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THE PLACENTA AND ITSTHE PLACENTA AND ITS
ABNORMALITIESABNORMALITIES
Dr. Robinson E. MbuDr. Robinson E. Mbu
Senior LecturerSenior Lecturer
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PLANPLAN
IntroductionIntroduction
ObjectivesObjectives
StructureStructure
Foetal circulationFoetal circulation
Maternal circulationMaternal circulation
FunctionsFunctions
The placental unitThe placental unit
Placental abnormalitiesPlacental abnormalities
The umbilical cordThe umbilical cord
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INTRODUCTIONINTRODUCTION
The concept of placenta was first introducedThe concept of placenta was first introduced
byby REALDUS COLUMBUSREALDUS COLUMBUS in 1559in 1559
MOSSMANMOSSMAN defined the placenta in 1937defined the placenta in 1937
As that part of the foetal membranes fusedAs that part of the foetal membranes fused
to the uterine mucosato the uterine mucosa
EmbryologicallyEmbryologically
Throphoblasts are formedThrophoblasts are formed
By the blastocystBy the blastocyst
As early as 72hrs. after fertilizationAs early as 72hrs. after fertilization
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INTRODUCTION cont’dINTRODUCTION cont’d
The throphoblasts proliferate rapidlyThe throphoblasts proliferate rapidly
And invade the surrounding deciduaAnd invade the surrounding decidua
Soon after implantationSoon after implantation
As invasion of the endometriumAs invasion of the endometrium
proceedsproceeds
Maternal blood vessels are invadedMaternal blood vessels are invaded
Forming intervillous spacesForming intervillous spaces
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OBJECTIVESOBJECTIVES
Holistic understanding of the placentaHolistic understanding of the placenta
– StructureStructure
– FunctionFunction
– Abnormal formsAbnormal forms
– Etc.Etc.
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STRUCTURESTRUCTURE
MeasuresMeasures 15-20cm15-20cm in diameterin diameter
2-3cm2-3cm thickthick
Weighs 1/6Weighs 1/6thth
of the foetus ( ~ 500gms)of the foetus ( ~ 500gms)
Has two surfaces :Has two surfaces :
– Foetal surface which contains :Foetal surface which contains :
The shinning amnionThe shinning amnion
Under which are vessels plastered by theUnder which are vessels plastered by the
chorionchorion
Both arteries and veinsBoth arteries and veins
Insertion of the umbilical cordInsertion of the umbilical cord
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STRUCTURE cont’dSTRUCTURE cont’d
Maternal surface:Maternal surface:
– Contains irregular lobesContains irregular lobes
– Divided by septaDivided by septa
– Made up of connective tissueMade up of connective tissue
– There are usually 16-18 of these irregular lobesThere are usually 16-18 of these irregular lobes
– CalledCalled COTYLEDONSCOTYLEDONS
– Formed during placentogenesisFormed during placentogenesis
– They only become larger as pregnancyThey only become larger as pregnancy
advancesadvances
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STRUCTURE cont’dSTRUCTURE cont’d
No new cotyledons are formed afterNo new cotyledons are formed after
this periodthis period
The placenta is located usuallyThe placenta is located usually
Anteriorly or posteriorlyAnteriorly or posteriorly
Near the fundusNear the fundus
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FOETAL CIRCULATIONFOETAL CIRCULATION
Foetal blood flows from the placentaFoetal blood flows from the placenta
Through two unbilical arteriesThrough two unbilical arteries
In which deoxygenated or venousIn which deoxygenated or venous
blood is transportedblood is transported
The vessels branch repeatedly andThe vessels branch repeatedly and
form capillary networksform capillary networks
In the terminalsIn the terminals
Oxygenated blood returns to theOxygenated blood returns to the
foetus
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FOETAL CIRCULATION cont’dFOETAL CIRCULATION cont’d
From the placentaFrom the placenta
Through the single umbilical veinThrough the single umbilical vein
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MATERNAL CIRCULATIONMATERNAL CIRCULATION
Maternal blood reaches the placentaMaternal blood reaches the placenta
Propelled by maternal arterialPropelled by maternal arterial
pressurepressure
There is no admixture of maternal andThere is no admixture of maternal and
foetal bloodfoetal blood
Venous exits are scattered at randomVenous exits are scattered at random
Over the entire base of the placentaOver the entire base of the placenta
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FUNCTIONS OF THEFUNCTIONS OF THE
PLACENTAPLACENTA
Exchange functions:Exchange functions:
– Waste products from the placentaWaste products from the placenta
– Cross the placental membraneCross the placental membrane
– To the maternal bloodTo the maternal blood
– Oxygen, nutrients and protectiveOxygen, nutrients and protective
antibodiesantibodies
– Leave from the mother across theLeave from the mother across the
placental membraneplacental membrane
– To the foetusTo the foetus
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PLACENTAL FUNCTIONS cont’dPLACENTAL FUNCTIONS cont’d
Endocrine functions:Endocrine functions:
– Chorionic gonadotropinChorionic gonadotropin
– HPLHPL
– Chorionic thyrotropinChorionic thyrotropin
– Chorionic adrenocorticotropinChorionic adrenocorticotropin
– Hypothalamic-like releasing hormones ofHypothalamic-like releasing hormones of
the placentathe placenta
– Pregnancy specific proteinPregnancy specific protein
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ENDOCRINE FUNCTIONS cont’dENDOCRINE FUNCTIONS cont’d
EstrogensEstrogens
ProgesteroneProgesterone
ProlactineProlactine
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PROTECTIVE FUNCTIONPROTECTIVE FUNCTION
Destroys the following :Destroys the following :
– BacteriaBacteria
– VirusesViruses
– PlasmodiumPlasmodium
– FungiFungi
– ETC.ETC.
