placenta/umbilical cord Flashcards by Julie Littlefield

A discoid, highly vacular organ which weighs about 600g at delivery and is usually 2-4 cm thick.

Placenta

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The maternal surface is highly irregular and divided into what?

cotyledons

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THe fetal surface of the placenta is very smooth and covered by what? (2)

chorionic and amnionic membranes

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What is the most important function of the placenta?

exchange of oxygen, waste products, and nutrients between mom and fetus

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What does the placenta convert fetal steroids to ?

estrogen

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Why does the placenta secrete progesterone?

to keep the myometrium quiet (secretes HCG in first trimester)

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What is formed by proliferation of chorionic villi or chorionic frondosom from trophoblastic tissue and the maternal decidua basalis?

Placenta

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Each functional unit of the placenta is known as what?

cotyledon

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How many cotyledons per placenta?

12-20

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Do we do placental grading anymore?

NO, used in 80’s and 90’s in hopes to associate it with the fetal well being

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What are extra chorial types?

Placentas in which the membranous chorion does not extend to the edge of the placenta.

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What are the two types of extra chorial?

Circumvallate placenta and circummarginate placenta

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What is a small central chorionic ring which is surounded by thickened amnion and chorion called? ( this could predispose early separation from the uterine wall, creating antepartum bleeding and threatenig abortion. )

Circumvallate placenta

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What is a central attachment of the membranes without a central ring?

Circummarginate placenta

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What are the accessory types of the placenta?

Succenturiate, bipartite, annular

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An accessory cotyledon with vascular connections to the main placenta???

Succenturiate

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Why is succenturiate type of placenta dangerous?

Dangerous at delivery because the vessels between can rip, causing massive bleeding. Also, if the vessels cross anterior to the internal os of the cervix, things can get dicey at delivery.

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What is it called when the placenta is divided into two lobes but united by primary vessels and membranes?

Bipartite

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What is a ring-shaped placenta, wrapping around the entire uterus or at least a large circumference of it?

Annular

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What is the typical thickness of the placenta?

less than 5cm (AP)

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What are some causes for placental thickness?

Gestational diabetes
Rh isoimmunization
Maternal infection
Multiple gestation
Chorioangioma
Maternal anemia
Hydrops fetalis
Sacrococcygeal teratoma
Partial Molar preg.
Placental abruption
chromosomal abnormalities

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A retro placental hematoma, which causes the mother terrible pain? Has a masslike appearance.

Placental abruption

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Do we measure placental thickness?

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What are some causes for decreased placental thickness? less than 1.5 cm

Maternal preeclampsia
IUGR
Maternal diabetes, not gestational
intrauterine infection

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When placental tissue implants near or even on top of the internal os of the cervix

Placenta previa

What causes placenta previa?

abnormally low implantation of the blastocyst

Placenta previa is more common in what situations?

multiparous women and patients with prior C-section or uterine surgery, and in women with intrauterine scarring (D&C's)

What are the classic symptoms of placenta previa?

PAINLESS vaginal bleeding during the 3rd trimester | ***********************************************************

The best diagnosis of placenta previa is in the 3rd trimester. WHY?

1st and 2nd trimester may have previa but with uterine growth the placenta moves up also called placental migration

Which is more likely to move up (migrate) an anterior placenta or posterior placenta?

anterior (anterior wall can expand more)

What can lead to a false positive diagnosis of previa? PITFALL

over distended maternal bladder, or have a focal myometrial contraction in lower uterine segment

When the placenta completely covers the internal cerival os. (symmetric, assymetric)

complete previa/total previa

Placenta partially covers the internal cervical os

Partial previa

The placenta encroaches on the internal os but does not cross it

marginal previa

When the placenta is in the lower uterine segment within 2cm of the internal os. This measurement is important. ******************

Low-lying placenta

Premature separation of all or part of a normally implanted placeta from the myometrium.

abruption

What are symptoms of placenta abruption?

