Placenta and amniotic fluid

What happens now?
 Development of the zygote, the study of
which is known as embryology or
developmental biology.
 The zygote undergoes a series of mitotic
cell divisions called cleavage.
 The stages of development are:
Fertilized ovum (zygote)  2-cell stage
 4-cell stage  8-cell stage 
Morula  Blastula  Early Gastrula
 Late Gastrula

Cleavage (divide via mitosis)
forms the 2 cell stage

They split again to form the 4
cell stage

And again to form the 8 cell
stage…

Next it becomes a blastula
 58 cell stage
 5 embryo producing
cells+53 cells form
trophoblast
 107 cell blastocyst
(8+99)
 no larger
 Released from zona
pellucida

The Regents Diagram…
1. Sperm and ovum
2. Zygote (fertilized ovum)
3. 2-cell stage
4. 4-cell stage
5. Morula
6. Blastula
7. Gastrula

Differentiation
(Organogenesis)
 Organogenesis is the formation
of the organs (Organo = organs,
genesis = creation)
 Arises from the layering of cells
that occurs during gastrula
stage
 The layers are germ layers; they
have specific fates in the
developing embryo:

Differentiation
(Organogenesis)
 Endoderm
 The innermost layer
 Goes on to form the gut
 Mesoderm
 In the middle
 Goes on to form the muscles,
circulatory system, blood and many
different organs
 Ectoderm
 The outermost
 Goes on to form the skin and nervous
system

Late Gastrula
Ectoderm
Endoderm
Mesoderm

Where does this all take
place?

Decidual structure
Decidua is an analogy to
deciduous leaves (to
indicate that it is shed
after childbirth)
 Decidua basalis
 Decidua capsularis
 decidua parietalis or
vera

Fusion of capsularis and
parietalis at 14-16wks
causes functional
obliteration of the
uterine cavity

8th week
1. Decidua parietalis
2. Decidua capsularis
3. Decidua basalis
4. Uterine cavity
 The decidua consists of various parts,
depending on its relationship with the
embryo:
 Decidua basalis, where the implantation
takes place and the basal plate is formed.
This can be subdivided into a zona
compacta and a zona spongiosa (where
the detachment of the placenta takes
place following birth).
 Decidua capsularis, lies like a capsule
around the chorion
 Decidua parietalis, on the opposite uterus
wall

5. Smooth chorion
(laeve)
6. Chorionic villi
7. Amniotic cavity
8. Decidua capsularis
and parietalis, grown
together

Decidual reaction
 polygonal or round
 Round and vesicular
nucleus
 Cytoplasm clear,
basophilic
 Pericellular membrane
Walls around
themselves and
around the fetus

Decidual blood supply
 Spiral arteries in the
parietalis retain smooth
muscle wall and
epithelium
 Cytotrophoblast invasion
of spiral arteries and
arterioles -vessel wall in
the basalis destroyed-not
responsive to
vasoconstrictors

Decidual histology
 True decidual cells
 Maternal bone marrow derived cells
 Decidual NK cells
 Secrete cytokines
 Express angiogenic factors
 Basalis-mainly arteries and widely dilated
veins(glands virtually disapperared)
 Invasion by trophoblasts

Decidual prolactin
 Paracrine between maternal and fetal tissues
 Amnionic 10,000ng/ml
 Maternal 150-200ng/ml
 Fetal 350ng/ml
 Role ?
 Transmembrane solute and water transport
 Stimulate T-cells
 Regulates angiogenesis

Implantation
 The embryo implants in the wall of the uterus on about the 7th day
of development

Blastocyst implantation
 Apposition- days 20-24 of cycle
endometrium primed by E&P
 Adhesion modification in expression of
cellular adhesion molecules
(integrins)
 Invasion

Gas and nutrient exchange
system
 Embryo is nourished in the first weeks
through simple diffusion
 Utero-placental circulation system in which
the circulation systems of the mother and of
the embryo get closer together, thus allowing
an exchange of gases and metabolites via
diffusion.
 Maternal and fetal blood never come into
direct contact with each other.

Trophoblast differentiation
 cytotrophoblast
inner layer
well demarcated
 Syncytiotrophoblast
outer layer
multinucleated

After implantation
 Villous trophoblast
• chorionic villi
 Extra-villous
trophoblast
• interstitial
• endovascular

Lacunar stage
 Through the lytic activity of the
syncytiotrophoblast the maternal capillaries
are eroded and anastomose with the
trophoblast lacunae, forming the sinusoids.
 Lacunae communicate with each other and
form a single, connected system that is
delimited by the syncytiotrophoblast and is
termed the intervillous space.

primary villi
 D11-13
 Syncytiotrophoblast
penetrated by cords of
cytotrophoblast

Secondary villi
After the 16th day
The extra-embryonic mesoblast also grows into
this primary trophoblast villus, which is now
called a secondary villus and expands into the
lacunae that are filled with maternal blood.
The ST forms the outermost layer of every
villus.

