High Risk & Multiple Gestation Flashcards
Twin gestation account for how many of all live births in the US?
3.2%
Twins have a __ times greater chance of perinatal death than a singleton.
5
Clinically, twin pregnancies present with symptoms of…
- increased MS-AFP
- earlier and more severe pelvic pressure causing hemorrhoids, constipation, backaches, shortness of breath
- increased fetal activity
- increased uterine size
T/F? The baby closer to the cervix is designated as Twin A.
true
Twins are either monozygotic or dizygotic, depending on…
the number of eggs fertilized at conception.
The term ‘zygosity’ refers to…
the number of zygotes involved.
The term ‘chorionicity’ refers to…
the type of placentation in a twin pregnancy.
T/F? The second trimester is the best time to determine chorionicity and amnionicity in multiples.
FALSE, first
In the first trimester, what do you look at to determine chorionicity?
The number of gestational sacs, amnions, and yolk sacs.
In the 2nd & 3rd trimester, what do you look at to determine chorionicity?
The genders, the number of placentas, the appearance of the dividing membrane.
If differing genders or two distinct placentas are noted then __chorionic placentation has occured.
di-
If the same gender and one placenta are noted, then what can we determine about the placentation?
It could be anything!! Look at the membranes next to narrow it down.
T/F? The dividing membrane in a di-di gestation is only two layers thick.
FALSE, four layers
T/F? The dividing membrane in a mono-di gestation is only two layers thick.
true
A cut-off level of greater than __ in septal thickness suggests dichorioncity.
2 mm
The type of chorionicity in monozygotic twinning is determined by…
how early the twins divided from the single zygote.
Identical twins occur when the embryo splits between __ and __ days post conception.
2 and 14
Identical twinning occurs in about __ pregnancies.
1/250
If the embryo splits before day 3, what kind of chorionicity results?
di-di
If the embryo splits between days 4 and 7, what kind of chorionicity results?
mono-di
If the embryo splits between 8 and 13 days, what kind of chorionicity results?
mono-mono
If the embryo splits after 14 days, what kind of chorionicity results?
mono-mono conjoined twins :(
Di-di twins occur when the embryo splits before day…
3.
Mono-di twins occur when the embryo splits between day…
4 and 7.
Mono-mono twins occur when the embryo splits between day…
8 and 13.
Conjoined twins occur when the embryo splits after day…
14.
Mono-di twins have how many placentas?
one
Di-di twins have how many placentas?
Either two separate placentas or one big fused one.
From the __ weeks, the number of sacs and/or placentas is an accurate method for determining chorionicity.
6th through 10th
Diamnionicity occurs in __% of cases.
90%
Amnionicity is established by the number of…
yolk sacs and/or amniotic sacs.
If it’s too early to identify the amnion, what can you use to determine amnionicity?
the number of yolk sacs
Mono-di twins have how many yolk sacs?
two
Mono-mono twins have how many yolk sacs?
one (or sometimes one partially divided yolk sac)
T/F? Identification of a single placenta differentiates between a monochorionic and a dichorionic gestation.
FALSE, does not differentiate
In the 2nd/3rd trimester, what ‘sign’ can we use to identify di-di twins?
‘twin peak’ or ‘lamba’ sign
T/F? Identification of two placentas differentiates between a monochorionic and a dichorionic gestation.
true
This is the most common kind of twinning.
mono-di
This is the least common kind of twinning.
mono-mono
The presence of more than three vessels in a cord is a strong indication of __ twins.
conjoined
With conjoined twins: the later the division of the embryo, the __ the number of shared organs.
greater
Conjoined twins are described by the…
site of union.
Thoracopagus twins are joined at the…
chest.
Pygopagus twins are joined at the…
sacrum.
Craniopagus twins are joined at the…
head.
Omphalpagus twins are joined at the…
abdominal wall.
Ischiopagus twins are joined at the…
pelvis.
The prognosis for conjoined twins is…
poor. Most are born prematurely, 40% are stillborn, and 35% die within a day.
Of the conjoined twins that survive, the riskiest separations involve a shared…
liver or heart.
Dizygotic (‘fraternal’) twins occur in about __ pregnancies.
1:83
Some factors associated with dizygotic twinning include…
- recent cessation of long term oral contraceptives
- maternal family history of multiples
- maternal age 35-40
- assisted reproduction
Is monozygotic or dizygotic twinning more common?
dizygotic
Dizygotic twinning is more common among __ than among caucasians.
african-americans
Women over __ have a higher incidence of dizygotic twinning.
40
Fetal growth discrepancy is defined as a greater than __ difference in the twins’ estimated weight, __ or greater difference in the AC, and __ or greater difference in femur length.
20%, 20 mm, 5 mm
Fetal growth discrepancy is generally caused by…
- placental insufficiency
- death of one twin after week 16
- chromosomal abnormalities
Fetal growth discrepancy can be described as mild (weight differences of __%) or severe (weight differences of __%).
