MULTIFETAL PREGNANCY Flashcards
(104 cards)
1
Q
What is the mechanism of dizygotic or fraternal twin formation?
A
Dizygotic twins result from the fertilization of two separate ova.
2
Q
What is the mechanism of monozygotic or identical twin formation?
A
Monozygotic twins result from the fertilization of a single ovum and are genetically identical.
3
Q
What determines the outcome of monozygotic twinning?
A
The outcome depends on when the division of the zygote occurs.
4
Q
When does diamniotic, dichorionic twinning occur?
A
It occurs when the zygote divides within the first 72 hours after fertilization.
5
Q
When does diamniotic, monochorionic twinning occur?
A
It occurs if the division occurs between the 4th and 8th day after fertilization.
6
Q
When does monoamniotic, monochorionic twinning occur?
A
It occurs approximately 8 days after fertilization when the chorion and amnion have already differentiated.
7
Q
What usually results if division occurs beyond 8 days after fertilization?
A
Conjoined twins.
8
Q
What is chorionicity?
A
Chorionicity refers to the type of placenta and determines the likelihood of twin-related complications.
9
Q
What type of placenta is monozygotic until proven otherwise?
A
Monochorionic placenta.
10
Q
What types of placenta can be either dizygotic or monozygotic?
A
Dichorionic placenta.
11
Q
What factors influence twinning?
A
Race, maternal age, parity, heredity, nutrition, fertility treatment, and pituitary gonadotropins.
12
Q
What increases the likelihood of twinning due to heredity?
A
A history of twins in first-degree relatives.
13
Q
How can sonography help determine chorionicity early in pregnancy?
A
By assessing the number of gestational sacs and placental masses.
14
Q
What sonographic feature indicates dichorionic twins?
A
Thick dividing membrane (≥2 mm) or the twin peak sign/lambda sign.
15
Q
What sonographic feature indicates monochorionic twins?
A
Thin dividing membrane (<2 mm) or the T-sign.
16
Q
What does the twin peak sign or lambda sign suggest?
A
Dichorionic twins.
17
Q
What does the T-sign suggest?
A
Monochorionic twins.
18
Q
What is the appearance of a dichorionic-diamniotic pregnancy on ultrasound?
A
Two separate compartments for the babies.
19
Q
What is the appearance of a monochorionic-diamniotic pregnancy on ultrasound?
A
Two yolk sacs with a thin membrane dividing them.
20
Q
What is the appearance of a monochorionic-monoamniotic pregnancy on ultrasound?
A
One yolk sac and a single amniotic cavity.
21
Q
What is the relationship between chorionicity and gender in twins?
A
Different genders indicate dichorionic twins, while same genders could be dichorionic or monochorionic.
22
Q
What clinical signs suggest multifetal gestation during the second trimester?
A
Uterine size larger than expected, palpable two fetal heads, and >1 fetal heart beats noted.
23
Q
What sonographic technique confirms twin pregnancy?
A
Identifying two fetal heads or abdomens in the same image plane.
24
Q
What imaging modality is preferred for conjoined twins?
A
MRI provides detailed assessment of pathology in conjoined twins.
25
How do B-hCG and maternal serum alpha-fetoprotein (MSAFP) levels differ in twin pregnancies?
Both are generally higher with twins compared to singletons.
26
What condition can also present with high levels of B-hCG?
Hydatidiform mole.
27
What imaging feature can differentiate dichorionic from monochorionic twins?
Membrane thickness: dichorionic membranes are thick (4 layers), while monochorionic membranes are thin (2 layers).
28
How should a pregnancy be managed if chorionicity is uncertain?
It should be managed as monochorionic until proven otherwise.
29
Why might MRI be used in twin pregnancies?
To assess pathology in twins, especially in cases of conjoined twins.
30
Why are fundic heights larger in multifetal pregnancies?
Between 20 and 30 weeks, fundic heights are approximately 5 cm greater than expected for singletons of the same fetal age.
31
What is the accuracy of sonographic determination of chorionicity based on gestational age?
It is most accurate in the first trimester and decreases with advancing gestational age.
32
What biochemical markers are unreliable for identifying multiple fetuses?
Serum and urine levels of B-hCG and maternal serum alpha-fetoprotein (MSAFP) are not reliable due to variability.
33
What are some maternal physiological burdens in multifetal pregnancy?
Increased risk of serious complications, hyperemesis gravidarum, hypervolemia, anemia, increased cardiac output, decreased vascular resistance, greater uterine growth, and compression of abdominal organs and lungs.
34
What is hyperemesis gravidarum?
Excessive nausea and vomiting during pregnancy.
35
Why is the iron supplement dose doubled in multifetal pregnancy?
