P-748 Cesarean scar defect does not predict embryo transfer outcomes: A retrospective cohort study

Study question

Is the presence of a cesarean scar defect associated with live birth outcomes at the time of embryo transfer?

Summary answer

The presence of a cesarean scar defect is not predictive of live birth rates at the time of embryo transfer.

What is known already

Cesarean delivery is associated with subsequent impaired fertility, with lower pregnancy and live birth rates and longer inter-pregnancy intervals, compared to patients who delivered vaginally. Studies exploring pregnancy rates after IVF and embryo transfer also suggest lower pregnancy rates among patients with prior cesarean delivery. A postulated mechanism by which a prior cesarean delivery may impact fertility is the cesarean scar defect, and prior studies have shown a possible association between a scar defect and suboptimal outcomes.

Study design, size, duration

We retrospectively identified a patient cohort based out of the Ottawa Fertility Centre in Ottawa, Ontario, Canada, between 2013 and 2019.

Participants/materials, setting, methods

This retrospective cohort study included 317 patients with a prior cesarean delivery. Embryo transfer outcomes compared between the two groups based on the finding of a cesarean scar defect. The primary outcome was live birth rate, secondary outcomes of positive hCG, clinical intrauterine pregnancy, miscarriage rate. We fit a multivariate log binomial regression model with a priori variables for the primary and secondary outcomes, adjusting for patient and cycle characteristics.

Main results and the role of chance

There was no statistically significant difference in live birth rate among patients with a cesarean scar defect compared to those without, 28.0% vs 29.5% respectively (adjusted RR 0.95, 95% CI 0.68-1.35). There was no statistically significant difference in any of the secondary outcomes. Area of the defect and subgroup analysis of fresh vs frozen embryo transfer did not demonstrate any difference. Secondary analysis of patients with retroverted uterus had significantly lower live birth rates compared to those with an anteverted uterus, 17.7% vs 32.4%, respectively (adjusted RR 0.56, 95% CI 0.34-0.91).

Limitations, reasons for caution

Although a multivariate log binomial model was used to adjust for clinically relevant confounders, there remains the possibility for residual confounding given the observational nature of our study.

Wider implications of the findings

The results of our study suggest that, after adjusting for patient and cycle characteristics, the presence of a cesarean scar defect may not impact live birth outcomes and secondary analysis of the impact of uterine retroversion requires more study.

Trial registration number

Not applicable

Flexible and extended dosing of nicotine replacement therapy or varenicline in comparison to fixed dose nicotine replacement therapy for smoking cessation: rationale, methods and participant characteristics of the FLEX trial

Quitting smoking is the single most effective strategy to reduce morbidity and premature mortality in smokers. Research has demonstrated the effectiveness of pharmacotherapy in smoking cessation, but few studies have directly compared varenicline and monotherapy nicotine replacement therapy (NRT) and none have examined varenicline and combinations of NRT products. The majority of smoking cessation trials involve carefully circumscribed populations, making their results less generalizable to those with severe medical conditions or psychiatric comorbidities. This paper reports on the rationale, methodology and participant characteristics of a randomized controlled trial designed to: (1) determine which pharmacotherapy - NRT, long term combinations of NRT, or varenicline - is most effective in achieving abstinence; (2) investigate the incidence of neuropsychiatric symptoms among participants over the course of their quit attempt; and (3) assess whether there is a significant difference in the incidence of neuropsychiatric symptoms in those receiving differing pharmacotherapies, and between those with and without psychiatric illnesses. The primary outcome was carbon monoxide confirmed abstinence from weeks 5-52 following a target quit date. Secondary outcomes included neuropsychiatric (i.e., depression, suicidal ideation, anxiety, anger) and withdrawal symptoms. Smokers (N=737) were randomly assigned to one of three treatment conditions, and were scheduled to attend 8 follow-up appointments over 12 months. All participants received 6-15 minute practical counseling sessions with nurse counselors experienced in treating tobacco dependence. We expect that the results will lead to an enhanced understanding of the efficacy of these pharmacotherapies, including those with a history of psychiatric illness.