary GI pathology
Management of echogenic fetal bowel
Detailed fetal USS by MFM MFM referral History Offer CF carrier screening Maternal serologies for CMV, toxoplasmosis Fetal genetic assessment with cfDNA Offer amniocentesis for genetic testing - Echogenic bowel is present as an isolated finding in 4-25% of fetuses with aneuploidy
Pregnancy monitoring
- Monthly growth scans
- Presence of echogenic bowel (both isolated and when present with other anomalies) has been associated with IUGR and IUFD
Congenital diaphragmatic hernia
- about
Congenital defect in diaphragm causing herniation of abdominal viscera into chest
90% will be left posterior
20% risk of aneuploidy so should offer amniocentesis
28% has associated cardiac anomaly
Overall survival is 30-70%
Morbidity and mortality depends on pulmonary hypoplasia and pulmonary artery hypertension
CONGENITAL PULMONARY AIRWAY MALFORMATION (CPAM)
Majority are small and do not cause problems for the fetus
Prognosis without hydrops is 100% survival
No need for chromosome testing if isolated
MFM to assess size
Cystic Hygroma
Multi-septate fluid in soft tissues due to lymphatic drainage issue
Usually seen in neck
Associated with T21, 18 and Turners
High fetal loss rate 80-90%
NECROTISING ENTEROCOLITIS
Ulcerative inflammation of the intestinal wall
Onset typically during first several weeks after birth
High mortality in premature infants
- Up to 40%
Neonatal encephalopathy
Clinically defined syndrome of disturbed neurological function within the first week of life, manifested by difficulty in initiating and maintaining respiration, depression of tone and reflexes, subnormal level of consciousness and often seizures (PMMRC)
Hypoxic-ischaemia encephalopathy
NE + convincing evidence of ante- or intra-partum hypoxia
INTRAVENTRICULAR HAEMORRHAGE
- incidence
- aetiology
- risk factors
15-20% of neonates born <32/40
Uncommon in term infants
Predisposing factors:
- Ischaemia / reperfusion
- Fluctuations in cerebral blood flow
- Increase in the cerebral venous pressures
Risk factors
Maternal: - Infection / inflammation - Haemorrhage Lack of AN steroids External factors: - Mode of delivery - Neonatal transport
Open NTDs
80% of NTDs
Defect only covered by a membrane or, rarely, nothing at all
Myelomeningocele (spina bifida)
- varying degrees to neurological impairment, depending on the level
- Can impair cognitive function, depending on associated ventriculomegaly or associated genetic syndrome
Meningocele
Myelocele
Encephalocele
Anencephaly - Absence of brain and lack of the cranial vault
Risk factors for NTD
The risk of recurrence for isolated NTDs is approximately 2-4% with one affected sibling
- With two affected siblings, the risk is ~10%
Folate deficiency Genetic factors Syndromes - 5-7% rate of aneuploidy Amniotic bands Fever / hyperthermia in the first trimester Pre-gestational diabetes Poorly controlled DM has been associated with NTDs Obesity - 2-fold increased risk Sodium valproate Alcohol
USS features of spina bifida
U-shaped vertebrae
Cystic sac may be visualised if myelomeningocele
Fetal head findings
- Lemon sign
- Banana sign
- Hydrocephaly
May have obvious disruption of the fetal skin contours
Arnold-Chiari type II malformation = Presence of both indirect cranial findings and a spinal defect
Choroid plexus cysts
Small fluid-filled structure within the choroid of the lateral ventricles of the fetal brain
Common sonographic finding during the second trimester
- Usually small (<1cm), sonolucent, well-defined borders
Isolated choroid plexus cysts are considered a variant of normal
Fetuses with choroid plexus cysts and additional anomalies are at increased risk of chromosomal abnormalities, especially trisomy 18
Cerebral palsy
- define
Group of disorders that can involve brain and nervous system functions such as movement, learning, hearing, seeing, thinking
Permanent
Non-progressive - although clinical expression may change over time as the brain matures
CP incidence
2 cases per 1000 live births
Incidence decreases with increasing gestational age
- 25% of all cases of CP born at <34/40
Increases with decreasing birth weight
More than half of CP cases are born at term
0.1% at term
15% at 22-27 weeks
70% of CP is due to non-birth events , 10% is acquired after birth
Perinatal hypoxia or ischaemia = <10% of CP in term or near term infants