Tertiary villi
 At the end of the 3rd week the villus
mesoblast differentiates into connective
tissue and blood vessels.
 Villi that contain differentiated blood vessels
are called tertiary villi
 The EEM remains in this stage, still
surrounded by cytotrophoblast.The outer
envelope of the villus is still formed by the ST

Free villi
 After 4th
month the cytotrophoblast in the
tertiary villi disappear slowly
 the villi divide further and become very thin.

1. Anchoring villus
2. Septum
3. Syncytiotrophoblast (ST)
4. Cytotrophoblast (CT)
5. Remainder of the cytotrophoblast layer
6. CT in the spiral artery wall
A-Basal plate and
myometrium
B-Chorionic plate

Ageing of the placenta
A. Langhans' fibrinoid layer
B. Rohr's fibrinoid layer
C. Nitabuch's fibrinoid layer

Cytotrophoblastic invasion
 destruction of the smooth
muscle layer
 partial replacement of the
endothelial cells
 change in elasticity of the spiral
arteries,
 Absent in
preecclampsia and
intra-uterine growth
retardation.
 excessive
proliferation of the
cytotrophoblast can
lead to tumor
formation, especially
to a chorion
carcinoma.

Placental tissue structure
Chorionic plate Basal plate
1 Amnion
2 Extra-embryonic mesoblast
3 Cytotrophoblast
4 Syncytiotrophoblast
5 Zona compacta
6 Zona spongiosa
7 Decidua basalis
8 Myometrium

Fetal circulation system
1. Umbilical arteries
2. Umbilical vein
3. Fetal capillaries
A network of fetal
capillaries (2 to 8) is
found in each villus;
20 to 40 first order stem
villi exist from each one
of which 20 to 50
second and third order
daughter villi arise.

Maternal circulation system
1. Spiral arteries
2. Uterine veins
3. Intervillous spaces
Spiral arteries (branches
of the uterine arteries)
High pressure
At the level of the
placenta (intervillous
spaces), therefore,
maternal blood is to be
found at times outside
the vessel network.

Blood pressure values and
oxygen distribution in the
intervillous spaces
Maternal blood is
pumped with high
pressure and leaves via
the uterine veins. At the
level of the placenta
(intervillous spaces),
therefore, maternal blood
is to be found at times
outside the vessel
network.

Development of the placenta (>
4th month)
1. Decidual tissue
2. Syncytiotrophoblast
3. Cytotrophoblast islands
4. Septum
The cytotrophoblast
islands move into the
periphery of the
cotyledons and,
together with the
decidual tissue, are
involved with formation
of the placental inter-
cotyledon septa.

Fibrinoid degradation
 The villus stems of the
placenta lengthen
considerably towards the end
of the pregnancy and the
fibrinoid deposits (extra-
cellular substance made up of
fibrin, placental secretions
and dead trophoblast cells),
accumulate in the placenta

Fibrinoid
degradation
structurally and
chemically closely related
to fibrin
can take up a maximum
of 30% of the placental
volume without affecting
its function.
When these deposits are
massive and block one or
more vessels to the villi,
they form white infarcts,
Functional importance
 sealing effects,
 Immunologic "barrier“
 anchoring of the
placenta.
A. Subchorial Langhans' layer
B. Rohr's layer
C. Nitabuch's layer

Placental barrier
 First trimester
1. Intervillous space
3. Cytotrophoblast
4. Villus mesenchyma
6. Hofbauer
macrophages

Placental barrier
 2nd
trimester
3. Cytotrophoblast
4. Villus mesenchyma
6. Hofbauer
macrophages

Placental barrier
 3rd
trimester
2. Placental barrier of a terminal
villus
4. Merged basal membranes
5. Endothelial cells
6. Rare cytotrophoblast cells
7. Basal membrane of the
capillaries
8. Basal membrane of the
trophoblast portion
9. Syncytiotrophoblast with
proliferation knots (nuclei rich
region)

Placental transport
 Passive transport
 Simple diffusion:
 non-polar molecules
 fat-dissolvable substances (e.g., diffusion of oxygen, carbon
dioxide, fats and alcohol).Water enters the placenta through
specialized pores (see osmosis).
 Osmosis: theaquaporines or water channels, proteins
localized within the plasma membrane.
 Simplified transport: transition from the side with higher
concentration to the one with lower concentration with the help
of transport molecules (e.g., glucose).

