Placenta and Umbilical Cord Flashcards
1
Q
gestational trophoblastic disease
A
- molar pregnancy
- may develop into choriocarcinoma
- inhomogeneous uterine texture
- various sized cystic structures within the placenta
- no identifiable fetal parts when complete molar pregnancy
- differential: intraplacental hemorrhage, degenerating uterine fibroid, prominent venous lakes
2
Q
placetnal physiology
A
- vital support organ for the developiong fetus
- maternal blood enters the intervillous spaces
3
Q
vasa previa
A
- bleeding, cord compression, prolapsed cord, and transverse fetal lie
- fetal vessels cross over the internal os
- differential: normal cord, velamentous cord, succenturiate placenta, or myometrial contraction
4
Q
battledore placenta
A
- cord inserts into the end margin of placenta
- differential: normal cord lying adjacent to placental margin, velamentous cord
5
Q
what does the placenta store?
A
carbohydrates, proteins, calcium, and iron
6
Q
succenturiate placenta
A
- result of lack of the adjacent chorionic vlli to atrophy
- 5% of pregnancies
- increased risk of velamentous cord and vasa previa
- additional placental tissue adjacent to main placenta
- connected by blood vessels
- differential: contraction or fibroid
7
Q
placental grade 2
A
calcifications along basal plate
chorionic plate becomes slightly lobular
8
Q
allantoic duct
A
elongated duct that contributes to the development of the umbilical cord
9
Q
false knot of cord
A
- coiling of the blood vessels, giving the appearence of knots
- blood vessels folding over on themselves mimicking umbilical nodules
- differential: normal cord coiling, true knots
10
Q
increta
A
- placenta invades the uterine myometrium
- extension of villi into the myometrium
11
Q
varix of the umbilical vein
A
- focal dilatation of the umbilical vein
- nearly always intraabdominal
- associated with normal outcomes
- dilatation of the umbilical vein
- located between the anterior abdominal wall and the fetal liver
- differential: gallbladder or technical error
12
Q
nuchal cord
A
- cord completely surrounds fetal neck with more than one loop
- significant finding at term
- fetus will turn in and out of the umbical cord throughout the pregnancy
- two or more complete loops or cord around the fetal neck
- flattening of cord
- differential: one complete loop around the neck, prolapsed cord
13
Q
intervillous thrombosis
A
- presence of thrombus within the intervillus spaces
- occurs in 1/3 of pregnancies
- little risk to fetus
- nonvascular
- anechoic or hypoechoic intraplacental mass
- differential: chorioangioma or placental lakes
14
Q
incompetent cervix
A
- cervical shortening
- generally painless
- decrease in cervical length >6mm on serial examinations increases risk of preterm labor
- risk factors include multiple pregnancies, history or premature labor, or previous history of cervical surgery
- funneling of amniotic fluid into the cervical canal
- differential: contraction or improper technique
15
Q
umbilical cord size
A
- length of the umbilical cord is equal to the CRL during the first trimester and continues to have the smae length as the fetus throughout pregnancy
- 40 to 60 cm in length during the second and thrid trimesters
- diameter < 2cm
- umbilical vein diameter < 9mm
- approximately 40 spiral turns
16
Q
retroplacental complex
A
area behind the placenta composed of the decidua, myometrium, and uteeroplacental vessels
17
Q
velamentous cord insertion
A
- inserts into the membranes before entering the placenta
- not protected by wharton jelly
- associated with preterm labor, abnormal fetal heart pattern, low apger scores, low birth weight, and intrauterine growth restriction
- differental: battledore placenta, normal cord adjacent to the placenta, succenturiate placenta
18
Q
amniochorionic separation
A
- amnion can be separated from the fetal surface of the placenta but cannot be separated from the umbilical insertion site
- chorion can be separated from the endo lining but not from the placental edge
- fluid between the fetal side of placenta and the amniotic membrane
- membrane may move
- differential: placental abruption or normal venous lake
19
Q
placentomalacia
A
- small placenta
- IUGR
- intrauterine infection
- chromosomal abnormality
- small placental size and thinning
- differential: succenturiate placenta or contraction
20
Q
choriocarcinoma
A
- malignant form of trophoblastic disease
- 50% are preceded by a molar pregnancy
- hypoechoic intraplacental mass
21
Q
umbilical cord cyst
A
- normal finding in the first trimester
- 50% of cases associated with fetal anomalies in the second and third trimester
- nonvascular anechoic enlargement of the umbilical cord
- differential: true or false knot
22
Q
placentomegaly
A
- primary causes are maternal diabetes and RH sensitivity
- associated with maternal anemia, twin-twin transfusion, fetal anomalies, and IUGR
- thickness >5cm
- homogeneous texture with anemia, hydrops, and RH sensitivity
- heterogeneous with triploidy, molar, or hemorrhage
23
Q
placental previa
A
- placental placement in front of the fetus relative tot he birth canal
- primary cause of painless vaginal bleeding in the third trimester
- complications include premature delivery, life threatening maternal hemorrhage, and increased risk of placental accreta, stillbirth, and IUGR
- 5% of cases diagnosed in second trimester resolve due to placental migration
24
Q
Placental anatomy
A
- formed by decidua basalis and decidua frondosum
- separated from the uterine myometrium by the retroplacental complex
25
Q
single umbilical artery
A
- more common in multifetal gesttations
- umbilical cord may demonstrate both single and double umbilical arteries within the same cord
- increased risk of associated fetal anomalies
