Test 1 (Twins & placenta) Flashcards
(225 cards)
1
Q
five fetus
A
quintuplets
2
Q
six fetus
A
sextruplets
3
Q
seven fetus
A
septuplets
4
Q
eight fetus
A
octuplets
5
Q
gestation of singleton
A
40 weeks
6
Q
gestation of twins
A
37 weeks
7
Q
gestation of triplets
A
34 weeks
8
Q
gestation of quadruplets
A
33 weeks
9
Q
Fetal mortality rates are _________ that of singleton pregnancies
A
3-6 X
10
Q
Neonatal mortality ______ that of single pregnancies.
A
7 X
11
Q
why are all muplitple pregnancies have a higher fetal and neonatal mortality?
A
primarly due to much higher incidence of premature labour
12
Q
what is the most reliable predictor of poor outcome?
A
amniotic fluid discordance
13
Q
dizygotic fertilization of____ova by __________
A
two ova by two separate spermatozoa
-not identical
14
Q
features of dizygotic zygotes?
A
- Two embryos
- Two chorions
- Two amnions
- Two placentas (which may fuse)
15
Q
increased chance of dizygotic twins if:
A
- increased maternal age
- frequent pregnancies
- pregnancy techniques
- heredity
- race
16
Q
monozygotic develop from _______ and ________ which after _________
A
Develop from one ovum and one spermatazoa which after fertilization split into two
17
Q
monozygotic twins are always ________
A
same gender
18
Q
features of monozygotic twins
A
- Two embryos
- One or Two chorions
- One or Two amnions
- One or Two placentas
19
Q
what do monozygotic twins have that are the same?
A
- genes
- blood group
- physical features
- eye and hair colour
- ear shape and creases
20
Q
what do monochorionic twins have a higher risk of?
A
3-5 times higher risk of perinatal mortality and morbidity than Dichorionic
21
Q
what does the chorion form?
A
a septum between the amniotic sac
22
Q
when is chorionic septum best visualized?
A
1st trimester
23
Q
chorionic septum thickness dichorionic
A
2-3mm
24
Q
chorionic septum thickness monochorionic
A
1.4mm
25
septum sign in di-chorionnic
twin-peak sign
| lambda sign
26
septum sign in mono
T-SIGN
27
what are primary complications of multifetal pregnancies?
- premature delivery
- IUGR
- demise of a co-twin
- congenital malformations
- CHD
28
since monochorionic twins share one placenta, what do they have a risk of?
haemodynamic complications
29
Discordant Growth
a significant size or weight difference between the two fetuses of a twin pregnancy
30
when is discordant growth more common in?
monochorionic pregnancies
31
What classifies growth discorance?
- weight discordance greater than 15-25%
| - EFW of smaller twin is under 10th percentile
32
equations for discordant growth?
larger twin EFW-smaller twin EFW/ larger twin EFW
33
IUGR
characterized by impaired fetal growth and inadequate placental function
34
the greater the discordance, the greater the liklihood:
- Placental insufficiency
- Twin-twin transfusion syndrome
- Higher incidence with a velamentous cord insertion
- Higher incidence with a single umbilical artery
35
sonograpahic features of discordant growth
- difference if CRL
- EFW difference at 15-25%
- oligohydramnios
36
growth differences of discordant growth weeks?
most profund >30 weeks
37
when is twin to twin transfusion only possible?
only in identical twins that are monochorionic, diamniotic
38
what happens to blood vessels in twin to twin transfusion?
single placenta contains blood vessel connections between the twins
39
what is twin to twin not caused by?
NOT inherited or genetic
| NOT caused by trauma
40
what is the smaller twin called in TTTS?
donor twin (does not get enough blood)
41
what is the larger twin called in TTTS?
recipient twin (overloaded with too much blood)
42
with TTTS, in attempt to reduce its blood volume, what does the recipient twin do?
increase urine production and this twin has distended bladder and polyhydramnios
(donor twin is opposite)
43
what will oligohydramnios in the donor twin cause?
"stuck twin" wrapped by amniotic membrane
44
alternate name for TTTS?
