Placenta and umbilical cord Flashcards
Placenta is formed by the
decidua basalis and decidua frondosum
Physiology of placenta
- vital support organ for developing fetus
major functioning unit of placenta
chorionic villus
- contains intervillous space
maternal blood enter the
intervillous space
Placenta Functions
Respiration
- oxygen in maternal blood passes through plac into fetal blood
- co2 returns through the plac to maternal blood
Placental Function
Nutrition
pass from maternal blood through plac to fetal blood
Placenta Function
Excretion
- wast products cross from the fetal blood through the plac to maternal blood
Placenta Function
Protection
provides a barrier between the mother and fetus, protecting the fetus from maternal immune rejection
Placenta Function
Storage
carbs, proteins, calcium, and iron are stored in plac and released into fetal circulation
Placenta Function
Hormone Production
produces hCG, estrogenm and progesterone
Plac Size
- varies with gestational age
- 2-3 mm thickness
- should exceed 4 cm
Normal sono appearence of placenta in 1st trimester
thickened area of hyper gestational age
Normal sono appearence of placenta in 2nd and 3rd trimester
- smooth, homogeneous medium-gray structures
- smooth border and edges
- hyperechoic chorion plate
cystic areas directley behind chorion plate
fetal vessels
plac may be located
ant, post, fundal, rt later, and lt lateral
plac may be implanted over or near
cervical os (previa)
grading is dependent on
echogenicity attributed to calcium and fibrous deposition with advancing age
cause premature maturation of plac
maternal hypertensions, smoking, iugr, multifetal gestation
- no calcification
- smooth basal and chorionic plate
- 1st and early second
Grade 0
- scattered calification throughout the plac
- most common up until 34 w
Grade 1
- calcifications along basal palte
- chorionic plate becomes slightly lobular
Grade 2
- marked calcifications
- distinct hyper loculations extending from chorionic to basal plate
- abnormal before 34 w
Grade 3
- in front of fetus relative to birth canal
- primary cause of painless vag bleeding in 3rd trim
Plac previa
plac previa risk factors
advanced maternal age, multiparity, previous c section, theraputic abortion, or closely spaced pregnancies
plac previa complications
premature delivery, life-theratening maternal hemorrhage, increased risk of plac accretta, stillbirth, and iugr
Plac previa complete
- painless vag bleeding
- placenta cover entire cervical os
plac pervia partial/ incomplete
- painless vag bleeding
- placenta covers one side of cervical os
plac previa marginal
- asymptomatic, painless vag bleeding
- edge of plac covers one side of the cervical os
plac previa low-lying
- asymptomatic
- painless vag bleeding
- edge of plac lies close by doesnt abut cx os, 2 cm
plac vasa previa
- bleeding
- cord compression
- prolapsed cord
- transverse fetal lie
- fetal vessels cross over internal os
Plac abruption
- premature plac detachment
- clinical findings include severe pelvic pain and vag bleeding
plac abruption risk factors
materal hypertension, smoking, diabetes, trauma, plac previa, and short umbilical cord
plac abruption sono findings
- hypoechoic retroplacental mass
- plac thickening
- well defined margins
- sub amniotic or preplacental locations are rare
plac accreta
- chorionic villi of the plac are indirect contact with uterine myo
- attributed to complete or partial absence of the decidua basalis
plac accreta risk factors
multiparity, plac previa, and previous c section
plac accreta sono findings
- obscured or absent retroplacental complex
- numerous plac lakes
plac increta
- plac invades the uterine myo
plac increta sono findings
extension of villi into myo
plac percreta
placental vessels invade uterine serosa and bladder
plac percreta sono findings
extension of villi outisde of ut
amniochorionic seperation
amnion
separated from fetal surface of plac but cant separate from umbilical insert site
amniochorionic seperation
chorion
separated from endo lining but cant separate from plac edge
amnionchorionic separation
- localized fluid between fetal side of plac and amniotic membrane
- membrane can move
Battledore plac
cord insert into end margins of plac
battledore plac sono findings
insertion of cord into end margin of plac
calcifications
- sign of mature plac
- assoc with smoking or thrombotic disorders
calcification sono findings
- hyper focus within the plac tissue
- posterior shadowing
circumvallate plac
- abnormal plac shape in which membrane insert away from plac edge toward center
- increase risk for sbruption, iugr, premature labor, perinatal death
fibrin deposits
- more commonly located along the subchorionic region of plac
- attributed to regulation of interbillous circulation
fibrin deposits sono findings
- hypo area beneath chorionic plate of plac
- traingular or rectangle in shape
intervillous thrombosis
- presence of thrombus within the intervillous space
- occurs in 1/3 pregnancies
- little risk to fetus
intervillous thrombosis sono findings
- anechoic or hypo intraplacental mass
- nonvascular
placental infarct
- results of ischemic necrosis
- occurs in 25% of pregnancies
- no clinical risk when small
placental infarct sono findings
- hypoechoic focal placental mass
- calcification may occur
