placental and umbilical cord pathology

the placenta includes:

• chorion frondosum (fetal portion)

• decidua basalis (maternal portion)

• placental substance (placental tissue itself)

functions of the placenta:

• respiration

• nutrition

• excretion

• storage

• protection

• hormonal

deoxygenated fetal blood is carried to the placenta by which vessles?

the 2 umbilical arteries

oxygenated blood returns to the fetus through which vessel?

a single umbilical vein

sonographic appearance of the placenta:

• homogeneous crescent-shaped structure with medium to bright echotexture

• evaluated after 12 wks but can be visualized around 9-12 wks

anterior placenta

the placenta attaches to the front wall of the uterus, closest to the abdomen

effects of an anterior placenta on pregnancy:

it may make it difficult to feel the baby’s kicks and movements

posterior placenta

the placenta attaches to the back wall of the uterus, closest to the spine

effects of a posterior placenta on pregnancy:

fetal movements can be felt more strongly as the baby is positioned closer to the front of the belly

fundal placenta

the placenta is positioned at the top of the uterus, near the openings of the fallopian tubes

effects of a fundal placenta on pregnancy:

unlikely to obstruct the cervix, causing placenta previa or a low-lying placenta, making vaginal delivery more likely

placental grading

ultrasound grading system of the placenta based on its maturity

placental grade 0:

• less then 18 wks

• uniform echogenicity

• smooth chorionic plate

placental grade I:

• 18-29 wks

• functional calcification/hyperechoic areas

• subtle indentations of chorionic plate

placental grade II:

• greater than 30 wks

• calcifications, hyperechoic areas

• deeper indentations of the chorionic plate

placental grade III:

• greater than 39 wks

• significant calcifications

• deep indentations reaching up to the basal plate

placental thickness

increases with gestational age in a linear fashion

sonographic appearance of placental thickness:

• can be seen getting 1 mm thicker per wk

• normal thickness after 23 wks - 1.5 - 4 cm

placentomegaly

• increased placental thickness

• >4 cm in thickness

placentomegaly is associated with:

• gestational diabetes

• rH isoimmunization

• maternal infection

• maternal anemia

• chromosomal abnormalities

decreased placental thickness

<1.5 cm (A-P)

decreased placental thickness is associated with:

• pre-eclampsia

• IUGR (intrauterine growth restriction)

• diabetes predating

• intrauterine infection

placenta previa

the placenta is located over or near the internal os of the cervix

complete placenta previa

the placenta completely covers the internal os

partial placenta previa

the placenta partially covers the internal os

marginal placenta previa

the placenta just reaches the internal os but does not cover it

low-lying placenta

the placenta extends into the lower uterine segment but does not reach the internal os

clinical symptoms of placenta previa:

painless, bright red vaginal bleeding in the 2nd and 3rd trimesters

placenta previa cannot be officially diagnosed until:

the 3rd trimester because it can migrate away from the cervix as the uterus expands with the growing gestation

placental invasion

• group of conditions resulting from defective decidual formation

• causes abnormal attachment of the placenta to the uterine wall

placenta accreta

chorionic villi are in direct contact with the myometrium but do not invade it

placenta increta

chorionic villi invade the myometrium

placenta percreta

chorionic villi penetrate the myometrium

placental insufficiency/uteroplacental vascular insufficiency

• the placenta is unable to deliver an adequate supply of nutrients and oxygen to the fetus and thus cannot fully support the developing baby

• occurs when the placenta either does not develop properly or because it has been damaged

• can result in IUGR

causes of placental insufficiency:

• diabetes

• post-term pregnancy

• preeclampsia (HTN, proteinuria, edema)

• smoking

• alcohol consumption

• drugs

succenturiated placenta

presence of 1 or more accessory lobes connected to the body of the placenta by blood vessels

risks of a succenturiated placenta:

• retained placenta tissue after delivery

• the blood vessels connecting the main placenta will be at risk of rupture

• fetal growth issues - IUGR

placental abruption/abruptio

• premature placental detachment

• often results in fetal death and may result in maternal death

• can occur any time during pregnancy

sonographic appearance of a normal retroplacental complex:

• located behind the placenta

• retroplacental complex of blood vessels

• identified as a hypoechoic space or as a poor echogenic region with linear horizontal echoes representing venous channels

identifying a normal retroplacental complex region is crucial for ruling out what?

placental abruption

sonographic appearance of a placental abruption:

• a hematoma in the area behind the placenta appearing as a thickened hypoechoic, heterogeneous or anechoic region within the retroplacental complex space

• no vascularity within the retroplacental hematoma

marginal abruption

the separation occurs at the edges of the placenta, leading to visible vaginal bleeding but often without significant impact on fetal oxygen supply (low-pressure bleeding)

partial abruption

the placenta detaches partially from the uterine wall, which can cause bleeding and may compromise the fetus depending on the severity

complete abruption

the placenta fully separates from the uterus, leading to high-bleeding and a significant risk to both the mother and baby due to loss of oxygen and nutrients (high-pressure bleeding)

clinical symptoms of placental abruption:

• vaginal bleeding

• abdominal pain

• back pain

• uterine tenderness

placental venous lakes

• pockets of pooled maternal blood located in the intervillous space

• not necessarily associated with any uteroplacental complication if found during 2nd or 3rd trimester

placental venous lakes can be abnormal if:

very diffuse - taking up more than 10% of the placenta or if seen very early in the pregnancy

placental chorioangioma

• most common tumor of the placenta

• benign vascular tumor of the placenta

umbilical cord

essential link for oxygen and important nutrients between mother, placenta and fetus