Fetal Structural Anomalies Flashcards
What is the incidence of cleft lip?
0.15% live births
What % of foetuses with cleft lip will also have cleft palate
80%
What ethnicity is most commonly affected by Cleft lip?
Asians
1: 600 Asians
1: 1100 Caucasians
What is the difference in incidence between genders with cleft lip and cleft palate?
Cleft lip: M > F
Isolated cleft palate: F > M
What % of foetuses with cleft lip have it as part of a syndrome?
30%
What % of foetuses with cleft palate have it as part of a syndrome?
50%
What is the antenatal detection rate of cleft lip vs isolated cleft palate?
Cleft lip: 20%
Isolated cleft palate: 0.3%
What are the four types in the classification system of Cleft Lip and palate?
I - Unilateral cleft lip (failure of lip / palate fusion)
II - Unilateral cleft lip and palate (failure of lip / palate fusion)
III - Bilateral cleft lip and palate (failure of lip / palate fusions)
IV - Midline cleft lip and palate (agenesis of the intermaxillary process) - highest risk of aneuploidy and associated anomalies
What are the risk factors for Cleft lip / palate?
- Genetic defects - Sonic hedgehog, TGF-alpha
- Medications - retinoids acid, valproic acid, methotrexate
- Smoking
- alcohol
- Folate deficiency
- Maternal obesity
When is cleft lip / palate surgically repaired?
Cleft lip: 2-3 months
Cleft palate: 9-18 months
What is the incidence of congenital diaphragmatic hernia?
1;4:10,000 live births
What is the incidence of left sided vs right sided vs bilateral congenital diaphragmatic hernias?
Left sided: 86%
Right sided: 13%
Bilateral: 1-2%
What is the definition of a congenital diaphragmatic hernia?
Developmental discontinuity of the diaphragm that allows abdominal content (may include stomach, bowel and liver) to herniate into the chest
What is congenital diaphragmatic hernia associated with?
Pulmonary hypoplasia and pulmonary hypertension***
- associated morbidity and mortality
Cardiac defects (28% association). Therefore, if CDH should do Fetal Echo
Polyhydramnios - oesophageal compression
Hydrops - compression of great vessels
What is the prognosis of congenital diaphragmatic hernia?
It depends on the severity of the lung hypoplasia
Severe: majority die
Moderate: 40-60% survival
Mild: 60-90% survival
What is the recommended timing and mode of delivery for congenital diaphragmatic hernia?
Deliver by 40/40
Routine obstetric indications for CS i.e. can have NVD
What is the incidence of choroid plexus cyst?
1-3% in the normal population
What are two examples of mid-trimester soft markers?
Choroid plexus cysts
Fetal echnogenic bowel
What is choroid plexus cyst a soft marker for?
Majority self-limiting and resolve on imaging by third trimester
Association with T18 with a LR = 9 - would have other anomalous findings
NOT associated with an increased risk of T21
What are the disadvantages of identifying and reporting soft markers?
Patient anxiety
Need for further counselling
Significant time and expense
Decision making regarding proceeding to further invasive testing
Risk of miscarriage / SROM / PTB from invasive testing
What percentage of foetuses with T18 will have a choroid plexus cyst?
30-50%
80% of babies with T18 will also have another structural anomaly
What is the management for a finding of a choroid plexus cyst?
Indication for detailed careful USS rather than invasive testing
If confirmed to be isolated (unilateral or bilateral)
No further discussion, investigation or follow up USS
When is it physiological to have midgut herniation?
First trimester - weeks 7-12
What is the incidence of fetal echogenic bowel in the second trimester?
1%
What is the definition of fetal echogenic bowel?
Abnormal bowel echogenicity equal to or greater than bone
What is the significance of a finding of fetal echogenic bowel?
In isolation, it is a benign condition
70% cases benign
However, it can be associated with:
- trisomy 21 (13 and 18 to lesser extent)
- Turners syndrome
- Amniotic haemorrhage (e.g. after amnio)
- Cystic fibrosis
- intrauterine CMV infection
- Meconium peritonitis
- FGR and stillbirth
What chromosomal abnormalities can be associated with fetal echogenic bowel?
Most commonly T21 (RR 5.5)
But also T13, T18 and sex chromosomes
It is an isolated finding in 9% of foetuses with aneuploidy
Tends to be multi focal
What are some non-chromosomal conditions associated with fetal echogenic bowel?
