Disease in Embryology Flashcards
when is the first screening of the foetus and what usually occurs
undertaken at 10 - 14 weeks CRL 45- 84mm
calculates due date and current gestational age
have maternal blood sample to test for T21 (downs) T18 Edwards and T13 Patau
what happens to likelihood of foetus having a cognitive disease with age of mother
increases
T21 most common then T18 then T13
what is a nuchal translucency and what’s normal
thickness of the skin at the back of the neck normal is less than 3.5 mm
may have lost of fluid which could show problems
when is the only range of times you can do a nuchal translucency
between 10 - 14 gestation
when the fetal lymphatic system is developing and peripheral resistance of the placenta is high
what happens after 14 weeks and of gestation in regards to nuchal translucency
lymphatic system is developed draining away excess fluid
any abnormalities casing fluid accumulation would be undetected
what are the causes of T21 and how common is it
non-disjunction (92%) or translocation (4%)
92% of affected pregnancies are terminated
1 in 800 people have it
what are the typical physiological consequences of T21
congenital heart disease 40% intellectual disability physical characteristics - small chin, shorter stature, sleep apnoea visual problems 80% (eg cataracts) hearing problems 90% (eg otitis media)
what is T18 and how common is it
Edwards syndrome
non-disjunction
1 - 3-5000
what is the prognosis and clinical consequences of T18
60% die in utero
lifespan 5-15 days
microcephaly, cleft lip, clenched hand or fist
what is T13 and how common is it
patois syndrome
non-disjunction or translocation
1 in 5-10,000
what is the prognosis of T13
60% die in utero 5-15 days alive severe mental disability seizures facial clefts
what is anencephaly and what is the prognosis
failure of fetal skull formation
exposure of brain contents to pressure effects
100% mortality
98% detection rate in frist trimester
what is the GIT derived from and in what week
endoderm
foregut - oesophagus - upper duodenum
midgut duodenum to 2/3 along transverses colon
hindgut 1/3 transverses colon to rectum
what happens to the midgut in 6th week gestation
midgut protrudes through umbilical cord and undergoes 270 rotation clockwise process is completed by the 12th week
what happens if herniation remains after 12 weeks
gastroschisis
omphalocele
what is gastroschisis
4 in 1000
herniation of intestinal contents most commonly bowl
may include liver and stomach
corrected through surgery after birth
what is omphalocele
1 in 4000
associated with higher rates of genetic defects
umbilical cord involvement
poorer outcome than gastroschisis
what specific conditions are screening for in the second trimester
detailed examination of the heart and brain
spina bifida
cleft
cardiac diseases
what diseases are only 50% likely to be detected
serious cardiac anomalies
transposition of great arteries
AVSD
hypo plastic left heart syndrome
which condition has the highest detection rate
anencephaly
which system develops the earliest
nervous system in week 3
but is also the last to be completed
describe the basic formation of the nervous system
develops from the neural plate folding to become the neural tube
what is the incidence of spina bifida and what causes it
1 in 500 to 1 in 2000
mostly isolated but can be genetic
failure of vertebral arches to close
which are the common regions affect by spina bifida and what’s the treatment
lumbar 75% and 15% sacral
folic acid supplementation
sodium valproate
what are the clinical consequences of spin bifida
dependant upon location leg weakness bladder and bowel incontinence sexual dysfunction risk of developmental delay
what causes cleft lip
failure of fusion in week 12
how common is cleft lip and what are midline clefts associated with
1 in 1000
60% are isolated
midline - associated with higher rates of genetic conditions
