Risk factors for placenta accreta spectrum in pregnancies conceived after frozen-thawed embryo transfer in a hormone replacement cycle.

OBJECTIVE: Assisted reproductive technology (ART), especially frozen-thawed embryo transfer (FET) in a hormone replacement cycle (HRC), is a risk factor for placenta accreta spectrum (PAS). This study aimed to clarify the risk factors for PAS related to the maternal background and ART techniques in pregnancies achieved after FET in an HRC. STUDY DESIGN: We performed a case-control study in two tertiary perinatal centres in Japan. Among 14,028 patients who delivered at ≥24 weeks of gestation or were transferred after delivery to two tertiary perinatal centres between 2010 and 2021, 972 conceived with ART and 13,056 conceived without ART. PAS was diagnosed on the basis of the FIGO classification for the clinical diagnosis of PAS or retained products of conception after delivery at ≥24 weeks of gestation. We excluded women with fresh embryo transfer, FET with a spontaneous ovulatory cycle, a donor oocyte cycle, and missing details of the ART treatment. Finally, among women who conceived after FET in an HRC, 62 with PAS and 340 without PAS were included in this study. Multivariate logistic regression models were used for case-control comparisons, with adjustment for maternal age at delivery, parity, endometriosis or adenomyosis, the number of previous uterine surgeries of caesarean section, myomectomy, endometrial polypectomy or endometrial curettage, placenta previa, the stage of transferred embryos, and endometrial thickness at the initiation of progestin administration. RESULTS: PAS was associated with ≥2 previous uterine surgeries (adjusted odds ratio, 3.57; 95 % confidence interval, 1.60-7.97) and the stage of embryo transfer (blastocysts: adjusted odds ratio, 2.89; 95 % confidence interval, 1.15-7.26). In patients with <2 previous uterine surgeries, PAS was associated with an endometrial thickness of <7.0 mm (adjusted odds ratio, 5.18; 95 % confidence interval, 1.10-24.44). CONCLUSION: Multiple uterine surgeries and the transfer of blastocysts are risk factors for PAS in pregnancies conceived after FET in an HRC. In women with <2 previous uterine surgeries, a thin endometrium before FET is also a risk factor for PAS in these pregnancies.

Novel application to evaluate endometrial blood flow using transvaginal superb microvascular imaging: A preliminary study describing physiological changes from ovulation to mid-luteal phase.

INTRODUCTION: We aimed to describe physiological changes in endometrial blood flow (minute arterioles running through the endometrium) from ovulation to the mid-luteal phase using superb microvascular imaging. MATERIAL AND METHODS: The study involved 17 women (median age, 32.5 years; first to third interquartile range, 29.8-40.0 years) with regular menstrual cycles who were managed in our institute from 2020 to 2021. The uterus was delineated at the sagittal section using transvaginal ultrasonography incorporated with superb microvascular imaging. For each participant, a total of 28 cycles were observed; 17 cycles observed within one day of ovulation and the implantation period, 5-7 days (D5-7) after ovulation in the same cycle, and nine cycles in which only ovulation was observed, and two cycles in which only D5-7 was observed. Therefore, 26 and 19 images at ovulation and D5-7, respectively, were acquired. Endometrial blood flow was evaluated by depth of the vascular signal in the endometrium and categorized as follows: signals only in the basal layer of the endometrium (grade 1), reaching up to half the endometrium (grade 2), and covering the whole endometrium (grade 3). Changes in the grade of endometrial blood flow from ovulation to D5-7 after ovulation, and the relationship between the grade of endometrial blood flow and the endometrial thickness on ovulation and D5-7 after ovulation, were analyzed. Statistical significance was set at p < 0.05. RESULTS: The endometrial blood flow from ovulation to D5-7 after ovulation during the same menstrual period showed a downgrade in 14 of 17 cycles (82.3%) and no change in the remaining three cycles (17.6%), indicating a decrease in the endometrial blood flow from ovulation to D5-7 after ovulation (p = 0.001). There were differences between the grade of endometrial blood flow and median endometrial thickness on ovulation (grade 1: 5.9 mm, grade 2: 9.1 mm, and grade 3: 11.2 mm); however, no differences in the endometrial thickness were found between the grades on D5-7 after ovulation. CONCLUSIONS: In the normal menstrual cycle, endometrial blood flow decreased from ovulation to the mid-luteal phase, and the endometrial thickness in the ovulatory phase was related to the endometrial perfusion.

Injury to the endometrium prior to the frozen-thawed embryo transfer cycle improves pregnancy rates in patients with repeated implantation failure.

AIM: This retrospective cohort study evaluated the effectiveness of injury to the endometrium prior to the frozen-thawed embryo transfer (FET) cycle in patients with repeated implantation failure (RIF) in our clinic. METHODS: Included in this study were 173 patients, aged ≤ 41 years, who failed to become pregnant after repeating fair and/or good embryo transfer more than twice between February 2012 and February 2015. The patients were divided into three groups: Group A (n = 38) underwent soft curettage to the endometrium twice, prior to the FET cycle; Group B (n = 45) underwent hysteroscopy prior to the FET cycle, with no significant factors, such as endometrial polyp; and Group C (n = 90) was the no-treatment group. RESULTS: The clinical pregnancy rate per transfer was found to be statistically significant between Group A at 42.1% (16/38) and Group C at 22.2% (20/90). The crude and adjusted odds ratios (OR) were 2.55 and 2.49 (95% confidence intervals 1.13-5.78, P = 0.03 and 1.01-6.17, P = 0.048) respectively. Group B with only hysteroscopy had a higher pregnancy rate of 35.6% (16/45) than Group C, but showed no statistical significance (P = 0.103). CONCLUSION: These results suggest that injuring the endometrium has a positive effect on pregnancy.