SM_210b: Anatomy and Physiology of Implantation Placentation Flashcards
Placenta has a ____ circulatory system
Placenta has a dual circulatory system (fetal and placental)
Placenta provides ____
Placenta provides fetal nourishment from maternal blood without allowing direct mixing with fetal blood
Describe three compartments of placenta
Three compartments of placenta
- Membranes: maternal + fetal
- Placental disc: maternal + fetal
- Umbilical cord: fetal
Three compartments of placenta are ____, ____, and ____
Three compartments of placenta are membranes, placental disc, and umbilical cord
- Membranes: maternal + fetal
- Placental disc: maternal + fetal
- Umbilical cord: fetal
Membranes of placenta have 3 layers: ____, ____, and ____
Membranes of placenta have 3 layers: amnion, chorion, and parietal decidua
- Amnion: fetal epithelial layer
- Chorion: fetal mesodermal layer
- Parietal decidua: maternal layer containing remodeled maternal blood vessels
Umbilical cord is composed of ____ including ____ and ____ and is cushioned by ____
Umbilical cord is composed of 3 vessels including 1 vein and 2 arteries and is cushioned by Wharton’s jelly
Placental disc components of fetal origin are ____ and ____
Placental disc components of fetal origin are chorionic plate (fetal surface) and villous tree
- Chorionic plate (fetal surface): arborizing fetal vessels
- Villous tree: fetal vessels surrounded by trophoblasts
Placental disc components of maternal origin are ____ and ____
Placental disc components of maternal origin are basal plate (maternal surface) and intervillous space (maternal blood)
- Basal plate (maternal surface): decidua (maternal), remodeled vessels (maternal), extravillous trophoblast (fetal), fibrinoid (fetal)
This is the ___
This is the chorionic plate (fetal surface)
Chorionic villi are ____
Chorionic villi are embryo derived structures containing fetal blood vessels and surrounded by trophoblast
- As gestation progresses, villi branch like branches of a tree
Describe the syncytiotrophoblast
Syncytiotrophoblast
- Outer layer
- Multinucleated (syncytium)
- Permeable to oxygen + nutrients
- Not permeable to blood
Describe the cytotrophoblast
Cytotrophoblast
- Inner layer
- Stem cells
- Continuous -> discontinuous
Describe the histology
Histology of placenta
Describe remodeled maternal vessels
Remodeled maternal vessels lose muscle and become lined by extravillous trophoblast cells to create low resistance vessels that supply blood to the intervillous space
Normal implantation is into ____
Normal implantation is into uterine wall
Ectopic pregnancy is ____
Ectopic pregnancy is implantation outside uterine wall, usually in fallopian tube
- High risk of rupture and hemorrhage
Placenta previa is ____
Placenta previa is low implantation over the cervical internal os
- Placenta blocks vaginal delivery
- Risks: maternal hemorrhage, fetal hypoxic injury
- Cesarean section
Normal implantation is into the ____ which separates at birth
Normal implantation is into the decidua which separates at birth
- Without decidua, placenta on myometrium (adherent)
Placenta accreta is ____
Placenta accreta is implantation on myometrium
Placenta increta is ____
Placenta increta is invasion into myometrium
Placenta percreta is ____
Placenta percreta is invasion through uterine serosa into adjacent structures
Describe placenta increta
Placenta increta
- Placenta invades myometrium
- Often C-section
- Hysterectomy
____ placental infections are most common
Ascending placental infections are most common
- Vaginal canal -> amniotic fluid
- Maternal inflammatory response: chorioamnionitis
- Fetal inflammatory response: inflammation in umbilical cord and placental vessels
Hematogenous infection (maternal sepsis) infects ____ and is ____
Hematogenous infection (maternal sepsis) infects intervillous spaces and is villitis
Ascending placental infections are usually ____ caused by ____ or ____
Ascending placental infections are usually bacterial caused by maternal genitourinary flora or maternal gastrointestinal flora
- Maternal genitourinary flora: Mycoplasmas, Gardnerella
- Maternal gastrointestinal flora: group B Strep, E. coli, Enterococcus
- Occassionally: Candida spp, HSV
Maternal inflammatory response to ascending placental infections is ____ originating from ____
Maternal inflammatory response to ascending placental infections is maternal neutrophils (acute inflammatory cells) originating from decidual vessels membrane and basal plate
Three stages of maternal response to ascending placental infections are ____, ____, and ____
