INTRA CAVITY FLUID WITH PREVIOUS CAESAREAN SECTION COMPROMISED CLINICAL PREGNANCY AFTER IVF/ICSI TREATMENT

Abstract

Caesarean section (CS) rates are rising worldwide, the scar is considered to have impact on the subsequent pregnancy. Researchers reported a lower pregnancy rate in patients with a previous CS compared to a previous vaginal delivery, but the potential causes are still to be determined. Lawrenz et al. reported the relationship between intra cavitary fluid (ICF) with uncompromised clinical outcomes on frozen embryo transfer (FET) cycles[1]. The goal of this study was to explore whether the presence of ICF influence the pregnant outcome of patients with CS in fresh embryo transfer cycles. Retrospective cohort study. A total of 1643 women with at least one previous delivery undergoing the first in vitro fertilization / intracytoplasmic sperm injection (IVF/ICSI) cycle and had their fresh embryo transferred during January 2015 to August 2019 in a university-based hospital were enrolled for analysis. According to the previous delivery method and the ultrasound monitoring results——ICF detected on day of embryo transfer, women were separated into three subgroups, cesarean group with intra cavity fluid (CS-ICF, n=114), cesarean group without intra cavity fluid (CS-noICF, n=572) and another 957 patients without ICF were included in vaginal delivered group (VD, n=957). Main outcome was clinical pregnancy rate. Baseline characteristics data, controlled ovarian hyperstimulation procedures and pregnancy outcomes were extracted from medical databases and were compared among three groups. Potential confounders were adjusted by multivariate logistic regression analyses, including age, previous delivery times, body mass index (BMI), failed attempts of IVF, endometrium thickness, embryo quality and stage of development. Baseline characteristics and the quality of embryos transferred in the three groups were comparable. Less number of embryos were transferred in CS groups than VD group influenced by clinicians’ preference(P<0.05). There was significantly lower clinical pregnancy rate (33.3% vs 45.2%, P=0.015) and twin pregnancy rate (7.9% vs 24.5%) in CS-ICF group compared with VD group, while the rates were comparable between CS-noICF group and VD group. There is a tendency that the live birth rate in VD group is higher than that in CS-ICF group. After adjusted for all the confounding factors listed above, the presence of ICF was an independent factor associated with lower clinical pregnancy rate (OR 0.586, 95%CI 0.375-0.914, P=0.018). Age and ratio of good quality embryos were also associated with clinical pregnancy rate. It is the presence of ICF but not the isthmocele per se that significantly compromised the clinical pregnancy rate in patients with CS. CS interferes with the integrity of uterine, ICF may accompany with inflammatory cytokines and potentially pathogenic bacteria, which further disrupt the endometrial receptivity. Large prospective cohort study is required to better understand the potential mechanism and explore effective therapeutic scheme.