Chapter 31: Multiple Gestations Flashcards
determination of the number of fetal amniotic membranes
amnionicity
lack of an embryo
anembryonic
measurements done on an embryo or fetus as a CRL or BPD
biometry
determination of the number of chorionic membranes adjacent to the uterus
chorionicity
two zygotes as a result of the fertilization of two ova
dizygotic
hormone that induces the growth of Graafian follicles
Follicle-stimulating hormone
mixing of the ovum and sperm within the fallopian tubes allowing for fertilization within the woman’s body
gamete intrafallopian transfer (GIFT)
increase in circulating blood volume
hypervolemic
surgical incision into the uterus
hysterotomy
injection of sperm into the oocyte
intracytoplasmic sperm injection
fertilization of the ovum outside of the uterus
in vitro fertilization
large fetus that falls into the 90th percentile for weight
macrosomic
one amnion
monoamniotic
one zygote
monozygotic
incidence of disease
morbidity
death rate because of a specific disease
mortality
edema, accumulation of fluid in tissues and in the peritoneal cavity, and chest in a fetus not affected by erythroblastosis fetalis
nonimmune fetal hydrops
low amniotic fluid levels
oligohydramnios
abundant
plethoric
too much amniotic fluid
polyhydramnios
four
quadruplet
use of heat to seal tisse
thermocoagulation
fertilized ovum with 23 pairs of chromosomes
zygote
one sac =
monochorionic
two sacs =
dichorionic
one yolk sac + two fetal poles
monoamniotic
two yolk sacs + two fetal poles
diamniotic
dichorionic/ diamnotic intertwin membrane
thick
monochorionic/diamnotic intertwin membrane
thin
TRAP sequence occurs in the _______ pregnancy
monochorionic/monoamniotic
one normal twin
one acardiac twin
TRAP sequence
Retrograde umbilical artery flow to the acardiac twin
TRAP sequence
TRAP sequence
Twin Reversed Arterial Perfusion sequence
In TRAP sequence only the ____ and _____ form in acardiac twin
lower pelvis
lower extremities
Placental arterial to arterial and venous to venous anastomoses occur which causes _____
TRAP sequence
The normal twin in TRAP sequence could have ______ because of increased load
congestive heart failure
The acardiac twin in TRAP sequence is supported by the normal fetus via _____
placental anastamoses
TTTS
twin to twin transfusion syndrome
TTTS occurs in the ______ pregnancy
monochorionic/diamnotic
arterial and venous anastamoses between placentas; flow shunting from one fetus to the other creating a perfusion imbalance
TTTS
Recipient twin
donor twin
TTTS
Sonographing findings in the ____ twin in TTTS include polyhydramnios, macrosomic, hypervolemic, plethoric, hydrops
recipient
Sonographic findings in the ____ twin in TTTS include oligohydramnios, growth restricted, hypovolemic, anemic
donor
A __% weight discordance can help in diagnosing TTTS
20
A ______ cord insertion is common in TTTS.