Placental transport
 Active transport:Transport through the
cellular membrane against a concentration
gradient using energy (Na+/K+ or Ca++)
 Vesicular transport (Endocytosis /
Exocytosis): Macro-molecules are captured
by microvilli and absorbed in the cells or
repelled (immunoglobulin).

 averages 22 cm (9 inch) in length
 2–2.5 cm (0.8–1 inch) in thickness
 weighs approximately 500 grams
 dark reddish-blue or crimson color
 Umbilical cord of approximately 55–60 cm, which
contains two umbilicalAs and one umbilicalV and
has an eccentric attachment.
 On the maternal side, these villous tree structures
are grouped into lobules called cotyledons

Placental functions
The placental
exchange surface
is enlarged from 5
m2
at 28 weeks to
roughly 12
m2
shortly before
delivery!

Placental functions
 Breathing function
 Nutritive and excretory functions
 Placenta and the immunological barrier
 Protein transfer
 Protective function
 Endocrinal function

Breathing function
The placenta, which plays the role of "fetal lungs", is 15
times less efficient (with equivalent weight of tissue)
than the real lungs.
The supply of the fetus with oxygen is facilitated by
three factors:
 difference of oxygen concentration and partial
pressure within the feto-maternal circulation system
 higher affinity of fetal hemoglobin (HbF) for oxygen
 Bohr effect

Nutritive and excretory functions
 Water diffuses into the placenta along an osmolar
gradient.The water exchange increases during the
pregnancy up to the 35th week (3.5 liter / day).
 The electrolytes follow the water, whereby iron and
calcium only go from mother to child.
 Glucose is the fetus' main source of energy and passes the
placenta via simplified transport. At the level of the
trophoblast the placenta can synthesize and store
glycogen in order to satisfy local glucose requirements
through glycogenolysis.

 Peptides and amino acids via active transport and thus insure the
fetus' own protein synthesis.
 Amino acids, precursors of fetal protein synthesis, stem from the
metabolism of the maternal proteins.The placental transport is
facilitated by the influence of hormones, e.g., GH (growth
hormone) andTSH (thyroid stimulating hormone) against a
concentration gradient (2-3 times higher in the fetus as in the
mother).
 Lipids and triglycerides are decomposed in the placenta, where
new lipid molecules are synthesized.
 Cholesterol passes through the placental membrane easily, just like
its derivates: e.g., steroid hormones.

 Water-soluble vitamins easily pass through the
placental membrane.The amount of the fat soluble
vitamins (A,D,E and K) in the fetal circulation is, on the
other hand, quite low.Vitamin K plays an important role
in blood coagulation and is applied to the child
immediately after birth, in order to prevent
hemorrhages.
 Placental exchange processes are also involved in the
removal of waste products from the fetal metabolism.
They cross over into the maternal blood in order to be
excreted by the mother (urea, creatinine, ureic acid).

Placenta and the immunological
barrier
 The fetus is not rejected even though its set of
chromosomes differs from that of its mother and
halfway represents an allogenic transplantation
 Fetal tissue and especially that of the placenta that stand
in direct contact to the maternal organismproduce no
tissue antigens
 HLA -G antigens, which do not distinguish between
individuals, occurs through the extravillous
cytothrophoblast.The HLA-G antigen takes over anti-
viral and immunosuppressive functions as well as non-
immunologic tasks.

Placenta and the immunological
barrier
 In addition, the placenta blocks cytotoxic maternal cell
effects by secreting various factors.The insufficiency of
these mechanisms may be responsible for immune-
dependent miscarriages.
 some steroid hormones (e.g., progesterone) have an
immunosuppressive effect on the lymphocytes of the
pregnant woman. Progesterone (the concentration of
which is especially elevated during pregnancy) seems to
play an important immunosuppressive role that is
mediated by the PBIF protein (Progesterone Induced
Blocking Factor).

Protein transfer
 The maternal proteins do not traverse the placental barrier,
with the exception of immunoglobulin (IgG).Through
pinocytosis of syncitiothrophoblast cells the mother thus
transfers to the fetus the variety of IgG that she has
synthesized during her life.This transfer occurs mainly
towards the end of pregnancy.Thereby the fetus obtains a
passive immunity that protects it against various infectious
diseases in the first six months of its life.The other
immunglobulins, mainly IgM proteins, do not pass through the
placental barrier.


