Abnormalities of the Placenta, Umbilical Cord and Membranes

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Abnormalities of the Placenta, Umbilical Cord

and Membranes

Williams Obstertics, twenty- second edition

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Placental Abnormalities

Abnormalities of the Membranes

Umbilical cord Abnormalities

Pathological Examination

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Placental AbnormalitiesPlacental Abnormalities

Abnormal Shape or Implantation

Degenerative Placental Lesions

Circulatory Disturbances

Hypertropic Placental Abnormalities

Placental Inflammation

Tumors of the Placenta

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Placental Abnormalities

Normal placenta (term placenta ) diameter : 22 cm thickness : 2.0 ~ 2.5 cm weights : approximately 470 g (about 1 lb).

Placental and fetal size and weight roughly correlate in a linear fashion

Fetal growth depends on placental weight which is less with small- -for- gestational age infants

-Heinonen and colleagues, 2001-

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Placental AbnormalitiesPlacental Abnormalities- - Abnormal Shape or Implantation-Abnormal Shape or Implantation-

Abnormality Definition Clinical significance

Multiple Placentas with a single fetus

Placenta bipartita or bilobata

- the placenta is separated into lobes

- division is incomplete and the vessels

of fetal origin extend from one lobe to

the other before uniting to form the

umbilical cord Placenta duplex, triplex

- two or three distinct lobes are separated

entirely and the vessels remain distinct.

Bilobed placenta

Succenturiate lobes

small accessory lobe ≥1, develop in

the membranes at a distant from the

periphery of the main placenta, to

which they usually have vascular

connections of fetal origin incidence : 5%

retained in the uterus

after delivery and may

cause serious hemorrhage accompanying vasa previa

- dangerous fetal hemorrhage at

delivery

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Membranaceous Placenta

all of the fetal membranes are

covered by functioning villi and the

placental develops as a thin

membranous structure occupying

the entire periphery of the chorion

serious hemorrhage d/t associated placenta previa or accreta

Ring – shaped Placenta

Placenta is annular in shape and

sometimes a complete ing of placental

tissue Variant of membraceous placenta

- tissue atrophy in a portion of the

ring a horseshoe shape in more

common Incidence : < 1/6000 deliveries

Antepartum & postpartum bleeding and fetal growth restriction

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Diagnosis Definition Clinical significance

Fenestrated Placenta Central portion of a discoidal placenta

is missing In some instances, there is an actual

hole in the placenta but more often

the defect involves only villous tissue

with the chorionic plate

mistakenly considered to indicate that a missing portion of placenta

Placenta

Accreta

Increta

Percreta

serious variations in which

trohpoblastic tissue invade the

myometrium to varying depths much more likely with placenta

previa or with implantation over a

prior uterine incision or perforation

Torrential hemorrhage

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Extrachorial Placentation

Circumvallate

Placenta

Circummarginate

placenta

When the chorionic plate, which is on the

fetal side of the placenta, is smaller than

the basal plate, which is located on the

maternal side, the placental periphery is

uncovered

Fetal surface of such a placenta presents

a central depression surrounded by a

thickened, grayish-white ring. Ring : composed of a double fold of

amnion and chorion with degenerated

decidua and fibrin in between Within the ring, the fetal surface presents

the usual appearance, except that the

large vessels terminate abruptly at the

margin of the ring

Ring dose not have the central depression with the fold of membranes

Antepartum hemorrhage

- from placental abruption

and fetal hemorrhage Preterm delivery Perinatal mortaliy Fetal malformations

less well defined

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Placental AbnormalitiesPlacental Abnormalities- Degenerative Placental Lesions -- Degenerative Placental Lesions -

Causes

: trophoblast aging or impairment of uteroplacental circulation

with infarction Deposition of calcium salts is heaviest on the maternal surface in the

basal plate.

