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MIDS 187 > Ch 6 Abnormal Placenta + Cord > Flashcards

Ch 6 Abnormal Placenta + Cord Flashcards

1
Q

Normal placental thickness?

A

2-4 cm

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2
Q

Placenta size is expressed how?

A

In terms of thickness

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3
Q

What conditions is placental thinning seen with?

A

-Hypertension
-Preeclampsia
-Placental infarctions
-IUGR

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4
Q

Do thick placentas (placentaomegaly) over 4cm typically have a normal outcome?

A

Yes

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5
Q

Placental thickening is m/c stimulated by what?

A

Myometrial contractions

(others are fibroids, abruption, etc)

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6
Q

Can the placental have different shapes?

A

Yes, can be bilobed or have accessory lobes

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7
Q

The selective loss of parts of the placenta + growth of other parts is referred to as what?

A

Trophoblastic trophotropism

(helps explain placental conditions like velamentous insertion + placental migration)

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8
Q

Where does placenta grow + where would it atrophy?

A

Grows: where there is sufficient decidua + vascular supply
Atrophies: due to not enough vascularity

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9
Q

What is a succenturiate lobe?

A

1 or more small accessory lobes that develop in the membranes at a distance from the periphery of the main placenta

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10
Q

What are succenturiate accessory lobes associated with?

A

Postpartum hemorrhage + infection

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11
Q

What is an annular placenta?

A

-Ring shaped placenta
-Attaches circumferentially into myometrium

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12
Q

What is associated with an annular placenta?

A

Prenatal + postpartum hemorrhage, due to poor separation

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13
Q

What is a circummarginate placenta?

A

When fetal membrane insertion is flat, is m/c

(20% of placentas)

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14
Q

What is a circumvallate placenta?

A

Thick, rolled chorioamniotic membranes peripherally

(1-7%)

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15
Q

Do circummarginate + partial circumvallate placentas have clinical significance?

A

No

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16
Q

What are complete circumvallate placentas associated with?

A

-Bleeding
-Abruption
-Preterm labor
-IUGR
-Perinatal death
-Fetal anomalies

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17
Q

Difference b/w circummarginate + circumvallate?

A

Marginate: smooth transition from membrane to villous chorion but there is increased distance from placental edge

Vallate: is similar, but there is a thick rolled edge at the transition

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18
Q

Classic SF of circumvallate placentas?

A

-Rolled up placental edge
-Can look like uterine synechiae b/c some views it appears as a linear structure protruding into fluid filled amniotic cavity

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19
Q

Can we see the “placental shelf” in circumvallate placentas?

A

Only early on in 2nd trimester, rarely seen by late 2nd trimester

(it is a transient + benign finding)

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20
Q

How common is placenta previa?

A

1 in 200 births

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21
Q

What is placenta previa?

A

When placenta implants in lower part of uterus + covers internal cervical os

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22
Q

Difference b/w placenta previa + low lying placenta?

A

Previa: inferior margin covers internal os

Low lying: inferior margin is within 2 cm of internal os

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23
Q

Should we do an EV if we see previa or low lying placenta?

A

Yes!

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24
Q

What other imaging modality can be used to evaluate placental invasion?

A

MRI

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25
Q

Risk factors for placenta previa?

A

-Advanced maternal age
-Previous C section/uterine scar
-Multiple gestations
-Previous elective abortions
-Smoking
-Cocaine
-Multiparity

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26
Q

How should we assess for placenta previa?

A

-Use CD over internal cervical os to look for vessels
-Measure from inferior tip placenta to internal os
-Ensure bladder isn’t too full
-Use EV or translabial to assess internal os

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27
Q

If a placenta is close to internal os in 1st trimester, will it ever move?

A

May migrate away from cx as pregnancy progresses

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28
Q

What does a morbidly adherent placenta mean?

A

-Abnormal implantation of placenta into uterine wall, describes accreta, increta + percreta

-Defect in decidua basalis which allows chorionic villi to invade into myometrium (sometimes extends into tissues as well)

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29
Q

What is placenta accreta?

A

When chorionic villi are abnormally adherent to uterine myometrium, instead of decidua

(m/c - 75%)

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30
Q

What is placenta increta?

A

When the villi infiltrate into the myometrial surface

(18%)

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31
Q

What is placenta percreta?

A

When the villi invade through myometrium into other maternal structures

(l/c - 7%)

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32
Q

Why has placenta accreta risen 10x in the US over the last 50 years?

A

Due to increased + repeat C sections

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33
Q

What is the m/c reason for an emergency postpartum hysterectomy?

A

A morbidly adherent placenta

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34
Q

Delivery is planned during what week range when a women has a morbidly adherent placenta?

A

Week 34-35

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35
Q

What are the 2 most important known RFs for placenta accreta?

A

-Placenta previa
-Previous C section

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36
Q

What is associated with placenta accreta?

