31. Multiple gestation

Question 1

definition of multiple gestation

Answer 1

pregnancy in which 2 or more embryos/fetuses occupy the uterus simultaneously

Question 2

predisposing factors for multiple gestation

Answer 2

advanced maternal age (≥ 35 y’)
previous multiple gestations
use of assisted reproductive techniques (IVF)
family history (maternal) of multiple gestations

Question 3

2/3 of all twin pregnancies are?

Answer 3

Dizygotic twins
Fertilization of two oocytes with two mature spermatozoa
Genetically different
Dichorionic-diamniotic

Question 4

1/3 of all twin pregnancies are?

Answer 4

monozygotic (identical) twins
Division of a single fertilized oocyte
into two embryonic layers

Question 5

how are monozygotic twins classified?

Answer 5

1. Dichorionic-diamniotic (25%)
2. Monochorionic-diamniotic (70%)
3. Monochorionic-monoamniotic (1-5%)
4. Conjoined twins (monochorionic-monoamniotic) (<0.1%)

Question 6

description of dichorionic-diamniotic

Answer 6

Single fertilization with early split, 2 placentas, 2 sacs
Cleavage in 0-4 days from conception:
Separate chorion and amnion

Question 7

description of monochorionic-diamniotic

Answer 7

Twins share 1 placenta, but have a separate amniotic sac (2 sacs)
Cleavage in 4-8 days from conception:
shared Chorion

Question 8

what occurs if cleavage is on 8-12 days from conception?

Answer 8

minochorionic-monoamniotic twins
share 1 placenta and 1 amniotic ac

Question 9

what occurs if cleavage is on +13 days from conception?

Answer 9

conjoined twins
Twins share 1 placenta and 1 amniotic sac, and are conjoined (shared body)
תאומים סיאמיים

Question 10

how do we diagnose twins?

Answer 10

1. PE:
   - Fundal height and abdominal size are unusually large for the gestational age.
   - Two or more fetal heart rates can be heard on auscultation.
   - Mother may present with severe nausea/vomiting (due to ↑↑ hCG).
2. US- Evidence of more than one fetus.

Question 11

what is Lambda sign?

Answer 11

a way to differentiate dichorionic twins on US
Both chorionic cavities are separated from one another. Separation of the chorionic and amniotic sacs resembles the Greek symbol λ (lambda) on US

Question 12

what is T-sign?

Answer 12

a way to differentiate monochorionic twins on US
One chorionic cavity is present and each twin has an individual amniotic sac.
Separation of the amniotic sacs resembles the letter T on US

Question 13

maternal Complications of multiple gestation

Answer 13

• Anemia
• HTN disorders of pregnancy
• Premature labor
• Postpartum uterine atony
• Postpartum hemorrhage
• Preeclampsia
• Cesarean delivery

Question 14

fetal complications of multiple gestations

Answer 14

• Malpresentation
• Placenta previa
• Abruptio placenta
• PROM
• Prematurity
• Umbilical cord prolapse
• IUGR, congenital anomalies
• Increased perinatal morbidity and mortality

Question 15

what is Twin-to-twin transfusion syndrome (TTTS)?

Answer 15

The presence of unbalanced arterio-venous anastomoses in the shared placenta (monochorionic) leads to a syndrome in which the circulation of one twin perfuses that of the other.

Question 16

what are the stages of Twin-to-twin transfusion syndrome (TTTS)?

Answer 16

Stage I = amniotic fluid imbalance;
stage II = donor bladder not visible on US examination; stage III = abnormal Doppler assessment;
stage IV = ascites/hydrops in one twin;
stage V = death of one/both twins

Question 17

which twin in TTTS have a more favorable prognosis?

Answer 17

the donor twin (smaller)

Question 18

Donor twin complications

Answer 18

hypovolemia, hypotension, oligohydramnios, anemia, IUGR.

Question 19

Recipient twin complications

Answer 19

hypervolemia, hypertension, thrombosis, polycythemia, edema, CHF

Question 20

management of TTTS

Answer 20

1. Pregnancy termination: selective (recipient twin survives) vs. non-selective (both fetuses).
2. Corrective laser procedures: ablation of the anastomosing vessels.
3. Expectant management (may be feasible in selected cases).
4. Amniocentesis to correct amniotic fluid volume abnormalities.

Question 20

management of TTTS

Answer 20

1. Pregnancy termination: selective (recipient twin survives) vs. non-selective (both fetuses).
2. Corrective laser procedures: ablation of the anastomosing vessels.
3. Expectant management (may be feasible in selected cases).
4. Amniocentesis to correct amniotic fluid volume abnormalities.

Question 21

Management of multiple gestation (antepartum)

Answer 21

1. High-risk pregnancies require more frequent prenatal care visits. From the 32nd week gestation → weekly prenatal care visits.
2. Frequent early evaluations for monochorionic twins to assess for TTTS.

Question 22

Management of multiple gestation (intrapartum)

Answer 22

Uncomplicated, dichorionic twin pregnancies → deliver at 38 weeks gestation.
Monochorionic twin pregnancies → deliver at 34-37 weeks gestation.

Question 23

Management of monoamniotic pregnancy

Answer 23

Considered very high-risk pregnancies.
1. Hospitalize at 24 gestational weeks.
- Perform US every other day during hospitalization.
- Perform x3 daily CTG monitoring during hospitalization.
2. Deliver at 32-34 weeks gestation.

Question 24

how do we decide about the delivery mode in multiple gestations?

Answer 24

Consider: fetal presentation (cephalic/cephalic in 40% of cases), fetal weight estimation, previous C-section, preterm twins, maternal conditions.