Protein transfer
 Other proteins:
Transferrin is another important maternal protein that,
as the name indicates, transports iron. On the surface of
the placenta specific receptors exist for this protein,
which, by means of active transport, enters into fetal
tissue.
 Protein can also be transferred from the fetus to the
mother; alpha-fetoprotein (the concentration of which
is elevated in several fetal abnormalities) can be detected
in the maternal circulation system.
 Maternal or placental polypeptide hormones do not
enter the fetal circulation system.

Protective function
Sexually transmitted diseases:
 After the 5th month of pregnancy treponema pallidum bacteria, the
syphilis pathogen, can pass through the placental barrier.
 HIV transmission from the mother to the fetus amounts to roughly
15 to 25%. It depends on the viremia status of the mother.
 Anti-HIV treatment during the pregnancy and birth as well as further
treatment of the newborn during the first few weeks.
 Birth via caesarian section
 No breastfeeding of the child
When all of these measures have been carried out the risk of infection for
the baby can be reduced to below 1%.

Protective function
Fetotoxic infections:
 The rubella virus may be responsible for a miscarriage
during pregnancy (before the first month), for
embryopathies (when the virus invades between the 1rst
and 3rd month) or for fetopathies (after the 3rd month).
 Toxoplasmosis is harmless for the mother, but can cause
severe anomalies in the fetus.
 Listeriosis can be responsible for miscarriages,
intrauterine death or neonatal sepsis due to
transplacental infection or for secondary late meningitis
due to a contaminated birth passage.

Protective function
Fetotoxic infections:
 The cytomegalovirus is generally the cause of infections
that remain subclinical. It can also be responsible for
miscarriages as well as for microcephaly and growth
retardation.The infection happens transplacental or
during birth.
 The parvovirus B19 is responsible for aplastic crises in
utero (marked decrease of blood cells).

Protective function
 In addition, the placenta also presents an
incomplete barrier against certain injurious
effects of drugs: Antibiotics and corticoids
can pass through the placental barrier.
Depending on their size, certain steroid
hormones get through as well.

Endocrinal function
The placenta and especially the syncytiotrophoblast can be seen as a
large endocrine gland.
Before implantation hormone production is ensured through ovarian
and hypophysial hormones.
At the beginning of the pregnancy the synthesis of estrogen and
progesterone is ensured by the corpus luteum graviditatis that is
maintained by the human chorion-gonadotropin (HCG), a product of
the trophoblast.The activity of the corpus luteum decreases
progressively with the beginning of the 8th week in order to be
entirely replaced by the placenta at the end of the 1st trimester
During the pregnancy the hormone concentration in the maternal
blood is regulated by the cooperation of the placental, hypophysial
and fetal suprarenal hormones as well as hormones from the gonads


Endocrinal function
a Placenta
b Fetal suprarenal glands
c corpus luteum graviditatis

Implantation and form
anomalies
 placenta previa

anomalies
 Ectopic, i.e., extra-uterine pregnancies

anomalies

anomalies
 Velamentous insertion

anomalies
 marginal

anomalies
 Eccentric insertion

anomalies
• Placenta multilobata

CLINICAL BIOCHEMISTRY AMNIOTIC FLUID
anomalies

anomalies
 placenta succenturia

anomalies
 bilobate when both segments of the placenta are almost
equal in size (right on the figure) and succenturiate when
there is a greater difference (left on the figure).When
there is not such a connection, the placenta is called
placenta spuria.

anomalies
•Circumvalate placenta

anomalies
 fenestrated placenta

anomalies
 Membranaceous placenta

Implantation and form anomalies
 Disc shaped placenta

Fetal erythroblastosis
 anemia (due to the
hemolysis)
 splenomegaly (location of
the macrophages that
destroy the erythrocytes)
 hepatomegaly (intensive
hematopoesis in order to
compensate the hemolysis)
 icterus (transformation of
hemoglobin of the destroyed
erythrocytes into bilirubin)

Inflammation of the placenta
 Bacterial infections can also strike the placenta
(placentitis) or the fetal membranes
(chorioamnionitis). Normally, these infections
are transmitted vaginally in the case of an early
rupture of the amnion. An infection rarely occurs
via the blood, i.e., when the fetal membrane is
still intact. Syphilis was earlier a frequent cause
for placentitis, also for placental tuberculosis,
whereby here the placenta was infected via the
blood

Hydatid mole
The hydatid mole pregnancy
corresponds to a cystic
chorion villus degeneration
Macroscopically, the mole
looks like a heap of
transparent bubbles, held
together by filaments, and
supported by a central core.

