pre-natal diagnosis and errors in gastrulation Flashcards
The study and treatment of Fetus
Prenatal paediatrics or Fetology.
Maternal Serum Screening
Referred to MSAFP plus, measures three other markers in addition to alpha-Fetoprotein
Maternal serum alpha-Fetoprotein (AFP)
a protein produced by the fetal liver whose level increases steadily during pregnancy
Human chorionic gonadotropin (hCG)
produced by the placenta, with levels peaking at about 14 weeks of gestation and dropping thereafter
Unconjugated estriol (uE3),
produced by the placenta
Inhibin-A
produced by the fetus and placenta
prenatal diagnosis is
routinely done
Maternal AFP are high when compared to normal levels at
the same week of gestation in a fetus with Neural tube defects.
Maternal hCG and inhibin-A levels are high, and estriol levels are low in
a downs syndrome fetes
these test are not for.. but are for
test for diagnosing birth defect, but only indicates the possibility of some types of birth defects. The MSAFP plus screen should always be followed by or combined with other tests because of high false-positive rate.
ultrasonography is used to
examine the fetus and could detect a variety of fetal anomalies.
also used for nuchal region translucency screening. Measures the thickness of the clear area at the back of the neck
Fetal echocardiography detects
abnormalities of the fetal heart and heart beat
Fetuses with Down syndrome and other chromosomal and major heart anomalies accumulate fluid
in the back of the neck during the first trimester of pregnancy.
Amniocentesis: Analyses
the amniotic fluid aspirated from the amniotic cavity between 14 – 16 weeks of gestation
Chorionic Villus Sampling
Analyses chorionic tissue sample
Gastrulation stage in embryonic development – beginning of the third week, is a highly sensitive stage for
teratogenic insult
Ingressing epiblastic cells whose fate has already been determined at or before the time of gastrulation may be damaged
by teratogens
High doses of alcohol during gastrulation may
kill cells of the anterior midline of the germ disc, leading to deficiency of midline in craniofacial structures and results to an abnormality called Holoprosencephaly.
holoprosencephaly
Midline cleft lip
Lack of nasal tissues
Eyes too close together
Caudal Dysplasia, also called Caudal Regression Syndrome, Caudal or Sacral Agenesis (e.g. Sirenomelia):
due to mesodermal insufficiency in the caudal-most region of the embryo, which contributes to the formation of the lower limbs, urogenital system and lumbosacral vertebrae.
Caudal Dysplasia defects
Hypoplasia and fusion of the lower limbs, vertebral abnormalities, renal agensis, imperforate anus, and abnormalies of the genital organs.
Caudal dysplasia or regression syndrome is associated with
maternal diabetes in humans
what is sirenomelia
the legs are joined together
error during gastrulation
situs inversus
a condition with transposition of the viscera in the thorax and abdomen. - error in gastrulation
Laterality sequences
Patients with these conditions do not have complete situs inversus but are predominantly bilaterally either left-sided or right-sided.
Those with left-sided bilaterality have
polysplenia.
Those with right-sided bilaterality have
asplenia or hypoplastic spleen
Patients with laterality sequences are also likely to have other
malformations, especially heart defects
Sacrococcygeal teratomas
a condition where remnants of the primitive streak persist in the sacrococcygeal region to form tumours.
Sacroccygeal tumour is the most common
gastrulation associated tumour in newborn.
These tumours commonly contain tissues derived from all the three germ layers.
