BackgroundCaesarean scar pregnancy (CSP) is a special type of ectopic pregnancy with a high risk of massive haemorrhage. Few studies have focused on the efficacy of prophylactic abdominal aortic balloon occlusion as a minimally invasive method in caesarean section. This study aimed to evaluate the effectiveness and safety of prophylactic abdominal aortic balloon occlusion for patients with type III CSP.MethodsThis was a prospective cohort study. Patients with type III CSP in the First Affiliated Hospital of Zhengzhou University from January 2020 to June 2022 were enrolled. Eligible patients received prophylactic abdominal aortic balloon occlusion (defined as the AABO group) or uterine artery embolization (defined as the UAE group) before laparoscopic surgery. Clinical outcomes included intraoperative blood loss, body surface radiation dose, hospitalization expenses, and time to serum β-hCG normalization, and safety were also assessed.ResultsA total of 68 patients met the criteria for the study, of whom 34 patients were in the AABO group and 34 patients were in the UAE group. The median intraoperative blood loss in the AABO and UAE groups was 17.5 (interquartile ranges [IQR]: 10, 45) and 10 (IQR: 6.25, 20) mL, respectively (P = 0.264). The body surface radiation dose of the AABO group was much lower than that of the UAE group (5.22 ± 0.44 vs. 1441.85 ± 11.59 mGy, P < 0.001). The AABO group also had lower hospitalization expenses than the UAE group (2.42 ± 0.51 vs. 3.42 ± 0.85 *10^5 yuan, P < 0.001). The average time to serum β-hCG normalization in the AABO group was 28.9 ± 3.21 d, which was similar to that in the UAE group (30.3 ± 3.72 d, P = 0.099). In addition, the incidence of adverse events in the AABO group was lower than that in the UAE group (5.9% vs. 58.8%, P < 0.001).ConclusionProphylactic AABO was equally as effective as UAE in patients with type III CSP but was safer than UAE during and after the operation.