- Infants with CP caused by an acute intrapartum hypoxic-ischaemic event are more likely to have spastic quadriparesis or dyskinetic CP
Prognosis with HIE
GRade 1 = good prognosis and intact survival
GRade 2 = 5% mortality, 25% neurological morbidity
Grade 3 = BAD
- >50% die, intact survival minimal
Therapeutic hypothermia
Lower body temp to 33-34 degrees for 72h, then slowly rewarm to normothermia
Eligible if:
- > 36/40
- <6h old
- Fulfil criteria related to both their condition at birth and their neurological status
Total body cooling reduced the rate of neurodevelopmental disability in survivors
RESPIRATORY DISTRESS SYNDROME
Aka hyaline membrane disease
Almost exclusively a disease of prematurity
deficiency of surfactant –> atelectasis, ventilation perfusion mismatch and hypoventilation
Treatment
- Antenatal steroids
- Early use of CPAC
- Early administration of surfactant
- Once RDS is established, it typically runs its course over 7 days or so
TRANSIENT TACHYPNOEA OF NEWBORN (TTN)
Most common cause of respiratory distress in term infants
Caused by delayed clearance of fetal lung fluid
Self-resolving disorder
- Usually within 24-72h
Treatment = supportive
Dx of exclusion
criteria (essential and suggestive) that define an acute intrapartum hypoxic event in the context of an infant that was born at term and subsequently diagnosed with CP
ESSENTIAL
Fetal umbilical artery acidaemia
- pH <7.0 or base deficit >12 mmol/L, or both
Spastic quadriplegia or dyskinetic cerebral palsy
Early onset of severe or moderate neonatal encephalopathy in infants of >34/40
Exclusion of other identifiable aetiologies
- e.g. trauma, coagulation disorders, infectious conditions, genetic disorders
SUGGESTIVE
Apgar score of <5 at 5 minutes and 10 minutes
CTG - Sudden and sustained bradycardia
Early evidence of multi-organ involvement
Early evidence of cerebral imaging abnormalities
Sentinel hypoxic event intrapartum, e.g. cord prolapse
Magnesium sulfate for neuroprotection
Indications:
Timing
Indications:
- Gestational age <30/40
- Early preterm birth is planned or expected within 24h
- When birth is planned commence MgSO4 as close to 4h before birth as possible
4g IV bolus MgSO4 over 20 mins, followed by IV infusion of 1g per hour until the birth or for 24h
Timing
- Minimum of four hours before birth
- However administer even if likely to delivery earlier as likely will still benefit
Administer regardless of:
- Plurality (number of babies in utero)
- Reason at risk of PTB
- Parity
- Anticipated mode of birth
- Whether or not antenatal corticosteroids have been given
Do not delay urgent delivery for MgSO4 - e.g. APH, severe fetal distress
Repeat doses
- If PTB again appears imminent, and still <30/40, then can consider repeat dose at discretion of the attending health professional
the pathophysiology of RDS.
Clinical diagnosis
Respiratory distress syndrome is due to lack of surfactant
Surfactant is a detergent-like lipoprotein produced by the fetal lungs from ~22/40
Reduces the surface tension within the alveoli, allowing the alveoli to remain open when the neonate initiates respiration
From 34-36 weeks, adequate surface is usually present
Without adequate surfactant, alveoli and respiratory bronchioles easily collapse due to high surface tension atelectasis, ve ntilation perfusion mismatch and hypoventilation hypoxaemia and hypercarbia
benefits of antenatal administration of corticosteroids as per Cochrane for preterm birth
Reduced respiratory distress syndrome – 34%
Reduced need for mechanical ventilation / CPAP
Reduced perinatal death – 28%
Reduced incidence of necrotising enterocolitis
Reduced intraventricular haemorrhage – 45%
Fewer infants having systemic infection within the first 48h of life
Treatment of RDS
Initial resuscitation - Keep baby warm and dry Admit to NICU O2 therapy CPAP – continuous positive airway pressure - Helps keep the lungs / alveoli open Intubation and assisted ventilation with PEEP (positive end expiratory pressure) Administer surfactant
Consider
- BSL monitoring +/- treatment of hypoglycaemia
- Screen for infection +/- IV antibiotics
MgSO4 and cerebral palsy
Significant reduction in CP/ moderate to severe CP / substantial gross motor dysfunction
No significant effect on perinatal mortality
30% reduction in CP
NNT 1 in 63
- Or 1 in 29 if <28/40
Increase in maternal hypotension and tachycardia / not other major outcomes
