Radiofrequency ablation (RFA)
All patients were admitted to the hospital in a day before the day of
the procedure of RFA after undergoing a comprehensive assessment before
fetal therapy procedure. All procedures were conducted by the
combination of one fetology specialist and one interventional ultrasound
specialist in the intrauterine therapeutic room of Medical Genetics
Center.
All patients were treated using the RF-1500 RFA system (MedSphere
international (Shanghai) CO., Ltd, China). According to RFA
protocol9, local anesthesia was conducted at the
planned puncture site on the maternal abdomen (2% lidocaine
hydrochloride administered subcutaneously).Under continuous sonographic
guidance, a 15cm or 20cm 17-gauge RFA electrode needle was inserted form
fetal abdomen or back to adjacent to the area of the umbilical cord
insertion, after confirmation of the location, the umbrella Electrode
were deployed.RFA energy was applied start from 20 watts, increasing 10W
per minute, until the impedance exceeds the critical value, when the
host stop active output. If the impedance don’t exceed, maintain
ablation 2-3min after reaching target temperature of 100 ℃. The
procedure was repeated for an additional one or two cycles using the
same heating algorithm, until cessation of cord blood flow was confirmed
using color and power Doppler velocimetry.
Follow-up was organized locally through multiple contact methods, such
as telephone and some internet contact. All surviving fetuses underwent
a head MRI after 28 weeks of gestation to assess fetal neurological
development and to determine if there was a brain injury. Pregnancy and
neonatal outcome data were obtained from the clinical notes or from
referring physicians, and missing data were collected by telephone
interview with the patients.