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OBGYN > many beans > Flashcards

many beans Flashcards

1
Q

what is the natural incidence of twins

A

1/80

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2
Q

what is Hellin’s Law

A

mathematical approximation of the natural incidence of higher order multiple pregnancies

x2 = 1/89
x3 = 1/89^2
x4 = 1/89^3

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3
Q

fertilization of a different ova at different times (different cycles) is called __

A

superfetation
aka superfecundation

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4
Q

sonographic feature of superfetation

A

twins with diff GA
*hard to differentiate from twins with IUGR

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5
Q

how to you confirm heteropaternal superfecundation

A

genetic testing
?after birth

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6
Q

fertilization of two ova is called

A

dizygotic (DZ)

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7
Q

a single fertilized ovum that splits into two is called

A

monozygotic (MZ)

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8
Q

dizygotic aka

A

fraternal
*non identical

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9
Q

which type of zygocity has an increased risk of anomalies

A

monozygotic

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10
Q

monozygotic aka

A

identical twins

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11
Q

inherited conditions seen in one MZ twin are __ in the other twin

A

likely also

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12
Q

how to definitively confirm prenatal zygocity

A

amniocentesis
chorionic villous sampling
cordocentesis

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13
Q

postnatal zygocity is confirmed by __

A

DNA fingerprinting

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14
Q

what is the incidence of multiples in general today

A

1.5%

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15
Q

what is the most common zygocity of triplets

A

2 fertilized ova (DZ) including one set of MZ

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16
Q

risk factors for DZ twin incidence

A

advanced mat age
ART
race (++Nigeria)
previous DZ twins
increased parity, height, obesity

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17
Q

ris

A
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18
Q

risk factors for MZ twins

A

conception within 1 y of ceasing to use oral contraceptives

  • considered a random event due to same rate worldwide
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19
Q

chorionicity refers to the no. of __

A

placentas
*chorionic sacs

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20
Q

amniocity refers to no. of __

A

yolk sacs
*amniotic sacs

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21
Q

if MZ splits very early (0-4 d), becomes __

A

DCDA
*still MZ origin

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22
Q

if MZ splits 4-8 d becomes __

A

MCDA

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23
Q

if MZ splits >8 d becomes __

A

MCMA

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24
Q

if MZ splits >13 d becomes __

A

conjoined

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25
Q

what combination of chorionicity and amniocity is NOT possible

A

DCMA

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26
Q

what options of chorionicity is possible with DZ twins

A

ONLY DCDA

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27
Q

chorionicity and amniocity of MZ twins depends on __

A

timing of twinning

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28
Q

there are __ in the intertwin membrane of DCDA twins that are MZ

A

4
*fused but separate placentas
*twin peak sign

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29
Q

there are __ in the intertwin membrane of DCDA twins that are DZ

A

4

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30
Q

there are __ in the intertwin membrane of MCDA twins

A

2

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31
Q

there are __ in the intertwin membrane of MCMA twins

A

0

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32
Q

‘time’ in twinning refers to the no. of days after __ that the twins separate

A

fertilization

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33
Q

what percentage of MZ twins split between 4-8 days

A

67%
*MCDA

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34
Q

how do you differentiate a DZ from a MZ pregnancy if both present as DCDA

A

you cannot UNLESS later on you can demonstrate each fetus is of a different sex

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35
Q

what are the main complications of multiples pregnancy

A

preterm delivery
PROM
IUGR

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36
Q

complications of MCMA twins (5)

A

TTTS
acardiac twins
twin embolization
cord entanglement
conjoined

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37
Q

demise of one twin followed by the clotting in the surviving twins’ circulation is called __

A

twin embolization syndrome

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38
Q

TTTS is easier to recognize if __

A

MCDA

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39
Q

what is the most common twin presentation

A

cephalic with vertex presenting part (against internal OS)

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40
Q

clinical manifestation of multiples on labs in 1st trimester will show __ betas and MSAFP

A

high

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41
Q

twins have a __ mortality rate than singletons

A

higher
* especially in MZ

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42
Q

u/s is most accurate in identifying DCDA twins from __ GA

A

6-9 w GA
*++thick septum

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43
Q

you see 2 YS, 1 GS, 2 fetal poles and an amnion between each embryo - what is the ddx

A

MCDA

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44
Q

you see no amnion between 2 embryos at 8w GA, 1 YS and 2 fetal poles - what is the ddx

A

MCMA
* bros before amnios

45
Q

you see 2 GS, with a YS and a fetal pole in each - what is the ddx

A

DCDA

46
Q

presence of 2 YS without visualization of the amniotic membranes confirms DA - T/F

A

TRUE
*should prompt followup for confirmation

47
Q

when one embryo dies and is resorbed while the other continues to grow this is called __

A

vanishing twin

48
Q

cause of vanishing twin

A

often idiopathic
more common with chromosomal abnormalities

49
Q

false appearance of a second GS called

A

pseudotwin

50
Q

cause of pseudotwin pregnancy

A

SCH
artifact

51
Q

visualization of 2 placentas reliably predicts __

A

DCDA

52
Q

visualization of a single placenta reliably predicts monochorionicity

A

NO
could be dichorionic with two fused placentas
*can only be differentiated by membranes

53
Q

twin peak sign is a sign of attachment with __ twins

A

DCDA fused placentas

54
Q

T intersection at placental attachment of amnions indicates __

A

MCDA
a single placenta

55
Q

a MZ pregnancy with DC can develop into different sexes - T/F

A

FALSE
identical twins regardless of chorionicity

56
Q

if placental CI close together or entagled in 2nd, 3rd trimester - likely __ pregnancy

A

MA
*likely no separating membrane whatsoever

57
Q

twin discordance represents a difference of 15% weight, of > __ weeks GA difference

