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

THE PLACENTA AND ITS THE PLACENTA AND ITS ABNORMALITIESABNORMALITIES

Dr. Robinson E. MbuDr. Robinson E. Mbu

Senior LecturerSenior Lecturer

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

PLANPLAN

IntroductionIntroduction ObjectivesObjectives StructureStructure Foetal circulationFoetal circulation Maternal circulationMaternal circulation FunctionsFunctions The placental unitThe placental unit Placental abnormalitiesPlacental abnormalities The umbilical cordThe umbilical cord

DR. R.E. MBU 2006DR. R.E. MBU 2006 33

INTRODUCTIONINTRODUCTION

The concept of placenta was first The concept of placenta was first introduced by introduced by REALDUS COLUMBUSREALDUS COLUMBUS in 1559 in 1559

MOSSMANMOSSMAN defined the placenta in 1937defined the placenta in 1937 As that part of the foetal membranes fused As that part of the foetal membranes fused

to the uterine mucosato the uterine mucosa EmbryologicallyEmbryologically Throphoblasts are formed Throphoblasts are formed By the blastocystBy the blastocyst As early as 72hrs. after fertilizationAs early as 72hrs. after fertilization

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 endometrium As invasion of the endometrium

proceedsproceeds Maternal blood vessels are invadedMaternal blood vessels are invaded Forming intervillous spacesForming intervillous spaces

DR. R.E. MBU 2006DR. R.E. MBU 2006 55

OBJECTIVESOBJECTIVES

Holistic understanding of the Holistic understanding of the placentaplacenta– StructureStructure– FunctionFunction– Abnormal forms Abnormal forms – Etc.Etc.

DR. R.E. MBU 2006DR. R.E. MBU 2006 66

STRUCTURESTRUCTURE

Measures Measures 15-20cm15-20cm in diameter in diameter 2-3cm2-3cm thick thick 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 the Under which are vessels plastered by the

chorionchorion Both arteries and veinsBoth arteries and veins Insertion of the umbilical cordInsertion of the umbilical cord

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

STRUCTURE cont’dSTRUCTURE cont’d

Maternal surface:Maternal surface:– Contains irregular lobes Contains irregular lobes – Divided by septaDivided by septa– Made up of connective tissueMade up of connective tissue– There are usually 16-18 of these irregular There are usually 16-18 of these irregular

lobeslobes– Called Called COTYLEDONSCOTYLEDONS– Formed during placentogenesisFormed during placentogenesis– They only become larger as pregnancy They only become larger as pregnancy

advancesadvances

DR. R.E. MBU 2006DR. R.E. MBU 2006 88

STRUCTURE cont’dSTRUCTURE cont’d

No new cotyledons are formed No new cotyledons are formed after this periodafter this period

The placenta is located usuallyThe placenta is located usually Anteriorly or posteriorlyAnteriorly or posteriorly Near the fundusNear the fundus

DR. R.E. MBU 2006DR. R.E. MBU 2006 99

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 venous blood In which deoxygenated or venous blood

is transportedis transported The vessels branch repeatedly and form The vessels branch repeatedly and form

capillary networkscapillary networks In the terminalsIn the terminals Oxygenated blood returns to the foetus Oxygenated blood returns to the foetus

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

FOETAL CIRCULATION FOETAL CIRCULATION cont’dcont’d

From the placentaFrom the placenta Through the single umbilical veinThrough the single umbilical vein

DR. R.E. MBU 2006DR. R.E. MBU 2006 1111

MATERNAL CIRCULATIONMATERNAL CIRCULATION

Maternal blood reaches the placentaMaternal blood reaches the placenta Propelled by maternal arterial pressurePropelled by maternal arterial pressure There is no admixture of maternal and There 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

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

FUNCTIONS OF THE FUNCTIONS 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 protective Oxygen, nutrients and protective

antibodiesantibodies– Leave from the mother across the Leave from the mother across the

placental membraneplacental membrane– To the foetusTo the foetus

DR. R.E. MBU 2006DR. R.E. MBU 2006 1313

PLACENTAL FUNCTIONS cont’dPLACENTAL FUNCTIONS cont’d

Endocrine functions:Endocrine functions:– Chorionic gonadotropinChorionic gonadotropin– HPLHPL– Chorionic thyrotropinChorionic thyrotropin– Chorionic adrenocorticotropinChorionic adrenocorticotropin– Hypothalamic-like releasing Hypothalamic-like releasing

hormones of the placentahormones of the placenta– Pregnancy specific proteinPregnancy specific protein

DR. R.E. MBU 2006DR. R.E. MBU 2006 1414

ENDOCRINE FUNCTIONS cont’dENDOCRINE FUNCTIONS cont’d

EstrogensEstrogens ProgesteroneProgesterone ProlactineProlactine

DR. R.E. MBU 2006DR. R.E. MBU 2006 1515

PROTECTIVE FUNCTIONPROTECTIVE FUNCTION

Destroys the following :Destroys the following :– BacteriaBacteria– VirusesViruses– PlasmodiumPlasmodium– FungiFungi– ETC.ETC.

