2. Stats
• 1% of all pregnancies.
• 97% of multiple pregnancies are twin pregnancies.
• Double the chance to have twins if conception is within one month
after stopping OCP.
• Increased with ART (1970’s).
• Increased perinatal mortality & morbidity.
3. Stats
Hellin’s Law
•
•
•
•
Twin 1 : 89
Triplets 1 : 892
Quadruplets 1 : 893
Quintuplets 1 : 894
• Frequency: Highest – Black
Lowest – Asian
• Increased with maternal age and parity.
• ART
4. Zygotes – Chorions - Amnions
• Zygosity = Type of Conception
• Chorionicity = # of Placenta’s
• Amnionicity = # of Amniotic Sacs
5. Monozygotic
• Also known as identical twins.
• No genetic predisposition.
• Fertilization of single ovum.
• Same sex.
• Identical – including HLA genes.
13. Prenatal Screening
Genetic Testing
• Age 32 consider invasive testing.
• Amniocentesis/CVS uncertain risk with twin gestation.
• Age 32 same Down’s Syndrome risk as singleton age 35.
17. Cervical Assessment
• Transvaginal US cervical assessment in the prenatal period has not
been determined due to lack of controlled studies.
• Good evidence that premature cervical change by digital
examination predicts preterm birth in twins.
18. Home Uterine Monitoring
• No reduction in the incidence of preterm labor, advanced cervical
dilation at presentation, or preterm birth in well-controlled
randomized clinical trials.
• Moderate evidence against home uterine activity monitoring in
multiple gestation.
19. Pre-Term Labor
Bedrest?
• Randomized controlled trials and a meta-analysis of hospital bedrest
in twin pregnancies have shown no reduction in preterm birth or
perinatal death.
• In uncomplicated twin pregnancies, hospital rest may result in
increased risk of preterm birth and maternal psychosocial stress.
• In women with twin pregnancy at high risk for preterm birth
because of premature cervical change, there is no evidence that
hospital bedrest will reduce the rate of preterm birth.
• There is insufficient evidence to support prophylactic activity
restriction or work leave in multiple gestation.
20. Pre-Term Labor
Tocolytics?
• Most randomized controlled trials have failed to show any benefit of
prophylactic oral or intravenous tocolytic therapy in multiple
gestation.
• There is moderate evidence against prophylactic tocolysis in the
management of multiple gestation, but it may be indicated on other
grounds.
21. Pre-Term Labor
Cervical Cerclage?
• Prophylactic cervical cerclage has not been shown to be effective in
preventing preterm birth in twin pregnancy in observational or
controlled trials.
• There is moderate evidence against routine prophylactic cervical
cerclage in multiple gestation.
• Cerclage may be indicated for the treatment of incompetent cervix
or other specific circumstances.
22. Pre-Term Labor
Cervicovaginal Fibronectin
• High NPV
• PPV for delivery before 37 weeks is 60 percent for patients in
preterm labor, 45 percent in asymptomatic high-risk women, and 30
percent in asymptomatic low-risk women.
• No interventional trials.
23. Mortality & Morbidity
• Twins = High-risk pregnancy.
• Fetal mortality rate for twins is 4x the mortality rate for single births.
• Neonatal mortality rate for twins is 5x the mortality rate for single
births.
• Increased prevalence of low birth weight infants secondary to
prematurity and IUGR.
24. Mortality & Morbidity
• Gestational HTN 3x greater risk – with earlier onset and increased
severity compared to single birth.
• Anemia 2X greater risk compared to single birth.
• Congenital Birth Defects 2X greater risk of neural tube defects,
gastrointestinal, and heart anomalies.
26. Vascular Anastomosis
• Only monochorionic twins.
• Approximately 100% of monochorionic twin placentas have vascular
anastomoses.
• Variations in the number, size, and direction.
28. TTTS
Twin-Twin Transfusion Syndrome
• TTTS results in hypoperfusion of the donor twin with hyperperfusion
of the recipient twin.
• Donor twin becomes hypovolemic and oliguric/anuric.
• Oligohydraminos develops in the amniotic sac of the donor twin.
• Oligohydraminos can result in “Stuck-Twin” phenomenon with the
twin fixed against the uterine wall.
30. TTTS
• Hydrops fetalis in either twin.
• Donor twin secondary to anemia and/or high-output heart failure.
• Recipient twin secondary to hypervolemia.
• Recipient twin risk of hypertension, hypertrophic cardiomegaly,
disseminated intravascular coagulation, and hyperbilirubinemia
after birth.
31. TTTS
• 60-100% fetal or neonatal mortality rate.
• Associated with premature delivery.
• Death of one twin is associated with neurologic sequelae in 25% of
surviving twins.
32. TRAPS
Twin Reverse Arterial Perfusion Syndrome
•
•
1% of monochorionic
.
Arterio-arterial anastomosis.
•
55% mortality in pump twin secondary to polyhydramnios and/or
high-output cardiac failure.
•
Acardiac twin receives blood supply via “pump” twin.
•
Results in absent/rudimentary development upper body structures.
•
Invasive treatment dependent on fetal progress of pump twin.
35. Single Fetal Demise
• 2-6% of twins pregnancies.
• Up to 25% in MC twin pregnancy.
• Increased perinatal morbidity and mortality of the surviving co-twin.
Related to blood loss of surviving twin.
19% perinatal death
24% having serious long-term sequelae
36. Discordant Fetal Growth
• Secondary to different genetic growth potentials, structural anomaly
of one fetus, or irregular placental implantation.
• Aneuploidy, congenital anomaly, or viral syndrome affecting only
one fetus must also be considered when discordant growth is
identified.
• Risk increased if weight discordance exceeds 25%.
• Discordance is an indicator for an increased risk of IUGR, morbidity,
and mortality for the smaller twin.
37. Cord Entanglement
• 70% of MCMA twins.
• Major cause for sudden intra-uterine fetal demise.
• Ultrasound diagnostic.
• Close fetal surveillance from 24 weeks onward.
• Prophylactic delivery via caesarean section at 32 to 34 weeks.
42. C-Section
Elective/Scheduled
First twin non-cephalic
Conjoined twin
Monoamniotic twin
Placenta previa
IUGR of dichorionic twin
Congenital abnormality
Emergency
Fetal distress
Cord prolapse of 1st twin
Non progress of labor
Collision of both twins
2nd twin transverse after delivery of 1st twin