→ further deposition occurs along the septa and both increase as

pregnancy progresses Calcification : 10 - 15% of all placentas at term

* By GA33wks : some degree of calcification ≥ ½ of placentas

- Spirt and colleagues ,1982 -

Diagnosis : Sonography

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Placental AbnormalitiesPlacental Abnormalities

Placental calcification

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Placental AbnormalitiesPlacental Abnormalities- Circulatory Disturbances-

Placental perfusion may be impaired by disruption of uterine vessels, placental vessels or the intervillous space

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Placental infarctions m/c placental lesions Etiology : continuum from normal changes to extensive and pathological involvement Incidence : 10% of 500 consecutive placentas from uncomplicated term pregnancies Several types (by lesion sites )

- located at the placental margin (90%) , size <1cm(90%)- underneath the chorionic plate - Subchorionic infarct : downward with their apices the intervillous space- Intercotyledonary septa : meet and form a column of cartilage – like material

extending from the maternal surface to the fetal surface

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Placental infarction

A: placental infarction, B: fibrin deposit, C: normal placenta

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Placental AbnormalitiesPlacental Abnormalities- Circulatory Disturbances -

Placental margin (90%)

sites Placental margin

cause occlusion of the maternal uteroplacental circulation

normal aging

finding around the edge of nearly every term placental : dense yellowish-white fibrous ring representing a zone of degeneration and necrosis

- incidental finding

Associated

Lesion

normal numerous – development of placental insufficiency thick, centrally located and randomly distributed

: preeclampsia or lutus anticoagulant these conspicuous lesions arise after occlusion of decidual artery

interrupts blood flow to the intervillous space

: necrosis of villous tissue develops from ischemia decidual a. occlusion : placental abruption

Histopathologic feature

Fibrinoid degeneration of the trophoblast, calcification and ischemic infarction

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Materal Floor infarction Uncommon lesion Incidence : 6/1000 deliveries - by Adams-Chapman and colleagues, 2002-

Etiopathogenesis : not well defined associated with thrombophilia (in some cases) Sites : not large areas of villous infarction massive net-like fibrin deposition throughout the placenta – Benirschke and Kaufmann , 2000 -

Fibroid deposition occurs within the decidua basalis (usually confined to the placental floor) → fibrin can extend into the intervillous space to envelop the villi which then atrophy associated outcome : fetal restriction, abortion , stillbirths, increased incidence of CNS injury and neurodevelopmental sequelae in these infants

not associated with preeclampsia, placental abruption

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Placental Vessel Thrombosis

When a stem artery from the fetal circulation in the placenta is occluded, it produces a sharply demarcated area of avascularity

Single a thrombosis : 5% of placentas in normal pregnancies

10% of diabetic woman Thrombosis of a single stem artery will deprive only 5% of the

villi of their blood supply associated with fetal growth restriction and stillbirth

- Benirschke and Kaufmann, 2000 -

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Placental AbnormalitiesPlacental Abnormalities- Hypertrophic Lesions of the chorionic villi -

skriking enlargement of the chorionic villi is commonly seen in association with severe erythroblastosis fetal hydrops. maternal diabetes fetal CHF maternal-fetal syphilis

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Placental AbnormalitiesPlacental Abnormalities- Microscopic Placental Abnormalities -

Syncytial knots: clumps of syncytial nuclei are found to project

into the intervillous space

- begining after 32wks The number of cytotrophoblastic cells becomes progressively

reduced as pregnancy advances. By term, such cells are few and inconspicuous In some maternal or fetal disorders, numerous cytotrophobalstic

cells are found in placentas

- Gestational hypertension , diabetes and erythroblastosis fetalis

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Placental AbnormalitiesPlacental Abnormalities-Placental Inflammation--Placental Inflammation-

Changes that are now recognized as various forms of degeneration and necrosis were formerly described under the term placentitis

e.g.) Small placental cysts with grumous contents were formerly

thought to be abscesses.