Hydatid mole
 Microscopically, the villus
degeneration exhibits no
vascularization, a
proliferation of trophoblasts
(from cytotrophoblasts –
Langhans' cells and from
syncytiotrophoblasts) and
dystrophic alterations of the
connective tissue with
stroma edema.

The chorion and amnion enclose the
embryo
The chorion surrounds
the entire embryo
The amnion encloses the
embryo and forms an
open volume between
the embryo & the
amnion called the
amniotic cavity
Amnion provides almost
all tensile strength

Development
 Amniogenic cells line the inner surface of
trophoblast
 Derived from fetal ectoderm of the
embryonic disc

Amnion & Amniotic Fluid
 Composition of Amniotic Fluid
 99% H2O
 Un-disolved material
 Organic & inorganic salts
 Pregnancy advancement changes its composition
 Meconium & urine

Amniotic Fluid
 Before 20 weeks gestation –
 AF is an ultrafiltrate of maternal serum
 Maternal & AF osmolality, sodium, urea,
and creatinine are roughly equal.
 At term
 Volume = 900cc
 Reflective of fetal renal function.
 Progressively hypotonic.
 Contains fetal debris: squamous cells,
mucin, lanugo.

Amniotic Fluid
 Amniotic fluid surrounds the fetus
during intrauterine development.
 This fluid cushions the fetus
against trauma,
 Has antibacterial properties to
lessen infections,
 Reservoir that may provide a
short-term source of fluid and
nutrients to the fetus.

Amniotic Fluid
 Amniotic fluid are required for the
fetal musculoskeletal system to
develop normally, for
gastrointestinal system
development, and for the fetal
lungs to develop.
 It is not surprising to find that
oligohydramnios and
polyhydramnios are associated
with increased rates of perinatal
morbidity and mortality.

Sources of amniotic fluid
 The two primary sources of
amniotic fluid are fetal urine and
lung liquid, with an additional
small contribution due to
secretions from the fetal oral-nasal
cavities.
 Fetal urine is a major source of
amniotic fluid in the second half of
pregnancy.

 Urine production Approximately
110/ml/kg every 24 hours at 25
weeks to approximately 190
ml/kg every 24 hours at 39
weeks
 At term, the current best
estimate of fetal urine flow rate
may average 700-900 ml/day.

 The fetal lungs are the second
major source of amniotic fluid
during the second half of
gestation.
 Studies in near-term fetal sheep
have shown that there is an
outflow from the lungs of 200-
400 ml/day

 The inward transfer of solute
across the amnion with water
following passively is the most
likely source of amniotic fluid very
early in gestation
 Part of AFV may be derived from
water transport across the highly
permeable skin of the fetus during
the first half of gestation, at least
until keratinization of the skin
occurs around 22-25 weeks.

Routes of amniotic fluid
removal
 The two primary routes of
amniotic fluid removal are fetal
swallowing and absorption into
fetal blood perfusing the fetal
surface of the placenta.
 Fetal swallowing plays an
important role in determining AFV
during the last half of gestation.

Routes of amniotic fluid
removal
 The fetus begins swallowing at the
same gestational age when urine
first enters the amniotic space,
that is around 8-11 weeks.
 It is estimated that the volume of
amniotic fluid swallowed in late
gestation averages 210-760 ml/day

Intermembranous &
transmembranous pathways
 As a further pathway, rapid
movements of both water and solute
occur between amniotic fluid and
fetal blood within the placenta and
membranes; this is referred to as the
intramembranous pathway.
 Movement of water and solute
between amniotic fluid and maternal
blood within the wall of the uterus is
an exchange through the
transmembranous pathway

Amniotic fluid volume
 The rate of change in AFV is a strong
function of gestational age.
 There is a progressive AFV increase from
30 ml at 10 weeks’ gestation to 190 ml at
16 weeks and to a mean of 780 ml at 32-
35 weeks, after which a decrease occurs
 The decrease in post-term pregnancies
has been found to be as high as 150
ml/week from 38 to 43 weeks

Individual amniotic fluid volumes from a
collection of 705 measurements in patients with a
normal pregnancy outcome

Regulatory mechanisms act at
three levels:
 Placental control of water and solute
transfer.
 Regulation of inflows and outflows
from the fetus: fetal urine flow and
composition are modulated by
vasopressin, aldosterone, and
angiotensin II in much the same way as
they in adults.
 Maternal effect on fetal fluid balance:
during pregnancy, there is a strong
relationship between maternal plasma
volume and AFV,