Three stages of maternal response to ascending placental infections
- Subchorionitis
- Chorioamnionitis
- Necrotizing amnionitis
Fetal inflammatory response to ascending placental infections is ____ originating from ____
Fetal inflammatory response to ascending placental infections is fetal neutrophils originating from fetal vessels
- Fetal vessels are in umbilical cord and on chorionic plate
Three stages of fetal response to ascending placental infections are ____, ____, and ____
Three stages of fetal response to ascending placental infections
- Phlebitis (vein)
- Arteritis (artery)
- Necrotizing funisitis (necrosis in Wharton’s jelly)
Hematogenous placental infections can be caused by ____, ____, or ____
Hematogenous placental infections can be caused by bacteria, viruses, or toxoplasmosis
- Bacteria: syphilis, TB, Listeria
- Viral: Cytomegalovirus, Rubella
Chronic villitis variant of hematogenous placental infection involves ____
Chronic villitis variant of hematogenous placental infection involves infiltration of villi by lymphocytes, plasma cells, and / or histiocytes
- Cytomegalovirus, toxoplasmosis, syphilis
Acute villitis variant of hematogenous placental infection involves ____
Acute villitis variant of hematogenous placental infection involves infiltration of villi by neutrophils
- Listeria (abscesses)
- Sometimes E. coli, TB
Maternal vascular malperfusion is ____ that presents with ____ and ____
Maternal vascular malperfusion is pathologic changes associated with uteroplacental insufficiency that presents with HTN and preeclampsia
In normal placentas, maternal vessels are ____ so they have ____ resistance and ____ flow
In normal placentas, maternal vessels are remodeled by trophoblasts so they have low resistance and high flow
In maternal vascular malperfusion, maternal vessels ____ so they have ____ resistance and ____ flow
In maternal vascular malperfusion, maternal vessels retain their muscular walls so they have high resistance and low flow
In maternal vascular malperfusion, decreased maternal blood flow leads to ___
In maternal vascular malperfusion, decreased maternal blood flow leads to chronic hypoxia
- Placenta adapts by increasing villous branching -> smaller terminal villi -> increased surface area for oxygen / nutrient exchange -> accelerated villous maturation
In maternal vascular malperfusion, vessel injury consists of ____ and ____
In maternal vascular malperfusion, vessel injury consists of replacement of necrotic wall by fibrinoid necrosis and foamy macrophages (atherosis)
Damaged placental vessels ____, leading to ____
Damaged placental vessels thrombose, leading to placental infarction
When placenta infarcts, ___
When placenta infarcts, intervillous space collapses and villi die
Describe retroplacental hematoma / abruption
Retroplacental hematoma / abruption
- Damaged vessels can rupture -> large retroplacental hematomas -> premature separation of placenta from uterus
Women with retroplacental hematoma / abruption usually present with ____
Women with retroplacental hematoma / abruption usually present with painful bleeding
(can be life-threatening)
Retroplacental hematomas extend into and infarct the ___
Retroplacental hematomas extend into and infarct the disc
Fetal vascular malperfusion is ____ caused by ____
Fetal vascular malperfusion is pathologic changes associated with fetoplacental insufficiency caused by processes that obstruct / compromise blood flow from the fetus to the placenta
Fetal vessels are ____, ____, ____, and ____
Fetal vessels are umbilical cord, chorionic vessels, stem villous vessels, and villous capillaries
____ is sole source of oxygenated / nutrient-rich blood to fetus
Umbilical cord is sole source of oxygenated / nutrient-rich blood to fetus
- Abnormal cords compromise delivery of this blood
Normal umbilical cords are inserted ____ on the disc and have ____
Normal umbilical cords are inserted centrally / paracentrally on the disc and have loose twists
Abnormal cord insertion is ____ and risks ____
Abnormal cord insertion is cord inserted into membranes (velamentous insertion) and risks kinks / injury
Abnormal cord twisting can lead to ___, ___
Abnormal cord twisting can lead to strictures, constricting blood flow
- Normal cords have 1-3 twists / 10 cm
Mechanical obstruction of umbilical cord can be ____ or ____
Mechanical obstruction of umbilical cord can be knots or entrapment
- Neck entrapment (nuchal cord)
- Body entrapment (body cord)
Thrombus formation is governed by ____ which consists of ____, ____, and ____
Thrombus formation is governed by Virchow’s triad, which consists of stasis, hypercoagulability, and vascular damage
