Effects of Power and Time on Ablation Size Produced by Radiofrequency Ablation: In vitro Study in Fresh Human Placenta

Abstract

Introduction: Radiofrequency (RF) current has been clinically used to coagulate some solid tumors. We investigated the effects of RF on fresh placenta to determine the possibility of its prenatal application in placental tumors. Materials and Methods: Total 196 fresh placentae were interstitially coagulated with a 2-cm RF needle at 14 power-duration combinations. We compared the horizontal length of coagulated area using ultrasound and microscopic measurements. Histological changes were also described. Results: We did not observe any significant change in lesion size from different power levels (p = 0.104 and 0.242 for ultrasound and microscopic measurements, respectively). Mean ± SD lesion length after 5 and 10 min of exposure measured by microscopy are 16.00 ± 2.22 and 17.00 ± 1.82 mm, respectively (p < 0.001). Ultrasound consistently over-measured lesion size by 2.87 ± 3.45 mm. We also observed a collapse of large vessels on chorionic plate adjacent to the RF site. Conclusion: Our in vitro experiment demonstrated placental tissue coagulation and collapse of chorionic vessels from RF. Projecting the area of placental coagulation should be based on duration of RF exposure, and not on the power level. An in vivo animal study is needed before these data are translated into clinical practice.