“Twin Oligohydramnios/polyhydramnios syndrome”
45
what does TRAP stand for?
Twin Reversed Arterial Perfusion sequence (TRAP) Acardiac Twin
46
what happens if TRAP?
Anastomosis of vessels establishes a connection between the 2 circulations (unbalanced AA anastomosis).
Retrograde perfusion interferes with normal cardiac development so the acardiac fetus becomes dependant on the perfusion if the "pump" twin
47
what are missing in an acardiac twin?
- head
- cervical spine
- upper limbs
48
what is blood that enters the acardaic twins abdomen?
deoxygenated blood that left the normal twin
49
why is the lower half but not the upper half of the acardaic fetus develop?
Most of the oxygen available is extracted when the blood enters the acardiac twin, allowing for some development of the lower body and extremities.
Once blood reaches the upper half of the body, oxygen saturation is extremely low, halting development of this area.
50
what is the acardiac twin known as?
parasite
51
what is the pump fetus?
the normal fetus
52
sonograhic findings of TRAP
- reversed arterial perfusion on doppler
| - umbilical cord with doppler shows arteries form placenta to acardiac twin, venous flow is opposite
53
fetus papyraceus
once the twin dies, most of the dead twin tends to be absorbed leaving behind a small flattened remnant
54
whata re complications for demise of co-twin?
twin embolization syndrome-the surviving healthy fetus affected by a monochorionic co-twin demise
55
what is another name for vanishing twin?
fetal resorption
56
vanishing twin
A fetus in a multi-gestation pregnancy which dies in utero and is then partially or completely reabsorbed
57
what complications may happpen if a fetus is absorbed in 1st trimester?
usually no further complications other than first trimester bleeding
58
what what complications may happpen if a fetus is absorbed in 2nd trimester?
- Premature labour
- Infection due to the death of the fetus
- Hemorrhage
- At the end of the pregnancy, a low-lying fetus papyraceus may block the cervix and require a cesarean to deliver the living twin.
59
what can the vanished twin die from?
- A poorly implanted placenta
- Developmental anomaly that may cause major organs to fail or to be missing completely
- A chromosomal abnormality incompatible with life. Frequently the twin is a blighted ovum, one that never developed beyond the very earliest stages of embryogenesis
60
Twin Embolization Syndrome
rare complication of a monozygotic twin pregnancy following an in uteri demise of the co-twin
61
what is the pathology of Twin Embolization Syndrome?
Acute haemodynamic shift from live to dead fetus resulting in hypoperfusion is more recently thought to play a role.
62
what is Twin Embolization Syndrome associated with?
There is usually an underlying twin-twin transfusion syndrome as a causative association.
63
thoracopagus
joined at chest
64
cephalo-thoracopagus
joined at head and chest
65
dicephalus
single trunk and 2 heads
66
craniopagus
joined at abdomen
67
omphalopagus
joined at abdomen
68
rachipagus
dorsal union of head and trunk
69
thoraco-omphalophagus
joined at chest and abdomen
70
Umbilical cord entanglement
one of more loops of cord being encircled around any part of the body or two umbilical cords getting entangled with each other
71
position
the part of the fetus that presents in the pelvis to the four quadrents of the maternal pelvis
72
lie
relationship between the longituidinal axis of the fetus and longitudinal axis of mother
73
when does the blastocyst begin the process of implantation?
after it attaches to the endometrial surface
74
what are the 2 cell layers of the trophoblast in the early stage of implantation?
- outer syncytiotrophoblast
| - inner cytotrophoblast
75
lacunae
blood filled spaces
76
where does the trophoblast network invade?
into the intervillous spaces
77
what is the appearance of the normal placenta?
- relatively homogenous
- retroplacental clear space is hypoechoic
- venous laking
78
what are placental venous lakes?
formation of hypoechoic cystic spaces centrally within the placenta
79
what is the colour flow of placental venous lakes?
low-velocity intraplacental laminar flow
80
what are placental venous lakes associated with?
