Cordocentesis and fetoscopy are prenatal diagnostic tests. Cordocentesis involves inserting a needle into the umbilical cord under ultrasound guidance to retrieve a small sample of fetal blood, in order to test for fetal abnormalities. Fetoscopy uses an endoscope inserted through the abdomen and uterus to access the fetus and amniotic cavity. The triple test analyzes maternal serum levels of alpha-fetoprotein, estriol, and hCG to assess risk of fetal abnormalities. Pre-implantation genetic diagnosis involves biopsy of polar bodies, blastomeres, or trophectoderm cells to test embryos for genetic disorders before implantation. Karyotyping and gene mapping are techniques used to identify chromosomal abnormalities
3. Cordocentesis, also sometimes called
Percutaneous Umbilical Cord Blood
Sampling (PUBS), is a diagnostic
test that examines blood from the
fetus to detect fetal abnormalities.
Cordocentesis is performed
after 17 weeks of pregnancy.
4. An advanced imaging ultrasound
determines the location where the
umbilical cord inserts into the
placenta. The ultrasound guides a
thin needle through the abdomen
and uterine walls to the umbilical
cord. The needle is inserted into
the umbilical cord to retrieve a
small sample of fetal blood.
6. PURPOSE
To Help In Diagnosis Of:
Malformations of the fetus.
Fetal infection (i.e. toxoplasmosis or
rubella)
Fetal platelet count in the maternal
circulation.
Fetal anemia.
Isoimmunisation.
7. COMPLICATION
Blood loss from the puncture site
Infection
Drop in fetal heart rate
Premature rupture of membranes
Fever
Chills
Leaking of amniotic fluid
8. Fetoscopy is an endoscopic
procedure during pregnancy to allow
access to the fetus, the amniotic
cavity, the umbilical cord, and the
fetal side of the placenta.
It is done during & after 18
weeks of pregnancy
9. PROCEDURE
A small (3–4 mm) incision is made in the
abdomen, and an fetoscope is inserted
through the abdominal wall and uterus into
the amniotic cavity. Fetoscopy allows
medical interventions such as a biopsy or a
laser occlusion of abnormal blood vessels.
11. PURPOSE
Evaluate the fetus for birth defects, such
as spina bifida as well as other defects
which can only be confirmed by a
Fetoscopy.
To collect samples of blood from the
umbilical cord, e.g. hemophilia or sickle
cell anemia.
Collect samples of skin tissue from the
fetus. The tissue can be tested for some
12. COMPLICATIONS
Miscarriage, as high as 12%.
Excessive bleeding, infection, or
excessive leakage of the amniotic
fluid.
Preterm rupture of the membranes.
Mixing mother’s blood with baby’s
blood.
13. Also called as “Triple screen“, the “Kettering
test”, the “Bart's test” or "Multiples of the
Median (MoM)“.
3 tests:
• Maternal Serum Alpha-fetoprotein
(MSAFP)
• Unconjugated estriol
• Human chorionic gonadotropin (hCG)
14. The triple test is an investigation
performed during pregnancy in the
second trimester (15-18 weeks) to classify
a patient as either high-risk or low-risk for
chromosomal abnormalities (and neural
tube defects).
The triple screen test involves drawing
blood from the mother. The blood sample
is then sent to the laboratory for testing.
AFP is is produced in the yolk sac and fetal
liver.
15. INCREASED MSAFP UE3 hCG
RISK OF
DOWN’S ↓ ↓ ↑
SYNDROME
TRISOMY 18 ↓ ↓ ↓
NTD’s ↑ NORMAL NORMAL
MOLAR ↓ ↓ ++↑
PREGNANCY
MULTIPLE ↑ NORMAL ↑
GESTATION
16. PRE-IMPLANTATION GENETIC
DIAGNOSIS / EMBRYO SCREENING
As PGD can be performed on cells from
different developmental stages, the biopsy
procedures vary accordingly. Theoretically, the
biopsy can be performed at all preimplantation
stages, but only three have been suggested: on
unfertilised and fertilised oocytes (for polar
bodies, PBs), on day three cleavage-stage
embryos (for blastomeres) and on blastocysts
(for trophectoderm cells).
17. ADVANTAGES
Helps prevents birth of children with
chromosomal anomalies and single
gene disorders.
Eugenics.
18. POLAR BODY BIOPSY
The first and second polar body of the
oocyte are extruded at the time of the
conclusion of the meiotic
division, normally the first polar body is
noted after ovulation, and the second
polar body after fertilization.
19. By analyzing polar bodies it is
possible to study maternal genetic
makeup.
The disadvantage of polar body
biopsy is that, it detect paternally
derived chromosomal disorders &
single gene disorders (autosomal
dominant disorders, autosomal
recessive disorders and sex-linked
disorders).
20. BLASTOMERE BIOPSY
It is also called Embryo biopsy, Cleavage-
stage biopsy.
Cleavage-stage biopsy is generally performed
the morning of day three post-
fertilization, when normally developing
embryos reach the eight-cell stage.
A hole is made in the zona pellucida and one
or two blastomeres containing a nucleus are
gently aspirated or extruded through the
opening.
22. Karyotyping
It is the procedure by which the chromosomes are
arranged based on the sizes, position of the
centromere & pattern of the chromosome binding
23. • The test can be performed on a sample of
blood, bone marrow, amniotic fluid, or tissue
from the placenta.The sample is placed into a
special dish and allowed to grow in the
laboratory. Cells are later taken from the
growing sample and stained. The laboratory
specialist uses a microscope to examine the
size, shape, and number of chromosomes in the
cell sample.
24. The stained sample is
photographed to
provide a karyotype,
which shows the
arrangement of the
chromosomes.
Certain abnormalities
can be identified
through the number or
arrangement of the
chromosomes.
Chromosomes contain
thousands of genes
that are stored in
DNA, the basic
genetic material.
25. GENE MAPPING
Gene mapping, also called genome
mapping, is the creation of a genetic
map assigning DNA fragments to
chromosomes.
26. TYPES
1. Genetic mapping:- The relative position
between 2 genes of a chromosome are
determined using linkage analysis.
2. Physical mapping:- Using techniques like
FISH technique, it is possible to determine
the absolute position of a gene on a
chromosome.
27. Fluorescent In Situ Hybridization (FISH)
FISH is the most commonly applied method to
determine the chromosomal constitution of an
embryo. In contrast to karyotyping, it can be used
on interphase chromosomes, so that it can be
used on PBs & blastomeres.
The cells are fixated on glass microscope slides
and hybridized with DNA probes. Each of these
probes are specific for part of a
chromosome, and are labelled with a
fluorochrome.
28. The use of probes for chromosomes X, Y, 13,
14, 15, 16, 18, 21 and 22 has the potential of
detecting 70% of the aneuploidies found in
spontaneous abortions.
In order to be able to analyse more
chromosomes on the same sample, up to
three consecutive rounds of FISH can be
carried out.