multiple gestations Flashcards

1
Q

whats thought to have an impact on the increasing number of multiples?

A
  • widespread use of assisted reproducvite technology and aging maternal population
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2
Q

Another term for chorionicity?

A

placentation

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3
Q

what does dichorionic refer to?

A

2 chorions produce 2 placentation sites

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4
Q

what is the least risky form of twinning?

A

dichorionic

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5
Q

dichorionic twinning accounts for what % of all natural twinning?

A

80%

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6
Q

what is monochorionic?

A
  • development of one chorion results in a shared placental site
  • places pregnancy at higher risk
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7
Q

monochorionic twinning accounts for what % of twin mortalities due to share vasculature?

A

50%

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8
Q

monoamniotic vs. diamniotic?

A

Monoamniotic: The development of a single amnion
Diamniotic: The presence of two amnions

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9
Q

what twin gestations have the highest incidence of mortality?

A

monoamniotic

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10
Q

why does monoamniotic twins have the highest risk of incidence of mortality?

A

because sharing the amniotic space increases risk for cord accidents

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11
Q

zygosity refers to?

A
  • the number of zygotes produced at the time of fertilization
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12
Q

zygotic (Fraternal) twins occurs when?

A
  • 2 seperate ova are fertilized by 2 seperate sperm cells

- not genetically identicle

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13
Q

what is the most common form of twinning?

A
  • dizygotic (faternal) twins
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14
Q

zygotic gestations are always?

A

always dichorionic diamniotic and represent the least risky type of twinning because a placental site is not shared

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15
Q

what ensures dizygosity?

A

identifying different genders in a multifetal gestation

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16
Q

monozygotic or identical twins result when?

A

one ovum if fertilized by a single sperm

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17
Q

what is the least common form of twinning and the most risky?

A

monozygotic

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18
Q

the earlier the cleavage occurs the more that is shared T or F?

A

False

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19
Q

what occurs is cleavage occurs 13 days after conception?

A

conjoined twins

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20
Q

clinical signs of multiple gestations? (5)

A
  • large for dates
  • hyperemesis
  • hypertension
  • increased human chorionic gonadotropin
  • increased alpha fetoprotein
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21
Q

premature labor is the most common complication of what?

A

multiple gestations because of increased uterine volume

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22
Q

Twin pregnancies are __X more likely than singleton pregnancies to be complicated by premature labor

A

5X

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23
Q

what is considered a significant finding associated with premature delivery?

A

cervical length of <2.5 cm or the presence of funneling

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24
Q

The birth weight of twins statistically averages ___% less than the birth weight of singletons of comparable gestational age?

A

10%

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25
Q

a fetal weight less than the 10th percentile is suggestive of?

A

IUGR

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26
Q

other signs of iUGR include?

A
  • oligohydramnios

- high resistance umbillical artery pulsed doppler waveform

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27
Q

IUGR may be the result of?

A

twin-twin transfusion syndorme

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28
Q

The incidence of a major fetal anomaly in a multiple gestation is __% compared with ___% in a singleton pregnancy

A

The incidence of a major fetal anomaly in a multiple gestation is 4% compared with 2% in a singleton pregnancy

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29
Q

with multiples what % if there of a chance of having down syndrome?

A

4.6%

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30
Q

congenital anomalies associated with multiples?

A
  • 4.6% risk of down syndrome
  • major malformations
  • anomalies affecting the central nervous system
  • cerebral palsy
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31
Q

maternal complications associated with multiples?

A
  • pregnancy- induced hypertension and preeclamsia are common
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32
Q

preeclampsia in a pregnancy with multiples presents?

A
  • earlier and more severe then in singleton pregnancies
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33
Q

features of eclampsia include? (4)

A
  • hypertension
  • edema
  • proteinuria
  • convulsions
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34
Q

hypertension is also associated with?

A
  • IUGR and placental abruption
35
Q

what to assess with interfetal membrane and placental sites?

A
  • number and location of placentas
  • membrane thickness
  • apperance of the membrane attachment
36
Q

Sonographic evidence of two placentas in separate locations indicates ?

A
  • dichorionic gestation
37
Q

Dichorionic pregnancies can also produce?

A
  • 2 placentas adjacent to each other which can fuse and appear as 1
38
Q

is no membrane exists between the cord insertion site what twins are most likely?

A

monochorionic, monoamniotic

39
Q

The intertwin membrane separating twins in a monochorionic pregnancy consists of how many layers of amnion?

A

2

40
Q

appearance of intertwin membrance?

A
  • thin, wispy, and measures <1mm thickness
41
Q
A

Second-trimester monochorionic, diamniotic twin gestation with thin membrane meeting the placenta to form a “T” shape (arrow)

42
Q
A

Dichorionic, diamniotic twin gestation demonstrating a twin peak or lambda sign at the membrane-placental junction (arrow)

43
Q

what is discordant growth?

A

A difference in growth between multiple fetuses is called discordant growth and is often the first sign of complications

44
Q

The growth of twins is considered discordant if?

