Teratology Flashcards
What is the incidence of structural abnormalities
Major
-3% live births
Minor
- 15% live births
- likelihood of having major abnormality increases with number of minor
1 minor = 3%
2 minor =10%
3 minor = 20%
Account for 25% of infant deaths
What are the causes of congenital malformation
Unknown (40%) Genetic (28%) Multifactorial (25%) Twnning (1%) Environmental (4%)
Which is the highest risk period for congenital malformation and why?
increasing rapidly from 0 to 5 weeks
Falls rapidly from 5 to 8 weeks
Slow decline from 8+
Most body systems develop in the first 10 wees
What is the definition of a malformation
Disturbed formation of a structure resulting in complete or partial absence or abnormal configuration
ASD, VDS, phocomelia
What is the definition of a disruptions
Structural alteration, due to a destructive process, of a structure that has already formed
Amniotic band syndrome
What is the definition of a deformations
Abnormal moulding of part of the foetus by mechanical forces
Clubfoot
What is the definition of a syndrome
Group of anomalies that occur together with a common cause
Down’s, Foetal alcohol
What is the definition of an association
Non random occurrence of two or more anomalies together but cause unkown
VACTERL
What are the principles of teratology
The factors that affect how easily a given agent can cause a congenital defect
What are the principles of teratology
Genetics
-of conceptus and mother
Timing
-of exposure
Dose and duration
-of exposure
Mechanism
- of action of the teratogen e.g. by inactivating genes or inducing enzymes
Manifestation
-of abnormality that has been caused
What are the TORCH infections
Toxoplasmosis
- hydrocephalus
- cerebral calcifications
Other
- syphilis, varicella,
Rubella
- deafness
- cataracts
- heart defects
Cytomegalovirus
- foetal death
- micocephaly
- intellectual impairment
Herpes simplex
- microcephaly
- micropthalmia
How does radiation act as a teratogen
Limb defects
Causes:
-healthcare: Xray-fluoroscopy, barium studies, plain film
CT
Extra careful in:
- young and child bearing age
- Pelvis
What are some teratogenic drugs
Thalidomide ACEi Warfarin SSRI Antiepileptcis
What does defects are caused by warfarin
skeletal abnoramlities
What does defects are caused by Antipyschotics and antianxiolytics
- limb/skeletal malformations
- CNS defects
- Cleft palate
- CHD
What does defects are caused by isoretinoin
- heart defects
- cleft palate
What does defects are caused by ACEi
-growth retardation, -foetal death
What does defects are caused by anti-epileptics
NTDs
Heart and limb malformations
What are some consequences of smoking
IUGR
Premature birth
Increased risk of oro-facial clefts
What are some consequences of alcohol in pregnancy
`Risk proportional to exposure
Accidental drinking in early pregnancy with subsequent abstinence unlikely to impact baby
Alcohol diffuse through placenta, enters foetal compartment, accumulates in amniotic fluid
- oxidative stress
- placental vasoconstriction
- mitochondrial damage
Foetal alcohol
What are the symptoms of foetal alcohol
Epicantal fold
Short palpebral fissure
Thin upper lip
Smooth filtrum
Flat nasal bridge and midface
Growth restriction
Intellectual disability
Behavioural problems
Heart defects
Brain/CNS defects
How can horomones be teratogenic
Androgenic agents
-masculinisation of female genitalia
Cortisone
-oro-facial clefts
How can maternal illness be teratogenic
Diabetes
- NTDs & CHD
Obesity
- CHD
- Ompalocoele
