Monochorionic Twins and Twin Transfusion Syndrome

1. Monochorionic Twins and Twin Transfusion Syndrome Emanuel P. Gaziano, M.D. Minnesotal Perinatal Physicians Abbott Northwestern Hospital, Minneapolis Professor, Department of Ob/Gyn University of Minnesota

2. Multiple Gestations • Twins occurrence • 1/90 Natural • 1/45 ART • Ovulation induction increases: • Twins rate 4X • Triplet or higher 72X • MZ twins 3.8X Logerot-Lebrun. Contracept Fertil Sex:1993;21:362 Luke B, Martin, JA. Clinical Obstetrics and Gynecology 47:1, 2004

3. Multiple Gestations • Membranes • Placental symmetry • Blood vessels Type of placenta determines frequency and severity of complications

4. What Type of Twining Event Has Occurred?

5. Dizygotic or “Fraternal” Twin“arise from two fertilized ova” • ~ 2/3 of spontaneous twin pregnancies are dizygotic Frequently affected by • Maternal ethnicity • Blacks highest in Africa > white intermediate in USA & Europe > Asians lowest in Japan & China • Maternal central gonadotropin levels – high FSH levels • Maternal Age • > 35 years old • Multi-parity • Maternal genetics • Previous / family history of dizygotic twins • Ovulation induction therapy

6. Dizygotic or “Fraternal” Twin “arise from two fertilized ova” • Dichorionic (2 placentas) & Diamniotic • Membrane: 4 layers (2 chorion & 2 amnion)

8. Monozygotic or “Identical” Twin“arise from one fertilized ovum” • Constant rate across population – 3-5 / 1000 • ~ 1/3 natural conception • Can occur in ART • Variable chorionicity • Variable amnionicity • Variable risk Depends on when the zygote (fertilized ovum) divides

9. Monozygotic or “Identical” Twin“arise from one fertilized ovum” • Monochorionic & Diamniotic • Dividing membrane: 2 layers of amnion with no interposing chorion

10. Placentation & Chorionicity

11. Placentation & Chorionicity Relative Risks

12. Diamniotic-Dichorionic Age risk for aneuploidy higher than singleton rate Early loss greater than singleton Greater congenital anomaly rate compared to singleton Diamniotic-Monochorionic Age risk for aneuploidy same as singleton rate Early loss rate greater than Di-Di twins Greater congenital anomaly rate compared to Di-Di twins Twin Gestations & Relative Risks

13. Chorionicity & Amnionicity • DC-DA • Thick membrane around each sac • MC-DA • Thick membrane around periphery, but thin membrane between sacs • MC-MA • Thick membrane around periphery and no visible membrane between sacs

14. Chorionicity & Amnionicity • DC-DA • Thick membrane around each sac • MC-DA • Thick membrane around periphery, but thin membrane between sacs • MC-MA • Thick membrane around periphery and no visible membrane between sacs

15. Chorionicity & Amnionicity • DC-DA • Thick membrane around each sac • MC-DA • Thick membrane around periphery, but thin membrane between sacs • MC-MA • Thick membrane around periphery and no visible membrane between sacs

16. Implications of Early Chorionicity Determination • The rate of miscarriage & perinatal death in monochorionic twins > dichorionic twins • Death of a monochorionic fetus is associated with a high chance of sudden death or severe neurologic impairment in the co-twin • Genetic disorders & chromosomal abnormalities is dependent on chorionicity • Management of pregnancy

17. Complications

18. Fetal Complications Preterm births Growth restriction Early post-maturity Fetal anomalies Maternal Complications Preeclampsia Placenta abruption Placenta previa Pre & postpartum hemorrhage Monozygotic twins  anomalies Monochorionic twins TTTS Acardiac twin Monoamniotic twins Cord entanglement Conjoining Death of a twin General Risks of Multiple Pregnancy

19. Monozygotic Twins • Congenital anomalies – structural • Twins - 2x singletons • Monozygotic - 2x dizygotic • 80 to 90 % of structural malformations are discordant

20. Monoamniotic Twins • Cord entanglement • Conjoining • Death of a twin

21. Monoamniotic Twins • The umbilical cords usually insert near one another • The placental vessels typically have large-caliber anastomoses between them • TTS is less common because imbalance in the two circulations could not be sustained for long period

22. Monoamniotic Twins • MC-MA twins have a further increased incidence of entangled cords

23. Conjoined Twins • form when a single fertilized egg fails to divide completely to create two distinct individuals • 1 in 50,000 to 1 in 200,000

