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DMST 315 OBGYN 3 > Multiples In Pregnancy > Flashcards

Multiples In Pregnancy Flashcards

1
Q

Twinning accounts for how many natural pregnancies?

A

1%

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2
Q

Twinning accounts for how many of all pregnancies?

A

3%

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3
Q

Twinning rate has increased since when? Why?

A
  1. 1980s
  2. LMA and ART
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4
Q

Why is there increased stats of twinning in LMA?

A

Due to an increase in FSH concentration as women age

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5
Q

Prenatal mortality for twinning is what in North America?

A

13- 14%

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6
Q

How much more higher is the mortality rate for twins compared to singletons?

A

5-10 x

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7
Q

Twinning mortality rate is higher initially in utero, what happens to the dead twin?

A

One twin may die in early pregnancy and be re-absorbed resulting in single tone pregnancy

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8
Q

Early u/s show that a large a number pregnancies start off how?

A

As twins

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9
Q

Why is there a loss in twins in utero? 3

A
  1. Spontaneous abortion
  2. Embryonic malformation
  3. Non viable pregnancy
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10
Q

What is a dizygotic twin - fraternal? 2

A
  1. Zygote meaning number of eggs
  2. Di = 2 eggs
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11
Q

What are monozygotic twins?

A

Identical

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12
Q

Dizygotic twins account for how many of the twins rate?

A

70%

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13
Q

How many births are dizygotic twins? (Ratio)

A

1/80 births

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14
Q

Is dizygotic twins hereditary or acquired?

A

Hereditary on maternal side

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15
Q

What happens with the fertilization of dizygotic twins?

A

Fertilization of two separate ova

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16
Q

What is the genetic similarity of the two dizygotic twins?

A

Same as siblings

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17
Q

What increases the rate for dizygotic twins? 3

A
  1. Young mother
  2. Late maternal age
  3. Parity (increased number increases incidence)
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18
Q

What is the hereditary for dizygotic twins?

A

Maternal side

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19
Q

What is the racial background of individuals often affected by dizygotic?

A
  1. Asian rates low
  2. African rates high
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20
Q

What pharmaceutical agents increase frequency of dizygotic twins? 2

A

Clovis and pergonal

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21
Q

Monozygotic twins account for what percentage of all twins?

A

30%

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22
Q

How random is the occurrence rate of monozygotic twins?

A

Random

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23
Q

What is the occurrence rate of monozygotic twins? (Ratio)

A

1/250 births

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24
Q

How is the ovum of the monozyogtic twins fertilized?

A

A single fertilized ovum replicates during early development

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25
Q

What is the genetic relation of monozygotic twins?

A

The same

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26
Q

What is the mortality rate of monozyogtic twins compared to dizygotic twins?

A

2x higher

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27
Q

Congenital anomalies occur how many times more often, in terms of monozygotic vs singleton?

A

2-3 times more often

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28
Q

What does chorionicity mean?

A

The number of placenta

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29
Q

What is the most important predictor of pregnancy outcome in twins?

A

Chorionicity

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30
Q

When is chorionicity best determined? (weeks)

A

10-14 weeks

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31
Q

What are the two signs of chorionicity?

A
  1. Lambda (twin peaks)
  2. T sign
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32
Q

What does Lambda sign mean? 2

A
  1. Dichorionic
  2. 2 placentas
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33
Q

What does the T sign mean? 2

A
  1. Monochorionic
  2. 1 Shared placenta
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34
Q

What do we need to do when we look at the membranes and placenta? 3

A
  1. Identify the number of placentas
  2. Identify the presence or absence of a separating membrane
  3. Identify the presence of a twin peak sign or T sign where the membrane meets the placenta
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35
Q

If chorionicity cannot be determined transabdominally, what needs to be done?

A

EV scan is recommended

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36
Q

What sign is seen with DC/DA?

A

Twin peaks sign where membrane meets placenta

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37
Q

What sign is seen with MC/DA? (in terms of the sign and the placenta)

A

T sign where membrane meets the placenta

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38
Q

What membrane is seen with MC/MA?

A

No membrane

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39
Q

How many placentas are seen with DC/DA ?

A

2 Placentas, may appear separate or fused

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40
Q

How many placentas are seen with MC/DA?

A

1 Placenta

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41
Q

How many placentas are seen with MC/MA

A

1 placenta

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42
Q

What is the membrane like for DC/DA?