placental lakes sono findings
- anechoic area with internal blood flow
placentomalacia
- small plac
- iugr
- intrauterine infection
- chromosomal abnormalities
placentomegaly
- primary causes include maternal diabetes and rh sensitivity
- assoc with maternal anemia, twin-twin transfusion, fetal anomalies and intrauterine infection
placentomegaly sono findings
- max thickness > 5 cm
- heterogeneous texture assoc with tripoloidy, molar pregnancy, or hemorrhage
- homogeneous texture assoc with anemia, hydrops, and eh sensitivity
succenturiate plac
- results of the lack of adj chorionic villi to atrophy
- approx 5% pregnancies
- increased risk of velamentous cord and vasa previa
succenturiate plac sono findings
- additional plac tissue adh to main plac
- connected to body of plac by blood vessels
Chorioangioma
- placental hemangioma
- arises from chorionic tissue of amniotic surface of plac
- fetaus demonstrates distress owing to vascular shunting from normal lac to hemangioma when large
choriangioma metastases to
lung, spleen, kidney, intestines, liver and brain
chrioangioma sono findings
- enlarge plac
- circular, solid hypo mass protruding from chorionic plate
- usually occur at umb insert
- poly, hydrops, iugr
choriocarcinoma
- malignant form of trophoblastic disease
- 50% are preceded by a molar pregnancy
choriocarcinoma sono findings
- hypo intraplac mass
gestational trophoblastic disease
- molar pregnancy
- complete molar pregnancy may cevelop into choriocarcinoma
- partial mole carries little malignant potential
Gestational trophoblastic disease sono findings
- inhomogeneous uterine texture
- various sized cystic structures within plac
- coexsist with decrease in afi
Umbilical cord normally inserts into
the center of the plac and midline of anterior abd wall of fetus
Umbilical vein carries
oxygenated blood
umbilical arteries return
venous blood back into plac
Umbilical cord is formed by the
fusion of the yolk sac and body stalk (allantoic ducts)
What covers the umbilical cord and blends into the fetal skin at the umbilicus?
amniotic membrane
Wharton’s jelly
composed of one vein and two arteries surrounded by myxomatous connective tissue
Umbilical Vein
- formed by the confluence of chorionic vein of plac
- enters umbilicus and joins the left portal vein of liver
Umbilical Arteries
- contiguous with hypogastic arteries on each side of the bladder
- exits umbilicus
- return venous blood from the fetus back to the plac
- demonstrate low resistance blood flow with continuous diastolic flow
length of umbilical cord in 1st trim equals
crown rump length
length during second and third trim
40-60 cm
Diameter of the umbilical cord
Umbilical vein diameter
cyst of umbilical cord
- normal findings in 1st trim
- 50% of cases assoc with fetal anomalies in 2nd and 3rd trim
cyst of umbilical cord sono appearence
- nonvascular anechoic enlargement
false knot of umbilical cord
coiling of blood vessels, giving the appearance of knots
false knot of umbilical cord sono findings
blood vessels folding over on themselves mimicking umbilical nodules
long cord
-cord >80 cm
long cord sono findings
nuchal cord
poly
true umbilical cord knot
vasa previa
nuchal cord
- cord completely surrounds fetal neck with more than one loop
- fetus will turn in and out of umbilical cord throughout the pregnancy
nuchal cord sono findings
- two or more complete loops of cord around neck
- flattening of cord
prolapsed cord
cord preceds the fetus in the birthing process
prolapsed cord sono findings
presence of cord before shortthe presenting fetal part
short cord
short cord sono findings
- limited fetal movement
- inadequate fetal descent
- cord compression
- oligo
single umbilical artery is more common in
multiple gestations
single umbilical artery demonstrates
both single and double umbilical arteries within same cord
single umbilical artery increases risk of
assoc fetal anomalies and iugr
single umbilical artery is assoc with
malformations of all major organ systems and chromosomal anomalies
single umbilical arteries sono findings
- two vessels of similar size within umbilical cord
- umbilical artery transverse dia >4 mm
- straight, noncoiled
Thrombosis of umbilical vessels
- primarily vein
- higher incidence in diabetic mothers
thrombosis of vessels
- absent or abd flow
- hypoechoic enlargement of 1 or more vessels
varix of umbilical vein
- focal dilation of vein
- always intraabdominal
- assoc with normal outcomes
varix of umbilical vein sono findings
- intraabdominal focal dilation of vein
- located between anterior abd wall and liver
velamentous cord insert
- umbilical cord insert into membranes before entering the plac
- not protected by Wharton’s Jelly
velamentous cord insert assoc with
preterm labor abnormal fetal heart pattern low apgar scores low birth weight iugr
velamentous cord insert sono findings
insert of umbilical cord into membrane adj to edge of plac margin
incompetent cervix
- cervical shortening
- painless
decrease in cervical length of > 6mm
increases risk of preterm labor
incompetent cervix risk factors
multiple pregnancies
hx of premature labor
previous hx of cervical surgery
incompenent cx cervical length
dilating of cervical os
> 3 - 6 mm
incompenent sono finding
funneling of amniotic fluid into cervical canal