Nonetheless, especially in cases of preterm and prolonged membrane rupture, bacteria invade the fetal surface of the placenta

→ chorioamnionitis

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Placental AbnormalitiesPlacental Abnormalities-Tumors of the Placenta--Tumors of the Placenta-

Gestational Trophoblastic Disease

Chorioangioma(Hemangioma)

Tumors Metastatic to the Placenta

Embolic Fetal Brain Tissue

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Chorioangioma (Hemangioma) The resemblance components to the blood vessels and stroma

of the chrionic villus Benign tumors of placenta Incidence : 1% Hamartomas of primitive chorionic mesenchyme Diagnosis : larger chorioangiomas – sonographic findings Associated symptome - small growths : asymptomatic - large tumors : hydramnios or antepartum hemorrhage Complication : associated with low birthweight : fetal death and malformations are uncommon

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Chorioangioma (Hemangioma)

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Siller and Skafish (1986 )

: Multiple placental chorioangiomas in which a blood group A

fetus bleed acutely into her O group mother

→ The mother showed evidence of acute hemolysis without anemia

and the fetus developed a sinusoidal heart rate pattern frequently

seen with we severe anemia Severe iron deficiency anemia in the neonate as the consequence

of chronic fetal-to-maternal bleeding from multiple small chorioangiomas

Large tumors provide an arteriovenous shunt that can lead to fetal heart failure

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Tumor Metastatic to the Placenta Malignant tumors rarely metastasize to the placenta Melanoma (1/3), leukemias and lymphomas 1/3 Tumor cells usually are confined within the intervillous space - the fetus : metastases (¼) Malignant cells seldom proliferate to cause clinical disease

Embolic Fetal Brain Tissue Fetal brain tissue occasionally is seen embolized to the placenta or

fetal lungs Usually has been described with “traumatic” deliveries This phenomenon is not without precedent because brain tissue has

been found in pulmonary veins following head trauma in older children and adults

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Abnormalities of the Membranes

Meconium Staining

Chorioamnionitis

Other Abnormalities

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Abnormalities of the Membranes- Meconium Staining -

Incidence : remarkably constant 20% of almost 250,000women delivered during the past 20years - in Parkland Hospital Preterm fetuses seldom pass meconium. <38 wks : uncommon >42 wks : increase to 25~30% Staining of the amnion can be obvious within 1~3hours after

meconium passage Although more prolonged exposure results in staining of the the

chorion, umbilical cord and decidua, meconium passage cannot be timed or dated accurately – Benirschke and Kaufmann(2000)

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Study Meconium Passage(%)

Eden and associates(1987)

39weeks 14

40weeks 19

42weeks 26

>42weeks 29

Usher and colleagues(1988)

39-40 weeks 15

41 weeks 27

42 weeks or greater 32

Steer and co-workers(1989)

<36 weeks 3

36-39 weeks 13

40-41 weeks 19

42 weeks or greater 23

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Clinical significance : perinatal morbidity and mortality↑ - by Nathan and co-workers in Parkland Hospital, 1994-

- perinatal mortality - 1.5 : 0.3 per 1000 - severe fetal acidemia (cord arterial pH < 7.0) - 7 : 3 per 1000 - cesarean delivery : doubled (14% : 7%) : neonatal morbidity and mortality ↑ - meconium aspiration syndrome (10% of exposed infants) : serious maternal risk ↑ - associated with amnionic fluid embolism → increases maternal mortality from cardiorespiratory failure and consumptive coagulopathy - Puerperal metritis : 4 times

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Abnormalities of the Membranes- Chorioamnionitis-

Imflammation of the fetal membranes is usually manifestation of imtrauterine infection

Associated with prolonged membrane rupture and long labor Characteristic : clouding of the membranes foul odor (depending on bacterial species and concentaraion ) Definition : mono-and polymorphonuclear leukocytes infiltrate the chorion, the resulting microscopical finding - cells origin : maternal Leudocytes are found in amnionic fluid (amnionitis) or the umbilical

cord(funisitis) - cell origin : fetus < 20 wks almost all polymorphonuclear leukocytes : maternal origin > 20 wks: Inflammatory response : maternal & fetal Preterm deliveries : m/c

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Abnormalities of the Membranes- Chorioamnionitis -

Accordign to some investigators these findings of inflammation may be nonspecific and are not always associated with other evidence of fetal or maternal infection

Management

: antimicrobial administration and expedient delivery

Explanation for many otherwise unexplained cases of ruptured membaranes, preterm labor or both

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Abnormalities of the Membranes-Other Abnormalities-

