Placenta & Umbilical Cord Flashcards
What are the functions of the placenta?
Respiration Nutrition Excretion Protection Storage Hormone Production pg. E 160 O 412
What is the placenta formed from?
chorionic villi (decidua frondosum) and
maternal decidua basalis
pg. E 160 O 411
What is the functional unit of the placenta?
cotyledon
pg. E 160
How many cotyledons are there in the typical placenta?
12-20
pg. E 160
What does a grade 0 placenta look like?
no calcifications
smooth chorionic surface
up to 28-31 weeks
pg. E 161 O 413
What does a grade 1 placenta look like?
scattered calcifications
slight contouring of chorionic surface
31-36 weeks
pg. E 161 O 413
What does a grade 2 placenta look like?
basal layer calcifications
lobular chorionic surface
36-38 weeks
pg. E 161 O 413
What does a grade 3 placenta look like?
basal layer calcifications cotyledon calcifications infarcts "fallout areas" 38 weeks + pg. E 161 O413
What is a extrachorial placenta? and what are the names of each?
membranous chorion does not extend to edge
2 types: circumvallate and circummarginate
pg. E 162
What is a circumvallate placenta?
membranes insert away from placenta edge toward the center
has central chorionic ring surrounded by thickened amnion and chorion
pg. E 162 O 415
What is the sonographic appearance of a circumvallate placenta?
rolled up placenta edge irregular fold or thickening of placenta upturned placental edge has cystic spaces thick placental cord insertion pg. O 415
What is a circummarginate placenta?
central attachment of the membranes without a central ring
pg. E 1162
What can happen with a circumvallate placenta?
early separation from uterine wall risk of abruption IUGR premature labor perinatal death pg. E 162 O 415
What are the accessory types of placentas?
succenturiate
bipartite
annular
pg. E 162
What is a succenturiate placenta?
results from the lack of adjacent chorionic villi to atrophy
additional placental tissue next to main placenta connects by blood vessels
pg. E 162 O 415
What is a bipartite placenta?
placenta divided into 2 lobes but united by vessels and membranes
pg. E 162
What is an annular placenta?
ring shaped placenta
pg. E 162
When is a placenta considered to be placentomegaly?
> 5 cm AP/ > 4 cm
pg. E 163 O 412
What are the causes of placentamegaly?
gestational diabetes Rh isoimmunization maternal infection chorioangioma multiple gestation maternal anemia hydrops fetalis sacrococcygeal teratoma partial mole chromosome anomalies abruption pg. E 163
When is a placenta too thin?
< 1.5 cm
pg. E 163
Why might a placenta be too thin?
pre-eclampsia IUGR diabetes (before pregnancy) intrauterine infection pg. E 163
What is placenta previa? what are the different types?
placenta near/on cervical os complete partial marginal low lying vasa pg. E 163 O 414
What are the risk factors for placenta previa?
advanced maternal age multiparity previous C-section therapeutic abortion ( due to scarring) closely spaced pregnancies pg. E 164 O 413
What are the symptoms of placenta previa?
painless vaginal bleeding in the 3rd trimester
pg. E 164 O 413
What are complications of placenta previa?
premature delivery
maternal hemorrhage
increased risk of placenta accreta, stillbirth, IUGR
pg. O 414
What is a complete previa?
placenta completely covers internal cervical os
pg. E 164 O 414
What is a partial previa?
placenta partially cover internal cervical os
pg. E 164 O 414
What is a marginal previa?
edge of placenta abuts cervical os
pg. E 164 O 414
What is a low lying placenta?
edge of placenta lies within 2 cm of cervical os
pg. E 164 O 414
What is a vasa previa?
fetal vessels cross over the internal os
pg. O 414
What is abruptio placenta?
premature separation of all or part of a normally implanted placenta
pg. E 165 O 414
What are risk factors for placental abruption?
maternal hypertension advanced maternal age multiparity smoking trauma cocaine fibroids pg. E 165 O 414
What are the symptoms for placental abruption?
severe pelvic pain
vaginal bleeding
pg. E 165 O 414
What are the sonographic findings of abruptio placenta?
elevation of placenta from UT wall
retroplacental fluid collection
thickened placenta
pg. E 165 O 414
What is placenta accreta?
chorionic vill are in direct contact w/ myometrium but do not invade
pg. E 166 O 414
What is placenta increta?
chorionic villi invade myometium
pg. E 166 O 414
What is placenta percreta?
worst; chorionic villi invade UT serosa or bladder
pg. E 166 O 414
What are placental lakes?
large pools of venous blood within placenta
pg. E 167 O 415
What is a placental infarct?
Ischemic necrosis of placental villi resulting from interference w/ maternal blood flow to intervillous space
pg. E 167 O 415
What are fibrin deposits?
pooling of maternal blood in subchorionic space
clinically insignificant
pg E 167 O 415
What is an intervillous thrombosis?
fetal bleeding into intervillous space
clinically insignificant
pg. E 167 O 415
What are the sonographic findings of a placental infarct?
anechoic areas in placenta
absence of blood flow on Doppler
pg. E 167
What is a subchorionic hematoma?
accumulation of blood beneath the chorion
pg. E 168
What is a chorioangioma?
placental hemangioma
vascular solid tumor of placental tissue
pg. E 168
What is choriocarcinoma?
malignant form of trophoblastic disease seen as a intraplacental mass
pg. O 416
What surrounds the umbilical cord?
Wharton’s jelly
pg. E 168 O 416
What is the umbilical cord formed from?
fusion of the yolk stalk and allantoic ducts
pg. O 416
What is the average length of the umbilical cord?
1st tri: equal to CRL
2nd and 3rd tri: 40-60 cm
pg. O 417
What is the most common umbilical cord abnormality?
single umbilical artery
pg. E 169
What are the associated abnormalities with single umbilical cord?
GU anomalies Trisomy 13 and 18 cardiovascular anomalies CNS anomalies omphalocele pg. E 169 O 417
What is an umbilical cord cyst?
nonvascular anechoic enlargement of umbilical cord
pg. E 170 O 417
What is a nuchal cord?
cord that wraps around the neck
pg. E 170 O 417
What is cord prolaspe?
cord protruding through cervix
pg. E 170 O 417
What is a velamentous insertion associated with?
vasa previa
pg. E 171
What is a velamentous cord insertion?
umbilical cord inserts into the membranes before the placenta
pg. O 417
What is umbilical vein thrombosis?
torsion or knotting of cord leading to no flow to fetus (death)
pg. E 171 O 417
What is a false knot?
coiling of the vessels appearing as a knot
pg. E 171 O 417
What is another name for a marginal insertion?
battledore insertion
pg. E 172 O 415
What is a battledore placenta?
cord inserts into the periphery of the placenta
pg. E 172 O 415
When taking a RI, what should the umbilical cord S/D ratio be for 25-29 weeks?
3.3 S/D ratio
When taking a RI, what should the umbilical cord S/D ratio be for 29-33 weeks?
2.9 S/D ratio
When taking a RI, what should the umbilical cord S/D ratio RI be for 33-40 weeks?
2.5 S/D ratio
In a normal pregnancy, the placental thickness should be relatively equal to what?
Gestational age in weeks + 10mm
URR EXAM
Does the umbilical vein carry oxygenated blood or deoxygenated blood?
Oxygenated blood from mother to fetus
Do the umbilical arteries carry oxygenated blood or deoxygenated blood?
Deoxygenated blood from fetus to placenta
Where does an allantoic cyst develop?
Umbilical cord
