What is the impact of placental tissue damage after laser surgery for twin-twin transfusion syndrome? A secondary analysis of the Solomon trial.

BACKGROUND: The introduction of the Solomon technique for the treatment of twin-twin transfusion syndrome (TTTS) increased placental exposure to laser energy. This study aims to identify the impact of power and energy used in laser treatment on placental tissue and pregnancy outcome.

METHODS: Pictures of all dye-injected placentas since the start of the Solomon trial were analyzed. Placental damage was scored using a grading system including visual scar depth and affected proportion of the vascular equator. Parameters analyzed included laser power and total energy, gestational age (GA) at laser, GA at birth, laser-to-delivery interval and preterm prelabor rupture of membranes (PPROM).

RESULTS: We included 122 cases in the analysis. More placental damage occurred more often in the Solomon group (42%) compared to the selective group (15%) (p < 0.001). In multivariate analysis, more placental damage was associated with higher laser energy (regression coefficient B 0.002) but not with higher power setting (regression coefficient B -0.442). More damage was associated with earlier GA at birth (regression coefficient B -0.167), higher incidence of PPROM <32 weeks (regression coefficient B 0.003) and a shorter laser-to-delivery interval (regression coefficient B -0.168).

CONCLUSIONS: Placental damage is positively associated with more laser energy but negatively associated with higher power setting. More placental damage was associated with a lower GA at birth, shorter laser-to-delivery interval and higher PPROM rate. Whether these results should lead to a change in surgical technique requires more research, both further ex-vivo experiments on human placentas and clinical studies.