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
2
Q
Another term for chorionicity?
A
placentation
3
Q
what does dichorionic refer to?
A
2 chorions produce 2 placentation sites
4
Q
what is the least risky form of twinning?
A
dichorionic
5
Q
dichorionic twinning accounts for what % of all natural twinning?
A
80%
6
Q
what is monochorionic?
A
- development of one chorion results in a shared placental site
- places pregnancy at higher risk
7
Q
monochorionic twinning accounts for what % of twin mortalities due to share vasculature?
A
50%
8
Q
monoamniotic vs. diamniotic?
A
Monoamniotic: The development of a single amnion
Diamniotic: The presence of two amnions
9
Q
what twin gestations have the highest incidence of mortality?
A
monoamniotic
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
11
Q
zygosity refers to?
A
- the number of zygotes produced at the time of fertilization
12
Q
zygotic (Fraternal) twins occurs when?
A
- 2 seperate ova are fertilized by 2 seperate sperm cells
- not genetically identicle
13
Q
what is the most common form of twinning?
A
- dizygotic (faternal) twins
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
15
Q
what ensures dizygosity?
A
identifying different genders in a multifetal gestation
16
Q
monozygotic or identical twins result when?
A
one ovum if fertilized by a single sperm
17
Q
what is the least common form of twinning and the most risky?
A
monozygotic
18
Q
the earlier the cleavage occurs the more that is shared T or F?
A
False
19
Q
what occurs is cleavage occurs 13 days after conception?
A
conjoined twins
20
Q
clinical signs of multiple gestations? (5)
A
- large for dates
- hyperemesis
- hypertension
- increased human chorionic gonadotropin
- increased alpha fetoprotein
21
Q
premature labor is the most common complication of what?
A
multiple gestations because of increased uterine volume
22
Q
Twin pregnancies are __X more likely than singleton pregnancies to be complicated by premature labor
A
5X
23
Q
what is considered a significant finding associated with premature delivery?
A
cervical length of <2.5 cm or the presence of funneling
24
Q
The birth weight of twins statistically averages ___% less than the birth weight of singletons of comparable gestational age?
A
10%
25
a fetal weight less than the 10th percentile is suggestive of?
IUGR
26
other signs of iUGR include?
- oligohydramnios
| - high resistance umbillical artery pulsed doppler waveform
27
IUGR may be the result of?
twin-twin transfusion syndorme
28
The incidence of a major fetal anomaly in a multiple gestation is __% compared with ___% in a singleton pregnancy
The incidence of a major fetal anomaly in a multiple gestation is 4% compared with 2% in a singleton pregnancy
29
with multiples what % if there of a chance of having down syndrome?
4.6%
30
congenital anomalies associated with multiples?
- 4.6% risk of down syndrome
- major malformations
- anomalies affecting the central nervous system
- cerebral palsy
31
maternal complications associated with multiples?
- pregnancy- induced hypertension and preeclamsia are common
32
preeclampsia in a pregnancy with multiples presents?
- earlier and more severe then in singleton pregnancies
33
features of eclampsia include? (4)
- hypertension
- edema
- proteinuria
- convulsions
34
hypertension is also associated with?
- IUGR and placental abruption
35
what to assess with interfetal membrane and placental sites?
- number and location of placentas
- membrane thickness
- apperance of the membrane attachment
36
Sonographic evidence of two placentas in separate locations indicates ?
- dichorionic gestation
37
Dichorionic pregnancies can also produce?
- 2 placentas adjacent to each other which can fuse and appear as 1
38
is no membrane exists between the cord insertion site what twins are most likely?
monochorionic, monoamniotic
39
The intertwin membrane separating twins in a monochorionic pregnancy consists of how many layers of amnion?
2
40
appearance of intertwin membrance?
- thin, wispy, and measures <1mm thickness
41
Second-trimester monochorionic, diamniotic twin gestation with thin membrane meeting the placenta to form a “T” shape (arrow)
42
Dichorionic, diamniotic twin gestation demonstrating a twin peak or lambda sign at the membrane-placental junction (arrow)
43
what is discordant growth?