- Stasis: cord compression / stricture, heart failure / anomalies, polcythemia
- Hypercoagulability: thrombophilic disorders, acquired or gentic
- Vascular damage: infection, meconium, mechanical
Pathologic findings of fetal vascular malperfusion are ____ and ____
Pathologic findings of fetal vascular malperfusion are thrombosed vessel and apoptosis of fetal vessels (avascular villi)
Describe consequences of fetal vascular malperfusion
Fetal vascular malperfusion consequences
- High grade fetal vascular malperfusion can result in fetal neurologic damage (i.e. cerebral palsy)
- In most severe cases, can result in intrauterine or neonatal fetal demise
Dizygous (fraternal) placentas are ___
Dizygous (fraternal) placentas are two eggs each fertilized by their own sperm
Monozygous (identical) placentas are ____
Monozygous (identical) placentas are 1 egg fertilized by 1 sperm
Describe chorions in twin placentas
Chorions in twin placentas
- Most twins have 2 chorions (dichorionic): 1/3 monozygous, 2/3 dizygous
- Monochorionic: nearly always monozygous
Describe amnions in twin placentas
Amnions in twin placentas
- Dichorionic always has two amniotic sacs (diamniotic)
- Monochorionic has one or two (monoamniotic): rarely monochorionic monoamniotic twins can be conjoined
All dizoygotic twins are ___ and placental discs can be ___
All dizoygotic twins are dichorionic diamniotic and placental discs can be either fused or separate
For monozygotic twins, chorionicity and amniocity are dependent on ___
For monozygotic twins, chorionicity and amniocity are dependent on when the ovum divides after fertilization
- < 2 days: dichorionic diamniotic
- 2-8 days: monochorionic diamniotic
- > 8 days: monochorionic monoamniotic
Dichorionic placenta has a dividing membrane that is ____
Dichorionic placenta has a dividing membrane that is thick, obaque, and firmly adhered to the disc because of the intervening chorion
- Could be either dizygotic or monozygotic
Monochorionic placenta has a dividing membrane that is ____
Monochorionic placenta has a dividing membrane that is thin, translucent, and not adhered to the disc because no intervening chorion
- Almost always monzygotic
Twin pregnancies are at increased risk of ____
Twin pregnancies are at increased risk of developing preterm labor
- Monochorionic placentas have additional risks: twin twin transfusion and twin reversed arterial perfusion, cord entanglement in monochorionic monoamniotic twins, more congenital malformations
Monochorionic twin placenta is almost always ____ and has ____
Monochorionic twin placenta is almost always monozygotic and has intertwin vascular connections
Problems of intertwin vascular connections are ____ and ____
Problems of intertwin vascular connections are twin twin transfusion and twin reversed arterial perfusion
Twin twin transfusion syndrome involves ____ and ____
Twin twin transfusion syndrome involves anemic donor twin and plethoric recipient twin
Twin reversed arterial perfusion involves a ____ and ____
Twin reversed arterial perfusion involves a pump twin (hydrops) and acardiac twin
Gestational trophoblastic disease involves ____
Gestational trophoblastic disease involves proliferative placental tissue tumors that develop from trophoblasts
- Produce B-hCG (tumor marker)
B-hCG is a tumor marker for ____
B-hCG is a tumor marker for gestational trophoblastic disease
- Gestational trophoblastic disease: proliferative placental tissue tumors
Gestational trophoblastic disease classificiation includes ____ and ____
Gestational trophoblastic disease classificiation includes hydatidiform mole (80%) or choriocarcinoma
- Hyaditidiform mole: complete or partial
Molar pregnancies have ____
Molar pregnancies have overrepresentation of paternal chromosomes
Describe complete molar pregnancies
Complete molar pregnancies
- Grape-like swollen villi
- Diffuse trophoblast hyperplasia
- Cystic swelling of all chorionic villi
Describe partial molar pregnancies
Partial molar pregnancies
- Only some villi are edematous and trophoblast hyperplasia only focal
- Embryo present but often abnormal and rarely visible
Compare complete and partial molar pregnancies
Complete and partial molar pregnancies
Choriocarcinoma is a ____
Choriocarcinoma is a pure trophoblast proliferation with NO chorionic villi
- Highly malignant
- Rapidly invasive and widely metastasizing (especially to lung, brain, and liver)
- Responds well to chemotherapy
Choriocarcinoma appears as ____ on histology
Choriocarcinoma appears as poorly differentiated syncytiotrophoblasts on histology