velamentous
joined by lower part of body, or twins in lower body and double upper body
terata catadidyma
back to back, coccyx and sacrum joined together
pyopagus
inferior parts of coccyx and sacrum fused; separate vertebral columns laying in same axis
ischiopagus
two separate heads on one body
dicephalus
two faces with one head and one body
diprosopus
single in upper body and double in lower body, or joined by some body part
terata anadidyma
fused in the cranial vault
cephalopagus
united at the face; may also be joined by the thorax
syncephalus
single head, thorax, and/or abdomen; pelvis, external genitalia, and limbs are duplicate
dipygus
united at midpoint of body
terata anacatadidyma
attached long part of thoracic wall; thoracic and abdominal organs may be abnormal
thoracopagus
attached from umbilicus to xiphoid cartilage
omphapagus
attached at the vertebral column above the sacrum
rachipagus
Conjoined twin happen in a ______ pregnancy
monochorionnic/monoamniotic
______ result from incomplete division after 13th day (stage 5)
conjoined twins
70% of conjoined twins are ____
females
The chance of multiple gestation with ART is __x higher than from natural conception
20
contributing factors to monozygotic twinning
maternal age, race, parity, hereditary
contributing facts to dizygotic twinning
heavily influenced by environmental factors, increase in FSH concentration
_____ twinning increases more often with increasing maternal age
Dizygotic
The maternal serum AFP is ___x MOM in multiple gestations
2.5
single ovum divides after fertilization; appears to be random and independent of most clinical and epidemiological factors
monozygotic
result of fertilzation of two ova; influenced by genetic factors, environmental factors, AMA, ART
dizygotic
The ____ is the outer layer of the placental membrane
chorion
The ____ is the inner layer of the placental membrane
amnion
always have 2 placentas
2 separate chorions
2 separate amnions
dizygotic
_____ twin pregnancies depends on which stage the single fertilized ovum divides
monozygotic
division of zygote before day 4 (stage 1 and 2 Carnegie stage) (25%)
dichorionic/diamniotic
division of zygote between days 4 and 8 (stage 3 and 4 Carnegie stage)
monochorionic/diamniotic
1 placenta 2 gestational sacs (75%)
monochorionic/diamniotic f
division of zygote occurs more than 8 days postfertilization (less than 1%)
monochorionic/monoamniotic
1 placenta 1 gestational sac
monochorionic/monoamniotic
division of zygote more than 13 days postfertilization
monochorionic/monoamniotic (conjoined twins)
Infant mortality is __x higher in twins
4
Infant mortality is __x higher in triplets
10
Women with multigestational pregnancies have a __x increase of severe complications
4
Fetal risk is largely dependent on ____
chorionicity
_____ twins are at a higher risk than ____ twins
monozygotic
dizygotic
Congenital anomalies in multiple gestations are __-__x more often
2
3
The most common congenital anomaly in twins is in the _____ system
cardiovascular
Most common discordant defect in MZ twin pair
normal fetus paired with one that has Turner Syndrome
most accurate time to determine amnionicity and chorionicity
first trimester
Dating is based on CRL of the ___ twin up to 13 weeks 6 days
larger
After 14 weeks, measurements of the ____ should be used from larger twin
HC
Twins conceived through IVF should be dated by _____ or embryonic age from fertilization
oocyte retrieval date
five or more days difference in CRL
significant discordance in first trimester
number of gestational sacs
chorionicity
1 gestational sac
monochorionic
2 gestational sacs
dichorionic
All dichorionic twin pregnancies must be _____
diamniotic
The amnion is usually visible by __-__ weeks
7
8
The number of yolk sacs is consistent with the number of ____
amnions
one yolk sac + 2 fetal poles
monoamniotic
Determination of chorionicity and amnionicity happpens between __ and __ weeks
11
14
presence of a triangular projection of placental tissue extending up into base of junction of two chorionic membranes