Abnormalities Definition & causes Clinical significance

Amnionic cyst lined by typical amnionic epithelium fusion of amnionic folds with

subsequent fluid retention

Amnion nodosum tiny, light tan , creamy nodules in the

amnion made up of vernix caseosa

with hair, degenerated squames and

sebum Oligohydramnios

Found in fetuses with renal agenesis prolonged preterm ruptured

membranes the placenta of the donor

fetus with twin-to-twin

transfusion syndrome

Amnionic band caused when disruption of the amnion

leads to formation of bands or strings

that entrap the fetus and impair growth

and development of the involve

structure

Intrauterine amputation

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Umbilical Cord Abnormalities

Length Cord Coiling Single Umbilical Artery Four-vessel cord Abnormalities of cord insertion Cord Abnormalities capable of impeding blood flow Torsion and Strictures Hematoma Cysts

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Length

: appreciable variation, extremes range

- no cord(achordia) ~ lengths<300cm

- mean length : 37cm

- excessively long cords : ≥ 70cm ( ≥2 SD )

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Short umbilical cords : associated with adverse perinatal outcomes such as fetal growth restriction, congenital malformations, intrapartum distress and risk of death (doubled) - Krakowiak and associates,2004 –

Excessively long cords : associated with - maternal systemic disease and delivery complications such as prolapse, cord entanglement, fetal distress, fetal anomalies and respiratory distress - perinatal mortality : increased nearly threefold, albeit with borderline statistical significance

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Determinants of cord length

- concept that cord length is influenced positively by both the

volume of amnionic fluid and fetal mobility

- heredity

Miller and associates identified the cord to be shortened appreciably when there had been either chronic fetal constraint from oligohydramnios or decreased fetal movement, such as with Down syndrome or limb dysfunction

Long cord Short cord

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Umbilical Cord Abnormalities Cord Coiling

Umbilical vessels : in a spiraled manner

Hypocoiled cords : increase in various adverse outcomes in fetuses - meconium staining, preterm birth and fetal distress

Hypercoiled cords : higher incidence of preterm delivery and cocaine abuse in one with hypercoiled cords - Rana and associates (1995) -

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Umbilical Cord Abnormalities Single Umbilical Artery

The umbilical cord : typically contains two arteries and a single vein

Risk factors : in women with diabetes, epilepsy, preeclampsia, antepartum hemorrhage, oligohydramnios and hydramnios → increased incidence

¼ of all infants with only 1artery have associated congenital anomalies

- two-vessel cords were identified in 1.5% of 879 fetuses aborted spontaneously : serious malformation, most associate with chromosomal abnormalities >1/2 of these - Byrne and Blane,1985-

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Diagnosis : routine ultrasound screening - GA 17~36wks : 98% of cases

Prognosis - fetal prognosis : depends on whether the two-vessel cord is associated with other abnormalities or whether it is an isolated finding - Perinatal prognosis : two-vessel umbilical cord is an isolated sonographic finding → better


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Budorick and co-workers (1995)

: no abnormal karyotypes and only one echocardiographic

abnormality in 31 fetuses with a two-vessel cord

Gossett and associates (2002)

: 74 such fetuses all had normal echocardiography

Catanzarite (1995)

- two of 46 fetuses : lethal chromosomal abnormalities

- 1/3 of 46 fetuses : tracheoesophageal fisrula

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When a two vessel cord is a nonisolated finding - aneuploid ≥ ½ - Budorick and associates (2001) –

- renal aplasia, limb-reduction defects, atresia of hollow organs in such fetuses, suggesting a vascular etiology - Pavlopoulos and colleagues (1998) –

Goldkrand and associates (2001) : growth restriction did not occur in anatomically normal fetus with a single artery

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Umbilical Cord Abnormalities Four – vessel cord

Venous remnant in 5%

Significance : unknown

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Umbilical Cord Abnormalities Abnormalities of Cord insertion

Cord insertion

: usually inserted at or near the center of the fetal surface of the

placenta

Furcate insertion

Marginal insertion

Velamentous insertion

Vasa Previa

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Umbilical Cord AbnormalitiesAnomalities Definition incidence Significance

Furcate insertion Umbilical vessels separate from the cord substance before their insertion into the placenta

