Multifetal Gestation

1. Multifetal Gestation Xiong yu Obstetric & Gynecology Hospital, Fudan University

2. Incidence twins：1:100。 triplets：1:10,000。 quadruplets：1:1,000,000。 quintuplets：1:100,000,000。

3. Incidence • Between 1980 and 2005,the number of live births from twin deliveries rose nearly 50 percent, and the number of higher-order multifetal births increased more than 400 percent. • However, changing infertility therapy has led to slight decreases in rates of higher- order multifetal births.

4. Factors that Influence Twinning Race Heredity Maternal Age and Parity Nutritional Factors Pituitary Gonadotropin Infertility Therapy Assisted Reproductive Technology (ART)

5. Factors that Influence Twinning Dizygotic twins：2/3 influenced remarkably by race, heredity, maternal age, parity, and, especially, fertility treatment monozygotic twins：1/3 1:250 independent of race, heredity, age, and parity

6. Dizygotic twins Two ovums，Two sperms。 Different Gene： appearance:different or alike gender：same or different Placenta： two placentas fuse to one placenta,twin peak,no communicated blood vessel Diamnionic/dichorionic (DA/DC)

7. Placenta and membrane of dizygotic twins two placentas two amnions two chorions fused placenta two amnions fused chorion

8. Monozygotic twins One ovum，One sperm。 Same Gene： appearance: same gender：same Four types: 1. DCDA 2. MCDA 3. MCMA 4. MCMA conjoined twins

9. Conjoined twins (1:60,000)

10. Importance of Chorionicity Chorionicity determine the outcome of twins, while not zygoticity. Compare to DCDA, higher incidence of abortion, perinatal mortality, preterm, FGR and morfamation in MC twins. If one twin died in MC twins, the other twin will be in high risk of sudden death and nervous system effects. -----Determination of chorionicity correctly is important to predict the prognosis and twin-specific complications.

11. Outcomes of Different Chorionic Twins

12. Sonographic Evaluation（prenatal)--- Dichorionic Diamniotic twins(DCDA) first trimester（before 8 weeks）：two sacs after 14 weeks：opposite gender（dizygotic） 10-14 weeks： two separate placentas dividing membrane: ≧2 mm one fused placenta,twin peak

13. Sonographic Evaluation（prenatal)---Monochorionic Diamniotic twins(MCDA) first trimester（before 8 weeks）：one sac after 14 weeks：same gender 10-14 weeks： dividing membrane: ‹2mm one placenta：none twin peak，T sign divided amnion

14. no divided amnion Sonographic Evaluation（prenatal)--- Monochorionic Monoamniotic twins(MCMA)

15. Determination of Chorionicity (postnatal) Gender Opposite: DC Same: DC or MC Placenta: two placentas：DC one placenta: number of membrane partition that separated twin fetuses 0： MCMA 2： MCDA 3 or 4： DCDA

16. Complications(maternal) Anemia: 74.6% Preeclampsia: 30% Postpartum hemorrhage: 2 times (average blood loss with vaginal delivery of twins is 1000 mL) Higher rate of CS: 53.3% Emergent peripartum hysterectomy: 3 times (twins), 24 times (triplets of quadruplets) Heart failure Depressive symptoms : 50% Maternal death

17. Complications (fetal) Abotion (3 times in twins, MC:DC 18:1) Malformations Placental vascular anastomosis (twin-twintransfusion syndrome, TTTS) Fetal-growth restriction Preterm delivery (60% twins, 93% triplets) Perinatal mortality

18. Outcomes in twins

19. Twin-specific Complications Twin pregnancy 70% 30% Dizygotic twins Monozygotic twins 35% 65% <1% DCDA MCDA MCMA DCDA Conjoined Twins TTTS Discordant Twins (sIUGR) TAPS TRAP Discordant Twins (one IUGR)

20. 1. Twin-Twin Transfusion Syndrome (TTTS) Definition blood is transfused from a donor twin to its recipient sibling. the donor becomes anemic and its growth may be restricted. the recipient becomes polycythemic and may develop circulatory overload manifest as hydrops. donor twin is pale, and its recipient sibling is plethoric.