A

Thick membrane

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43
Q

What does the membrane look like for MC/DA?

A

Thin membrane

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44
Q

With dizygotic twins there will always be how many placentas?

A

2

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45
Q

If 2 placentas implant close together, what may happen?

A

They can fuse together

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46
Q

Some placental tissue may group up where? (In terms of fused placentas)

A

Between the membranes

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47
Q

What is the twin peak sign or lambda sign?

A

When some placental tissue grows up between the membranes

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48
Q

How does monochorionic/ diamniotic occur? What is a sign?

A
  1. If twinning or division occurs after implantation, only one placenta is formed.
  2. The membrane between the babies create a T sign
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49
Q

What re the different types of monozygotic twinning? 4

A
  1. Dichorionic- diamniotic (Di/DI)
  2. Monochorionic- diamniotic (Mono/Di)
  3. Monochorionic- monoamniotic (mono/ mono)
  4. Conjoined twins
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50
Q

Dichrionic- diamniotic twins occur with how many of dizygotic twins?

A

All cases

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51
Q

What is Di/DI?

A

Two placentas/ two amniotic sacs

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52
Q

Can Di/Di occur with monozygotic twins (one ovum)?

A

Yes

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53
Q

How can Di/Di happen with monozygotic twins? 3

A
  1. Morula splits before it implants
  2. 2 Days post fertilization
  3. Each implant separately
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54
Q

How many monozygotic twins are di/di?

A

18-30%

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55
Q

What are complications of di/di?

A

Increased risk of preterm delivery

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56
Q

Monochorionic- diamniotic can be shortened to what abbreviation?

A

Mono/di

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57
Q

When does division occur with Mono/di?

A

At blastocyst stage, after the inner cell mass of the embryo forms

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58
Q

When does Mono/di occur?

A

Day 4-8 post fertilization

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59
Q

What is a Mono/Di pregnancy?

A

2 fetuses in separate amniotic sacs with a single chorionic sac. (1 placenta)

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60
Q

How many of all monozygotic twins are mono/di?

A

70%

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61
Q

What are complications of mono/ di?

A

Vascular distribution due to shared placenta

62
Q

When does mono/mono occur? 2

A
  1. At embryonic disc stage after the amniotic sac has formed
  2. Day 8-12 post fertilization
63
Q

What is mono/mono?

A

No membrane between fetuses, one placenta

64
Q

How many monozygotic twins are mono/mono?

65
Q

What is the complications associated with mono/mono?

A

Increased risk of mortality due to cord entanglement

66
Q

What is the chorion and amniotic sac for conjoined twins?

67
Q

When does incomplete division occur with conjoined twins?

A

At embryonic disc stage

68
Q

When does conjoined twins occur?

A

Day 13 post fertilization

69
Q

Is there a membrane with conjoined twins?

70
Q

What is the sonographic protocol for twins? 4

A
  1. Identify the number of fetuses present
  2. Identify the position of both fetuses
  3. Label the presenting twin (closest to the cervix) as A and label which side of the mom (uterus) this baby is on (left or right)
  4. Identify chorionicity/ amnionicity by presence of membrane, # of placentas, Presence of twin peak sign or T sign
71
Q

For better consistency in monitoring to reduce confusion, rather than labelling twins A/B at each scan based on proximity to cervix, it is now recommended to assign each individual twin as what?

A

Fetus 1 and fetus 2

72
Q

Identifying features of each fetus are what? 8

A
  1. Presentation
  2. Presenting/trailing
  3. Left/ right side
  4. Gender
  5. Larger, smaller
  6. Placental position/ cord insertion
  7. Markers
  8. Structural abnormalities
73
Q

What do we need to do with each fetus during protocol?

A

Scan each fetus as a singleton and complete all documentation before moving to the next fetus

74
Q

What do we need to do with biometry measurements for twins?

A

Enter biometry measurements into separate calculation packages (fetus a/b)

75
Q

What do we need to show to demonstrate multiple fetuses and compare size? 2

A
  1. Head
  2. Abdomen
76
Q

What do we need to do with sonographic protocol? 2

A
  1. Rule out polyhydraminos
  2. Rule out fetal demise (papyraceus fetus)
77
Q

What are 2 abnormal twinning variation?

A
  1. Conjoined twins
  2. TRAP syndrome
78
Q

Conjoined twins are most commonly joined where? What is the occurrence rate?

A
  1. At the chest or abdomen (thorocopagus or omphalopagus)
  2. 70%
79
Q

70% of conjoined twins are which gender?

