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OB-GYN Board Review > Placenta and Umbilical Cord > Flashcards

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
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2
Q

placetnal physiology

A
  • vital support organ for the developiong fetus
  • maternal blood enters the intervillous spaces
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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
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4
Q

battledore placenta

A
  • cord inserts into the end margin of placenta
  • differential: normal cord lying adjacent to placental margin, velamentous cord
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5
Q

what does the placenta store?

A

carbohydrates, proteins, calcium, and iron

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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
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7
Q

placental grade 2

A

calcifications along basal plate

chorionic plate becomes slightly lobular

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8
Q

allantoic duct

A

elongated duct that contributes to the development of the umbilical cord

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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
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10
Q

increta

A
  • placenta invades the uterine myometrium
  • extension of villi into the myometrium
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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
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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
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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
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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
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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
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16
Q

retroplacental complex

A

area behind the placenta composed of the decidua, myometrium, and uteeroplacental vessels

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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
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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
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19
Q

placentomalacia

A
  • small placenta
  • IUGR
  • intrauterine infection
  • chromosomal abnormality
  • small placental size and thinning
  • differential: succenturiate placenta or contraction
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20
Q

choriocarcinoma

A
  • malignant form of trophoblastic disease
  • 50% are preceded by a molar pregnancy
  • hypoechoic intraplacental mass
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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
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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

OB-GYN Board Review (12 decks)

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