• Fetoscopy;
  • laser ablation;
  • monochorionic;
  • twins;
  • TTTS

Objective  To assess the safety and efficacy of a modified fetoscopic laser ablation technique for the management of severe twin–twin transfusion syndrome (TTTS) in a large series of pregnancies.

Design  Prospective cohort study.

Setting  Tertiary referral fetal medicine unit.

Population  Women with pregnancies complicated by severe TTTS (Quintero stage III or IV), before 26 weeks of gestation.

Methods  Fetoscopic laser ablation of placental anastomoses was performed. The sonoendoscopic approach was used to identify the placental vascular equator and to photocoagulate crossing vessels.

Main outcome measures  Overall survival, fetal and perinatal mortalities, gestational age at delivery, birthweight, operating time and recurrence of TTTS.

Results  A total of 77 women underwent the procedure. The mean gestational age at treatment was 20 (range 16–26) weeks. On average, four vessels were ablated during each procedure, with a mean operative time of 15 (range 5–25) minutes. None of the women required a repeat fetoscopic laser treatment for recurrence of the TTTS. There was at least one survivor in 74% (57/77) of pregnancies, and the overall survival rate was 57% (88/154).

Conclusions  Fetoscopic laser ablation is a safe and effective form of treatment in the management of severe TTTS. The technique of identifying the common villous district of the placenta by ultrasound and photocoagulating any vessels crossing the vascular equator appears to be an acceptable alternative to both the nonselective and highly selective methods described so far. This approach is associated with a short operating time, low likelihood of TTTS recurrence or fetal anaemia and with survival results that are equivalent to previously reported techniques.