title: The role of laser surgery in dissecting the etiology of absent or reverse end-diastolic velocity in the umbilical artery of the donor twin in twin-twin transfusion syndrome.
abstract: OBJECTIVE
  This study was undertaken to gain insight on the cause of absent or reverse end-diastolic velocity (AREDV) in the umbilical artery (UA) of the donor twin by analysis of individual placental mass and vascular anastomoses in patients with twin-twin transfusion syndrome (TTTS) treated with laser.
  
  
  METHODS
  TTTS patients who successfully underwent selective laser photocoagulation of communicating vessels (SLPCV), 16 and 26 weeks' gestation, with both twins born alive and complete Doppler and placental data were considered eligible for the study. Doppler examination of the UA was performed before and 24 hours after SLPCV. Abnormal UA Doppler findings were defined as persistent AREDV. Pre- and post-SLPCV UA Doppler results yielded the following 4 groups: (1) normal-normal; (2) normal-abnormal; (3) abnormal-normal; and (4) abnormal-abnormal. The types of vascular anastomoses were categorized during surgery. Individual placental territory (IPT) was defined as individual placental weight divided by total placental weight x 100.
  
  
  RESULTS
  There were 132 cases in group 1 and no patients in group 2. AREDV resolved in 78% (28/36) of patients (group 3) and remained unchanged in 22% (8/36) (group 4). The mean IPT-donor in group 4 was significantly smaller than in group 1 (P = .015). Patients with preoperative AREDV (groups 3 and 4) were more likely to have artery-to-artery anastomoses (P = .002). However, AREDV resolved in 57% (16/28) patients without artery-to-artery anastomoses.
  
  
  CONCLUSIONS
  Preoperative AREDV may result from a small IPT, placental vascular anastomoses, or both. AREDV resulting from a small IPT may have a similar cause to that of singletons, and may be inferred by lack of postoperative resolution. Resolution of AREDV after SLPCV implies the presence of an adequate IPT and removal of donor hypotension.
authors.affiliation: Chang Gung Memorial Hospital, Linkou Medical Center, Tao-Yuan Hsien, Taiwan.
authors.forename: Yao-Lung
authors.initials: YL
authors.lastname: Chang
authors.forename: Ramen H
authors.initials: RH
authors.lastname: Chmait
authors.forename: Patricia W
authors.initials: PW
authors.lastname: Bornick
authors.forename: Mary H
authors.initials: MH
authors.lastname: Allen
authors.forename: Rubén A
authors.initials: RA
authors.lastname: Quintero
mesh_terms: D001783:Blood Flow Velocity; D005260:Female; D005330:Fetofetal Transfusion / Q000503:physiopathology* / Q000601:surgery; D005333:Fetus / Q000601:surgery*; D005865:Gestational Age; D006801:Humans; D017075:Laser Coagulation; D016015:Logistic Models; D011247:Pregnancy; D012189:Retrospective Studies; D014469:Umbilical Arteries / Q000002:abnormalities / Q000503:physiopathology* / Q000601:surgery*