twin peak sign
T-sign
monochorioncic
lambda sign
dichorionic
wedge shaped junction formed by placental tissue extending into base of chorionic membranes
lambda sign
T shaped junction formed when two amniotic membranes fuse with one placenta
T sign
membrane composed of two layers of chorion and two layers of amnion (more than 2mm)
dichorionic/diamnotic
two layers of amnion with no interposing chorion
monochorionic/diamnotic
Twins of different sex are virtually all _____ pregnancies
dichorionic/diamniotic
The membrane thickness is more reliable before __ weeks
26
Growth rates of normal multiples follow singletons until around __ weeks
30
At around 30 weeks the ___ and ___ may start to lag behind singleton pregnancies
BPD
AC
one of the most common problems encountered in multiple gestations
growth discordance
fetal weight percentages that differ by more than 20%
growth discordance
increased resistance to blood flow within UAs; decreased resistance in MCAs
IUGR
two sacs identified early in pregnancy, but subsequent sonograms only confirm one fetus
vanishing twin
viable gestational sac growth
0.12 cm/day
nonviable gestational sac growth
0.025 cm/day
smaller gestational sac than expected for menstrual age; irregular margin of sac; crescent-shaped sac with an incomplete trophoblastic ring
vanishing twin
fetal loss in 2nd/3rd trimester of monozygotic twins; fetus becomes paperlike and preserved in a distorted form
fetus papyraceous
transient polyhydramnios of one fetus in a monochorionic/diamniotic exerting lethal compressive effect on other twin
fetus papyraceous
In triplet pregnancies, __% secondary to fetilization of two ova
60
In triplet pregnancies, __% arise from fertilization of three ova
30
In triplet pregnancies, __% arise from fertilization of a single ovum
10
Maternal complications are __x higher in multiple gestation pregnancies
3
primary risk factors for fetal mortality and long term morbidity
premature delivery
low birth weight
Twins are __x more likely to be preterm
6
Twins are __x more likely to be born before 32 weeks
13
increased risk of congenital anomalies
monozygotic twins
increased risk for TTTS and TRAP sequence
monochorionic twins
fetal vessels overlying the cervical os because of the insertion of the umbilical cord into amniotic membrane rather than the placenta
vasa previa
associated with fetal mortality resulting from rapid fetal exsanguination at time of membrane rupture
vasa previa
commonly referred to as acardiac twinning
Twin Reversed Arterial Perfusion
one normal twin “pump twin”
one amorphous twin “acardiac twin”
twin reversed arterial perfusion
does not have a well defined cardiac structure; hemodynamically dependent on pump twin for all circulation
twin reversed arterial perfusion
arterial to arterial and venous to venous anastamoses occur on surface of placenta
twin reversed arterial perfusion
Blood enters the acardiac twin through _____ arteries and perfuses only the caudal aspect of the fetus
hypogastric
usually only lower pelvis and extremities tends to develop; more cephalic structures completely absent or severely maldeveloped
twin reversed arterial perfusion
The blood returning from the acardiac twin flows back to the placenta via the _____
umbilical vein
The pump twin is at a ___% risk of morbidity or mortality secondary to developing high output congestive heart failure
50
Treatment of TRAPS before __ weeks increases survival rate
18
Diagnosis of TRAPS sequence can be sonographically done at __ weeks
11
arterial to venous anastamoses occur within the shared placenta; returning blood from one fetus shunted directly to other fetus
Twin-to-Twin transfusion syndrome
The ____ twin is larger and possibly has polyhydramnios
recipient
The ____ twin is smaller and possibly has oligohydramnios
donor
The donor twin may also be referred to as the ____
stuck twin
The ____ twin becomes growth restricted, hypovolemic, and anemic.
donor
The ____ twin becomes macrosomic, hypervolemic, and plethoric.