Congenital infection
- CMV is most common (tends to be focal)
- Also toxoplasmosis
Cystic Fibrosis (tends to be multifocal)
Fetal alcohol syndrome
Intra-amniotic haemorrhage
Meconium peritonitis
What are some differential diagnoses for a finding of fetal echogenic bowel?
- Intra-amniotic bleeding - swallowing of blood
- Congenital malformations of the bowel
- IUGR with mesenteric ischaemia (increased risk of perinatal morbidity and mortality)
What is the management for a pregnancy affected by isolated fetal echogenic bowel?
Detailed tertiary anatomy scan
TORCH serology
- If other anomalies noted counsel for amniocentesis and MFM referral
- May need referral to genetic counselling, cystic fibrosis carrier testing
If isolated anomaly:
- Monthly growth scans
- Due to increased risk of IUGR and intrauterine fetal death
How is fetal ventriculomegaly (cerebral) graded?
Lateral cerebral ventricular measurement
Normal <10mm
Mild 10-11.9mm
Moderate 12-14.9mm
Severe > 15mm
What is the differential diagnosis for fetal ventriculomegaly?
Normal variant (mild) Choroid plexus cysts Aneuploidy Infection Cerebral haemorrhage Infarction of brain tissue Abnormal neuroanatomy with obstruction and hydrocephalus (e.g. NTDs, Dandy walker malformation)
For a fetus diagnosed with ventriculomegaly, what percentage will be affected by aneuploidy?
5-17%
What is the pathophysiology of FNAIT?
Maternal paternal platelet type incompatibility
Leads to production of
Maternal platelet specific alloantibodies
Leads to
Fetal / neonatal thrombocytopenia
What is the incidence of FNAIT?
1:8000 pregnancies
What is the management of FNAIT?
IVIG
Shown to improve the platelet count in foetuses at risk of NAIT
What is the incidence of non-immune fetal hydrops?
1:1500-3800
What is the definition of fetal hydrops?
USS findings of at least two of the following
Ascites Pleural effusion Pericardial effusion Skin oedema Polyhydramnios Placentomegaly
What percentage of hydrops is non-immune?
90%
What are the underlying conditions that lead to non-immune hydrops?
<24/40: Aneuploidy
> 24/40: Cardiovascular abnormalities
What is the perinatal mortality rate of non-immune hydrops?
50-98%
(Huge range, but take home message is that it’s high)
Worse mortality with pleural effusions
What are the risk factors for gastroschisis?
Young maternal age
Smoking
Use of vasoactive agents
What is the definition of gastroschisis?
Full thickness anterior abdominal wall defect with bowel protruding through the defect
Usually occurs on the right side of a normally inserting umbilical cord
Defect is NOT covered by membrane (as opposed to omphalocoele)
What is the timing and mode of delivery for a pregnancy affected by gastroschisis?
Consideration of 37-38/40
Mode of delivery as per normal obstetric indications
What is the survival rate of liveborns with gastroschisis?
90-95%
What is the risk of
A) IUFD
B) SGA
With Gastroschisis
IUFD - 10%
SGA - 20%
What is the incidence of Fetal Alcohol Syndrome
1:1000 births
4% in heavy alcohol drinkers
Up to 33% in women who drink > 18units per day
What are the neonatal effects of fetal alcohol exposure?
Neonatal withdrawal
- irritability, hypotonia, tremors
Neonatal jaundice
What are the diagnostic criteria / levels for Fetal Alcohol Syndrome
- Confirmed maternal alcohol exposure
- Dysmorphic features: short palpebral fissure, flattened upper lip, Phil true and mid face
- Fetal growth restriction
- CNS involvement
- reduced cranial size at birth
- structural brain anomalies: microcephaly, corpus callosum agenesis, cerebellar hypoplasia
- Neurological signs: impaired fine motor skills, neurosensory hearing loss, poor tandem gait, poor hand-eye coordination
Other than the Diagnostic criteria for Fetal Alcohol Syndrome, what are some manifestations of the Syndrome?
Mental retardation (most common and serious)
Congenital heart disease: ASD or VSD
Renal hypoplasia, hydronephrosis, bladder diverticula
Short stature and skeletal deformities
What are the long term effects of fetal alcohol syndrome / exposure?
Increased risk of neglect and abuse
Attention and memory deficits, hyperactivity
Learning difficulties
Dose-response relationship between alcohol intake (especially first trimester) and reduced height and weight in children
Increased risk of aggressive behaviour, psychiatric disorders and substance abuse