80
Q

How many conjoined twins are still born?

81
Q

How many conjoined twins die on day one of life?

82
Q

What is the sonographic appearance of conjoined twins? 4

A
  1. Lack a separate membrane
  2. Inability to separate fetal parts
  3. More than 3 vessels in the cord
  4. Complex anomalies
83
Q

What is diprosopus?

A

Duplication of anatomy seen in conjoined twins

84
Q

What are examples of diprosopus?

A

Duplication of face or head

85
Q

What is TRAP sequence? (acronym breakdown)

A

Twin reversed arterial perfusion

86
Q

What is TRAP sequence also called?

A

A cardiac parabolic twin or a cardiac monster

87
Q

TRAP sequence happen with what individuals?

88
Q

TRAP sequence results from what?

A

Large arterial venous anastomosis (shunts) in the placenta

89
Q

What is the blood flow seen with TRAP sequence with doppler? 3

A
  1. Reversal of normal blood flow for the acardiac twin
  2. Flow towards it in the umbilical arteries
  3. Flow away from it in the umbilical vein
90
Q

What is seen with TRAP sequence?

A

Either no heart (acardiac) or a very abnormal heart in one twin

91
Q

What prevents TRAP twin from surviving on its own?

A

No head/heart

92
Q

A TRAP sequence twin is perfused how?

A

Completely perfused by the other donor twin

93
Q

What does the TRAP sequence baby develop?

A

Only the lower limbs and trunk

94
Q

The donor twin in TRAP is at high risk for what?

A

Developing hydrops due to high cardiac output resulting in cardiac failure

95
Q

What is fetus in fetu? How easy is this to identify? 2

A
  1. A parasitic twin within abdomen of its sibling
  2. Difficult to distinguish from a teratoma
96
Q

What is an identifying factor of the coexisting twin for fetus in fetu?

A

Hydatidiform mole

97
Q

What kind of pregnancy is fetus in fetu?

A

Heterotopic pregnancy

98
Q

What is superfetation? How common is it? Who is affected?

A
  1. Fertilization of two separate ova months apart
  2. Extremely rare
  3. Women undergoing fertility treatments
99
Q

What is Twin to twin transfusion syndrome abbreviated to?

100
Q

What are 5 complications with twins?

A
  1. TTTS
  2. Twin embolization syndrome
  3. Premature delivery
  4. Congenital anomalies
  5. Cord accidents
101
Q

TTTS occurs with what kind of twins?

A

Monochorionic twins

102
Q

TTTS affects what percentage of MC twins?

103
Q

What is seen with TTTS in the placenta?

A

Arteriovenous fistulas in the placenta

104
Q

In terms of TTTS what does AV fistulas look like in placenta? Which is worse?

A
  1. A-A or V-V or A-V
  2. A-V is the worse because of difference in pressure gradient
105
Q

What happens to the donor with TTTS?

A

Anemic donor and fluid overload

106
Q

What is the mortality rate for TTTS?

107
Q

What is seen with stuck twin? (TTTs)2

A
  1. Donor twin may have little or no flood
  2. Amniotic membrane holds baby tightly to uterine wall
108
Q

Stuck twin can occur in ___________ twin pregnancy as well where in one twin has what? 2

A
  1. Dichorionic
  2. One has Placenta insufficiency (IUGR) and the other twin as normal growth
109
Q

What is the sonographic appearance of stuck twin? 4

A
  1. Disparity in amniotic fluid
  2. Single placenta/ Monochorionic
  3. Thin or no membrane seen
  4. Hydrops of one twin
110
Q

What is the discrepancy in size for Stuck babies?

111
Q

How many stages are there in TTTS?

112
Q

What this the sonographic appearance of TTTS during stage 1?

A

Oligohydraminos in donor/ polyhydraminos in recipient due to unequal blood flow

113
Q

What is the sonographic appearance of TTTS during stage 2?

A

Bladder not visualized in donor, due to blood being diverted to vital organs

114
Q

What is the sonographic appearance of TTTS during stage 3?

A

Doppler signals abnormal

115
Q

What does abnormal doppler signals mean with TTTS? 4

A
  1. The heart function of one or both twins is affected
  2. DV: reversed flow
  3. Absent/ reversed diastolic flow
  4. MCA: Low resistance (PI)
116
Q

What kind of growth is seen with TTTS?

