Effects of oil-soluble versus water-soluble contrast media at hysterosalpingography on pregnancy outcomes in women with a low risk of tubal disease: study protocol for a randomised controlled trial

Abstract

IntroductionIn recent years, due to various factors, the rate of infertility in China has increased and now affects over 10% of women of reproductive age. Hysterosalpingography (HSG) is a common diagnostic procedure during fertility examinations. However, there is no consensus on the choice of contrast agents and their effects. As the largest multicentre, randomised controlled trial (H2Oil trial from the Netherlands) has shown that oil-soluble contrast at HSG can enhance fertility compared with water-soluble contrast, we propose this study to examine whether the use of oil-soluble contrast media results in increased rates of pregnancy in Chinese women undergoing HSG.Methods and analysisThis study is a single-centre, randomised, controlled, parallel-group, superiority trial. Patients with low risk of tubal disease will be randomised to undergo HSG using iodinated oil injection (OSCM group, oil-soluble contrast media) or ioversol injection (WSCM group, water-soluble contrast media). To evaluate the potential superiority of the OSCM group, with 1:1 allocation ratio, 90% statistical power and a two-sided significance level of 5%, we have calculated a sample of 520 women per group to be enrolled, for a total of 1040 including 10% loss to follow-up or protocol variation. The primary outcome is the rate of ongoing pregnancy during 6 months after randomisation. The secondary outcomes will consist of thyroid function of patients and newborns, pain scores during HSG, rate of live birth, clinical pregnancies, miscarriages, ectopic pregnancy, time to ongoing pregnancy, time to live birth, cost calculations of the OSCM group/WSCM group, and assisted reproductive technology treatments between the two groups.Ethics and disseminationThis protocol received authorisation from the Medical Research Ethics Committee of International Peace Maternity and Child Health Hospital on 18 January 2020 (approval no GKLW2020-02). The findings will be reported in peer-reviewed publications and presentations at international scientific meetings.Trial registration numberChiCTR2000031612.