21. Vascular Anastomoses With rare exceptions, vascular anastomoses between twins are present only in monochorionic twin placentas. Three types: Arterio-Arterial(A-A): most common, 75% monochorionic twin placentas. Venous –Venous(V-V): 50% Arterio-Venous(A-V): 50%

22. Vascular Anastomosesin TTTS Pure superficial vascular anastomoses occur TTTS rarely. Pure deep anastomosis almost occurr TTTS. Superficial and deep anastomosis result to 79% TTTS. Functional arterial anastomosis with compensation for twins bloodstream, there is a lower incidence of TTTS in arterial anastomosis. No A-A anastomosis, 61% twins will occur TTTS. A-A anastomosis, 15% twins will occur TTTS.

23. Fetal Brain Damage Quarello (2007): 315 liveborn fetuses with TTTS Cerebral abnormalities: 8% Cerebral palsy, microcephaly, porencephaly, and multicystic encephalomalacia Donor: ischemia results from hypotension, anemia, or both. Recipient: ischemia develops from blood pressure instability and episodes of severe hypotension

24. Fetal Brain Damage (one twin demise) Pharoah and Adi (2000): 348 survivors whose twin sibling had died in utero. The prevalence of cerebral palsy was 83 per 1000 live births–--a 40-fold increased risk over baseline. Even with delivery immediately after the co-twin demise is recognized, the hypotension that occurs at the moment of death has likely already caused irreversible damage.

25. Diagnosis (Prenatal) monochorionicity same-sex gender hydramnios defined if the largest vertical pocket is > 8 cm in one twin and oligohydramnios defined if the largest vertical pocket is < 2 cm in the other twin umbilical cord size discrepancy cardiac dysfunction in the recipient twin with hydramnios abnormal umbilical vessel or ductus venosus Doppler velocimetry significant growth discordance

26. Quintero staging system Stage I: polyhydramnios(>8cm) in recipient / aligodramnios(<2cm) in donor, but urine still visible sonographically within the donor twin's bladder Stage II: criteria of stage I, but urine is not visible within the donor's bladder Stage III: criteria of stage II and abnormal Doppler studies of the umbilical artery, ductus venosus, or umbilical vein. Such as AEDV or AEDF in donor, ductus venosus regurgitation or Umbilical vein pulsatilityin recipient. Stage IV: ascites or frank hydrops in either twin Stage V: demise of either fetus

27. Diagnosis (Postnatal) MCDA: number of placenta, chorionic membrane, amniotic membrane same-sex gender Examination in neonate： discordance in hemoglobin:≥5g/l discordance in red blood cell: ≥ 109 discordance in body weight : ≥15-20%

28. Treatment 1 Conservative treatment： Observation and Rest Drug： ---Indomethacin：reduced the volume of amniotic fluid ---Digoxin：acting on donor, increase cardiac output and relieve symptoms ----Not the main method, may be useful to one fetal but have adverse effects on the other twin.

29. Treatment 2 Invasive treatment Amnioreduction Septostomy (intentional creation of a communication in the dividing amnionic membrane) Fetoscopic Laser Occlusion of Chorioangiopagous Vessels (FLOC) Selective feticide RFA（Radio Frequency Ablation ） Umbilical cord ligation Monopolar or Bipolar coagulation

30. 2.TRAP(Twin Reversed Arterial Perfusion) Sequence Incidence: rare, about 1 in 35,000 births Definition：one twin has anabsent, rudimentary, or nonfunctioning heart(acardiac twin)，the other twin is normal (pumptwin). TRAP sequence has been associated withadverse perinatal outcomes. Placentation: majority of acradic twins ismonochorionic diamniotic. vascular anastomoses: arterial-to-arterial (A-A)

31. Diagnosis The diagnosis is made with ultrasound. Thefeatures useful in thediagnosis of acardia includeabsence of normal cardiac structure and cardiacmovement and variable structural abnormalities.

