title: Midtrimester isolated polyhydramnios in monochorionic diamniotic multiple gestations.
abstract: OBJECTIVE
  To identify risk factors for development of twin-twin transfusion syndrome (TTTS) in monochorionic diamniotic multiple gestations complicated by midtrimester isolated polyhydramnios (iPoly).
  
  
  METHODS
  A retrospective study of patients referred for possible TTTS between 16 and 26 gestational weeks was performed. IPoly was defined as a maximum vertical pocket of ≥8 cm in the iPoly twin's sac and >2 and <8 cm in the co-twin's sac on the consultative ultrasound.
  
  
  RESULTS
  Of 628 consecutive patients referred for possible TTTS, 74 were diagnosed with iPoly. The majority of these patients (n = 52, 70.3%) were not subsequently diagnosed with TTTS, and of these, 40 were managed expectantly and 12 had amnioreductions because of symptomatic iPoly; 30-day perinatal survival of at-least-one twin in the non-TTTS group was 93.0% (40/43). TTTS developed in the 22 remaining patients, of which 63.6% were of advanced Quintero Stage. Nineteen underwent laser surgery; 30-day perinatal survival of at-least-one twin was 84.2% (16/19). In a multivariate logistic regression model, 2 characteristics were associated with the development of TTTS: (1) gestational age <20 weeks at the time of diagnosis of iPoly (odds ratio, 13.48; 95% confidence interval, 3.40-53.48; P = .0002); and (2) intrauterine growth restriction of the co-twin (odds ratio, 7.28; 95% confidence interval, 1.72-30.88; P = .0071).
  
  
  CONCLUSIONS
  Among referred patients with midtrimester iPoly, 29.7% subsequently developed TTTS. Early diagnosis (<20 weeks) and/or co-twin intrauterine growth restriction were significant risk factors for development of TTTS in these patients.
authors.affiliation: Department of Obstetrics and Gynecology, Kaiser Permanente Los Angeles, Los Angeles, CA.
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Chon
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Korst
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA.
authors.forename: Arlyn
authors.initials: A
authors.lastname: Llanes
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA.
authors.forename: David A
authors.initials: DA
authors.lastname: Miller
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Ouzounian
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA.
authors.forename: Ramen H
authors.initials: RH
authors.lastname: Chmait
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005330:Fetofetal Transfusion / Q000209:etiology*; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D006831:Polyhydramnios / Q000175:diagnosis*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011272:Pregnancy, Multiple; D012189:Retrospective Studies; D014430:Twins, Monozygotic
keywords: TTTS; monochorionic diamniotic twins; polyhydramnios; twin-twin transfusion syndrome