A difference in growth between multiple fetuses is called discordant growth and is often the first sign of complications
44
The growth of twins is considered discordant if?
the difference in their birth weights is greater than 20% of the larger twin's weight
45
mono mono twins lack what?
an intertwin membrance, allowing the umbilical cords of the twins to intertwine
46
what is the main factor contributing to increased mortality rates of monoamniotic twins?
cord entangelment
47
what method is most common methods of evaluating AFV in a multiple gestation?
the single pocket method and subjective evaluation
48
what measurement if considered excessive (polyhydramnios)
MVP that exceeds 8cm or AFI exceeding 25cm
49
in multiples, excess fluid may be a feature of?
recipient twin in a gestation with twin-twin transfusion syndrome
50
what MVP measurement suggests oligohydramnios?
< 2cm or AFI less than 5cm
51
olihydramnios can be caused by?
- IUGR
| - a complication associated with a donor twin in gestations with twin-twin transfusion syndrome
52
what is concidered "stuck" to the uterine wall?
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
MVP stands for?
maximum vertical pocket
54
what % of patients with three or more gestational sacs are at risk for spontaneous reduction before 12 weeks of gestation?
50%
55
The risk of co-twin death for monochorionic twins are what times higher than dichorionic twins?
5X
56
what is a vanishing twin?
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
vanishing twin during early pregnancy is often associated with?
- vaginal bleeding
| outcome for surviving fetus is good
58
what does fetal papyraceus refer to?
- 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
Co-twin demise in a diamniotic pregnancy results in?
reabsorbtion of the amniotic fluid around the dead twin
60
what is a conjoined twins (pagus=joined)?
monozygotic twins that are physically untied at birth as a result of incomplete division of the embryonic disk
61
conjoined twins occurs in?
1 in 100 000
62
3 forms of conjoined twins?
1. craniopagus
2. thoracopagus
3. omphalopagus
63
Conjoined twins should be suspected when?
monoamniotic twins do not move away from each other and is confirmed when fusion of the fetal parts is identified
64
twin-twin transfusion syndrome is caused by?
unbalenced shunting of blood from one twin to the other
65
vascular connections are found in virtually all?
monochorionic twins
66
donor vs. recipient twin?
The “donor” twin pumps blood from its arterial system into the venous system of the “recipient” twin
67
what twin recieves less blood and is usually growth restricted, hypocolemic, and anemic?
donor twin
68
what twin receives too much blood, and although it may be normal in size, it is often macrosomic and hypervolemic?
recipient
69
The extra blood flow and work placed on the recipient twin's heart can result in?
fetal hydrops or heart failure
70
Monochorionic twins should be evaluated with?
serial examinations for growth (>20% difference in weight)
71
Placental insufficiency and twin-twin transfusion syndrome are often not apparent until?
later in gestation
72
Twin-twin transfusion syndrome resulting in “stuck” twin (arrow). Fetus appears adhered to anterior uterine wall.
73
what is trap syndrome?
- 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
in Trap syndrome what twin has normal circulation?
- the pump twin, or normal twin
75
in trap what twin lacks functional heart?
the recipient twin
76
The blood flowing to the acardiac twin through?
the umbilical arteries and into the internal iliac arteries is retrograde
77
in Trap syndrome what occurs?
- 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
clubbing of feet or absent toes is common in?
trap syndrome
79
sonographic findings is associated with twin-twin transfusion syndrome?
Monochorionicity with unequal distribution of AFV
80
What would you expect to see in the donor twin affected by twin-twin transfusion syndrome?
IUGR
81
Which of the following is a reason for the increased incidence of multiple gestations?
Later life pregnancies
82
which of the following is a common maternal complication in pregnancies with multiple gestations?
Preeclampsia
83
complications related to the death of one twin results in the most danger to the other twin in what syndrome?
Twin embolization syndrome
84
Monozygotic, embryonic division between 0 and 3 days after conception results in which type of placentation??
. Dichorionic, diamniotic
