M13: Multiples in Preg & Doppler Flashcards
SEE NORMAL TWINNING FROM OB/GYN 1
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why does chronicity refer to
when is it best determines
of placentas
b/w 10-14 wks
most important predictor of preg outcomes in twins
what signs do we look for
of placentas
lambda - means dichorionic, some of the placental tissue growing up b/w the membranes
T sign - monochorionic…. would have to be Mono/Di to see this
what does a thicker membrane b/w the fetuses suggest
dizygotic twins
most common type of monozygotic twins
monochorionic, diamniotic
whats a structure we can look for when to determine if there are 2 membranes
yolk sac
1 yolk sacs mean 1 membrane
least common type of monozygotic twins
monochorionic, monoamniotic
describe a papyraceous fetus
mummified skeletal remains of a demised twin… would occur later in gestation (if the demise is earlier body would reabsorb it)
when would mono/mono twins be conjoined
where are they most commonly conjoined
prognosis
if the egg splits after day 13
chest (thoracopagus) or abdomen (omphalopagus)
more are still born or die after 1 day of life
the majority of conjoined twins are what gender
female (70%)
what is diprosopus
duplication of anatomy or a single body part
what does TRAP syndrome stand for
other names
twin reversed arterial perfusion
acardiac parabolic twin
acardiac monster
w/ what type of twining does TRAP occur
mono/mono only
w/ TRAP, what type of connections are formed in the placenta
can be artery - artery
vein - vein
describe how TRAP syndrome works
the pump/donor twin pumps deoxygenated blood from the umbilical artery to the placenta… that blood is shunted along the surface of the placenta to the second acardiac twin… the deoxygenated blood enters the acardiac twin through the umbilical artery and leaves deoxygenated through the umbilical vein.
there is reversed flow in the umbilical artery of the acardiac twin
how does TRAP affect the development of the acardiac twin
-only the lower limbs and trunk will develop due to lack of nutrients and 02
-no heart of very abnormal, often no head
… acardiac twin is completely supplied by the donor twin
US appearance of TRAP
lack of separating membrane
inability to separate fetal parts
more than 3 vessel cord
complex anomalies
donor twin is at high risk for developing which condition
hydrous due to volume overload and high cardiac output… also leads to cardiac failure
what is a fetus in fetu
US appearance
a parasitic twin w/in the abdomen of its sibling
teratoma
what is a heterotypic preg
one normal preg
one ectopic
describe superfetation
fertilization of 2 separate ova months apart
on other type of abnormal twinning variation
hydatidiform mole w/ coexisting twin
complications w/ twins
twin to twin transfusion syndrome (TTTS) twin embolization premature delivery congenital anomalies cord accidents
w/ what type of twinning does TTTS occur
what is TTTS
monochorionic only
arteriovenous fistula in the placenta (A-A, V-V, A-V), high mortality rate
which type of fistula in the placenta is the worst
artery to vein due to difference is press
describe what happens to the donor w/ a TTTS
small and hypotensive
oligohydramnios
stuck twin appearance
Usually anemic
describe what happens to the recipient w/ a TTTS
large and hypertensive due to fluid overload
polyhydramnios
oedematous/hydropic appearance
general US appearance of TTTS
size discrepancy of >20% disparity of amniotic fluid single placenta thin or non membrane seen hydrous of one twin
what is a stuck twin
when the donor twin has little to no amniotic fluid and the amniotic membrane hold the baby tight against the uterine wall
one other cause of stuck twin other than TTTS
how can you tell the two apart
a dichorionic preg w/ placental insufficiency causing IUGR…
one baby will be small, the other will be normal
describe twin embolization syndrome
occurs when theres a demise of a twin in monochorionic twins…. clots can pass from the demised twin to the surviving twin and cause an infarct in the live fetal brain or liver…
… or it can cause sever hypotension in the surviving twin due to the demised twins placenta becoming low pressure and allowing blood to pool in the placenta.
would lead to asphyxia
in what type of twining is twin embolization syndrome
monochorionic only
US appearance of twin embolization syndrome
ventriculomegaly, porencephalic cysts (from brain hemorrhage), cerebral atrophy or micoencephaly
normal length for cervix
~2.5 cm
genetic and developmental abnormalities are more common in what type of twins
monozygotic
do dizygotic twins have the same risk of developing anomalies as a singleton
yes
why would a fetal reduction be performed
improve morbidity and mortality for a successful preg
which vessels to we do doppler on w/ a TTTS
for each fetus:
umbilical artery
middle cerebral artery
ductus venosus
what are the normal waveforms for all the vessels sampled w/ doppler w/ TTTS
umbilical artery: low resistance w/ lots of diastolic flow
middle cerebral artery: high resistance
ductus venosus: triphasic venous flow (like the HV’s)
w/ fetal doppler, what measurement do we use for each vessel
pulsatility index to look for changes in diastolic flow
describe an abnormal waveform for the umbilical artery
no diastolic flow is bad
reversed diastolic flow is worse
how to located the ductus venosus
whats its appearance w/ colour doppler
from the AC, find the ductus by following the umbilical vein posterior to the IVC
aliasing due to high velocity
describe abnormal flow for the ductus venosus
why does it occur
reversal of the A wave
due to myocardial impairment and increased ventricular EDP from increased RV afterload
which middle cerebral artery should you sample
at what angle
the one closest to the transducer
0 degrees
what can cause an abnormal waveform of the MCA
how will it change
vasodilation in the fetal brain w/ brain sparing IUGR
reduced PI and increased diastolic flow