recipient
Cardiac abnormalities that may occur with TTTS are normally
right sided
results from hypertrophied ventricular heart walls and interventricular septum obstructing right ventricular outflow
pulmonary stenosis or atresia
A _____ cord insertion has a risk greater than 50% for TTTS
velamentous
TTTS usually presents in the ____ trimester
second
If left untreated, TTTS has a mortality rate of __-___% for both twins
60
100
single placenta, same sex fetuses, weight discordance greater than 20%, significant discrepancy in AFV
TTTS
removing fluid from polyhydramniotic sac returning it to normal volume
serial reduction amniocentesis
occurs when miniscule vascular anasatmoses occur in placenta, causes chronic and slow intertwin blood transfucion
twin anemia polycythemia sequence (TAPS)
In TAPS, the donor twin is ____
anemia
In TAPS, the recipient twin is ____
polycythemic
Big differences in hemoglobin levels
TAPS
increased peak systolic velocity in MCA is indicative of
anemia
Decreased peak systolic velocity in MCA is indicative of
polycythemia
increased placental thickeness and echogenicity, starry sky appearance of liver
TAPS
__% of conjoined twins are stillborn
60
Conjoined twin are classified by ___ and ____
site
pagus
joined at buttocks
pyopagus
joined at thorax
thoracopagus
joined at abdominal wall
omphalopagus
joined at head
craniopagus
joined at ishia
ischiopagus
joined at head and thorax
cephalothoracopagus
70% of all conjoined twins are ____
cephalothoracopagus
Conjoined twins arise from ____/_____ pregnancies
monochorionic/monoamniotic
incomplete division of embryo occurring after day 13 during Carnegie Stage 5
conjoined twins
lack of visualization of separating membrane between twins, inability to separate fetal bodies or heads, more than 3 vessels in a single umbilical cord, complex fetal structural anomalies
conjoined twins
Conjoined twins can be diagnosed as early as __ weeks gestation
7
__% of twins are thoracopagus and share a heart
75
parasitic twin found within abdomen of its sibling
Fetus in fetu
The tumor found in fetus in fetu is a _____
benign hamartoma
Fetus in fetu happens more commonly in the _____
upper retroperitoneum
direct injection of potassium chloride or lignocaine into fetal heart or umbilical vein in designated twin
dichorionic selective reduction
potential exists for thromboembolic substance to be released into surviving twin
monochorionic selective reduction
Multiple births increase with ____, ____, _____, _____, and the use of _____
delayed childbearing
race
genetics
environmental factors
ART
______ twinning is a random event of ovum division after fertilization.
monozygotic
____ twinning is influenced by by genetic factors, environmental factors, AMA, and the use of ART and is the result of two ova fertilization
dyzygotic
Two placentas and membrane sets occur with dizygotic twin gestations, resulting in ________ configuration.
dichorionic/diamniotic f
Number and chorionicity can be determined in the first trimester; however, as many as 20% of twin pregnancies result in a ______
singletone delivery
The ______ is a lambda shaped extension of two fused placentas between the membranes, where as a ____ describes the membrane appearance with one placenta and two amnions
twin peak sign
T sign
A gestational sac lacking fetal membranes is a ______ pregnancy
monoamniotic
Biometric measurements for twins mimic a singleton pregnancy until approximately __ weeks, when growth may slow
30
Increased resistance to blood flow within the UAs or a decreased resistance observed in the MCAs may occur in the setting of ____ with a multiple pregnancy
IUGR
_____ is the demise of a fetus in a twin pregnancy, which results in the preservation of a paperlike fetus within the uterus
fetus papyraceous
The risk of _____, defined as fetal vessels overlying the cervical os because of insertion of the umbilical cord into the amniotic membrane rather than the placenta, increases with multiple pregnancies and ART
vasa previa
_____ or _____ is a complication seen in monozygotic twins when one twins heart supports two fetuses through arterial to arterial and venous to venous anastamoses occurring of the surface of the shared placenta
acardiac twinning
TRAP sequence
The ____/_____ twin gestation is at risk for the development of TTTS, in which a shared placenta develops arterial to venous anastamoses. The perfusion imbalance of the returning blood results in disparate fetal size and fluid levels
monochorionic/diamniotic
_____ are the result of the incomplete division of the embryoduring the implantation stage occuring after day 13 (carnegie stage 5)
conjoined twins
What is the least related two twinning/
a. choriocarcinoma
b. IUGR
c. preterm birth
d. fetal anomalies
aS
Spontaneously occurring monozygotic twinning is noted to be influenced by:
random factors
A large for date uterus may be a result of all except:
a. macrosomic fetus
b. uterine fibroids
c. oligohydramnios
d. multiple gestation pregnancy
c
Increased maternal serum alpha-fetoprotein (MSAFP) levels can be the result of all except:
a. fetal open neural tube defects
b. placental masses
c. fetal abdominal wall defects
d. uterine fibroids during pregnancy
d
What is not a risk factor for a multiple pregnancy?
