Hysteroscopic resection vs dilation and evacuation for treatment of caesarean scar pregnancy: study protocol for a randomised controlled trial

BACKGROUND: Caesarean scar pregnancy (CSP) is a type of ectopic pregnancy where the fertilised egg is implanted in the muscle or fibrous tissue of the scar after a previous caesarean section. Management options for women who opted for termination of CSP include sharp curettage, dilation and evacuation (D&E), excision of trophoblastic tissues, local or systemic administration of methotrexate, bilateral hypogastric artery ligation, and selective uterine artery embolisation with curettage and/or methotrexate administration. Recently hysteroscopic resection has also been proposed as an alternative option. OBJECTIVE: To compare the surgical outcome of hysteroscopic resection with dilation and evacuation (D&E) for the treatment of caesarean scar pregnancy (CSP). METHODS: Parallel-group, non-blinded, randomised clinical trial conducted at a single centre in Italy. Eligible women are those with singleton gestations at less than 9 weeks of gestation, and with thickness of myometrial layer ≥1 mm at the level of the ectopic. Inclusion criteria are women with CSP with positive embryonic/fetal heart activity who opted for termination of pregnancy. Patients will be randomised 1:1 to receive either hysteroscopic resection (i.e. intervention group) or D&E (i.e. control group). In both groups, 50 mg/m2 (based on DuBois formula for body surface area) of methotrexate (MTX) will be injected intramuscularly at the time of randomisation (day 1) and another dose at day 3. A third dose of MTX is planned in case of persistence of fetal heart activity on day 5. Participants will receive either D&E or hysteroscopic resection from 3 to 7 days after the last dose of MTX. A sample size of 54 women is planned. MAIN OUTCOME MEASURES: The primary outcome is the success rate of the treatment protocol, defined as no requirement for further treatment until complete resolution of the CSP as demonstrated by negative beta hCG levels and absence of residual gestational material on ultrasound examination.. STUDY HYPOTHESIS: Hysteroscopic surgery is superior to D&E for the treatment of CSP. WHAT IS NEW? The results of the trial will provide information on the best treatment for CSP.