Should a day
come in 22 nd century where routine amniocentesis followed by preservation of
“Amniotic Stem Cells” for later use if warranted??
Q 1. What is meant by prenatal
foetal abnormality diagnosis ? Ans: Prenatal
diagnosis is the branch of medicine and obstetrics in particular and
implies those studies and some special techniques
that reveal the normality or the presence of disease in foetus of
various kinds including chromosomal /
genetic diseases . All such special techniques
of prenatal diagnosis are performed during pregnancy and may be direct methods ( invasive) or indirect methods (maternal serum markers).
Q.3:
When fetal genetic conditions are warranted? Ans: .Exclusion of fetal genetic abnormalities ( Prenatal
diagnosis) is a standard part of modern
obstetric care and there are many indications of such foetal chromosomal analysis
. Such are 1) family history of genetic diseases 2) Recurrent foetal loss of uncertain
origin 3) Past history of unexplained Rec miscarriages/ abortions and most importantly
abnormal serum markers and abnormal NT
scan parameters .
Q.4: What is the drawbacks of direct tets like
CVS amniocentesis?. Ans:
Unfortunately, many of the current methods rely on invasive methods (CVS/amniocentesis) and are
associated with an inherent risk of fetal loss. Consequently there has
been a long term advantage for need of NIPD(Non Invasive prenatal diagnois) .
What is cffdna test in maternal blood?
Recently an extremely sensitive test for the most common aneuploidies and in particular. Down syndrome has been
proposed to be performed on
maternal blood. This test is based on the count of fragments of specific chromosomes in maternal blood
although not belonging to
diagnostic tests but to probabilistic
ones this test is absolutely the most
accurate so far available with
values around 99.99% sensitivity and 0.2% false
positives . Also ultrasound
in th second trimester of pregnancy that can
detect any malformation or fetal
abnormality(TIFA ) and fetal echocardiography which
analyzes sonographically the fetal heart . Al these tests carried out on foetus collectively not only anatomically but also from the dynamic functional point of view may
be considered methods of prenatal diagnosis. This
technique however cannot identify
genetic diseases but there are some markers either in serum or in foetal morphology
which may raise an suspicion of some chromosomal / genetic diseases of
foetus(genetic sonogram).
Role
of Molecular genetics ?? Ans:- The phenomenal
developments in molecular genetics and
technological refinements which have occurred over the past
decades have
revolutionized the area of
prenatal genetics , state of the art care
commences with comprehensive preconceptional counseling .WE cannot perform such tests without the
consent of couple as we practice in HIV blood tests (one may opt out or opt in) .
Conclusion:- Prenatal diagnosis is now feasible from the moment of conception onward
. Imaging techniques ( NT Scan
parameters & Anomaly Scan ) have
allowed non invasive diagnosis to a
great extent but not confirmatory of chromosomal / genetic disorders though
such procedures NT scan and Anomaly scan cab exclude anatomical abnormalities
and syndromes. However such may fatal or compatible with life and may of genetic disorders or nongenetic
etiology. NIPT on the contrary (minimally invasive techniques )concentrate on sampling maternal
blood for fetal cells or markers of feto placental metabolism.
It
is true that invasive techniques
have been rapidly expanding and becoming safer comprising
of A) chorionic villus
sampling B) early amniocentesis or
C) midtrimester amniocentesis as well as very early fetoscopy
and umbilical vein sampling .
Advances in
prenatal diagnostic techniques
allow for earlier more rapid and more effective detection of congenital disorders
Recent advances in non invasive detection
methods such as fetal
ultrasound and the isolation of fetal cells in the maternal
circulation allow the intrauterine diagnosis
of congenital infections and chromosomal
and Mendelian disorders as well
as hematologic disorders.
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