Due to higher blood volume expansion and increased risk of anemia.
36
By what percentage does cardiac output increase in multifetal pregnancies compared to singletons?
Another 20% above singleton pregnancies.
37
Why is vascular resistance lower in twin gestations compared to singleton pregnancies?
Due to physiological adaptations to accommodate multifetal growth.
38
What is the risk of spontaneous abortion in singleton pregnancies?
0.009000000000000001
39
What is the risk of spontaneous abortion in multiple pregnancies?
0.073
40
Which type of placentation is more common in miscarriages involving multiple gestations?
Monochorionic placentation.
41
How does the incidence of congenital malformations in twins compare to singletons?
406 per 10,000 twins versus 238 per 10,000 singletons.
42
Which type of twin gestation has a higher malformation rate: monochorionic or dichorionic?
Monochorionic twins.
43
Why do multifetal gestations often result in low birth weight?
Due to restricted fetal growth and preterm delivery.
44
What factors contribute to growth restriction in monochorionic twins?
Unequal allocation of blastomeres, vascular anastomoses, and discordant structural anomalies.
45
What is the relationship between pre-pregnancy BMI and hypertensive disorders in multifetal pregnancies?
BMI ≥30 kg/m² is an independent risk factor for preeclampsia.
46
Why does multifetal pregnancy have a higher chance of preeclampsia?
Due to greater placental mass and abnormal remodeling of spiral arteries.
47
Why do young primigravida and elderly primigravida patients have a higher risk of hypertension?
Their spiral arteries are either too immature or too aged, leading to higher vascular resistance.
48
Why is preterm birth more common in multifetal pregnancies?
Uterus stretching increases with the number of fetuses, leading to higher chances of preterm labor.
49
What are the cognitive outcomes of twins compared to singletons?
Generally similar, but cerebral palsy risk is higher in twins and higher-order multiples.
50
What are some complications unique to monochorionic twins?
Twin-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence (TAPS), and conjoined twins.
51
What is twin-twin transfusion syndrome (TTTS)?
A condition where blood is transfused from a donor twin to a recipient twin, leading to anemia and growth restriction in the donor and polycythemia and circulatory overload in the recipient.
52
What are the diagnostic criteria for TTTS?
1. Monochorionic diamniotic pregnancy. 2. Oligohydramnios (vertical pocket <2 cm) in the donor sac and polyhydramnios (vertical pocket >8 cm) in the recipient sac.
53
What are the management options for TTTS?
Expectant management, amnioreduction, fetoscopic laser ablation, septostomy, and selective feticide (not practiced in the Philippines).
54
What is the most common type of conjoined twins?
Thoracopagus twins (joined at the chest or thorax).
55
What is an external parasitic twin?
A grossly defective fetus or merely fetal parts attached externally to a relatively normal twin.
56
What is a fetus in fetu?
An internal parasitic twin where one embryo is enfolded within its twin, losing normal spatial arrangement and organ presence.
57
What are the survival chances of twins with TTTS?
Survival is possible if the condition is diagnosed early and treated, especially in Stage I.
58
Between the donor and recipient twin in TTTS, which is more likely to survive?
The recipient twin.
59
What is Twin Anemia-Polycythemia Sequence (TAPS) characterized by?
Significant hemoglobin differences between donor and recipient twins without discrepancies in amniotic fluid volumes typical of twin-twin-transfusion syndrome.
60
What are the neonatal criteria for diagnosing TAPS?
Intertwin hemoglobin difference >8.0 g/dL and intertwin reticulocyte count ratio >1.7.
61
What is the antenatal diagnostic method for TAPS?
MCA-PSV (Middle Cerebral Artery - PSV) by Doppler.
62
What is the MCA-PSV fetal criterion for anemia in TAPS?
MCA-PSV >1.50 MoM in the donor.
63
What is the MCA-PSV fetal criterion for polycythemia in TAPS?
MCA-PSV <0.80 MoM in the recipient.
64
Describe TAPS Stage 1.
MCA-PSV donor >1.5 MoM and MCA-PSV recipient <1.0 MoM with no signs of fetal compromise.
65
Describe TAPS Stage 5.
Intrauterine demise of one or both fetuses preceded by TAPS.
66
What is Twin-Reversed Arterial Perfusion (TRAP) also known as?
Acardiac twin.
67
What is the key feature of TRAP sequence?
A recipient twin lacks a heart and other structures, while the donor twin shows features of heart failure.
68
How does blood flow in TRAP sequence?
Reverse blood flow of deoxygenated arterial blood from the donor to the recipient twin through an artery-to-artery placental shunt.
69
What is the treatment option for TRAP sequence?
