The progression of disease stage in twin-twin transfusion syndrome

Objective: To estimate the frequency of progression or regression of disease stage in pregnanciescomplicated by twin–twin transfusion syndrome (TTTS) managed with non-placental lasertechniques.Methods: A cohort of TTTS pregnancies within the sole perinatal center for the state of WesternAustralia was examined. All cases of prenatally identified TTTS from 1992 to 2002 were staged atdiagnosis (retrospectively prior to 2000, prospectively since). Amnioreduction and septostomy werethe principal therapies used. Features associated with progression, regression or stability wereidentified.Results: During the study period, 71 cases of TTTS were managed. Amnioreduction was performedin 73.2%, with no difference in the median number of procedures by stage (p = 0.178). In 21.1% ofcases, TTTS resolved completely with persistent normalization of amniotic fluid volumes afteramnioreduction (median number of procedures: 2). Disease resolution was associated withpregnancy prolongation, greater gestational age at delivery (36 weeks vs. 28.4 weeks, p50.001) andincreased perinatal survival (100% vs. 42.6%, p50.001) compared with stage progression. Logisticregression analysis predicted that the probability of both infants surviving was 80% if the pregnancyremained at Stage I or II throughout, compared with a probability of 50% if it reached Stage III ormore at 26 weeks, and only 25% if the disease reached Stage III or more at 16 weeks’ gestation.Conclusion: Pregnancy outcome for TTTS managed with amnioreduction techniques is correlatedwith stage at diagnosis and the subsequent disease evolution. However, the progression of stage inTTTS is unpredictable and the likelihood of spontaneous fetal demise was not different betweenstages.