A

Discordant growth

117
Q

What is the sonographic appearance of TTTS during stage 4?

A

Hydropic recipient twin

118
Q

What is the sonographic appearance of TTTS during stage 5?

A

One or both fetal demise

119
Q

With TTTS can polyhydraminos occur?

A

Yes with one twin

120
Q

How do you do an AFI on a twin pregnancy?

A
  1. Measure deepest vertical pocket (DVP), ideally in view of the dividing membrane
  2. Oligohydraminos is <2cm,
  3. Polyhydraminos is >8cm
121
Q

What is doppler used for with TTTS?

A

Performed to assess blood flow to each fetus

122
Q

What vessels are sampled for TTTS? 3

A
  1. Umbilical artery (low resistance)
  2. Middle cerebral artery (high resistance)
  3. Ductus venosus (triphasic)
123
Q

What is the preferred measurment for TTTS?

124
Q

TTTS doppler demonstrating no diastolic flow or reverse diastolic flow can be expressed with what?

125
Q

How do we calculate PI?

126
Q

What is normal fetal doppler of the umbilical artery? 3

A
  1. Lots of diastolic flow
  2. S/D ratio = 2
  3. PI at 28 weeks = 1
127
Q

What is bad in terms of fetal doppler of the umbilical artery?

A

No diastolic flow

128
Q

What is abysmal fetal doppler of the umbilical artery?

A
  1. Reverse diastolic flow
  2. PI of 6.02
129
Q

How do we get a doppler of the ductus venosus?

A

From the AC locate the ductus by following the umbilical vein posterior towards the IVC

130
Q

Aliasing when looking at doppler of the ductus venosus means what?

A

High velocity flow in the ductus venosus

131
Q

What is seen with abnormal ductus venosus? 2 (Think peaks)

A
  1. First peak corresponds to ventricular systole
  2. Second peak corresponds with passive filling of the ventricular diastole
132
Q

What does Abnormal ductus venosus look like?

A

Reversal of the A wave

133
Q

Abnormal waveforms of the abnormal ductus venosus represent what/

A

Myocardial impairment and increased ventricular end-diastolic pressure from an increased in the right ventricle afterload

134
Q

What does MCA stand for?

A

Middle cerebral artery

135
Q

Where do we sample the MCA for doppler?

A

MCA closest to the transducer

136
Q

What angle do we need fro MCA doppler?

137
Q

In terms of MCA doppler, vasodilation occurs with what?

A

Brain sparing IUGR

138
Q

What is the PI for MCA doppler? What about the Diastolic flow?

A
  1. PI reduces
  2. Diastolic flow increases
139
Q

Twin embolization occurs when?

A

There is a demise of a twin in monochorionic twins

140
Q

What can happen with twin embolization syndrome causing infarcts to the fetal brain or liver?

A

Clots can pass from demised twin to surviving twin causing infarcts in fetal brain or liver

141
Q

Twin emboliztion syndrome may cause severe hypetention to the suriving twin, why?

A

Due to demised twin’s placenta becoming a low pressure bed allowing blood to pool in this placenta

142
Q

What does twin embolization syndrome cause to the suriving twin?

A

Asphyxia (low oxygen) in the live surviving twin

143
Q

What is the sonographic appearance of twin embolization syndrome? 4

A
  1. Ventriculomegaly
  2. Porencephalic cysts
  3. Cerebral atrophy or Microcephaly
  4. Demise of co-twin in DI/DI twin can result in a parlay race out fetus (bones remains)
144
Q

Why does premature delivery happen?

A

Uterus is unable to accommoadate 2 fetuses to term

145
Q

What happens to the cervix during premature delivery?

A

It shortens

146
Q

To look out for premature delivery, what must be done with all twin pregnancies fetal assessments visits?

A

An EV measurement of the cervix until 32 weeks gestation

147
Q

Genetic developmental abnormalities are more common in what kind of twin?

A

Monozygotic twin

148
Q

In terms of monozygotic twins, how more higher is the incident rate for congenital anomalies?

149
Q

What types of twins have the same risk of congenital anomalies as singletons?

A

Dizygotic twins

150
Q

What kind of twin has cord entanglement pretty much all the time?

A

In MC/MA twins

151
Q

What does cord accidents increase the risk of?

A

Cord accidents

152
Q

What are examples of cord accidents? 3

A
  1. May tangle
  2. Prolapse
  3. Strangle

DMST 315 OBGYN 3 (21 decks)

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