High intensity focused ultrasound combined with ultrasound-guided suction curettage treatment for cesarean scar pregnancy: a comparison of different HIFU sonication strategies

Objective To explore a new high-intensity focused ultrasound (HIFU) sonication strategy for cesarean scar pregnancy (CSP) and to compare the clinical effectiveness and safety of this new HIFU sonication strategy with the conventional HIFU sonication strategy followed by ultrasound-guided dilation and curettage (USg-D&C) for CSP. Materials and methods 91 patients with CSP treated by HIFU and USg-D&C in People's Hospital of Deyang City between January 2017 and December 2019 were retrospectively reviewed in this study. Based on the HIFU sonication strategy, patients were divided to two groups: 44 patients were exposed to 'C-shape' sonication layer by layer around the implantation location of the pregnancy sac (control group), while the other 47 patients were exposed to 'I-shape' sonication layer by layer only on the deep part which close to the bladder of the implantation location of the pregnancy sac (experimental group). The differences in clinical efficacy between the two groups were analyzed. Baseline characteristics, technical parameters of HIFU treatment and USg-D&C data were recorded. Adverse events were also recorded. Results No statistically significant difference was observed between the two groups in baseline characteristics including age, body mass index (BMI), menopause time, largest diameter of gestational sac, pretreatment serum beta-hCG, thickness of gestational sac, embedding myometrium, previous cesarean sections and interval from last cesarean section (CS). The average treatment intensity in the experimental group was significantly lower than that in the control group (p < .05). The median sonication time, total energy used for HIFU ablation, and energy efficiency factor (EEF) in the experimental group were significantly lower than the control group (p < .05). No statistically significant difference was observed between the two groups in treatment power and treatment time (p > .05). Sciatic/buttock pain and postoperative lower abdominal pain in the control group were significantly stronger than that in the experimental group (p < .05). There were no statistically significant differences in post-HIFU vaginal bleeding and discharging, urinary tract irritation, the operation time of USg-D&C, the amount of vaginal bleeding during USg-D&C, and the time for serum beta-hCG back to a normal level between the two groups (p > .05). Conclusions The 'I-shape' strategy of HIFU treatment for CSP was effective and safe, with shorter sonication time, less energy input and lower incidence of sonication-related pain occurred in postoperative lower abdominal and sciatic nerve/buttock.