What is known as the 40 week organ?
The placenta is the primary site of ___ and ___ exchange between the fetal and maternal circulations.
The function of the placenta depends on proper ___.
The placental tissues are derived from both the mother (___) and the fetus (___).
The ___ ___ of the uterus develops into the decidual layers.
What is the area underlying the implantation site of the blastocyst called?
What is the tissue overlying the implanted blastocyst called?
decidua parietalis, decidua vera
What is the decidualized endometrium along the remainder of the inner surface of the uterus called?
During implantation, fetal trophoblastic tissue invades the ___ endometrium.
chorionic villi, sinusoidal spaces
Chorionic tissue forms ___ ___ which interact with the maternal decidua to form a network of ___ ___.
What allows close approximation of fetal and maternal circulations for passage of nutrients and oxygen?
What initially covers the entire surface of the chorionic sac?
8, chorion laeve, smooth chorion
After __ weeks, the villi along the surface of the gestational sac opposite the implantation site become compressed as the sac grows. Degeneration of these villi forms the ___ ___, also known as the ___ ___.
The chorion at the base of the implantation site rapidly proliferates, forming the ___ ___.
The ___ ___ becomes the placenta.
As the pregnancy progresses, the chorionic villi branch and gradually develop into a complex system of __-__ subunits or lobules.
A fully developed placenta has a __ shape.
The fetal surface of the placenta is termed the ___ ___ and is continuous with the surrounding chorion.
the structure that attaches a developing fetus to the uterus and that enables the exchange of nutrients, wastes, and gases between the mother and the fetus
The maternal surface of the placenta, which is continuous with the decidua basalis, is termed the ___ ___.
left ventricle, ductus arteriosus
Fetal-umbilical circultaion originates with deoxygenated blood pumped by the ___ ___ of the fetal heart, through the ___ ___, and into the descending aorta.
hypogastric arteries, umbilical cord
Fetal blood continues through the ___ ___ to the umbilical arteries and into the ___ ___.
Within the placenta, the ___ ___ freely divide into multiple capillary branches that course through the villi.
spiral arteries, uterine arteries
Oxygenated maternal blood is delivered to the placenta through the ___ ___ which are branches of the ___ ___.
Maternal blood enters the ___ ___, where it flows around and over the chorionic villi.
There is normally only a ___ layer of tissue separating fetal blood from the maternal blood.
The process of placental circulation permits exchange of oxygen and nutrients with fetal blood in the ___ ___.
The placenta can be identified on sonography as early as ___ menstrual weeks.
The early ___ ___ appears as an area of appearent thickening in the decidualized endometrium.
Between which weeks does the placenta normally appear uniform in echotexture and thickness?
The placenta should measure less than __-__ cm thick.
Another term for intraplacental sonoluciencies is ___ ___.
After ___ weeks, intraplacental sonoluciencies and placental calcifications may begin to appear.
The placental location is usually in the ___ to ___ portion of the uterus, reflecting the site of implantation.
bladder, fibroids, contractions
Apparent location of the placenta can change markedly with distension of the ___, ___ and ___.
Many ___ ___ appear to migrate with growth and expansion of the uterus.
subplacental venous complex
The placenta is separated from the uterus by a ___ ___ ___.
The ___ can usually be identified as a hypoechoic layer beneath the basilar veins.
The ___ ___ can be recognized on sagittal scans as an echogenic line surrounded by a hypoechoic zone of variable thickness.
The ___ ___ can be identified at the leading edge of the cervical canal.
Calcium deposition in the placenta normally occurs as the placental grade increases which is usually in the ___ trimester.
Calcium may be deposited along the ___ ___ of the placenta and along the septa separating the placental lobes.
More than 50% of placentas show evidence of calcification after ___ weeks.
___ ___ results from a very low lying placenta or a placenta which covers the os.
___ ___ results from a lack of formation of a normal decidual plate. The chorionic villi extend into the myometrium and the placenta cannot separate normally following delivery. Hemrrhage can result.
___ ___ results from premature separation of the placenta prior to delivery with formation of a retroplacental blood clot. The blood supply to the fetus is compromised.
A numerical grade is assigned to the placenta based on the appearance of ___ within the placenta.
A grade ___ is given to a placenta with small calcifications.
A grade ___ is given to a placenta with calcification of the basilar plate with comma-like echogenicities extending into the placenta from indentations of the chorionic plate.
A grade ___ is given to a placenta with extensive basal echogenicities and the curvilinear echogenicities extending from the chorionic plate reach the basal plate.
What can cause premature placental calcifications?
DM, Rh sensitization
What can cause delayed placental calcification?