Measurement of amniotic
fluid volume
 Single vertical pocket  Amniotic fluid index

Oligohydramnios
 Diminished amniotic fluid
volume (AFV)
 Amniotic fluid volume of less
than 500 mL at 32-36 weeks'
gestation - Amniotic fluid
volume depends on the
gestational age; therefore,
the best definition may be AFI
less than the fifth percentile.
 Single deepest pocket (SDP)
of less than 2 cm
 Amniotic fluid index (AFI) of
less than 5 cm or less than the
fifth percentile

Oligohydramnios-causes
 Fetal
 Chromosomal anomalies
 Congenital abnormalities
 Growth restriction
 Demise
 Post-term pregnancy
 Ruptured membranes
 Placental
 Abruption
 TTTS
 Maternal
 Uteroplacental insufficiency
 Hypertension
 Pre-ecclampsia
 Diabetes
 Iatrogenic
 PG synthesis inhibitors
 ACE inhibitors
 Idiopathic

Congenital anomalies associated
with oligohydramnios
 Amnionic band syndrome
 Cardiac
 Fallots tetralogy
 Septal defects
 CNS
 Holoprosencephaly
 Meningocele
 Encephalocele
 microcephaly
 Cloacal dysgenesis
 Chromosomal
 Triploidy
 Trisomy 18
 Turner syndrome
 Cystic hygroma
 Diaphragmatic hernia
 Genitourinary
 Renal dysgenesis/aplasia
 Urethral obstruction
 Bladder exystrophy
 Meckel gruber syndrome
 Uretro-pelvic junction obstruction
 Prune belly syndrome
 Hypothyroidism
 Skeletal
 TRAP sequence
 TTTS
 VACTERL association

Oligohydramnios
 Fetal mortality rates as high as 80-90% have been
reported with oligohydramnios diagnosed in the second
trimester.
 Midtrimester PROM often leads to pulmonary hypoplasia,
fetal compression syndrome, and amniotic band syndrome.
 Oligohydramnios is a frequent finding in pregnancies
involving IUGR and is most likely secondary to decreased
fetal blood volume, renal blood flow, and, subsequently,
fetal urine output.
 AFV is an important predictor of fetal well-being in
pregnancies beyond 40 weeks' gestation
 AFV is a predictor of the fetal tolerance of labor,

Oligohydramnios
 Ultrasonography
 diagnosis is confirmed
 ultrasonography of the
fetal anatomy
 Sterile speculum
examination
 Pooling in posterior fornix
 Nitrazine paper turns blue
 arborization or ferning
pattern
 amnioinfusion

Polyhydramnios
 Polyhydramnios is the
presence of excess amniotic
fluid in the uterus.
 Deepest vertical pool is more
than 8 cm
 AFI is more than 95th
percentile for the
corresponding gestational
age.
 The incidence is 1-3% of all
pregnancies.
 About 20% are associated
with fetal anomalies.
 The diagnostic approach to
polyhydramnios consists of
(1) physical examination of
the mother with an
investigation for diabetes
mellitus, diabetes insipidus,
and Rh isoimmunization;
(2) sonographic confirmation
of polyhydramnios and
assessment of the fetus;
(3) fetal karyotyping; and
(4) maternal serologic testing
for syphilis.

polyhydramnios
 Maternal hyperglycemia
 GIT anomalies(obstructive)
 Esophageal atresia
 Tracheoesophageal fistula
 Duodenal atresia
 Nonimmune hydrops
 CNS anomalies
 Anencephaly
 Open spina bifida
 Thoracic malformations
 Diaphragmatic hernia
 Congenital infections
 Syphilis, hepatitis
 Chromosomal anomalies
 High output Cardiac failure
 Fetal anemia
 Sacrococcygeal teratoma
 chorioangioma
 Fetal polyuria
 Fetal
pseudohyperaldosteronism
 Fetal bartter
 Nephrogenic diabetes
insipidus
 Placental chorioangioma
 Maternal substance abuse

Amniotic fluid testing
Chromosome and DNA analysis
Biochemistry
Fetal infections
Rh disease and other alloimmunisation
Lung maturity
Chorioamnionitis
Obstetric cholestasis
Fetal therapy- decompression
severe oligohydramnios
multifetal pregnancy reduction
throxine therapy

Alpha fetoprotein
 Measurement of AFP in
maternal serum and amniotic
fluid is used extensively for the
prenatal detection of some
serious fetal anomalies.

AFP Biochemistry
 AFP is produced initially by the
fetal yolk sac in small quantities
and then in larger quantities by
fetal liver as the yolk sac
degenerates.
 Trace amounts are also
produced in the fetal gut and
kidneys.