A

So much

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37
Q

1st trimester SF suspicious for placenta accreta?

A

-Implantation of gest sac in lower uterus
-Multiple irregular vascular spaces in placental bed
-C section scar implantation

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38
Q

What is lacunae?

A

Small cavity/depression

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39
Q

In 2nd trimester, multiple vascular lacunae within placenta has a high or low chance for placenta accreta?

A

High sensitivity, low false-positive rate

(increased chance for placenta previa as well)

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40
Q

There is a loss of the normal hypoechoic retroplacental zone (clear space b/w placenta + uterus) with what condition?

A

Placenta accreta b/c placenta is growing into the uterine wall + removing that space

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41
Q

What is the most important SFs associated with placenta accreta in 3rd trimester?

A

Multiple vascular lacunae being present

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42
Q

Do placental venous lakes have an adverse pregnancy outcome?

A

No

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43
Q

What are placental venous lakes?

A

Irregular anechoic structures within placental tissue found under chorionic plate

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44
Q

Do venous lakes occur as gestational age increases or decreases?

A

Increases

45
Q

Why does placental infarction occur with venous lakes?

A

Due to obstruction of spiral arteries found at periphery of placenta

46
Q

What are placental infarctions associated with?

A

Retroplacental hemorrhage in up to 25% of term placentas

47
Q

Why do subamniotic cysts occur?

A

From rupture of chorionic (fetal) vessels close to umbilical cord insertion into placenta

(associated with IUGR in 10% cases)

48
Q

SF of subamniotic cysts?

A

-Multiple
-Protruding into amniotic cavity
-Anechoic

49
Q

List the 2 primary nontrophoblastic tumors of the placenta?

A

-Chorioangiomas
-Teratomas

50
Q

What is a chorioangioma?

A

-Benign vascular malformation of placenta
-Arises from primitive chorionic mesenchyme

51
Q

Are chorioangiomas symptomatic?

A

-Small solitary ones are asymptomatic + little significance
-Multiple large ones (over 5cm) are symptomatic + associated with maternal/fetal complications in 30-50% of cases

52
Q

What do chorioangiomas contain that can lead to severe fetal complications?

A

Arteriovenous shunts

53
Q

What is placental abruption?

A

Premature separation of all/part of placenta from myometrium

(1% of pregnancies have this)

54
Q

Placental abruption is classified according to the location of what?

A

Separation

(marginal, partial or complete)

55
Q

How may the pt present with placental abruption?

A

-Acute abdominal + pelvic pain
-Vaginal bleeding
-Uterine tenderness
-Fetal distress

56
Q

The resulting hemorrhage with placental abruption may occur as what types of blood clots?

A

-Retroplacental
-Intraplacental
-Marginal
-Subchorionic

(clots form to stop bleeding)

57
Q

RFs of placental abruption?

A

-Hypertension
-Cocaine
-Smoking
-Trauma
-Uterine anomalies
-PROM

58
Q

What is the amniotic band syndrome?

A

Sporadic condition due to rupture of amnion (w/o rupture of chorion), leading to oligohydramnios + passage of fetus from amniotic to chorionic cavity

(appears as echogenic lines/circle/band)

59
Q

Early rupture of the amniotic cavity can lead to what?

A

Severe malformations of cranium, CNS, face + viscera

60
Q

If amniotic bands tear, what can this lead to?

A

-Congenital amputations (ex toe comes off)
-Constriction rings
-Bizarre nonanatomic facial clefts

61
Q

What is PMD?

A

Placental mesenchymal dysplasia - it is a newly recognized, rare placental vascular anomaly characterized by mesenchymal stem villous hyperplasia

62
Q

What can PMD be mistaken for?

A

Molar pregnancy b/c of “grapelike vesicles”

63
Q

What is a SUA?

A

-Single umbilical artery
-One of the m/c congenital anomalies

64
Q

Is left or right umbilical artery m/c absent with SUA?

A

Left

65
Q

If a fetus has SUA, what else should we be looking for?

A

High rate for other anomalies

66
Q

Which 2 chromosomal abnormalities have been reported with SUA?

A

Trisomy 13 + 18

67
Q

What is PRUV?

A

-Persistent right umbilical vein
-Common vascular variant where right umbilical/portal vein remains open (rather than the left one)

68
Q

Is it hard to diagnose PRUV?

A

No, is often overlooked though

69
Q

SF of PRUV?

A

Umbilical vein curves toward the left-side of stomach rather than toward the liver

70
Q

Where is the GB located in regards to the PV with PRUV?

A

Is medial to vein (rather than normal lateral position)

71
Q

Is PRUV normally an isolated finding?

A

Yes tho can have an increased risk of other anomalies like cardiac malformations

72
Q

What is body stalk anomaly?

A

Complete absence of umbilical cord

(fatal condition linked to cocaine abuse)

73
Q

What is limb body wall complex?

