The effectiveness of immediate versus delayed tubal flushing with oil-based contrast in women with unexplained infertility (H2Oil-timing study): study protocol of a randomized controlled trial.

BACKGROUND: In women with unexplained infertility, tubal flushing with oil-based contrast during hysterosalpingography leads to significantly more live births as compared to tubal flushing with water-based contrast during hysterosalpingography. However, it is unknown whether incorporating tubal flushing with oil-based contrast in the initial fertility work-up results to a reduced time to conception leading to live birth when compared to delayed tubal flushing that is performed six months after the initial fertility work-up. We also aim to evaluate the effectiveness of tubal flushing with oil-based contrast during hysterosalpingography versus no tubal flushing in the first six months of the study. METHODS: This study will be an investigator-initiated, open-label, international, multicenter, randomized controlled trial with a planned economic analysis alongside the study. Infertile women between 18 and 39 years of age, who have an ovulatory cycle, who are at low risk for tubal pathology and have been advised expectant management for at least six months (based on the Hunault prediction score) will be included in this study. Eligible women will be randomly allocated (1:1) to immediate tubal flushing (intervention) versus delayed tubal flushing (control group) by using web-based block randomization stratified per study center. The primary outcome is time to conception leading to live birth with conception within twelve months after randomization. We assess the cumulative conception rate at six and twelve months as two co-primary outcomes. Secondary outcomes include ongoing pregnancy rate, live birth rate, miscarriage rate, ectopic pregnancy rate, number of complications, procedural pain score and cost-effectiveness. To demonstrate or refute a shorter time to pregnancy of three months with a power of 90%, a sample size of 554 women is calculated. DISCUSSION: The H2Oil-timing study will provide insight into whether tubal flushing with oil-based contrast during hysterosalpingography should be incorporated in the initial fertility work-up in women with unexplained infertility as a therapeutic procedure. If this multicenter RCT shows that tubal flushing with oil-based contrast incorporated in the initial fertility work-up reduces time to conception and is a cost-effective strategy, the results may lead to adjustments of (inter)national guidelines and change clinical practice. TRIAL REGISTRATION NUMBER: The study was retrospectively registered in International Clinical Trials Registry Platform (Main ID: EUCTR2018-004153-24-NL).

Predicting successful intended vaginal delivery after previous caesarean section: external validation of two predictive models in a Dutch nationwide registration-based cohort with a high intended vaginal delivery rate.

OBJECTIVE: To externally validate two models from the USA (entry-to-care [ETC] and close-to-delivery [CTD]) that predict successful intended vaginal birth after caesarean (VBAC) for the Dutch population. DESIGN: A nationwide registration-based cohort study. SETTING: Seventeen hospitals in the Netherlands. POPULATION: Seven hundred and sixty-three pregnant women, each with one previous caesarean section and a viable singleton cephalic pregnancy without a contraindication for an intended VBAC. METHODS: The ETC model comprises the variables maternal age, prepregnancy body mass index (BMI), ethnicity, previous vaginal delivery, previous VBAC and previous nonprogressive labour. The CTD model replaces prepregnancy BMI with third-trimester BMI and adds estimated gestational age at delivery, hypertensive disease of pregnancy, cervical examination and induction of labour. We included consecutive medical records of eligible women who delivered in 2010. For validation, individual probabilities of women who had an intended VBAC were calculated. MAIN OUTCOME MEASURES: Discriminative performance was assessed with the area under the curve (AUC) of the receiver operating characteristic and predictive performance was assessed with calibration plots and the Hosmer-Lemeshow (H-L) statistic. RESULTS: Five hundred and fifteen (67%) of the 763 women had an intended VBAC; 72% of these (371) had an actual VBAC. The AUCs of the ETC and CTD models were 68% (95% CI 63-72%) and 72% (95% CI 67-76%), respectively. The H-L statistic showed a P-value of 0.167 for the ETC model and P = 0.356 for the CTD model, indicating no lack of fit. CONCLUSION: External validation of two predictive models developed in the USA revealed an adequate performance within the Dutch population.