title: Optimal method and timing of intrauterine intervention in twin reversed arterial perfusion sequence: case study and meta-analysis.
abstract: BACKGROUND
  The objective of this study was to define the optimal method and timing of intervention in twin reversed arterial perfusion (TRAP) sequence.
  
  
  METHODS
  During a period of 20 years (1993-2013), we performed endoscopic laser coagulation of umbilical cord vessels or intrafetal laser in 67 pregnancies with TRAP sequence. These data were combined with those reported in the literature to determine the survival rate of the pump twin for different methods and timing of interventions.
  
  
  RESULTS
  A variety of techniques were used to interrupt the blood supply to the acardiac twin. Most procedures were performed at or after 16 weeks, and with most methods the survival rate of the pump twin was about 80%. Good results were also obtained for triplet pregnancies. In 18 of 30 cases (60%) diagnosed at 11-14 weeks, there was spontaneous cessation of flow in the acardiac twin before planned intervention at 16-18 weeks, and in 11 of these (61.1%) the pump twin died or suffered brain damage. In 103 pregnancies treated by intrafetal laser at 12-27 weeks, there was no correlation between gestational age at treatment and survival rate, but there was an inverse association between gestational age at treatment and gestational age at birth.
  
  
  CONCLUSIONS
  In TRAP sequence, survival may be improved by elective intervention at 12-14 weeks.
authors.affiliation: Harris Birthright Research Centre of Fetal Medicine, King's College Hospital, London, UK.
authors.forename: Petya
authors.initials: P
authors.lastname: Chaveeva
authors.forename: Leona C
authors.initials: LC
authors.lastname: Poon
authors.forename: Alexandros
authors.initials: A
authors.lastname: Sotiriadis
authors.forename: Przemek
authors.initials: P
authors.lastname: Kosinski
authors.forename: Kypros H
authors.initials: KH
authors.lastname: Nicolaides
mesh_terms: D004200:Diseases in Twins / Q000401:mortality / Q000601:surgery*; D005260:Female; D005332:Fetoscopy / Q000379:methods* / Q000401:mortality; D006801:Humans; D017075:Laser Coagulation / Q000379:methods; D011247:Pregnancy; D059285:Pregnancy, Twin; D018570:Risk Assessment; D015996:Survival Rate; D013997:Time Factors; D014470:Umbilical Cord / Q000601:surgery*