A

> 2 w

58
Q

if one placenta viewed at 2nd, third trimester - sonographer must try to document __

A

twin peak sign and location of placental CI

59
Q

TTTS is a __ pregnancy complicated by a twin-twin connection of blood supplies in the placenta

A

monochorionic

60
Q

anastomosis between donor artery and recipient vein is the __

A

infrafetal placental shunt

61
Q

TTTS usually presents with __ pregnancies

A

MCDA
*two amniotic sacs

62
Q

in TTTS, the donor twin is aka as the __

A

stuck twin

63
Q

in TTTS, the donor twin often associated with

A

oligohydramnios

64
Q

in TTTS, recipient twin is usually larger and at risk of __

A

strain on the heart (LGA)
polyhydramnios (increased urinary output)
hydrops

65
Q

in TTTS, amniotic fluid discordance only seen if __

A

diamniotic

66
Q

‘stuck twin’ sign aka

A

cocoon sign

67
Q

TTTS with unequal passage of RBC via placental anastomoses is referred to as

A

twin anemia polycythemia sequence
TAPS
*dx via pulsed Doppler of MCAs

68
Q

in twin anemia polycythemia sequence, the donor twin becomes __ while the recipient becomes __

A

donor becomes anemic
recipient becomes polycythemic

69
Q

what does TAPS stand for

A

twin anemic polycythemia sequence

70
Q

do you expect to see hydramnios issues or stuck twin with TAPS

A

no
*only indication is elevated PSV in donor MCA and decreased PSV in recipient MCA (higher resistance) from anastamosis

71
Q

what are causes of TAPS

A

chronic TTTS from tiny, unidirectional anastomoses

secondary to TTTS laser ablation

72
Q

what does TRAP sequence stand for

A

twin reversed arterial perfusion

73
Q

when MC have one acardiac live fetus perfused by ‘pump’ twin - this is called

A

TRAP sequence

74
Q

what is the most common physical deformity possible with TRAP sequence

A

acardiac twin demonstrating acardis-acephalus (no head no heart)

75
Q

what causes imbalance of intrafetal circulation in TRAP sequence

A

placental artery-artery anastomoses within a shared placenta

76
Q

TRAP secuence usually occurs with what sex of twins

A

female

77
Q

in an acardiac twin with TRAP sequence, what waveform would you expect from the umbilical vein

A

reversed flow (toward placenta, away from fetus)

78
Q

TRAP sequence blood flows __grade into acardiac twin via umbilical artery

A

retrograde into fetus

79
Q

in acardiac TRAP sequence twin, there will be gradual loss of normal form and relative sparing of __ body

A

lower body

80
Q

sonographic features of pump twin in TRAP sequence gestation

A

normal or increased AF

+/- hydrophic

81
Q

sonographic features of acardiac twin in TRAP sequence gestation

A

absent/ rudamentary heart, head, upper limbs

hydrops

2VC

82
Q

how many umbilical arteries in acardiac twin TRAP sequence

A

1

83
Q

what is the most important aspect of scanning TRAP sequence

A

pulse the umbilical vessels of abnormal twin to prove reversed flow in umbilical artery

84
Q

twin embryos develop but don’t fully separate is called

A

parasitic twin

85
Q

parasitic twin aka

A

asymmetrical

unequal conjoined twin

86
Q

what is the chorionicity and amniocity of unequal conjoined twins

A

can only be MCMA

87
Q

term for situation where one fetus enveloped inside its twin

A

fetus in fetu

88
Q

the fetus in fetu chorionicity/amniocity is usually

A

can ONLY be MCMA

89
Q

the fetus in the host with a fetus in fetu situation demonstrates __

A

living organ system with torso and limbs

blood supply

no functional brain heart lungs GI or urinary tract

90
Q

DZ twins usually have __ defects

A

non concordant

91
Q

oligohydramnios resultant from __ anomaly

A

fetal GU tract anomaly

IUGR

92
Q

polyhydramnios usually due to __ anomaly

A

neural tube defect

upper GI tract obstruction

fetal hydrops

93
Q

when MC twins with demise of one twin and subsequent vascular injuries to surviving twin referred to as __

A

twin embolization syndrome

94
Q

vascular injuries associated with twin embolization syndrome result from disseminated __ coagulation

A

intravascular
(excessive clotting)

95
Q

porencephaly / schizencephaly are complications of __ syndrome

A

twin embolization syndrome
*abnormal cystic areas to brain w/ communication of lat ventricles

96
Q

when one fetus dies and is pressed against the uterine wall by growth of surviving twin, this is called __

A

fetus papyraceous
aka fetus compressus, paper-doll fetus

97
Q

incomplete division of obryonic disc by __ d after fertilization results in conjoined twins

A

> 13d

98
Q

what sex is more commonly associated with conjoined twins

A

female

99
Q

__ is when conjoined twins at the xiphoid

A

xiphopagus

100
Q

__ is when conjoined twins at the umbilicus

A

omphalopagus

101
Q

__ is when conjoined twins at the rump

A

ischiopagus

102
Q

__ is when conjoined twins at the sacral spine

A

pygopagus

103
Q

__ is when conjoined twins at the head

A

craniopagus

104
Q

__ is when conjoined twins at the chest

A

thoracopagus

105
Q

which is the most common attachment of conjoined twins

A

thoracopagus

106
Q

3 or more fetuses in one or more chorionic sacs are referred to as

A

high order pregnancies

107
Q

chance of survival __ with no. of fetuses

A

decreases

108
Q

combination of an extra uterine and intra uterine pregnancy is called

A

heterotopic pregnancy
*usually associated with ART

109
Q

multifetal pregnancy reduction aka

A

selective fetocide

OBGYN (8 decks)

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