- increased placental thickness
- placenta accreta spectrum and abnormal placental vilous adherence
- placental insufficiency, especially if seen early in pregnancy
81
where does normal placenta attach?
decidua basalis
82
how does the decidua seperate at delivery?
cessation of intra-placental flow as the myometrium contracts
83
when is low lying placenta or placenta previa seen and is considred normal?
1st and 2nd trimester
84
when is <14cm length of placenta abnormal?
20 weeks
85
when is <15cm length of placenta abnormal?
23 weeks
86
when is >3cm thickness of placenta abnormal?
20 weeks
87
when is >4cm thickness of placenta abnormal?
23 weeks
88
where should the cord insert on the placenta?
in the middle of the placenta
89
succenturiate lobe
single or multiple lobes connected to the main body of placenta by velamentous connection of the umbilical vessel (vessels traversing the membrane).
90
why must the accessory lobe of the placenta be reported?
make sure the placental accessory lobe is reatined after delivery
91
why is vascularity connection between the main placenta and succenturiate lobe important?
vessels are in proximity of the cervix this could be Vesa Previa
92
bilobed placenta
two similarly sized placental lobes separated by intervening membrane.
93
is there connected between bilobed placenta?
some vascular connection between lobes and umbilical cord may insert between lobes in membranes
SAME RISKS AS SUCCENTURIATE LOBE
94
Velamentous cord insertion
umbilical cord inserts into the fetal membranes (choriamniotic membranes), then travels within the membranes to the placenta (between the amnion and the chorion).
95
circumvallate placenta
fetal membranes (chorion and amnion) "double back" on the fetal side around the edge of the placenta.
96
does the circumvallate placenta cause harm?
not to the fetus but is associated with increased chances of placental abruption and hemorrhage
97
what can a free membrane of circumvallate placenta mimic?
a fetal membrane such as amniotic bands which have more ominous implications
98
another name for placenta membranacea
placenta diffusa
99
what is placenta membranacea?
all or most fetal membranes remain covered by chorionic villi, because the chorion has failed to differentiate into chorion leave and chorion frondosum.
100
sonographic examination of Placenta membranacea?
placenta that is covering most or the entire uterine wall
101
what condition is Placenta membranacea associated with?
placenta accreta, increta, percreta, and vasa previa
102
what are pregnancy complications of Placenta membranacea?
- Recurrent antepartum hemorrhages
- Second trimester miscarriages
- Preterm delivery
- IUGR
- Fetal demise
103
what are delivery complications associated with Placenta membranacea?
- post pardum hemorrhage
| - placental retention
104
Placenta Previa
placenta that partially or completely covers the internal os
105
what are the 3 degrees of placenta previa?
- complete previa
- marginal previa
- low lying placenta
106
low lying placenta
or placental the edge is within 2 cm but not covering any portion of the internal os
107
complete previa
IO completely covered
108
marginal previa
IO partially covered
109
placenta previa risk factors
```
Maternal age
Parity
Smoking
Endometrial scar
Symptoms:
Bleeding ++
```
110
what are the symtoms of placenta previa?
asymtomatic until the time of labour and delivery
111
where is low lying placenta easier to diagnose?
anterior extending down in lower uterine segment
112
can TVS be used in late pregnancy with bleeding?
no, use transperineal
113
what is the first modality to diagnose placenta previa?
US
114
what are the factors contributing to the relatively high false positive diagnosis of Placenta Previa?
- Distortion of lower segment (by over distended bladder)
| - Focal myometrial contractions
115
placenta acreta
villi invade decidua
116
placenta increta
villi invade myometrium
117
placenta percreta
villi invade myometrium and serosa
118
risk factors for placenta creta
- Prior uterine surgery
- Placenta previa
- Unexplained elevated maternal serum (MS) Fetal Protein
- Increased maternal free placental lactogen
- Advancing maternal age
119
sonographic signs of placenta accreta
- Presence of coexisting placenta previa
- Loss of the normal hypoechoic retro- placental – myometrial interface
- Thinning of disruption of the hyperechoic subvesicular uterine serosa
- Numerous placental lakes
120
colour doppler for placenta creta
- Diffuse lacunar blood flow throughout the placenta
- Absence of normal sub-placental venous flow
- Demonstration of vessels crossing the placental-myometrial disruption site
- Dilated vascular channels between placenta and bladder or cervix
121
management of placenta creta?
