Twinning

Reproductive Technology

  1. Determine the commonly utilized assisted reproductive technologies (ART)
  1. Evaluate the procedure (steps) of IVF and when it is implicated for use
  1. Evaluate the procedures of GIFT, ZIFT, embryo cryopreservation, and preimplantation genetic diagnosis/testing and when each is implicated for use
  1. Assess the potential complications of assisted reproductive technologies (ART) including ovarian hyperstimulation syndrome, pregnancy with multiples, etc.
  1. Determine the similarities and differences between monozygotic and dizygotic twin pregnancies
  1. Assess the terminology surrounding the number of placentas and the number of amniotic sacs
  1. Analyze the structural characteristics of the amnion, chorion, and placenta for each twin type

Monozygotic Twinning

Dizigotic Twinning

  1. Evaluate the formation and timing of each type of monozygotic twins
  1. Assess the formation of dizygotic twins

Complications of Twinning

  1. Which type(s) of twin pregnancies are more at risk for perinatal mortality? Why?
  1. Describe vanishing twin & fetus papyraceus.

TTTS

  1. Assess the risk factors for twin-to-twin transfusion syndrome (which type of twinning)? Describe the underlying mechanisms that result in twin-to-twin transfusion syndrome.
  1. Why are both twins at risk of fetal death in twin-to-twin transfusion syndrome (TTTS)? Be able to specifically describe the clinical concerns for the donor twin and for the recipient twin.
  1. How is an AA anastomosis protective or beneficial in twin-to-twin transfusion syndrome (TTTS)?

TRAP

  1. Assess the risk factors for twin reversed arterial perfusion (TRAP) sequence (which type of twinning). Describe the underlying mechanisms that result in TRAP sequence.
  1. Why is the pump twin at risk of fetal death in TRAP sequence?
  1. What are the risk factors for umbilical cord entanglement (which type of twinning)? What are the complications of umbilical cord entanglement?

Does Polyhydramnios or Oligohydramnios result?

Twin Reversed Arterial Perfusion (TRAP) syndrome, a rare and severe complication of monochorionic twin pregnancies, involves abnormal blood flow between twins due to an arterial connection through the placenta. In this condition, one twin (the "pump twin") supplies blood to the other twin (the "acardiac twin"), which lacks a functioning heart and other critical organs. The excess embryonic fluid, or polyhydramnios, often observed in TRAP syndrome is primarily due to the acardiac twin's inability to regulate amniotic fluid production. Normally, amniotic fluid levels are balanced by the fetus swallowing the fluid and the kidneys excreting it as urine. However, the acardiac twin usually lacks functional kidneys and a gastrointestinal system, so it cannot swallow or process the fluid. This imbalance leads to an accumulation of amniotic fluid around the pump twin. Additionally, the pump twin's heart has to work harder to circulate blood for both twins, which can lead to high output heart failure. This strain may exacerbate fluid imbalances and contribute to polyhydramnios.