Ablative effect of the interstitial laser setting in the human placental model.

Aim: To assess the impact of laser power and time on interstitial ablation generated by neodymium-doped yttrium aluminium garnet (Nd:YAG) and diode laser in the human placental model.

Methods: The experiment was carried out in a simulation model of interstitial laser ablation on ex-vivo placental tissue. One-hundred and forty-four pieces of fresh placentae were interstitially ablated with Nd:YAG or diode laser at various power (15, 20, 25, 30 W)-time (5, 10, 15 s) combinations. The ablation tissues were evaluated using both sonographic and histopathologic measurements.

Results: Laser generator, power, and time significantly affected the ablation size (p < 0.001). The coagulation zone continuously increased with extending time at the power of 15, 20, and 25 W. When adjusting to the power of 30 W, increased time from 10 to 15 s did not induce the larger coagulation diameter. The maximal diameter was obtained at the laser power of 20 W for 15 s. The ablation from the diode laser was greater than that from Nd:YAG laser. The sonographic evaluation overestimated the ablation size by an average of 24%.

Conclusion: Diode laser destroys greater tissue than Nd:YAG laser. Different power settings of interstitial laser ablation produce diverse patterns of correlation between laser time and coagulation size.