Module 16 : Placenta Pathology Flashcards
what are the grades of the placenta
- 0, I, II, III
what is a grade 0 placenta
- homogeneous
- chorionic plate is straight
- < 18 weeks
what is a grade I placenta
- scattered echogenic areas
- subtle undulations
- 18-22 weeks
what is a grade II placenta
- indentations
- linear echogenic area
- 22-36 weeks
what is a grade III placenta
- indentations to basal layer
- cystic areas
- shadowing calcs
- > 36 weeks
what measurement is considered placentomegaly
- > 4cm thick
what was the aetiology of placentomegaly
- maternal diabetes
- maternal anemia
- hydrops
- placental hemorrhage
- intrauterine infection
- partial mole
- chromosomal abnormalities
what does the thickness of the placenta depend on
- gestational age
what does a thin placenta usually result in
- placental insufficiency
- may cause IUGR
what are the 2 etiologys of thin placenta
- vascular deficiencies or infarct
- pre eclampsia - toxaemia of late pregnancy
do intraplacental lesions have any clinical significance
- no
what is a maternal lake
- subchorionic fibrin deposition
- right along placental edge on baby side
what is a placental lake
- perivilus fibrin deposit
- on maternal side
what are the 4 intraplacental lesions
- maternal lake
- placental lake
- intervillous thrombosis
- septal cysts
what are the characteristics of placental infarcts
- microscopic triangular shaped lesions on maternal side of placenta
- due to obstruction of maternal blood flow
- > 10% extensive
- not seen with ultrasound
where do most placenta look like they are in the 1st and early second trimester
- low
what other factor can make the placenta look like
- bladder distended
what are the characteristics of placental previa
- low lying
- marginal or partial or complete
what is the clinical history of placenta previa
- painless vaginal bleeding
what are the characteristics of low lying placenta
- < 2cm from internal os but not overlaying it
what is partial placenta previa
- placenta touches the internal os
what is complete placenta previa
- placenta completely covers the internal os
what are some factors to take into account when assessing for placenta previa
- empty bladder some if fully distended
- if cervix looks longer than 4cm empty bladder
- assess for uterine contraction cervix area
is the placenta is < 2cm away from internal os at 18 weeks scan what is done
- if still same after post void
- patient returns in a few weeks
- EV of the cervix with color doppler is performed at 24-28 weeks (look for vaso previa)
- patient will continue to return every 2 weeks until placenta moves away
protocol for EV with placenta previa
- use condom or on latex probe cover
- experience
- no bleeding for 24 hours
- insert under visualization
- no or ver little pressure against cervix
what are the 3 types of placental shape
- succenturiate
- extrachorial
- membranacea
characteristics of succentruriate placenta -
- accessory lobe
- separate piece of placenta connected to main placenta via vessels within membrane
- increased risk of retained products
- could have vasoprevia
characteristics of extrachorial placenta
- chorionic plate does not extend to edge of placenta
- chorionic membrane extends over placenta
- circummarginate
- circumvallate
- may cause antepartum hemorrhage
what is a circummarginate placenta
- a flat ring at attachment to chorionic plate
what is a circumvallate placenta
- fold in membrane at site of attachment
what is a synechie (amniotic sheet) placenta
- are of scarring in endo does not stretch like rest of uterus
- leave appearance of membrane that just ends
- can see fetal parts on both side of membrane but fetus not attached to it
characteristics of placenta membranacea
- entire uterine surface is covered with placenta
- failure of smooth chorion to compress and become chorionic membrane in embryology
what are the 2 variations in cord insertion
- battledore
- velamentous insertion
what is a battledore cord insertion
- marginal cord insertion
- cord < 2cm from placental edge
what is a velamentous insertion
- cord inserting into the chorionic membrane and then vessels track to placenta
what is vasa previa
- fetal vessels across internal os
what are the 2 common locations of placental hemorrhage
- marginal
- retroplacental
what’re the 3 different formations of placental abruption
- external bleeding no hematoma
- retroplacental hematoma whiteout external bleeding
- subchorionic hematoma with or without bleeding
what may cause a placental abruption
- trauma
- short umbilical cord
- PIH
- maternal vascular disease
- maternal smoking and or drug usage
- fibroids
what are the symptoms of placental abruptions
- preterm labor contractions
- bleeding
- pain
- fetal distress
what is the sonographic appearance of placental abruption
- sonolucent or complex mass beneath placenta or beneath chorionic membrane
what are the 2 tumors of the placenta
- teratoma = rare germ cell tumor
- chorioangioma = vascular well defined complex mass
- mets
what is is placenta Creta and what are the 3 types
- when the placenta does not attach properly to basalts but rather invades beyond the basalis
- accreta
- increta
- percreta
what is accreta
- attaches to myometrium
what is increta
- invades myometrium
what is percreta
- invades through perimetrium and even beyond
what are some characteristics of placenta accreta
- increase risk of bleeding post part
- increase risk after c section because of scar
- may result in hysterectomy
- extremely dangerous for mother
what is the diagnosis of acreta
- very difficult on ultrasound
- only anterior placentas
- absent or severely thinned myometrium
- extension to adjacent organs
- color doppler
what are the common risks with placenta accreta
- placenta previa
- prior c section