Fetoscopic laser photocoagulation of placental vessels or intrauterine blood transfusion.
70
What are the complications of complete hydatidiform mole with coexisting normal fetus?
Persistent trophoblastic disease requiring chemotherapy, heavy bleeding, preeclampsia, or preterm delivery.
71
How is twin discordancy calculated?
(Larger twin weight - Smaller twin weight) / Larger twin weight.
72
What percentage weight discordancy is significant in twins?
Greater than 20%.
73
What is the most important determinant of discordant growth in monochorionic twins?
Unequal placental sharing.
74
What is 'vanishing twin syndrome'?
The early disappearance of one fetus in a twin pregnancy.
75
What is 'fetus papyraceous'?
A dead fetus flattened through desiccation.
76
What is the recommended delivery time for monochorionic twins?
By 37 weeks' AOG.
77
What is the main risk to the surviving twin after the death of a monochorionic co-twin?
Exsanguination into the dead twin through vascular anastomoses, leading to hemodynamic changes and ischemic brain damage.
78
What are the possible abnormalities in the surviving twin after co-twin death in monochorionic twins?
Neural tube defects, microcephaly, hydrocephalus, porencephaly, and multicystic encephalomalacia.
79
What causes maternal DIC in single fetal death in twins?
Thromboplastins from the dead fetus and placenta entering maternal circulation, activating the extrinsic coagulation pathway.
80
What is the role of platelet count and fibrinogen level monitoring in maternal DIC?
Used before delivery as maternal DIC is rare.
81
Which type of twins has a higher risk of neurodevelopmental impairment after co-twin demise?
Monochorionic twins.
82
What is the recommended weight gain for women with a normal BMI in a twin pregnancy according to the Institute of Medicine?
"37 to 54 lbs."
83
What is the daily recommended caloric intake for women with twins?
"40 to 45 kcal/kg/day (20% protein, 40% carbohydrates, 40% fat)
84
What is the cornerstone of fetal assessment in twin pregnancy?
"Identification of abnormal fetal growth or discordancy."
85
What is the significance of SVP <2 cm in amniotic fluid assessment?
"It indicates oligohydramnios and may suggest uteroplacental pathology."
86
At what SVP value is polyhydramnios indicated?
"SVP ≥8 cm."
87
What ultrasound measurements define oligohydramnios and polyhydramnios in the four quadrants?
"Oligohydramnios: <5 cm; Polyhydramnios: >25 cm."
88
At what gestational age should ultrasound be done to assess viability, chorionicity, and Crown-Rump Length in twin pregnancies?
"10 to 13 weeks."
89
What is the significance of a thickened nuchal translucency?
"It is commonly seen in Down syndrome."
90
What is the recommended time frame for a Congenital Anomaly Scan (CAS) in twin pregnancies?
"18 to 22 weeks; optionally 24 to 26 (28) weeks for better fetal heart evaluation."
91
Why is monochorionic twin pregnancy monitored more frequently than dichorionic twins?
"Due to higher risk of complications like TTTS
92
What is the recommended monitoring frequency for monochorionic twins starting at 16 weeks?
"Ultrasound every 2 weeks."
93
At what frequency should dichorionic twins be monitored for fetal growth after 20 weeks?
"Every 4 to 6 weeks."
94
What tests are commonly used to assess fetal well-being in twin pregnancies?
"Nonstress Test (NST) or Biophysical Profile (BPP)."
95
When is pulmonary maturation usually synchronous in twins?
"By approximately 32 weeks."
96
What is the planned delivery time for uncomplicated dichorionic-diamniotic twins?
"38 + 0 to 38 + 6/7 weeks."
97
When should uncomplicated monochorionic-diamniotic twins be delivered?
"36 + 0 to 36 + 6/7 weeks."
98
What is the delivery recommendation for monochorionic-monoamniotic twins?
"Elective cesarean section between 32 + 0 and 34 + 0 weeks after corticosteroids."
99
What is the recommended route of delivery for cephalic-cephalic twin presentations?
"Vaginal delivery if there are no standard indications for cesarean."
100
What is the maximum allowable time interval between the delivery of twins to avoid fetal distress and acidosis?
"30 minutes."
101
In cases of TTTS, TAPS, or sFGR after 26 weeks, what is the management recommendation?
"Prompt delivery of both twins if impending death of one twin is suspected."
102
What is the oxytocin regimen for induction or augmentation of labor in twin pregnancies?
"The same as in singleton pregnancies."
103
What is the most common initial sign of uterine rupture during TOLAC in twin pregnancies?
"Fetal heart rate changes."
104
What is the primary approach for detecting fetal complications in monochorionic twins?
"Serial ultrasounds."
