title: The progression of disease stage in twin-twin transfusion syndrome.
abstract: OBJECTIVE
  To estimate the frequency of progression or regression of disease stage in pregnancies complicated by twin-twin transfusion syndrome (TTTS) managed with non-placental laser techniques.
  
  
  METHODS
  A cohort of TTTS pregnancies within the sole perinatal center for the state of Western Australia was examined. All cases of prenatally identified TTTS from 1992 to 2002 were staged at diagnosis (retrospectively prior to 2000, prospectively since). Amnioreduction and septostomy were the principal therapies used. Features associated with progression, regression or stability were identified.
  
  
  RESULTS
  During the study period, 71 cases of TTTS were managed. Amnioreduction was performed in 73.2%, with no difference in the median number of procedures by stage (p = 0.178). In 21.1% of cases, TTTS resolved completely with persistent normalization of amniotic fluid volumes after amnioreduction (median number of procedures: 2). Disease resolution was associated with pregnancy prolongation, greater gestational age at delivery (36 weeks vs. 28.4 weeks, p < 0.001) and increased perinatal survival (100% vs. 42.6%, p < 0.001) compared with stage progression. Logistic regression analysis predicted that the probability of both infants surviving was 80% if the pregnancy remained at Stage I or II throughout, compared with a probability of 50% if it reached Stage III or more at 26 weeks, and only 25% if the disease reached Stage III or more at 16 weeks' gestation.
  
  
  CONCLUSIONS
  Pregnancy outcome for TTTS managed with amnioreduction techniques is correlated with stage at diagnosis and the subsequent disease evolution. However, the progression of stage in TTTS is unpredictable and the likelihood of spontaneous fetal demise was not different between stages.
authors.affiliation: School of Women's and Infants' Health, The University of Western Australia, Perth, Australia.
authors.forename: J E
authors.initials: JE
authors.lastname: Dickinson
authors.forename: S F
authors.initials: SF
authors.lastname: Evans
mesh_terms: D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005330:Fetofetal Transfusion / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality / Q000473:pathology; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D014427:Twins; D014904:Western Australia / Q000453:epidemiology