- information on it is very important for delivery
| - prenatal diagnosis allows uterine conservation and avoidance of massive blood loss at delievery
122
what is placenta abruption?
seperation of the palcenta prior to delivery of fetus
123
what is antepartum hemorrhage associated with?
- Abdominal pain
- Uterine hyper-tonicity (rigid or stiff uterus)
- Uterine tenderness
- Variable evidence of maternal hypovolemia (state of decreased blood volume; more specifically, decrease in volume of blood plasma)
- Shock
124
what does placenta abruption look like?
subplacental hematoma between the placenta and uterine wall
125
when in pregnancy does subchorionic hematoma occur?
occur anytime during pregnancy, it is more common in the first half of pregnancy, and its appearance will change as the hematoma organizes.
126
what is placental hematoma caused by?
bleeding from fetal vessels and located on the fetal surface of the placenta under chorion
127
berus mole
very large subchorionic haemorrhage
128
sonographic findings of placental hematoma
- acute is similar to echogencity of placenta
- organized becomes more hypoechoic and look like myometrium
- thickening of placenta (worse outcome)
129
how does a retroplacental hematoma appear?
mass of variable echogenicity between the uterine wall and the uterine surface of placenta.
130
what is a maternal floor infarction?
diffuse entity overtaking the villi with a fibrinoid deposition at the maternal surface and basal plate, reaching in the placental substance.
131
what does fibrin surrounding the villi do?
villi destructs nutrient exchange from mother to fetus.
132
when are infarctions associated with increased paerinatal mortality?
when they are larger than 3cm or involving more than 5% of placenta
133
what can lead to placental infarctions?
both maternal and fetal thrombophilias
134
placental infarction sonographic appearance
- Hyperechoic placental masses or (especially in maternal surface) placental thickening
- Hyperechoic placental masses may be associated with central hypoechoic spaces as they organize.
135
what commonly present with maternal floor infarction?
subchorionic cysts
136
how is maternal floor infarction clinicallt characterized?
severe early onset fetal growth restriction with features of uteroplacental insufficiency.
137
what is a risk when you have subchorionic cysts?
very high recurrence rate and carries a significant risk of fetal demise
138
what are pathological characteristsics of suchorionic cysts?
massive and diffuse fibrin deposition along the decidua basalis and the perivillous space of the basal plate
139
what are subchorionic cysts caused by?
maternal vascular disease
140
what does subchoronic cysts result in?
uteroplacental ischemia and infarction of the villi
141
what is the most common bengin tumor is the placenta?
chorioangioma
142
what can large chorioangioma lead to?
Cardiac failure
Anemia
Hydrops
Death
143
how do chorioangiomas appear?
as solid placental masses bulging towards the fetal surface of the placenta.
144
what is the sonographic appearance of a chorioangioma?
- Well circumscribed solid tumours in the placenta
- They can range from hypoechoic to hyperechoic compared to echogenicity of placenta.
- If > 5cm then Poor Outcome.
145
how is the umbilical cord developed?
enveloped body stalk + ductus omphalo-entericus + umbilical coelom
`
146
where does fusion occur in the umbilical cord?
between the 2 extra-embryonic mesoderm layers
147
what is the diameter of the umbilical cord?
1-2 cm
148
what is the length of the umbilical cord?
30-90 cm (average 55cm)
149
what does the interior umbilical cord contain?
whartons jelly (embryonic form of connecting tissue
150
what is the purpose of whartons jelly?
protects the umbilcal vessels from possible mechanical pressure and creasing
151
what does the umbilical cord contain? (vessels)
- 2 relatively small umbilical arteries
| - one larger umbilical vein
152
is the umbical arteries deoxygenated or oxygenated?
Deoxygenated blood is returned from the fetal circulation to the placenta via the paired umbilical arteries.