a. Decreased morbitidy
b. IUGR
c. TTTS
d. low birth weight
a
A monozygotic pregnancy with two placentas and two amnions is labeled as:
dichorionic/diamniotic
A pregnancy consisting of two amnions, one chorion, and one placenta is:
monochorionic/diamniotic
Preeclampsia, hypertension, placental abruption, placenta previa, and postpartum hemorrhage are:
a. associated with TTTS
b. maternal complications of a multiple gestation pregnancy
c. risks of TRAP
d. fetal complications of twinning
b
The risk of an adverse outcome or abnormality with multiples is greatest with:
a. dichorionic/diamniotic twins
b. monochorionic/diamniotic twins
c. monochorionic/monoamniotic twins
d. dichorionic/monoamniotic twins
c
Sonographic determination of chorionicity and amnionicity is most accurate in:
the first trimester
To determine chorionicity, search for all except:
a. the T sign
b. The lambda sign
c. the Y sign
d. a separating membrane of at least 1.5 mm
c
An intertwin biometric discrepancyof more than 20% suggests:
a. TRTS
b. likelihood of gender difference
c. positional variation
d. discordant growth
d
Growth restriction in discordant twins is assessed by evaluating all except:
a. UA with Doppler
b. MVP
c. middle cerebral artery (MCA) with Doppler
d. biometry
b
The rate of spontaneous demise of a singleton and single twin demise is approximately :
21%
What is least likely to contribute to an adverse outcome with a twin pregnancy?
a. a higher rate of csection
b. age
c. preeclampsia
d. diabetes
a
A primary fetal risk factor for mortality and long term morbiditywith multiple gestations is:
a. postpartum hemorrhage
b. oligohydramnios
c. discordant fetal position
d. low birth weight
d
An abnormality revealing a normal twin combined with a poorly defined twin possessing an irregular or no cardiac structure is:
TRAP sequence
TRAP sequence is commonly referred to as:
acardiac twinning
TTTS is associated with ____ cord insertion
velamentous
Conjoined twins connecting at the thorax are classified as:
thoracopagus
Twins of different sex originate from two separate ____ and are thus _____
ova
dizygotic
If two discrete placentas can be identified on ultrasound, the pregnancy must be _____
dichorionic
Monozygotic twinning is the result of a ____ ovum
single
Several authors have reported that the growth rates of normal multiples in the second and third trimesters follow that of singleton pregnancies until around ___ weeks.
30
Triplet or higher order gestations, biometric parameters may start to lag sooner in pregnancy, except for ______ which seems to closely follow nomograms developed for singletons
femur length
An _____ resistance to blood flow within the umbilical arteries or a _____ resistance observed in the MCAs may occur in the setting of IUGR
increased
decreased
ART has been shown to increase the rate of fetal vessels overlying the cervical os, also known as _____
vasa previa
Concordant defects in twins is mostly related to _____ twins.
monozygotic
Chorionicity and amnionicity determination utilizing ultrasound is most accurate in the ____ trimester.
first
An accurate and easy method of determining the type of twinning involves counting the number of ____ sacs.
yolk
The ____ sign refers to the presence of a triangular projection of placental tissue extending into the vase of the junction of two chorionic membranes.
twin peak
In a twin pregnancy, fetuses measuring ___ or more days difference by CRL are considered discordant.
5
Conjoined twins are the result of incomplete division of the embryo during the implantation stage occurring after day ___
13
An early twin pregnancy that delivers a singleton fetus is known as a ______ pregnancy
vanishing twin
All multiple gestations should be considered _____ pregnancies
high risk
A gestational sac lacking fetal membranes is a _____ pregnancy
monoamniotic
Periodically removing fluid from a twin polyhydramniotic sac is known as _______ amniocentesis
serial reduction
The highest risk form of twinning is _____
monoamniotic
Selective reduction should never be performed on a _____ pregnancy due to the risk of passing a ______ substance from demise twin into the surviving twin
monochorionic
thromboembolic
