multiples- test 4

Question 1

T/F

There is a greater danger when twins share a single placenta or single sac

Answer 1

True

Question 2

2 types of twins

Answer 2

Monozygotic
Dizygotic

Question 3

what is zygosity

Answer 3

Number of oocytes released from ovary and fertilized by spermatazoa

Question 4

When should you determine zygosity?

Answer 4

Should only be determined > 6 wks GA

Question 5

what is “vanishing twin” phenomenon.

Answer 5

one twin may die and is expelled or absorbed by mother

Question 6

what is Chorionicity?

Answer 6

Number of chorionic sacs (placentas)

Question 7

when is chorionicity determined

Answer 7

Assessed > 4.5-5 wks

Question 8

can two placentas appear as one?

Answer 8

yes.

Question 9

what is amnionicity

Answer 9

Number of Amniotic sacs

Question 10

when is amnionicity determined?

Answer 10

Assessed > 8 wks GA

Best identified in 1st trimester

Question 11

The process of twinning is diagrammed here. A dividing membrane that is “monochorionic” implies monozygous twinning.

However, a “dichorionic” twin placenta could result from either dizygous or monozygous twinning (the former more likely)

Question 12

Answer 12

diamniotic
monochorionic

Question 13

Answer 13

dichorionic
diamniotic

Question 14

how many chorion and amnions does Dizygotic Twins havw

Answer 14

ALWAYS dichorionic and diamniotic

Question 15

One blastocyst which divides, producing two embryos

Answer 15

Monozygotic Twins (30%)

Question 16

Majority of monozygotic twins are _____________, _____________

Answer 16

monochorionic, diamniotic

Question 17

Monozygotic Twins

Cleavage at the 2-cell stage (days 1-3) results in _______________, _____________

Answer 17

dichorionic-diamniotic (di-di),

DCDA gestation; 20 % of MZ twin pregnancies.

Question 18

Monozygotic Twins

Cleavage during the blastocyst stage, before implantation (days 4-8) results in _____________, ______________

Answer 18

monochorionic-diamniotic (mono-di),

MCDA gestation; 75% of MZ twin pregnancies.

Question 19

Monozygotic Twins

Cleavage after implantation results in ______________, ______________

Answer 19

monochorionic-monoamniotic (mono-mono),

MCMA gestation (days 8-13); 5% of MZ twin pregnancies.

Question 20

Monozygotic Twins

Division > 2 weeks results in _______________: <1% of MZ twin pregnancies.

Answer 20

conjoined twins

Question 21

dichorionic vs monochorionic thickness

Answer 21

dichorionic
>2mm
4 layers (amnion-chorion-chorion-amnion)

Monochorionic
< 2 mm
2 layers
(amnion-amnion)

Question 22

what is another way to tell the difference between dichorionic or monochorionic besides thickness

Answer 22

Dichorionic
“twin-peak”/lambda sign

Monochorionic
T-shaped junction

Question 23

Question 24

Answer 24

dichorionic
diamniotic

Question 25

Answer 25

monochorionic monoamniotic

Question 26

Answer 26

dichorionic diamniotic

Question 27

Answer 27

monochorionic diamniotic

Question 28

The successful fertilization of a second ovum released during an ongoing pregnancy, resulting in twins of unequal age.

Answer 28

Superfetation

Question 29

Placenta can support up to _____________

Answer 29

3000 grams

Question 30

Determine the gender of the twins (if twins are opposite sex, they are _______________; same-sex twins are indeterminate)

Answer 30

dizygotic

Question 31

The twin closest to the cervix is ALWAYS called ______________

Answer 31

Baby A

Question 32

Sonographic observations associated with increased fetal morbidity and mortality:

Answer 32

One gestational sac smaller than the other Sac appearing “too small” for the fetus One fetus visibly smaller than the other Abnormal Doppler tracings