- assocaited with malformations of all major organ systems, chromosomal abnormalities
- increase risk of IUGR
- umbilical artery >4mm diameter
- straight, noncoiled umbilical cord
26
Q
short cord
A
- cord length <35cm
- limited fetal movement
- inadequate fetal descent
- cord compression
- oligo
27
Q
long cord
A
- cord length >80cm
- associated with nuchal cord, poly, cord knot, and vasa previa
- nuchal cord, poly, true umbilical cord knots
- differential: gastroschisis or normal cord with poly
28
Q
thrombosis of the umbilical vessels
A
- primarly the umbilical vein
- results from both primary and secondary causes
- higher incidence in diabetic mothers
- absent or abnormal blood flow
- hypoechoic enlargement of one or more umbilical vessels
29
Q
placetnal lake
A
- AKA venous lake
- anechoic or hypoechoic area
- internal blood flow
- differential: intervillous thrombosis or placental infarct
30
Q
placental infarct
A
- result of ischemic necrosis
- 25% of pregnancies
- no clinical risk when small
- hypoechoic focal placental mass
- calcification may occur
- differential: intervillous thrombosis or placental lake
31
Q
chorioangioma
A
- placental hemangioma
- arise from chorionic tissue of the amniotic surface of placenta
- insignificant when small
- fetal distress due to vascular shunting fromt eh normal placenta to the hemangioma
- metastases to the lung, spleen, kidney, intestines, liver, and brain
- sono findings: enlarged placenta, solid hypoechoic mass protruding from the chorionic plate, IUGR, hydrops, poly
32
Q
rick factors of placetal previa
A
advanced maternal age, multiparity, and previous cesaren section, therapeutic abortion, or closely spaced pregnancies
33
Q
differentials of previa
A
- myometrial contraction
- overdistention of bladder
- uterine leiomyoma
- improper technique
34
Q
placental grade 0
A
no calcifications
smooth basal and chorionic plate
first and early second trimester
35
Q
braxton-hicks contraction
A
spontaneous uterine contraction occuring throughout pregnancy
36
Q
umbilical arteries
A
- umbilical arteries are contiguous with the hypogastric arteries on each side of the fetal bladder
- return venous blood from the fetus back to the placenta
- demonstrate low-resistance blood flow with continuous diastolic flow
37
Q
percreta
A
- placental vessels invade the uterine serosa or bladder
- most severe
38
Q
what are the function of the placenta?
A
- respiration
- nutrition
- excretion
- protection
- storage
- hormone production
39
Q
circumvallate placenta
A
- abnormal placental shape, membranes insert away fromt he plasental edge toward the center
- increases risk for abruption, IUGR, premature labor, and perinatal death
- rolled up placental edge
- upturned edge edge contains hypoechoic or cystic spaces
- differential: abruption, amniotic fluid, synechiae
40
Q
placental maturity and grading
A
- scale 0 to 3
- dependent on echogenicity sttributed to calcium and fibrous deposition with advancing age
- maternal hypertension, cigarette smoking, IUGR, and multifetal gestation may cause premature maturation
- delayed maturation associated with maternal diabetes mellitus
41
Q
prolapsed cord
A
- cord precedes the fetus in the birthing process
- presence of teh cord before the presenting fetal part
- differential: vasa previa or nuchal cord
42
Q
anatomy of umbilical cord
A
- formed by fusion of the yolk stalk and body stalk (allantoic ducts)
- amniotic membrane covers the umbilical cord and blends into the fetal skin at the umbilicus
- one vein and two arteries surrounded by myxomatous connective tissue (Whartons jelly)
43
Q
What is the major functioning unit of the placenta and contains the intervillous spaces?
A
chorionic villus
44
Q
fibrin deposits
A
- more commonly located along the subchorionic region of the placenta
- attributed to the regulation of intervillous circulation
- triangle or rectangular in shape
- hypoechoic area beneath the chorionic plate of the placenta
- differential: venous lake or subchorionic hematoma
45
Q
what is the measurement of the placenta?
A
varies with gestational age
2-3 cm thick
thickness should not exceed 4 cm
46
Q
umbilical vein
A
- formed by the confluence of the chorionic veins of the placenta
- joins the left portal vein of the fetal liver
- carries oxygenated blood to the fetus
47
Q
accreta
A
- chorionic villi in direct contact with the uterine myometrium
- attributed to complete or partial absence of decidua basalis
- risk factors: multiparity, placenta previa, previous c-section
- sono findings: obscured or absent retroplacental complex, numerous placental lakes
48
Q
what is the sonographic appearence of placenta during second and third trimesters?
A
- solid, homogeneous medium gray
- smooth
- hyoerechoic chorionic plate
- fetal vessels behind chorionic plate
- placental lakes, insignificant and commonly seen after 25 weeks
49
Q
which hormones does the placenta produce?
A
hCG, estrogen, and progesterone
50
Q
classification of previa
A
- complete: bleeding, covers os
- partial: bleeding, cover one side of os
- marginal: asymptomatic or bleeding, edge of os
- low-lying: asymptomatic, within 2 cm of os
51
Q
placental grade 1
A
scattered calcifications throughout
most common up until 34 wks
52
Q
what is the measurement of the cervical length?
A
2.5-5cm
53
Q
abruption
A
- premature placental detachment
- severe pelvic pain and vaginal bleeding
- risk factors: maternal hypertension, smoking, diabetes, trauma, placenta previa, and short cord
- sono findings: hypoechoic retroplacental mass, placental thickening, well defined margins
- differential: fibroid, contraction, normal, amniochorionic separation
54
Q
placental grade 3
A
marked calcifications
hyperechoic lobulations extending from the chorionic to basal plate
abnormal before 34 wks