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THE PLACENTAL UNITTHE PLACENTAL UNIT
VF=Foetal vessels, TC=Connective tissueVF=Foetal vessels, TC=Connective tissue
VM=Maternal vesselsVM=Maternal vessels
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PLACENTAL AGINGPLACENTAL AGING
Decrease in thickness of syncytiumDecrease in thickness of syncytium
Partial disappearance of cytotrophoblastsPartial disappearance of cytotrophoblasts
((LANGHANS CELLSLANGHANS CELLS))
Decrease in stromaDecrease in stroma
Thickening of basement of the endotheliumThickening of basement of the endothelium
and trophoblastsand trophoblasts
Obliteration of certain vesselsObliteration of certain vessels
Deposition of fibrinDeposition of fibrin
On the surface of the villi/intervillous spaceOn the surface of the villi/intervillous space
Decrease in efficiency of placentalDecrease in efficiency of placental
exchangeexchange
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PLACENTA BIPARTITA ,PLACENTA BIPARTITA ,
TRIPARTITATRIPARTITA
Two or three placentasTwo or three placentas
With equal dimensionsWith equal dimensions
Attached to one umbilical cordAttached to one umbilical cord
Clinical importance is thatClinical importance is that
One of them may left in-uteroOne of them may left in-utero
After a normal deliveryAfter a normal delivery
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BIPARTITE AND TRIPARTITEBIPARTITE AND TRIPARTITE
PLACENTASPLACENTAS
AnnotatedAnnotated
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CIRCUMVALLATE ORCIRCUMVALLATE OR
CIRCUMMARGINATE PLACENTACIRCUMMARGINATE PLACENTA
1% of placentas1% of placentas
Small central chorionic plate ( smallSmall central chorionic plate ( small
placenta)placenta)
Surrounded by a thick whitish ringSurrounded by a thick whitish ring
Composed of a double foldComposed of a double fold
Of amnion and chorionOf amnion and chorion
Predisposes to premature marginalPredisposes to premature marginal
separationseparation
APH, premature delivery, premature death.APH, premature delivery, premature death.
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CIRCUMVALLATE PLACENTACIRCUMVALLATE PLACENTA
AnnotatedAnnotated
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SUCCENTURIATE PLACENTASUCCENTURIATE PLACENTA
Inappropriately divided placentaInappropriately divided placenta
One large placentaOne large placenta
And a small ( succenturiate) lobeAnd a small ( succenturiate) lobe
Clinical significance is that the smallClinical significance is that the small
lobelobe
Could be forgotten in-uteroCould be forgotten in-utero
Following a normal deliveryFollowing a normal delivery
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SUCCENTURIATE PLACENTASUCCENTURIATE PLACENTA
AnnotatedAnnotated
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BATTLEDORE PLACENTABATTLEDORE PLACENTA
PlacentaPlacenta
Where the cordWhere the cord
Is inserted marginallyIs inserted marginally
Clinical significance is that umbilical vesselsClinical significance is that umbilical vessels
Could run through membranesCould run through membranes
And may ruptureAnd may rupture
Causing foetal bleeding (Causing foetal bleeding ( VASSAVASSA
PRAEVIAPRAEVIA ))
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BATTLEDORE PLACENTABATTLEDORE PLACENTA
AnnotatedAnnotated
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THE CRETASTHE CRETAS
Placenta AcretaPlacenta Acreta
– Throphoblastic invasion of theThrophoblastic invasion of the
endometrial basement membraneendometrial basement membrane
Placenta IncretaPlacenta Increta
– Invasion of the myometriumInvasion of the myometrium
Placenta PercretaPlacenta Percreta
– Perforation of the uterusPerforation of the uterus
These are all histological diagnosesThese are all histological diagnoses
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PLACENTA PRAEVIAPLACENTA PRAEVIA
Presence of the placentaPresence of the placenta
In the lower uterine segment ( LUS)In the lower uterine segment ( LUS)
Formed from 28 weeks of gestationFormed from 28 weeks of gestation
RevisitRevisit PLACENTA PRAEVIAPLACENTA PRAEVIA
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THE UMBILICAL CORDTHE UMBILICAL CORD
30-100 cm long ( ~ 55 cm)30-100 cm long ( ~ 55 cm)
1-2.5 cm thick1-2.5 cm thick
Has two arteries and one veinHas two arteries and one vein
The vessels are embedded in a whitishThe vessels are embedded in a whitish
substancesubstance
Called WHARTON JELLYCalled WHARTON JELLY
Inserted centrally , laterally or marginallyInserted centrally , laterally or marginally
There is also velamentous insertionThere is also velamentous insertion
This is a rare insertionThis is a rare insertion
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THE UMBILICAL CORDTHE UMBILICAL CORD
cont’dcont’d
In velamentous insertion:In velamentous insertion:
– The cord stops at some distanceThe cord stops at some distance
– Before sending down vesselsBefore sending down vessels
– Like the maize stemLike the maize stem
– These vessels could be found in theThese vessels could be found in the
lower uterine segmentlower uterine segment
– And may bleed during contractionsAnd may bleed during contractions
– Or vaginal examinationOr vaginal examination
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UMBILICAL CORD INSERTIONSUMBILICAL CORD INSERTIONS
AnnotatedAnnotated