Congenital defects and their scientific basis Flashcards
Congenital =
Present at birth
What % of liveborn infants are affected by congenital defects?
3%
Malformation =
Primary disturbance in embryogenesis
Disruption =
Secondary disturbance due to early influence of external factors
Deformation =
Late changes in a previously normal structure. Due to prolonged mechanical distress.
Causes of neonatal death:
- Preterm birth complications
- Intrapartum complications (e.g. asphyxia)
- Sepsis
- Congenital abnormalities
Congenital defects occur most commonly in
Low/middle income countries
What does CD being common in low/middle income countries mean?
May be preventable (e.g. food shortages, endemics)
Single gene defects and chromosomal defects are examples of what kind of abnormalities?
Primary/malformation
Teratogens cause what kind of abnormalities?
Secondary/disruptions
Ex of teratogens:
- Congenital infections
- Drugs and enviornmental pollutants
- Maternal metabolic disease
- Radiaition exposure
TORCH infections
Toxoplasmosis Rubella Cytomegalovirus Herpes Syphillis
Maternal metabolic diseases in pregnancy:
Diabetes, thyroid problems
Malformations at 2-4 weeks may cause
Polytrophic field defects
What is a polytrophic field defect?
Occurs early in trilaminar disc, can lead to scattered pattern of abnormalities
Ex of polytrophic field defects:
Di George
VACTERL (3+ of these)
DiGeorge =
Affects heart and thymus
VACTERL
Vertebral abnormalities Anal atresia Cardiac abnormalities Trachea-esophageal distula Renal anomalies Limb anomalies
Malformations at weeks 4-8
Monotrophic field defects
Ex of monotrophic field defects =
Cleft lip/palate
Ex of monotrophic field defect >9 weeks
Organ: spina bifida, cardiac
Ex of disruption:
Amniotic bands
Poland anomaly
Poland anomaly can be caused by …
Maternal cocaine use
Poland anomaly =
Interruption of subclavian artery vascular supply. Development of pectoral muscles effected.
Ex of deformation
Clubbing of feet
Developmental displacement of hip
When is developmental displacement of the hip seen?
breach position
Name 2 common sequences
Potter
Pierre-Robin
Potter’s sequence is triggered by
Renal agenesis which causes oligohydramnosis
Potter’s sequence causes:
Pulmonary hypoplasia
Squashed baby
Limb abnormalities, clubbed feet
Growth restriction
Oligohydranosis =
Reduced amniotic fluid
Pierre-Robin sequence is characterised by:
Abnormally small mandible
Glossoptosis, backwards displacement of tongue
U-shaped cleft palate
Micrognathia
Small mandible
A set of signs and symptoms that are correlated with each other =
Syndromes
Syndromes can be due to:
genetics (single gene, chromosomal)
teratogens
What is seen in congenital rubella?
- Jaundice
- Hepato-splenomegaly
- Calcification in brain and behind eyes
What is seen in foetal alcohol syndrome?
- IUGR
- Learning difficulties
- Dysmorphic features
- Behaviour problems
2 ways to reduce incidence =
Prevention
Screening
Ex of prevention methods:
Oral folate
Iodine and folic acid fortification
Rubella immunisation
Avoid known risk factors: radiation, alcohol, meds, foods
Pre-conception screening =
Genetic counselling
Antenatal screening in T1
Triple test
Nuchal fold
Triple test looks for
Downs syndrome
Edwards syndrome
Pataus syndrome
Nuchal fold test can look for
Downs syndrome
DiGeorge
T2 scans:
Anomaly scans
Screening after birth:
Newborn screening examination