SEVERE abdominal PAIN with or without vag bleeding

Predisposing conditions to placental abruption

``` maternal hypertension advanced maternal age multi parity maternal vascular disease smoking trauma cocaine use uterine fibroids ```

Two types of abruption?

concealed, external abruption

Abruption that occurs in 20% of cases and hemorrhage is confined to the uterine cavity. The detachment can be complete and the consequences are severe because so much blood is lost between the mother and the fetus and pocketed between the placenta and uterine wall, instead of going to the baby.

Concealed

Abruption that occurs when blood drains through the cervical os and the patient presents clinically wth painful vaginal bleeding. Detachment is usually not as severe as concealed.

External abruption

Abnormal attachment of the placenta to the uterine wall.

Placental invasion

What is the most strong predisposing fctor in placental invasion?

prior uterine surgery (c-section)

low lying placenta or placenta previa that is anterior, and history of prior c-section are likely (60%chance) to result in what

placental invasion highly likely | **********************************

3 types of placental invasion

placenta accreta placenta increta placenta percreta

Chorionic villi are in direct contact with myometrium but do not invad it

placenta accreta

Chorionic villi invade the myometrium

placenta increta

Chorionic villi go through the myometrium to the serosa or outer covering of the uterus and often g into the bladder

placenta percreta

Large pools of maternal venous blood within the placenta. they are of no consequence clinically and appear as anechoic or hypoechoic round areas within the placenta which may exhibit slow venous flow under real-time conservation.

placental lakes

the pooling of maternal blood in the subchorionic space (superficially). of not clinical significance

fiber and deposition

caused by fetal bleeding into the intervillous space. no association with Rh incmpatibility ******* Of no significance

intervillos thrombosis*****************************

ischemic necrosis of placental villi from interference with maternal blood flow to the intervillous space

placental infarction (seen with hypertensive patients) (intervillous thrombosis is common with this) (anechoic or hyporechoic areas seen in placenta on ultrasound but no flow)

An accumulation of blood beeneath the chorion. Common finding in the 1st trimester. Radiologist wont mention it.

subchorionic/sub membranous hematoma

what is the most positive predictive value in predicting a good outcome for the fetus?

fetal heart beat

Vascular tumor of the placental tissue which occurs in 1 in 5000 pregnancies

chorioangioma

What are complications with chorioangioma when the tumors are large? >5cm

Polyhydramnios and fetal hydrops | associated with increased maternal serum alpha-fetoprotein

On ultrasound a solid well circumscribed placental mass, possibly near the cord insertion site.

chorioangioma

What does the umbilical cord contain?

2 umbilical arteries (deoxygenated blood away from the fetus) 1 Umbilical vein (oxygenated blood from mom to fetus)

What gives the candy cane appearance?

Umbilical arteris are longer than the vein and are twisted around the vein

what is the cord surrounded by?

protective Wharton's jelly

WHat is the function of the umbilical cord

to allow the exchange of oxygenated blood and wastes between the mother and the fetus

How long is the cord at term?

50-60cm

What is the most commonly encountered cord abnormality in 1% of all pregnancies

two vessel cord (only one ear of mickey mouse) use color around bladder and will see only one artery

Is a two vessel cord concerning?

the fetus is not at risk due to 2 vessel cord but it could be associated with fetal abnormalities

What abnormalities may be associated with two vessel cord?

``` unilateral renal agenesis or other genitourinary tract anomalies trisomy 13,18,21 cardiovascular anomalies omphalocele central nervous system anomalies ```

Wharton's jelly accumulation can appear as what?

umbilcal cord cyst

Umbilical cord cysts

developmental and usually asymptomatic/ originate as remnants of the omphalomesenteric duct when they are close to the fetus/ originate from allantoic duct when small and located away from the fetus

How do you differentiate an umbilical cord cyst from a umbilical vein Varix?

Varix will have flow but no flow in a cyst

Are nuchal cords important to image?

No, they are inconsequential. Occur in 2nd and 3rd trimester and you never documet them. Dr will check for the cord around the neck before delivery.

When the cor protrudes through the cervix or next to a presenting part in an open cervix.

Umbilical cord prolapse

Is umbilical cord prolapse important?

Yes absolutely an emergency. THe baby can asphyxiate by cuttingoff his own blood supply

"vessesls first" When cord crosses the cervical os, passing between the cerivx an the presenting part when membranes are intact. associated with velamentous insertion of the cord

vasa previa

What can occur secondary to knotting or torsion of the cord but is not commoly associated with that?

Umbilical vein thrombosis ( most likely, it may occur after percutaneous umbilical cord blood sampling procedure or intrauterine transfusion )

When is umbilical vein thrombosis more frequently seen?

in infants of diabetic mothers and in fetuses with nonimmune hydrops (outcome is almost always fetal death )

What is rare an associated with monochorionic, monoamniotic twins?

umbilical knots

When attachment of the cord is to the membranes rather than to the placental mass itself?

velamentous insertion

The cord travels for some length under the membranes before it attaches to the edge of the placenta

velamentous insertion ( can be associated with IUGR, preterm birth, and congenital anomalies )

Another name for marginal insertion? *************

Battledore insertion (KNOW)

When the attachment of the cord is at the edge of the placenta instead of centrally?

Marginal insertion ( battledore insertion )