OP09.07: Outcomes of Caesarean scar pregnancies classification with new Delphi consensus criteria

This study aims to assess the effectiveness of the new Delphi consensus definition of Caesarean scar pregnancy (CSP) in predicting clinical outcomes during early gestation. A retrospective cohort study was conducted on 64 women diagnosed with CSP and managed at Hung Vuong Hospital, a tertiary obstetrics and gynecology hospital in South Vietnam. CSP cases were categorised into three subgroups using the new Delphi consensus criteria, based on the extent of gestational sac penetration across two imaginary lines: the uterine cavity line (UCL) and/or the serosal line (SL). Type 1 CSP comprised 17 cases (26.5%) where the largest portion of the gestational sac crossed the UCL. Type 2 included 26 cases (40.7%) where the largest part of the gestational sac was embedded in the myometrium without crossing the SL, while Type 3 encompassed 21 cases (32.8%) where the gestational sac crossed the SL. The mean gestational age was 6.5 ± 1.5 weeks, with fetal heartbeat detected in 26 cases (40%). The mean residual myometrium thickness was 1.39 ± 1.77mm. Twenty-one patients (32.8%) underwent invasive surgical interventions (laparotomy, operative hysteroscopy), with a mean blood loss of 175 ± 247ml. Type 3 CSP cases were over ten times more likely to require invasive interventions compared to Types 2 or 1 (85% vs 7.7% and 5.8%, respectively; P < 0.00001). Blood loss in Type 3 CSP was significantly higher compared to Type 2 (310 +/- 315 vs 120 +/- 202.2ml, P = 0.02) and Type 1 (310 +/- 315 vs 91.7 +/- 129.3ml, P = 0.007). The use of Delphi consensus criteria for defining CSP during early gestation has significant implications for clinical decision-making, patient management, and CSP follow-up.