153
after birth what do the umbilical arteries become?
umbilical ligament
154
what is the path of the umbilical vein?
It goes superiorly towards the liver to join the proximal portion of the LPV.
155
what does the umbilical vein become after birth?
ligementem teres
156
what is a very long cord associated with?
Asphyxia
Death due to knots
Multiple loops of nuchal cord
Cord prolapse
157
what is a short umbilical cord associated with?
aneuploidy, and extreme IUGR.
158
what is umbilical coiling?
distance between the same umbilical artery making one turn around the umbilical vein
159
what is lower degrees of coiling associated with?
lesser degrees of fetal growth
160
in the 2nd and 3rd trimester what is the largest contributer to the size of umbiliccal cord?
whartons jelly
161
what is a small diamter in the umbilical cord a marker for in the 1st trimester?
pregnancy failure
162
what is a small diamter (thin) in the umbilical cord a marker for in the 2nd or erd trimester?
IUGR
163
what is a thick cord in the umbilical cord a marker for in the 2nd or erd trimester?
```
Aneuploidy
Diabetes,
Fetal macrosomia,
Placental abruption,
Rhesus isoimmunization
```
164
what is Rhesus Isoimmunization?
a small amount of the baby's blood can enter maternal circulation and if she is Rh-negative and baby os Rh-positive the mother produces antibodies against antigen on baby
165
when can Rhesus disease become worse?
with each additional Rh incompatible pregnancy.
166
what are the 2 types of umbilical cord tumors?
hemangioma
| teratoma
167
are the umbilical cord tumors mailignant or benign?
benign
168
hemangiomas
- occur near placental end
| - may arise from one or more umbiical vessels or from remnant of embryonic vessles
169
what are hemangiomas associated with?
still birth
170
what is the appearance of an hemangioma?
Multicystic appearance and may be impossible to differentiate from a teratoma, hematoma or umbilical cord cyst.
171
what is another name for hemangioma?
Angiomyxomas
172
teratoma appearance
solid with/without cystic area
173
what does a teratoma contain?
Contains tissue from all three germ cell types and occur in places where the components of the tumour are foreign to surrounding tissue.
174
what is absent coiling associated with?
- single umbilical artery
- both marginal and velamentous umbilical cord insertions
- multiple gestations
- aneuploidy
- preterm delivery
- fetal demise
175
where are umbilical cysts most frequently seen?
portions closest to fetus
176
where do umbilical cysts develop from?
allantois and omphalomesenteric duct
177
where may pseudo-cysts develop?
through liquefaction of Wharton’s Jelly giving the umbilical cord a hydropic appearance.
178
if unbilical cord cysts perisist in the 2nd and 3rd trimester what could this cause?
- Chromosomal abnormalities: Trisomy 13 and 21
| - Structural abnormalities: genitourinary and gastrointestinal anomalies
179
what is nuchal cord?
cord around neck
180
what is single unbilical artery (SUA)?
congenital absence of either the right or left umbilical artery.
181
in SUA, which artery is more common absent?
left umbilical
182
when is SUA increased?
twins
| maternal diabetes
183
what is SUA due to?
secondary atresia or atrophy rather than primary agenesis of the artery
184
what are associations with SUA?
- Intra-uterine growth restriction (IUGR)
- Aneuploidy
- Renal abnormalities
- Cardiac abnormalities
185
what is Velamentous and marginal cord insertions?
When the cord inserts into the membranes and not the placental disc.
186
when can Velamentous and marginal cord insertions be identified?
early as 10 weeks and routinely 11-14 weeks
187
what is Velamentous and marginal cord insertions associated with?
- IUGR
- preterm delivery
- congenital anomalies
- low apgar scores
- neonatal death
- retained placenta after delivery
188
what is vase previa associated with?
- placenta previa
- multiple gestations
- in vitro pregnancies
189
with vasa previa what should be offered prior to onset of labour?
elective caesarean
190
what is given before an early C-section?
Corticosteroids at 28 to 32 weeks to promote fetal lung maturation and hospitalization at about 30 to 32 weeks.