The measurement of the placenta should be taken in the ___ of the placenta and should be perpendicular to it. It should measure less than ___.
maternal diabetes, Rh sensitization, feto-maternal hemorrhage, chronic intrauterine infection, TTTS, chromosomal abnormalities, fetal hydrops
What are some causes of placentomegaly?
IUGR, intrauterine infection, chromosomal abnormalities
What can cause an abnormally small placenta?
A thin layer of placenta covering nearly the entire surface of the uterine cavity
Development of placental tissue separate from the main body of the placenta; accessory placenta
anomaly in which the chorionic plate of the placenta is smaller than the basal plate
when the interface between the placenta and the fetal membranes remain flat
What involves the infolding of fetal membranes and placenta on the fetal surface.
bleeding during delivery
What is a risk with placenta succenturiate?
What is the term that describes placental implantation over the cervical os?
painless vaginal bleeding during the 2nd or 3rd trimester
What is often the symptom for placenta previa?
What is the usual method of delivery for placenta previa?
relationship of the placenta to the internal os
How is placenta previa categorized?
when the placenta completely covers the internal os
when the placenta partially covers the internal os
when the placenta is on the side of the internal os, but does not cover it
when the placenta is in the lower uterine segment but is not touching or on the edge of the internal os
With a complete previa, you should also look for an ___.
What position can the mother be put in to get a good look at the internal os?
What kind of sonography may be useful in seeing the internal os clearly?
You should never perform a ___ scan on a pregnant woman in preterm labor.
Transperineal sonography should be done with a ___ transducer.
abnormal adherence of the placenta to the myometrium is called ___.
invasion of the chorionic villi has occured superficially into the myometrium
invasion of the chorionic villi has occured deep into the myometrium
invasion of the chorionic villi has occured through the myometrium
abnormal adherence of the placenta to the uterine wall; there is complete or partial absence of the decidua basalis; the chorionic villi adhere directly into the myometrium
villi are attched but do not invade the myometrium
villi invade the myometrium
villi penetrate completely through the myometrium to the serosal surface of the uterus
what is the most important risk factor for placenta accreta?
placenta accreta is more common in ___ females, especially those with a Hx of previous ___.
what is common during delivery with a placenta accreta?
what poses a risk with retained placenta fragments?
what is usually required with placenta accreta?
lack of visualization of the myometrium
what may suggest a diagnosis of placenta accreta?
the normal placenta separates from the underlying myometrium prematurely. usually associated with severe pain and vaginal bleeding.
pathology that separates the basal plate of the placenta from the uterine wall
seen at the periphery of the placenta, commonly elevating the edge of the placenta
most small hematomas are ___.
the presence of a hematoma may result in placenta ___ by separation of the chorionic villi from the maternal blood vessels.
If a hematoma involves __-__% of the maternal surface, there will likely be siginificant hypoxia to the fetus.
The cause of bleeding for a hematoma is not usually known but is usually associated with ___.
hematoma the originates from bleeding at the margin of the placenta
a subchorionic hemorrhage has been associated with decidual necrosis from ___ ___.
an acute hematoma may be ___ and ___ with the placenta.
___ hematomas are not as clinically significant.
The most common placental mass is a ___.
Placental masses are ___.
the ___ ___ serves as aconduit for oxygen and nutrients between the mother and fetus.
A normal umbilical cord is __-__ cm long.
An umbilical cord normally inserts near the ___ of the placenta.
The umbilical cord consists of ___ artery and ___ vein.
Whartons jelly, amnion
The umbilical cord is surrounded by ___ ___ and ___.
The umbilical cord is __-__ cm in diameter.
what may be useful in identifying the number of vessels of an umbilical cord?
spectral doppler ri
what should be used on the umbilical cord if evaluating for IUGR?
What is the most common abnormality associated with the umbilical cord?
A 2VC is an ancreased risk for what?
When a 2VC is present, the artery will be ___ and may approach the size of the ___.
The ___ ___ may be counted at the cord insertion into the fetus towards the bladder.
marginal insertion, battledore placenta
Eccentric umbilical cord insertion is common and not clinically significant. this is known as ___ ___ or a ___ ___.
focal umbilical cord masses are uncommon and are usually localized deposits of ___ ___.
a cystic mass of the umbilical cord may represent a ___ ___. it will normally resolve before birth and has been associated with an omphalocele.
a knot in the umbilical cord may result in ___ ___ and fetal distress.
a true knot is associated with a ___ umbilical cord.
cord compression may compromise ___ to the fetus.
a ___ insertion of the umbilical cord in which the major umbilical vessels separate in the fetal membrane before reaching the placental disk. this could lead to a greater chance of cord trauma with bleeding during delivery.