Perinatal outcome following amniotic septostomy in chronic TTTS is independent of placental angioarchitecture.

Objectives: To determine whether the vascular anatomy of monochorial placenta influences the success of amniotic septostomy for the treatment of chronic mid-trimester twin-twin transfusion syndrome, we report placental anastomoses and perinatal data of 13 pregnancies treated by amniotic septostomy in combination with amnioreduction (AR). The placental anastomoses were delineated postnatally by perfusion studies. Perinatal outcome was also evaluated in relation to umbilical artery Doppler waveform of the donor twin.

Results: The median gestational age at septostomy was 21 weeks (range 18 to 25.5 weeks). Amniotic septostomy in combination with single AR procedure successfully resolved polyhydramnios in all cases. The median gestational age at delivery and the septostomy to delivery interval were 27 weeks (range 20 to 34 weeks) and 4 weeks (range 0.3 to 13.6 weeks), respectively. Of the 26 fetuses, 10 died in utero and four died within a week of life, with a combined survival rate of 46%. There was no relation between the clinical outcome and angioarchitecture of the placenta. However, pregnancy loss was higher in the donor twin with absent end-diastolic flow umbilical artery Doppler waveform than those with end-diastolic flow (85 vs 17%; p < 0.001).

Conclusion: This study suggests that although amniotic septostomy is a promising method for the correction of oligohydramnios and/or polyhydramnios, perinatal survival rate does not depend on angioarchitecture of the placenta. Instead, umbilical artery Doppler waveform of the donor twin may be a better marker for survival rate.