Question 33

Results from arteriovenous communication between the circulatory systems of monochorionic twins (10-15%) Recipient twin becomes hypervolemic, large for GA, produces excessive urine leading to hydramnios, heart working hard to pump extra blood (can lead to heart failure) Donor twin hypovolemic, leading to severe, generally symmetric growth restriction, produces little urine resulting in oligohydramnios; “stuck-twin” Prognosis is poor for both twins

Answer 33

Twin Transfusion Syndrome

Question 34

in twin transfusion syndrome what are the two twins called

Answer 34

recipient twin and donor twin

Question 35

what is the prognosis for twin transfusion syndrome

Answer 35

poor for both twins

Question 36

Monochorionicity Marked discordance in AFV Discordance in size Larger twin in hydramniotic sac, large bladder, possibly hydropic with enlarged heart Smaller twin in oligohydramniotic sac, bladder NWV – “stuck-twin” Check cord Dopplers (🡩 RI?, 🡫, absent, or reversed end-diastolic flow?)

Answer 36

twin transfusion syndrome

Question 37

Staging of TTTS

Question 38

Staging of TTTS-Doppler Specifics

Question 39

treatment of twin transfusion syndrome

Answer 39

-Therapeutic amniocentesis -Amniotic septostomy -Fetoscopic laser surgery (occlusion of chorioangiopagous) 80% one twin survives 65-70% both twins survives <5% have severe disabilities https://youtu.be/JW-_L5aBQew -Selective termination -Hysterotomy with removal of one twin -Endoscopic umbilical cord ligation

Question 40

twin transfusion syndrome can be suspected when one twin is at least _____________ larger than the other.

Answer 40

25%

Question 41

An AC difference of ≥ 20 mm on a scan within 2 weeks of delivery or a weight estimation difference > 20% of larger twin’s weight - associated with discordant growth A 2 week difference in GA is suggestive

Answer 41

helps determine twin transfusion syndrome

Question 42

-Acardiac parabiotic twin -Occurs with monozygotic, monochorionic twins or triplets -Blood flow reverses to acardiac twin -“Perfused” twin received unoxigenated blood, resulting in aplasia or hypoplasia of the heart, head, and upper limbs -“Pump” twin is usually normal but may have congestive heart failure and become hydropic -Associated with hydramnios -https://www.youtube.com/watch?v=cbo2XLbhjJA

Answer 42

Twin Reversed Arterial Perfusion Sequence (TRAP)

Question 43

Twin Reversed Arterial Perfusion Sequence (TRAP) what are the two twins called

Answer 43

perfused and pump twin -“Perfused” twin received unoxigenated blood, resulting in aplasia or hypoplasia of the heart, head, and upper limbs -“Pump” twin is usually normal but may have congestive heart failure and become hydropic

Question 44

Subtypes of TRAP Sequence

Answer 44

Question 45

Subtypes of TRAP Sequence Most common Absence of head and upper torso and limbs Lower limbs, genitalia and abdominal organs are present.

Answer 45

Acardius Anephus

Question 46

Subtypes of TRAP Sequence Least differentiated type Made up of a mass of bone, muscle, fat, and connective tissue.

Answer 46

Acardius Amorphus

Question 46

Subtypes of TRAP Sequence Most developed type Rudimentary cranial structures, with trunk, limps and abdominal organs. Lacks rudimentary heart

Answer 46

Acardius Anceps

Question 47

Subtypes of TRAP Sequence Rarest Fetal head is the only developed structure Umbilical cord insertion is directly into the fetal head

Answer 47

Acardius Acormus

Question 48

what is this called Death of a monochorionic twin may be followed by the development of emboli (clots) that can travel to the remaining twin through the placenta causing neurologic damage or injury to other organs including the small intestines and kidneys.

Answer 48

Twin Embolization Syndrome

Question 49

Results from late and incomplete division of the monozygotic embryonic disk Most cases have symmetry of joined regions

Answer 49

CONJOINED TWINS