24. Twin Reversed Arterial Perfusion“Acardiac Twin” • 1% of MC Pregnancies • 1 in 35,000 Pregnancies • Acardiac twin perfused by deoxygenated blood from “pump” twin Flow in umbilical artery of abnormal twin is toward fetus

25. Twin Reversed Arterial Perfusion“Acardiac Twin” • Delayed cardiac function of one twin

26. Twin Reversed Arterial Perfusion“Acardiac Twin” • Commonly edematous, cystic appearing mass (similar to cystic hygroma) • Absent cranium, cervical spine and upper extremities • No cardiac structures or activity • Lower half of body better developed

27. Twin Reversed Arterial Perfusion“Acardiac Twin”

28. Twin Twin Transfusion • A syndrome occurring in MC pregnancies due to artery to vein anastomoses in which the donor twin partially perfuses the recipient twin. • Also known as TTTS or TOPS (Twins oligohydramnios, polyhydramnios sequence.)

29. Twin-twin Transfusion Syndrome Outcome: • Without treatment, mortality is 90-100% • Neurological morbidity: 37% • If one fetus dies, there is a 25% risk of severe neurologic impairment probably due to hypotension, hypoxia or thromboembolism Adegbite AJOBG 190:156, 2004 Turrentine et al. Am J Perinatol 13:351,1996

30. Outcome • Less than 28 weeks survival 21% irrespective of method of management including decompression amniocentesis or tocolytics. • Gondoulin W, et al. 1990, Obstet Gynecol 75:214.

31. Frequency • About 15% of monochorionic twins will show some evidence of twin to twin transfusion syndrome

32. Frequency TTTS Twin Gestation Diamniotic Dichorionic (70-80%) TTTS Rare Diamniotic monochorionic (20-30%) MC-TTS (6-15%) MC-non TTS (85-94%)

33. Etiology • MC Twins • Vascular anastomoses • Unequal placental sharing • Abnormal size of umbilical cord • Velamentous insertion of cord

34. 4 to 7 Days after fertilization

35. Vascular arrangementTTTS

36. Surface Vessels on Chorionic Plate • Artery to vein anastomoses primary defect • Actually fewer balanced anastomoses • Nose to nose A-V connections Gaziano E, Harkness, U. Doppler Velocimetry and Multiple Gestation.In Doppler Ultrasound in Obstetrics and Gynecology, D. Maulik, ed. 2005

37. Contrast Medium Demonstrating Vascular Anastomoses in MC Twins

38. Etiology: Hemoglobin Differences • Mean hemoglobin difference is 4.8 gr/dl. • In cordocentesis studies any range of hemoglobin differences have been observed even in the presence of hydrops in the recipient. • Neonatal criteria is more rigid for diagnosis requiring 5.0 gr/dl difference Gaziano E, Harkness, U. Doppler Velocimetry and Multiple Gestation.In Doppler Ultrasound in Obstetrics and Gynecology, D. Maulik, ed. 2005

39. Diagnosis: 1st Trimester • NT in DiMo twins • If NT abnormal measure DV • Abnormal NT + Abnormal DV predicts TTTS Sebire Human Reproduction, Vol.15, No. 9, 2008-2010, September 2000

40. 20 week scan TWIN A: HC=23 1/7ths Wks TWIN B: HC=20 6/7ths Wks TWIN A: AC=23 4/7ths Wks TWIN B: HC=19 5/7ths Wks

41. 20 week scan

42. 20 week scan TWIN B: Cord Insertion TWIN B Umbilical Artery Doppler

43. Ultrasound of TTTS • Features of MC Placenta • Fused placenta • Thin dividing membrane • Dissimilar AF volumes

44. Sonographic Signs TTTS • Oligohydramnios • Donor sac <2 cm • Hydramnios • Recipient sac >8cm • Growth discordance • Thin dividing membrane • Same gender pair Blickstein I. Obstet Gynecol 1990;76:714-22

45. Ultrasound of TTTS

46. TTTS

47. Ultrasound TTS • Assess cord insertion site for each twin

48. Ultrasound TTTS • Assess for velamentous insertion

49. Ultrasound TTTS • Assess Placental Mass

50. Other sonographic signs TTTS • Echogenic bowel • Cardiac: enlargement, tricuspid regurgitation, ROF obstruction • Pulmonary artery calcification