DR. R.E. MBU 2006DR. R.E. MBU 2006 1616

THE PLACENTAL UNITTHE PLACENTAL UNIT

VF=Foetal vessels, TC=Connective tissue VF=Foetal vessels, TC=Connective tissue VM=Maternal vesselsVM=Maternal vessels

DR. R.E. MBU 2006DR. R.E. MBU 2006 1717

PLACENTAL AGINGPLACENTAL AGING

Decrease in thickness of syncytiumDecrease in thickness of syncytium Partial disappearance of cytotrophoblasts Partial disappearance of cytotrophoblasts

((LANGHANS CELLSLANGHANS CELLS)) Decrease in stromaDecrease in stroma Thickening of basement of the Thickening of basement of the

endothelium and trophoblastsendothelium and trophoblasts Obliteration of certain vesselsObliteration of certain vessels Deposition of fibrin Deposition of fibrin On the surface of the villi/intervillous spaceOn the surface of the villi/intervillous space Decrease in efficiency of placental Decrease in efficiency of placental

exchangeexchange

DR. R.E. MBU 2006DR. R.E. MBU 2006 1818

PACENTA ABNORMALITIESPACENTA ABNORMALITIES

Placenta Bipartita , TripartitaPlacenta Bipartita , Tripartita Circumvallate or Circummarginate Circumvallate or Circummarginate

placentaplacenta Succenturiate placentaSuccenturiate placenta Battledore placentaBattledore placenta Placenta acretaPlacenta acreta Placenta incretaPlacenta increta Placenta percretaPlacenta percreta Placenta praevia Placenta praevia

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 that Clinical importance is that One of them may left in-uteroOne of them may left in-utero After a normal deliveryAfter a normal delivery

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

BIPARTITE AND TRIPARTITE BIPARTITE AND TRIPARTITE PLACENTASPLACENTAS

AnnotatedAnnotated

DR. R.E. MBU 2006DR. R.E. MBU 2006 2121

CIRCUMVALLATE OR CIRCUMVALLATE OR CIRCUMMARGINATE PLACENTACIRCUMMARGINATE PLACENTA

1% of placentas1% of placentas Small central chorionic plate ( small Small 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 marginal Predisposes to premature marginal

separationseparation APH, premature delivery, premature death.APH, premature delivery, premature death.

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

CIRCUMVALLATE PLACENTACIRCUMVALLATE PLACENTA

AnnotatedAnnotated

DR. R.E. MBU 2006DR. R.E. MBU 2006 2323

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 Clinical significance is that the

small lobesmall lobe Could be forgotten in-uteroCould be forgotten in-utero Following a normal delivery Following a normal delivery

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

SUCCENTURIATE PLACENTASUCCENTURIATE PLACENTA

AnnotatedAnnotated

DR. R.E. MBU 2006DR. R.E. MBU 2006 2525

BATTLEDORE PLACENTABATTLEDORE PLACENTA

Placenta Placenta Where the cordWhere the cord Is inserted marginallyIs inserted marginally Clinical significance is that umbilical Clinical significance is that umbilical

vesselsvessels Could run through membranesCould run through membranes And may ruptureAnd may rupture Causing foetal bleeding ( Causing foetal bleeding ( VASSA PRAEVIAVASSA PRAEVIA

))

DR. R.E. MBU 2006DR. R.E. MBU 2006 2626

BATTLEDORE PLACENTABATTLEDORE PLACENTA

AnnotatedAnnotated

DR. R.E. MBU 2006DR. R.E. MBU 2006 2727

THE CRETASTHE CRETAS

Placenta AcretaPlacenta Acreta– Throphoblastic invasion of the Throphoblastic invasion of the

endometrial basement membrane endometrial 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

DR. R.E. MBU 2006DR. R.E. MBU 2006 2828

PLACENTA PRAEVIAPLACENTA PRAEVIA

Presence of the placentaPresence of the placenta In the lower uterine segment In the lower uterine segment

( LUS)( LUS) Formed from 28 weeks of Formed from 28 weeks of

gestationgestation Revisit Revisit PLACENTA PRAEVIAPLACENTA PRAEVIA

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 whitish The 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 insertion This is a rare insertion

DR. R.E. MBU 2006DR. R.E. MBU 2006 3030

THE UMBILICAL CORD THE UMBILICAL CORD cont’dcont’d

In velamentous insertion:In velamentous insertion:– The cord stops at some distance The 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 the These vessels could be found in the

lower uterine segmentlower uterine segment– And may bleed during contractions And may bleed during contractions – Or vaginal examinationOr vaginal examination

DR. R.E. MBU 2006DR. R.E. MBU 2006 3131

UMBILICAL CORD INSERTIONSUMBILICAL CORD INSERTIONS

AnnotatedAnnotated