Aim To evaluate the effects of operator experience on outcome for fetoscopic laser ablation in a single centre.

Methods A cohort of consecutive monochorionic twin (MC) pregnancies complicated by severe TTTS (≤26 weeks) treated by fetoscopic laser ablation (FLA) (October 2004–June 2010).

Results Over 6 years 199 MC twins with severe TTTS were managed with FLA in a single centre by two operators. Over this time period the number of cases performed per annum increased from 5.25 per calendar month (pcm) in 2008–2009 to 17 in 2009–2010. Operator A performed 152 cases and operator B 47. There was no significant difference in outcomes between the two operators with both operators achieving an 85% survival ≤1 baby at 28 days. Logistic regression analysis revealed that the number of cases that need to be performed to reach the overall survival for ≤1 baby of 85% was 65. This took the centre 1.47 years to achieve. After 178 cases the unit had reached a survival ≤1 baby of 90% over 1.95 years. Univariate regression analysis suggested that operator experience may have an effect on survival. However, a multivariate analysis revealed that GA at delivery was the only significant factor. Influence of operator experience using Learning Curve-cumulative Summation Test for Quantitative & Individualized assessment of competency suggests that 60 procedures need to be performed as an individual to reach competency.

Conclusion These data indicate that large numbers of cases and experience of the operator are important factors in outcome for severe TTTS treated by FLA.