15-25%, > 25%
This treatment consists of serial amniocenteses to normalize the intrauterine pressure, prevent premature labor, and relieve maternal symptoms.
therapeutic amniocentesis
The stress of a multiple pregnancy can affect the maternal respiratory, GI, renal & musculoskeletal systems causing…
- preeclampsia
- HTN
- placenta abruption
- hemorrhage
- anemia
- UTIs
This is the resorption of a non-viable fetus in a twin gestation.
vanishing twin
Sonographically, a vanishing twin is seen as…
- a lack of multiple sacs on follow-up u/s
- failure of sac growth in one twin
- irregularly marginated sac
- the ‘vanishing’ sac may mimic an implantation bleed in the cavity
This is a serious condition that occurs in monozygotic twins with a shared placenta.
twin to twin transfusion syndrome (TTTS)
TTTS is also known as…
‘cross transfusion’ or ‘third circulation’
This results when the vascular supply of the twins develops an artery-to-vein anastomosis.
TTTS
T/F? Both twins are at risk of dying with TTTS.
true
Sonographically, the donor twin in TTTS is seen as…
- small for dates
- oligohydramnios
- a ‘stuck’ twin with empty bladder and restricted movement**
The ‘stuck’ twin syndrome usually manifests itself between __ weeks gestation.
16-26
Sonographically, the recipient twin in TTTS is seen as…
- hydropic (swollen)
- ascites
- enlarged liver, heart, and kidneys
- polyhydramnios
This is the passage of thromboplastic material from a dead monochorionic twin to the remaining living twin through shared intraplacental vasculature.
twin embolization syndrome
Twin embolization syndrome can result in __ for the living twin.
neurological, GI, or genitourinary deficits***
Sonographically, the twin embolization syndrome is seen as…
- intrauterine death of one twin**
- hydrops
- polyhydramnios
- intraparenchymal hemorrhage
- encephaly
- enlarged, echogenic kidneys
This is a form of monozygotic twinning in which a severely malformed acardiac twin is perfused by the normal twin.
acardiac twin
Acardiac twin is also known as…
parabiotic twin.
The acardiac twin is often also…
aencephalic.
Perfusion of the acardiac twin is accomplished through what two kinds of anastomoses?
one vein-to-vein and one artery-to-artery
T/F? The normal co-twin in an acardiac pair has a typical level of risk.
FALSE, higher risk for CHF and hydrops
In this condition, the acardiac/acephalic twin receives all of its blood supply from the normal ‘pump’ twin.
Twin reversed arterial perfusion (TRAP sequence)
In TRAP sequence, blood enters the acardiac/acephalic twin through its umbilical __ and exits through the umbilical __.
artery/vein
T/F? TRAP sequence occurs only in a monochorionic gestation.
true
TRAP complicates approximately __ of monochorionic twins and 1:__ births.
1%, 1:35,000
Sonographically, TRAP sequence is seen as…
- polyhydramnios
- mono-di or mono-mono gestation
- extremely malformed acardiac twin
- hydropic pump twin
This is characterized by a macerated fetus, resulting from fetal death after it was too large to be reabsorbed.
fetus papyraceous
This is the term for when, hours after death, the skin of the fetus detaches from the underlying tissues.
‘skin slippage’
This is a system designed to detect fetal asphyxia and assess fetal well being.
biophysical profile (BPP)
The BPP parameters are…
- fetal breathing movements
- gross body movements
- fetal tone
- amniotic fluid volume
- non-stress test
In a BPP, fetal breathing must last at least…
30 seconds over a 30 minute period.
In a BPP, at least __ episodes of fetal body and/or limb movements must be seen over 30 minutes.
3
In a BPP, all fetal extremities should appear __ and the fetal chin __ OR at least __ episode of limb extension/flexion.
flexed, tucked to the chest; one
In a BPP, the amniotic fluid volume should exceed…
5 cm.
In a BPP, at least __ episodes of pulse acceleration of greater than __ over 30 minutes.
two, 15 bpm for 15 seconds
Fetal Doppler plays a vital role in the diagnosis of __ and in the assessment of __.
fetal cardiac defects and other non-cardiac malformations; the hemodynamic responses to hypoxia and anemia
Fetal Doppler measures the resistance of blood flow within the…
placenta.
Fetal Doppler has a good correlation between the absence of effective diastolic flow and…
poor outcomes.
This has a characteristic saw-tooth appearance of arterial flow in one direction and continuous umbilical venous flow in the other.
umbilical artery flow
With advancing gestation umbilical arterial Doppler wave forms demonstrate a progressive rise in __ and a decrease in __.
end-diastolic velocity, pulsatility index
Fetal Doppler of the umbilical vein showing pulsations later in pregnancy is an ominous sign that indicates…
CHF in a compromised fetus.
Cervical cerclage is most often recommended between __ weeks of pregnancy.
14-16
In this cervical condition, there are changes in the length and shape of the inner cervical os.
cervix funneling