AFP Biochemistry
 Concentrations of AFP in fetal
serum
 Early in embryonic life:1/10 the
concentration of albumin in fetal
serum
 16 weeks gestation:3,000,000
ng/ml
 At term:declines steadily to 5000
to 120,000 ng/ml

AFP Biochemistry
 The rise and fall in
concentration of AFP in the
amniotic fluid roughly parallels
that in the fetal serum but
lower in concentration
 20,000 ng/ml at 16 weeks
gestation

Clinical significance of
AFP
 Maternal serum and amniotic
fluid AFP are useful tests for
detecting some serious fetal
anomalies
 Maternal serum AFP is elevated
in 85% to 95% of cases of fetal
open neural tube defect and is
low in about 30% of cases of
fetal Down’s syndrome.

Acetyl cholinesterase
 A useful adjunct in the diagnosis
of neural tube defects is the
measurment of
acetylcholinesterase (AChE,EC
3.1.1.7) in amniotic fluid
 The usual technique for
identification of AChE is
polyacrylamide gel
electrophoresis.

Acetyl cholinesterase test
sensitivity
 A study of more than 5000
patients reported that
determination of AChE by
electrophoresis had specificity
of 99.76% and following
sensitivities:

 Testing amniotic fluid for AFP and AChE can predict open
neural tube defects more accurately than maternal
serum screening.
 Patient with unexplained high maternal serum AFP levels
and normal ultrasonography findings should be offered
amniotic fluid testing.
 Any patient who has had a child with a neural tube defect
has 3% to5% risk for recurrence and also should be
offered amniotic fluid AFP testing
 Any elevation of AFP in amniotic fluid should lead to
AChE analysis

 Testing should be performed at or before 16
weeks gestation.
 Determination of fetal karyotype is also
reasonable.

AF and Respiratory distress
syndrome (RDS)

syndrome (RDS)
 Respiratory distress syndrome (RDS) was
associated with a significant mortality rate
approaching approximately 30%.
 In the 1950s, it was discovered that the
resistance of pulmonary alveoli to collapse
during expiration was mainly caused by the
presence of a surface tension-lowering material
lining the alveolus (surfactant).
 As the lungs develop, significant quantities of
surfactant are washed out of the fetal lung and
accumulate in the amniotic fluid.

syndrome (RDS)
 all of the available biochemical tests for
fetal lung maturity rely on the amniotic
fluid content of surfactant
 adult mature surfactant is approximately
80% phospholipids, about 10% protein,
and about 10% neutral lipids (primarily
cholesterol).
 The major species of phospholipid in
surfactant is phosphatidylcholine (also
referred to as lecithin), which accounts
for 80% of the total phospholipid

L/S ratio test
 The L/S ratio test remains one of the most
commonly used tests, and one of the
standardized tests against which all other tests
are compared.
 With a L/S ratio of 1.5-1.9, approximately 50% of
infants will develop RDS. Below a ratio of 1.5, the
risk of subsequent RDS increases to 73%.
 One of the major disadvantages of the L/S ratio
is the inability to use this test in the setting of
contaminated amniotic fluid. Both blood and
meconium staining of amniotic fluid have been
found to interfere with L/S ratio determinations.

PG determinations:
 It is found that the false-positive
rate for PG determination was
1.8%. This rate is significantly
lower than the false-positive rate
they found for the L/S ratio(5%)
 PG performs much better than the
L/S ratio in predicting babies who
will develop RDS. Finally, PG
determinations accurately predict
pulmonary maturity and give a
better indication of pulmonary
immaturity than does the L/S ratio

Saturated Phosphatidylcholine
 Saturated Phosphatidylcholine has
been found to predict pulmonary
maturity
 Respiratory distress syndrome was
correctly predicted 55.5% of the time by
L/S ratio and 82% of the time by SPC.
 Pulmonary immaturity = an SPC <500
μg/dl
 In addition, the SPC was found to be
valid in the presence of blood and
meconium, whereas the L/S ratio was
not.

 The lung profile includes the L/S
ratio, desaturated lecithin, PG and
PI concentrations.
 lung profile help to form a clearer
picture of fetal lung development
 The L/S ratio had a false-positive
rate of 3%-5%, which was reduced
to less than 1% with the combined
lung profile test
Lung Profile

Microviscosimeter
 Microviscosimeter testing
measures surfactant associated
with a phospholipid membrane
using fluorescent dye techniques.
 The microviscosimeter commonly
used in the fetal lung maturity
analyzer or FELMA machine.