Rare

Margnial Inserion Battledore placenta

: cord insertion at the placental

margin

7% at term Cord being pulled off during delivery of the placenta

Velamentous Insertion

Umbilical vessels separate in

the membranes at a distance

from the placental margin Reach surrounded only by a

fold of amnion

1.1% more frequently

with twins 28% of triples

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Vasa Previa Associated with velamentous insertion when some of the fetal

vessels in the membranes cross the region of the cervical os below the presenting fetal part

Incidence : 1/5200 pregnancies

- ½ : associated with velamentous inserion

- ½ : marginal cord insertions and bilobedor, succenturiate-lobed

placentas Risk factors

- bilobed , succenturiate or low-lying placenta

- Multifetal pregnancy

- Pregnancy resulting from in vitro fertilization

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Diagnosis : color Doppler examination (low sensitivity with ultrasound) - Perinatal diagnosis : associated with increased survival (97:44) - Antenatal diagnosis : associated with decreased fetal mortality compared with discovery at delivery Hemorrhage antepartum or intrapartum : vasa previa and a ruptured fetal vessel exists Detecting fetal blood - Apt test - Wright stain : to smear the blood on glass slides stain the smears with Wright stain and examine for nucleated RBC - normally are present in cord blood but not maternal blood - risk of low lying placenta : 80%

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Umbilical Cord Abnormalities Cord Abnormalities capable of impeding blood flow

Knots

false Result from kinking of the vessels to

accommodate to the length of the cord

True Result from active fetal movements Venous stasis

→ mural thrombosis and fetal hypoxia,

causing death or neurological

morbidity

Incidence : 1.1%

Stillbirth incidence : 6%

esp)

high incidence : monoamnionic twins

False knot(Lt), true knot (Rt)

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Loops

: Coiled around portions of the fetus, usually the neck.

longer cords

- one loop of nuchal cord : 20~34%

- Two loops in 2.5 ~ 5%

- three loops : 0.2~0.5%

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coiling of the cord around the neck is an uncommon cause of antepartum fetal death or neurological damage

Entwined cords cause intrapartum complications As labor progresses and there is fetal descent, contractions may

compress the cord vessels

→ fetal heart rate deceleration that persist until the contraction

ceases In labor 20% of fetuses with a nuchal cord have moderate to severe

valiable heart rate deceleration

→ have a lower umbilical artery pH

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Umbilical Cord Abnormalities Torsion and Strictures

Torsion Incidence : rare Result from fetal movements during which the cord normally

becomes twisted fetal circulation is compromised

Stricture More serious Most infants with this finding are stillborn Associated with an extreme focal deficiency in Wharton jelly In monoamnionic twinning, a significant fraction of the high

perinatal mortality rate is attributed to entwining of the umbilical cords before labor

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Umbilical Cord Abnormalities Hematoma

accumulations of blood are associated with short cords, trauma and entanglement

result from the rupture of a varix, usually of the umbilical vein with effusion of blood into the cord

caused by umbilical vessel venipuncture

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Umbilical Cord Abnormalities Cysts

True false

Size

Causes

Small

Derived from remnants of the umbilical vesicle or the allantois

Considerable size

Result from liquefaction of Wharton jelly

: found along the course of the cord and are designate true and false according to their origin

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Placenta and cord – including the number of vessels- should be examined grossly following all deliveries

Decision to request pathological examination will depend on clinical and placental findings

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Pathological placental examination in the following circumstances

Perinatal deathPreterm deliveryFetal growth abnormalitiesFetal malformations HydropsAny other fetal disordersMultiple pregnancyMaternal disordersGross placental lesions

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Placental AbnormalitiesPlacental Abnormalities- Abnormal Shape or Implantation-- Abnormal Shape or Implantation-

Circumvallate(left) and cricummarginate(right) variaties of extrachorial placentas

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Placental AbnormalitiesPlacental Abnormalities- Abnormal Shape or Implantation-- Abnormal Shape or Implantation-

Anomaly of Placental site

www.realpt.co.krVelamentous Insertion

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Vasa previa

Internal cx os

Abnormalities of the Placenta, Umbilical Cord and Membranes

Healthcare

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