191
why is Umbilical arterial Doppler assessment used?
in surveillance of fetal well-being in the 3rd trimester of pregnancy.
192
what is abnormal umbilical artery doppler a marker of?
of uteroplacental insufficiency and consequent IUGR or suspected pre-eclampsia
193
what has umbilical artery doppler assessment been shown to improve?
perinatal mortality and morbidity in high risk obstetric situations
194
umbilical cord doppler indications
- Assessment of fetal growth and well being in the 3rd trimester: routinely includes umbilical Doppler assessment
- Indicated in scenarios where there is increased risk of FGR or poor perinatal outcome
195
maternal conditions umbilica cord doppler
- diabetes mellitus
- chronic renal disease
- hypertension
- prothrombotic states
- pregnancy related conditions
196
suspected IUGR umbilical cord doppler
- previous pregnancy with IUGR or fetal death in utero
- decreased fetal movement
- oligohydramnios
- polyhydramnios
- multifetal pregnancy
197
what is normal umbilical venous doppler?
comprises of a monophasic non-pulsatile flow pattern with a mean velocity of ~10-15 cm/s
198
what does the presence of pulsatility imply?
a pathological state
199
when does pulsatility not imply a pathological state?
- Early in pregnancy: up to ~13 weeks gestation
| - The presence of pulsatility may be higher in chromosomally abnormal fetuses even in early pregnancy
200
what is a proplapsed cord?
Umbilical cord prolapse happens when the umbilical cord precedes the fetus’s exit from the uterus.
201
what does amniochorionic membranes consist of?
fused amnion and smooth chorion
202
when does memnranes fuse and finnish fusing?
begins at the end of 1st trimester and completes by 20 weeks.
203
what is elevation or bulging of amniochorionic membrane associated with?
placental abruption and subchorionic hematoma
204
what is Premature rupture of membranes (PROM)?
Rupture of the amniochorionic membrane prior to onset of labour.
205
what is the major concern with PROM?
chorioamnionitis if PROM is longer than 24 hours with or without labour
206
what are causes of PROM?
Incompetent cervix, multiple gestations, multiple amniocentesis and polyhydramnios
207
what may Chorioamnionitis cause?
fetal or maternal dealth
208
is pregnancy is less than 32 wks with PROM
Pregnancy is usually continued under very close assessment because the fetus is immature and high risk for neonatal respiratory distress syndrome.
209
is pregnancy is more than 32 wks with PROM
Labour may be induced or a C-section can be performed.
210
what does amniotic fluid consist of?
- Desquamated fetal epithelial cell
- Organic and inorganic salts
- Proteins, fats, enzymes, hormones, carbohydrates, and pigments
- Later urine and meconium are added
211
what is the functin of amniotic fluid?
- Amniotic fluid provides a medium in which fetus can move, grow and develop without pressure.
- It maintains the environment temperature and helps maturation of fetal lungs
212
when is urine production the major source of amniotic fluid?
after 16 weeks
213
what do we measure when measuring AFV?
longest single pocket free of umbilical cord and fetal small parts
214
AFV measurment oligohydramnois
<2cm
215
AFV measurment normal
2-8 cm
216
AFV measurment polyhydramnios
>8cm
217
what is oligohydramnois associated with?
- Maternal drug intake
- IUGR
- Urinary tract anomalies
218
how is oligohydramnois defined?
as more than 2 standard deviation (2 SD) below the mean for the specific GA.
219
when is oligohydramnois reccomended for screening?
The 5th percentile value
220
what is the normal cervical length?
greater than 30mm
221
Cervical Incompetence
A medical condition in which a pregnant woman's cervix begins to dilate (widen) and efface (thin) before her pregnancy has reached term.
222
what may cervical incompetence cause during the 2nd and 3rd trimesters?
miscarriage or preterm birth
223
what is another sign of cervical incompetence?
is funnelling at the internal orifice
224
what is cervical funneling?
Opening of the internal cervical os with protrusion of the amniotic sac into the cervical canal.
225
when is funneling normal?
after 32 weeks