32. Malformations of Acardia Four groups: acardius acephalus, acardius amorphus or anideus, acardius acormus, and acardius anceps or paracephalus.

33. Management The pump twin is usually morphologically normal, and the risk of aneuploidy is 9%. The goal of antepartum management of a pregnancy complicated by the TRAP sequence is to maximize outcome for the structurally normal pump twin. Expectant management: serial sonographic evaluation Selective feticide: radiofrequency ablation (RFA) of the cord of the acardius, 95% pump twin survival. Criteria: twin weight ratio >0.70 elevated combined ventricular output elevated cardiothoracic ratio congestive cardiac failure polyhydramnios

34. 3. Discordant Twins (Diagnosis) Weight Discordancy(%) =weight (large)-weight (small)/ weight (large) Diagnosis: Weight Discordancy ≥ 25% Simple: abdominal circumferences difference ≥ 20 mm Hollier (1999): 1370 twin pairs Weight discordancy ≥ 25%: predicts an adverse perinatal outcome. Weight discordancy ≥ 30%: relative risk of fetal death is 5.6. Weight discordancy ≥ 40%: relative risk of fetal death is 18.9.

35. Discordant Twins (sIUGR, MCDA) Distinguish with TTTS One small，the other normal. One oligohydramnios ，the other normal volum of amniotic fluid .

36. Management: Discordant Twins in DC Before 28 weeks: follow up, ultrasound weekly. After 28 weeks: intensive care surveillance: daily nonstress testing (NST） terminate in time if abnormal apperance.

37. Management: Discordant Twins in MC 10-20% IUGR fetus will die and result in the bad outcome of nervous system in 20% survival fetus. Treatment Protocols（before 26 weeks）： Expect treatment close ongoing surveillance terminate in time if abnormal ultrasonic apperance Termination of pregnancy：abortion Laser Selective feticide (sIUGRfetus)

38. 4.Monoamnionic Twins 1% monozygotic twins high perinatal mortality: 17% cord entanglement (>50%) congenital anomaly preterm birth FGR vascular anastomoses

39. Management problematic unpredictability of fetal death resulting from cord entanglement lack of an effective means of monitoring 26-28 weeks: elective hospitalization daily: nonstress testing (NST） corticosteroids for lung maturation: betamethasone 32-34 weeks: Elective delivery a second course of betamethasone 34 weeks: cesarean delivery

40. Delivery When How Evaluation

41. Time of Delivery According to the Chorionicity No obvious complications： DCDA：37-38 weeks MCDA：34-36 weeks MCMA：32-34 weeks

42. Mode of Delivery 1 cephalic-cephalic: 42% Generally advocated vaginal delivery If a first twin is cephalic, delivery can usually be accomplished spontaneously or with forceps. Hogle (2003) perfomed an extensive literature review and concluded that planned cesarean delivery does not improve neonatal outcome when both twins are cephalic. Muleba (2005) identified increased rates of respiratory distress in the second twin of preterm pairs regardless of the mode of delivery or corticosteroid use.

43. Mode of Delivery 2 cephalic–noncephalic : 45% , cephalic-breech, and cephalic-transverse: The optimal delivery route for cephalic–noncephalic twins is controversial. A randomized study found that cesarean section and vaginal delivery were no differences in neonatal outcomes. Prerequisite for vaginal delivery is the obstetrician's technology and experience. As the number of trained doctors with experiences of assisted breech delivery and internal podalic version were reduced quickly, patients faced with two options: cesarean section or external podalic version on the second fetal.

44. Mode of Delivery 3 Breech presentation:13% As in singletons, if a first fetus presents as a breech, major problems may develop if: The fetus is unusually large, and the aftercoming head is larger than the birth canal The fetus is sufficiently small. The extremities and trunk may deliver through an inadequately effaced and dilated cervix, but the head may become trapped above the cervix The umbilical cord prolapses. Therefore, cesarean section is always recommended.

45. Thank you!