OC15.05: Systemic methotrexate treatment in Caesarean scar pregnancy: a multicentre data analysis on treatment efficacy and predicting factors

Caesarean scar pregnancy (CSP) is a type of abnormal blastocyst implantation adherent to a uterine scar caused by previous Caesarean section. With the increasing Caesarean section rates, the prevalence of CSP is rising. The aim of this study was to evaluate the efficacy of systemic MTX in CSP patients and to define clinical predicting factors for successful treatment. This retrospective data analysis is including 69 patients from the international CSP registry, which received systemic MTX as first-line treatment. Patients were divided into an effective and ineffective treatment group. Inefficacy was defined by the need for secondary treatment. These two subgroups were then compared to each other regarding patient characteristics including previous medical history, clinical presentation and ultrasound parameters. Cut-off values for predicting factors were determined using ROC (receiver operating characteristics) curves. Secondary treatment was required in 65.2% of patients (n = 45). The overall success rate of single-line systemic MTX treatment was 34.8% (n = 24). Peak beta-hCG (human chorionic gonadotropin) levels, CRL (Crown–rump length) and the presence of a fetal heartbeat showed significant differences (p < 0.05) between the effective and ineffective subgroups. The effective group showed a mean CRL of 3.9 mm ± 2.7 and a mean beta-hCG value of 13257.7 IU/L ± 16558.6 whilst the ineffective group had a mean CRL of 12.5mm ± 11.7 and a mean beta-hCG of 33059.1 IU/L ± 30785.9. When a beta-hCG cut-off below 2000 IU/L is used the success rate of systemic MTX increases from 34.8% to 54.5%. For a CRL cut-off of 2.5mm effectiveness increases from 34.8% to 55.6%. In the majority of cases the use of single systemic MTX in the treatment of CSP was not successful. Even with beta-hCG levels below 2000 IU/l or a CRL below 2.5mm only half of the patients were successfully treated. For CSP other methods such as suction evacuation, surgical excision or balloon treatment should be considered as first-line treatment.