Relationship between residual collateral vessels in preventive uterine arterial embolization and the risk of bleeding during the operation of curettage for cesarean scar pregnancy

Objective: To explore the relationship between residual collateral vessels in uterine arterial embolization (UAE) and the risk of bleeding during the operation of curettage for cesarean scar pregnancy. Methods: A total of 499 patients who underwent preventive UAE before curettage for scar pregnancy in Shandong Provincial Hospital from January 2012 to June 2019 were included. Clinical data of the patients were retrospectively collected and analyzed. In patients with uterine collateral circulation, collateral vessels were embolized as much as possible. Angiography was performed after UAE. All the cases were divided into 3 grades according to residual staining in middle and lower part of corpus uteri as follows, grade A: no or mild staining, grade B: moderate staining, grade C: intense staining. Blood loss of the patients during curettage was recorded, and the incidence rate of minor hemorrhage (< 50 ml) and massive hemorrhage (> 500 ml) of the 3 grades were calculated respectively. The results of three grades groups were compared with those of control group (patients without collateral circulation) by using Chi-square test or Fischer exact probability. Results: According to angiogram acquired after UAE, collateral vessels were found in 53 patients, with 25 cases in grade A group, 15 cases in grade B group, and 13 cases in grade C group, respectively. Thirty-six patients underwent transcatheter embolization of collateral vessels. The incidence rate of minor hemorrhage in type B and C [60.0% (9/15), 46.2% (6/13)] was lower than that in control group (87.9%, 392/446), with significant difference found (X² = 9.972, P = 0.002, X² = 19.090, P < 0.001). Significant difference was found in the incidence rate of massive haemorrhage between group C (23.1%, 3/13) and control group (2.2%, 9/446) (X² = 14.480, P = 0.001). Conclusion: As for cesarean scar pregnancy cases with uterine collateral vessels, embolization of collateral vessels may reduce the amounts of bleeding during curettage. Residual staining of middle and lower part of corpus uteri may be helpful in predicting the risk of massive haemorrhage during curettage. (authors)