Surfactant/Albumin Ratio
 A recently introduced TDx FLM assay is an
automated fetal lung maturity test based on the
principle of fluorescent polarization used
previously with the microviscosimeter.
 A surfactant albumin ratio of 50-70 mg
surfactant/g of albumin has been considered
mature in most studies
 The TDx test correlates well with the L/S ratio
and has few false-immature results, making it an
excellent screening test
 It only requires approximately 1 ml of amniotic
fluid and the test can be performed in less than
an hour,

Shake test
 this test use the principle that when
ethanol is added to amniotic fluid, the
nonsurfactant foam causing substances
in amniotic fluid are removed.
 any stable foam layer that persists after
shaking is due to the presence of
surfactant in a critical concentration.
 when serial dilutions of ethanol are
used, the surfactant can be quantified.
 it is found that the shake test was
comparable to the L/S ratio and had a
high predictive value for RDS when
applied to uncontaminated amniotic
fluid.

Tap Test
 the tap test examines the ability of surfactant within
amniotic fluid to break down bubbles within an ether
layer.
 the test is performed on 1 ml of amniotic fluid mixed
with a drop of 6N hydrochloric acid and 1.5 ml of
diethylether
 the tube is tapped 4 times and examined for the
presence of bubbles within the ether layer.
 in mature samples, the bubbles quickly breakdown,
whereas in immature amniotic fluid specimens more
than 5 bubbles persist in the ether layer.
 this rapid test was comparable with the phospholipid
profile

Visual Inspection
 The basis is whether or not
newspaper could be read
through the amniotic fluid
sample, that is, was the fluid too
turbid to read text through.
 with clear fluid (readable
newsprint) the sensitivity of an
immature result is 98%.

Optical Density at 650 nm
with a OD 650 value of 0.15 or greater, the L/S
ratio was always greater than 2.0
when the OD 650 was less than 0.15, only 6% of
L/S ratios were greater than 2

Diabetes and pulmonary
maturity

Amniotic fluid and renal
maturity

AF assesment and Renal
maturity
 The fetal kidneys start to develop during
the 4th and 5th weeks of gestation and
begin to excrete urine into the amniotic
fluid at the 8th to 11th week
 At the 20th week the fetal kidneys
produce most of the amniotic fluid
 Renal maturity is defined by the increase
in glomerular filtration and by the
maturity of renal tubular cells that begin
to express various tubular transporters
over the months of gestation

maturity
 Glomerular filtration in the fetal kidney
can be assessed by the concentrations of
creatinine and urea in the amniotic fluid
 Creatinine concentrations of 2 mg/dl
represent an age of at least 37 weeks of
gestation
 The function of the renal tubule system,
specifically proximal tubules, can also be
assessed by the concentrations of ß2-
microglobulin and NAG in the third
trimester of gestation

maturity
 ß2-Microglobulin produced by the
fetus is filtered and reabsorbed by
proximal tubules, with an expected
reduction in its concentrations at
week 36 in normal pregnancies.
 This reduction can be considered
as an index of renal tubular
maturation

maturity
 Analysis of creatinine and urea
in amniotic fluid permits an
evaluation of renal maturation.
 Creatinine values in the amniotic
fluid that best represent fetal
maturity are 1.5 to 2.0 mg/dl

AF and Bone Healing
 Hyaluronic acid (HA) is a linear
polysaccharide with a high molecular
weight.
 It is found in all extracellular matrices
and has the same structure in all species.
 If HA is administered during surgery,
scar formation is prevented.
 HA is known to reduce scar formation by
inhibiting lymphocyte migration,
proliferation and chemotaxis,
granulocyte phagocytosis ,
degranulation, and macrophage motility

AF and Bone Healing
 HA influences and enhances tissue
regeneration through its ability to
retain large amounts of water.
 HA has been reported to increase
osteoblastic bone formation in
vitro through increased
mesenchymal cell differentiation
and migration.

AF and Bone Healing
 Human amniotic fluid (HAF), obtained by
amniocentesis during the second trimester
of gestation, contains high molecular weight
HA in high concentrations.
 It has been showed that HASA (HA-
stimulating activator) which is present in
HAF, stimulates the wound to increase the
production of endogenous HA.
 HAF may increase both endogenous and
exogenous HA in the application region.
 HAF has been reported to enhance new
cartilage formation.

Risk and complications
 Pain
 Leakage
 Hemorrhage
 Abortion
 Fetal injury
 Orthopaedic abnormalities
 alloimmunisation

Placenta and amniotic fluid

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