A

the difference in their birth weights is greater than 20% of the larger twin’s weight

45
Q

mono mono twins lack what?

A

an intertwin membrance, allowing the umbilical cords of the twins to intertwine

46
Q

what is the main factor contributing to increased mortality rates of monoamniotic twins?

A

cord entangelment

47
Q

what method is most common methods of evaluating AFV in a multiple gestation?

A

the single pocket method and subjective evaluation

48
Q

what measurement if considered excessive (polyhydramnios)

A

MVP that exceeds 8cm or AFI exceeding 25cm

49
Q

in multiples, excess fluid may be a feature of?

A

recipient twin in a gestation with twin-twin transfusion syndrome

50
Q

what MVP measurement suggests oligohydramnios?

A

< 2cm or AFI less than 5cm

51
Q

olihydramnios can be caused by?

A
  • IUGR

- a complication associated with a donor twin in gestations with twin-twin transfusion syndrome

52
Q

what is concidered “stuck” to the uterine wall?

A

The confining amniotic membrane in the presence of reduced fluid restricts fetal movement of the affected twin and causes it to appear “stuck” to the uterine wall

53
Q

MVP stands for?

A

maximum vertical pocket

54
Q

what % of patients with three or more gestational sacs are at risk for spontaneous reduction before 12 weeks of gestation?

A

50%

55
Q

The risk of co-twin death for monochorionic twins are what times higher than dichorionic twins?

A

5X

56
Q

what is a vanishing twin?

A

In approximately 21% of twin gestations diagnosed in the first trimester, one twin dies, leaving behind an empty sac

  • This twin and its gestational sac may be completely reabsorbed, disappearing altogether
57
Q

vanishing twin during early pregnancy is often associated with?

A
  • vaginal bleeding

outcome for surviving fetus is good

58
Q

what does fetal papyraceus refer to?

A
  • Refers to a twin fetus that has died early in development and has been pressed flat against the uterine wall by the living fetus

-

59
Q

Co-twin demise in a diamniotic pregnancy results in?

A

reabsorbtion of the amniotic fluid around the dead twin

60
Q

what is a conjoined twins (pagus=joined)?

A

monozygotic twins that are physically untied at birth as a result of incomplete division of the embryonic disk

61
Q

conjoined twins occurs in?

A

1 in 100 000

62
Q

3 forms of conjoined twins?

A
  1. craniopagus
  2. thoracopagus
  3. omphalopagus
63
Q

Conjoined twins should be suspected when?

A

monoamniotic twins do not move away from each other and is confirmed when fusion of the fetal parts is identified

64
Q

twin-twin transfusion syndrome is caused by?

A

unbalenced shunting of blood from one twin to the other

65
Q

vascular connections are found in virtually all?

A

monochorionic twins

66
Q

donor vs. recipient twin?

A

The “donor” twin pumps blood from its arterial system into the venous system of the “recipient” twin

67
Q

what twin recieves less blood and is usually growth restricted, hypocolemic, and anemic?

A

donor twin

68
Q

what twin receives too much blood, and although it may be normal in size, it is often macrosomic and hypervolemic?

A

recipient

69
Q

The extra blood flow and work placed on the recipient twin’s heart can result in?

A

fetal hydrops or heart failure

70
Q

Monochorionic twins should be evaluated with?

A

serial examinations for growth (>20% difference in weight)

71
Q

Placental insufficiency and twin-twin transfusion syndrome are often not apparent until?

A

later in gestation

72
Q
A

Twin-twin transfusion syndrome resulting in “stuck” twin (arrow). Fetus appears adhered to anterior uterine wall.

73
Q

what is trap syndrome?

A
  • Rare condition that complicates approximately 1% of monochorionic pregnancies
  • Occurs because of paired artery-to-artery or vein-to-vein anastomosis within the shared placenta
74
Q

in Trap syndrome what twin has normal circulation?

A
  • the pump twin, or normal twin
75
Q

in trap what twin lacks functional heart?

A

the recipient twin

76
Q

The blood flowing to the acardiac twin through?

A

the umbilical arteries and into the internal iliac arteries is retrograde

77
Q

in Trap syndrome what occurs?

A
  • Limited amount of oxygen and nutrients are delivered to the torso and lower extremities of the fetus
  • Results in abnormal development, especially of the upper body
78
Q

clubbing of feet or absent toes is common in?

A

trap syndrome

79
Q

sonographic findings is associated with twin-twin transfusion syndrome?

A

Monochorionicity with unequal distribution of AFV

80
Q

What would you expect to see in the donor twin affected by twin-twin transfusion syndrome?

A

IUGR

81
Q

Which of the following is a reason for the increased incidence of multiple gestations?

A

Later life pregnancies

82
Q

which of the following is a common maternal complication in pregnancies with multiple gestations?

A

Preeclampsia

83
Q

complications related to the death of one twin results in the most danger to the other twin in what syndrome?

A

Twin embolization syndrome

84
Q

Monozygotic, embryonic division between 0 and 3 days after conception results in which type of placentation??

A

. Dichorionic, diamniotic