Our research mainly focused on pregnant patients with PAS. The purpose of the research was to analyze the relevant clinical factors that affect hysterectomy. Through univariate and multivariate logistic regression analysis, we found that the rate of hysterectomy was related to the bleeding during the delivery, the placenta type by MR or US and the type of ovarian artery.
In our research, the rate of hysterectomy in the group with a bleeding volume greater than or equal to 500 ml was 29.4%, while that in the group with a bleeding volume less than 500 ml was 9.8%. There is no doubt that bleeding is related to hysterectomy for the reason that failure to stop bleeding in time will result in unstable hemodynamics and even hemorrhagic shock that endangers the patient’s life. Currently, there is no direct study on the relationship between hysterectomy rate and bleeding in patients with PAS after the UAE. Previous study had shown that the average bleeding volume of patients with PAS after successfully retaining the uterus with preoperative UAE was about 400ml. Based on this, it was speculated that a larger bleeding volume may lead to a bad outcome and a higher hysterectomy rate.
In addition, in our study, we found that the hysterectomy rate of patients with PAS was related to the type of placenta diagnosed by prenatal MR or ultrasound. We used the MR and US imaging features of PAS and combined the depth of implantation to divide them into placenta accreta, placenta increta and placenta percreta. The hysterectomy rate of penetrating placenta accreta was 50%, which was higher than the hysterectomy rate of placenta increta and placental accreta, which were 15.8%% and 0% respectively. Some scholars revealed that the depth of placenta implantation was associated with the severity of outcomes; A large-scale retrospective analysis in China found that the hysterectomy rate for penetrating placenta accreta was 43.3%, and the hysterectomy rate for placental accreta was 11.2%, which were statistically significant and similar to our research. Another study also showed the rate of hysterectomy during cesareans and the total hysterectomy rate were significantly higher in the percreta than the accreta group (52.9% vs 20.9%, 84.3%vs 23.8%). Compared to our research, the rate of hysterectomy during cesareans was similar to our study, while the total hysterectomy rate in the percreta group was quite higher than our results(50%). It was speculated that this was related to the fact that the patients included in our study were diagnosed with PAS by US or MR before surgery and trended to make adequate preparations to prevent severe bleeding, such as UAE, which could reduce the rate of hysterectomy, to some extent. Moreover, for patients with stable hemodynamics and no life-threatening bleeding, we preferred to leave the placenta in situ when the implanted placenta could not be separated from the uterine wall, which could reduce the occurrence of major bleeding that might cause emergency hysterectomy to a certain extent[26, 27].
In last, our research demonstrated that the ovarian artery flow defined by initial aortography as having three types was predictive of failure of UAE and the need of hysterectomy. In contrast to the type Bilateral, the type No and the type Unilateral had the lower rate of hysterectomy(11.1%vs 54.5%, 13.8%vs 54.5%), which was statistically significant. At present, no studies have been reported on the blood supply of the ovaries in patients with placental implants. However, the study of Makoto Aoki et al. revealed that the ovarian artery flow might lead to the failure of UAE and the subsequent hysterectomy in patients with primary postpartum hemorrhage. Similarly, several scholars shown that OAE to be an effective and safe adjunct to UAE when hypertrophic ovarian artery(ies) require intervention among the patients with the uterine fibroids[29, 30]; Hyun S Kim et al. found that Uteroovarian anastomoses in young patients are associated with higher rates of repeat intervention after UAE. Several researches above had shown to a certain extent that the failure of UAE was related to uterine-ovarian anastomosis, especially the ovarian artery could be greatly dilated during pregnancy to accommodate the increased blood flow. Based on this, it was speculated that the bilateral hypertrophic ovarian-uterine anastomosis perhaps had a larger blood supply to the uterus that was temporarily ischemic due to UAE at early stages, which led to the failure of UAE and had to perform repeated UAE or hysterectomy to stop bleeding.
Although some patients’ initial aorta angiography showed hypertrophic ovarian-uterine artery anastomoses, all ovarian arteries were not superselected and embolized for the uncertainty of the supplementary embolization effect of OAE to UAE and the impact on fertility potential.
In spite of some studies had shown that UAE did not affect the pregnancy rate of patients, there were also some studies that had shown that UAE could increase the rate of PAS, miscarriage in patients and other Pregnancy complications[34–36]. Especially in pregnant patients who had the hypertrophic ovarian-uterine artery anastomoses, the embolic material might reach the ovary through the anastomoses so that ovarian function and fertility might be affected somehow[37, 38].
As for the abnormal branches, although it was not associated with the rate of hysterectomy, 28.2% (24/85) of patients with PAS in our study had the abnormal branches that supply to the uterus. However, abnormal branches were present in 39.3% (24/61) of patients with a history of cesarean section, not in patients without a history of cesarean Sect. 45.83% (11/24) of patients with PAS had more than one abnormal branch in our study.
The abnormal branch of the internal iliac artery was the most commonly involved artery, accounting for 42% of all abnormal blood branch vessels in our study. The second most common collateral vessel was the inferior vesical artery, which accounts for 35.5% of all abnormal blood vessels, and the internal pudendal artery, the obturator artery, the vaginal artery as well as the abnormal branches of the external iliac artery together accounted for the remaining 22.5%. Cesarean section surgery easily led to adhesion of the surgical incision and surrounding pelvic tissues. It was speculated that the incision of cesarean section was related to the abnormal connection of small branches of internal iliac artery. Therefore, Careful attention should be paid to the collateral vessels when performing UAE for the reason that patients with a history of cesarean section are more likely to have complicated collateral vessels supplying the uterus.
In our study, ten patients used gelatin sponge and microcoils to supplement and strengthen the embolization effect. One was because of uterine arteriovenous malformations, and the rest was because of the abundant blood supply to the placenta from uterine arteries.
Regarding the complications of UAE, there were no serious complications such as uterine necrosis, perforation, and pulmonary embolism in this study. Only 14.1%(12/85)of patients had symptoms of low fever after UAE.
Our study had several limitations, one of which was its retrospective design. In addition, hematologic parameters and time interval between delivery and embolization were not included in the analysis. Furthermore, our study did not have long-term follow-up to evaluate the impact of UAE on fertility and ovarian function. Nevertheless, one of the strengths of our study was the first study to study hysterectomy-related factors in patients with PAS after the treatment of UAE, this study also revealed the frequency of abnormal collaterals after cesarean section and included the factors of uterine-ovarian artery anastomosis to analysis.