Appraisal of the selectivity index in a cohort of patients treated with laser surgery for twin–twin transfusion syndrome

Objective

The selectivity index (SI) has been proposed as a measure of technical success in laser surgery for twin–twin transfusion syndrome. Surgeries with an index >–0.25 have been considered highly selective. The purpose of this study was to evaluate the applicability of this index in our patient population.

Study Design

The SI was assessed in 314 consecutive laser surgeries and correlated with perinatal survival.

Results

A total of 310 patients (98.7%) underwent a completely selective procedure. The SI was 0.8 in the selective laser photocoagulation of communicating vessels group vs 0.3 in the nonselective laser photocoagulation of communicating vessels group (P = .001). In the selective group perinatal survival of at least 1 twin (92.6% vs 50%) and survival of the donor (75.4% vs 0%) was significantly better (P = .05).

Conclusion

The SI as originally proposed is misleading and of limited use as it does not differentiate selective from nonselective procedures. We propose instead using a ratio of selective/nonselective procedures, and selectively coagulated/total number of coagulated vessels to appraise center-specific and patient-specific surgical performance of laser surgery for twin–twin transfusion syndrome.

Key words: laser photocoagulation, selectivity, twin–twin transfusion syndrome