bio

1. DR. R.E. MBU 2006DR. R.E. MBU 2006 11
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

4. DR. R.E. MBU 2006DR. R.E. MBU 2006 44
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

7. DR. R.E. MBU 2006DR. R.E. MBU 2006 77
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

10. DR. R.E. MBU 2006DR. R.E. MBU 2006 1010
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

12. DR. R.E. MBU 2006DR. R.E. MBU 2006 1212
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

18. DR. R.E. MBU 2006DR. R.E. MBU 2006 1818
PACENTA ABNORMALITIESPACENTA ABNORMALITIES
 Placenta Bipartita , TripartitaPlacenta Bipartita , Tripartita
 Circumvallate or Circummarginate placentaCircumvallate or Circummarginate placenta
 Succenturiate placentaSuccenturiate placenta
 Battledore placentaBattledore placenta
 Placenta acretaPlacenta acreta
 Placenta incretaPlacenta increta
 Placenta percretaPlacenta percreta
 Placenta praeviaPlacenta praevia

19. DR. R.E. MBU 2006DR. R.E. MBU 2006 1919
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

20. DR. R.E. MBU 2006DR. R.E. MBU 2006 2020
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.

22. DR. R.E. MBU 2006DR. R.E. MBU 2006 2222
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

24. DR. R.E. MBU 2006DR. R.E. MBU 2006 2424
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

29. DR. R.E. MBU 2006DR. R.E. MBU 2006 2929
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

31. DR. R.E. MBU 2006DR. R.E. MBU 2006 3131
UMBILICAL CORD INSERTIONSUMBILICAL CORD INSERTIONS
 AnnotatedAnnotated