A

Very short umbilical cord

74
Q

Length of a short cord?

A

Less than 35cm (associated with anomalies + is lethal/deathly)

75
Q

The length of cord is an index of fetal what?

A

Activity - depends on tension created by fetus in 1st/2nd trimester

76
Q

Difference of vasa + placenta previa?

A

Placenta: covers cervix
Vasa: blood vessels from cord cover cervix

77
Q

What is suggested for moms to do for a good outcome if they have vasa previa, as it gets closer to end of pregnancy?

A

To do close follow up with possible hospitalization from 32 weeks onward

78
Q

Best way to screen for vasa previa?

A

EV in late 1st or early 2nd trimester

79
Q

Is the morbidity + mortality rate high with vasa previa?

A

Yes! 50-60% in intact membranes, 70-100% with ruptured membranes

80
Q

The presence of umbilical cord cysts seen b/w 7-13 weeks have been reported at 3%, 20% of cases are associated with what?

A

Chromosomal/structural defects

81
Q

The fetus is more likely to be abnormal if a umbilical cord cyst is located where?

A

-Near placental/fetal extremity of cord
-Or if cyst persists beyond 12 weeks gest

82
Q

What are true umbilical cord cysts derived from?

A

-Embryonic remnants of allantosis + omphalomesenteric duct
-Located near cord insertion into fetal abdomen

(no risk of chromosomal anomalies)

83
Q

What is edematous whartons jelly?

A

Complex umbilical cord mass containing cystic + solid components + internal calcifications

(suggestive of teratoma)

84
Q

Is distinction b/w a hemangioma with degeneration of Wharton jelly + a teratoma hard to tell apart?

A

Yes

85
Q

Normally, the herniation of midgut resolves by what week?

A

Week 14 - though it can persist into 2nd trimester + is consistent with an umbilical hernia

86
Q

What is an umbilical hernia associated with?

A

Chromosome abnormalities

87
Q

Difference in umbilical hernia, gastroschisis + omphalocele?

A

Hernia: completely covered by skin
Gastroschisis: no skin/membrane
Omphalocele: thin translucent membrane

88
Q

2 m/c reasons why cord hematomas form?

A

Due to amniocentesis or cordocentesis

89
Q

Hematomas of umbilical cord are rare, do they have high mortality rate?

A

Yes!

90
Q

How to differentiate b/w cord hematoma from solid vascular lesions like teratomas + hemangiomas?

A

CD

91
Q

Is umbilical cord artery /vein thrombosis with occlusion rare + associate with high perinatal mortality?

A

Yes

92
Q

Thrombosis can form secondary to cord impairments like?

A

-Torsion
-Knotting
-Compression
-Hypercoiling
-Hematoma

93
Q

Mechanical cord compression/accident can be caused by what?

A

-Nuchal/body cords
-Cord prolapse
-Cord entanglements

94
Q

Abnormal cord position can occur from what?

A

-True knots
-Hypercoiling/twisting
-Long cords
-Abnormal insertions
-Strictures

95
Q

What is a nuchal cord?

A

When the umbilical cord loops around the fetuses neck once or more times

(present in 24% of deliveries)

96
Q

Is nuchal cord very serious?

A

Not if cord is only wrapped around once, if 3-4 times than yes but it is often resolved as the baby moves around

(is rarely associated with complications)

97
Q

What is cord prolapse?

A

When cord slips down through cervix in front of baby at time of labor + delivery

98
Q

How can we assess for cord prolapse?

A

CD - see flow of cord within the dilated endocervical canal + vagina

(very important we detect this)

99
Q

Do true or false knots have significance?

A

True

100
Q

What is a true knot?

A

When fetus actually passes through a loop or loops of cord

(fetuses 4x at risk for stillbirth)

101
Q

What is the risk of a true knot?

A

Risk of tightening during labor

102
Q

What is the purpose of cord coiling?

A

Makes cord flexible + strong, provides resistance to external forces that could compromise blood flow

(5% of fetuses have absence of coiling)

103
Q

What are hypercoiled + hypocoiled cords associated with?

A

Hyper: aneuploidy, demise, etc
Hypo: vascular thrombosis of chorionic plate, etc

104
Q

Entanglement of cords is risk in what type of twins?

A

MA twins (70%)

105
Q

What is cord stricture?

A

Localized narrowing of cord with disappearance of Wharton jelly

106
Q

What type of cord would experience cord stricture?

A

Long, hypercoiled cords + highly active fetuses

107
Q

When do we use CD on umbilical artery?

A

ONLY when clinically indicated, do not do it always as it is not required in the protocol

108
Q

Should we use CD on the umbilical artery with low risk pregnancies?

A

No, not of any value to this group of women. Only do it when mom has certain risk factors present.

109
Q

Do we want high or low flow in diastole with cord doppler?

A

High

(with MCA doppler we want low diastole flow)

MIDS 187 (19 decks)

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