Aim To evaluate the effects of operator experience on perinatal outcome in a single centre.

Methods A cohort of consecutive monochorionic twin (MC) pregnancies complicated by severe twin to twin transfusion syndrome (TTTS) (≤26 weeks) treated by fetoscopic laser ablation (FLA) (October 2004 to November 2009).

Results Of the 164 MC twins; 5% were Quintero stage II, 79% stage III and 16% stage IV. The median gestational age (GA) at FLA was 20+2 weeks (95% CI 16 to 25+3). The median interval from FLA to delivery was 88.5 days (7 to 127) and GA of live born 33+5 weeks (28+2 to 36+1). Excluding pregnancy losses <24 weeks 100% of pregnancies had one live birth. In the first half (n=82) of the cohort, in 13% there were no survivors, in 55% both twins survived to birth, 43% both twins survived to 28 days postdelivery (at least one survivor in 76%). In the second half (n=82), corresponding values were 6%, 37%, 33% and 79%. Univariate logistic regression analysis indicated that lower Quintero stage (OR 3.84 (1.55 to 9.54)) and prolongation of GA increased survival of the twins (OR 0.75 (0.63 to 0.89), p<0.01). Increasing operator experience led to a significant reduction in perinatal death (OR 0.28 (0.1 to 0.74), p<0.01). GA at delivery (OR 0.93 (0.89 to 0.97), p≤0.01) was the only significant predictor of cerebral morbidity. Changes in use of trochar portals, selectivity of procedure and ablation at peripheral margins of the placenta will be described.

Conclusion These data indicate that relatively large numbers treated and experience with FLA minimises adverse outcome in MC pregnancies with severe TTTS.