O-022 Early tubal flushing with oil-based contrast during hysterosalpingography versus no tubal flushing in women with unexplained infertility – H2Oil-timing randomized controlled trial
Authors: Kamphuis D , Rosielle K , Van Welie N , Brinkhuis E , Van Dongen A , Bourdrez P , De Krom G , Stoker J , Lambalk N , Hemingway A , Cao S , Wentao L , Mol B W , Dreyer K , Mijatovic V 
Published: July 2024

Study question

In women with unexplained infertility, does tubal flushing with oil-based contrast during HSG early in the fertility work-up reduce time to ongoing pregnancy?

Summary answer

In women with unexplained infertility, tubal flushing with oil-based contrast during HSG early in the fertility work-up does not reduce time to pregnancy.

What is known already

In couples with unexplained infertility, tubal flushing with oil-based contrast during HSG is known to increase live births and reduce time to pregnancy compared to HSG with water-based contrast. It is unknown whether tubal flushing with oil-based contrast incorporated early in the fertility work-up will have this effect as compared to 6 months later in the fertility work-up.

Study design, size, duration

Between August 2019 and May 2023, we performed a multicenter, randomized trial in 15 Dutch hospitals. After informed consent, participating women were randomized to immediate HSG (oil-based contrast) or HSG delayed by six months. This allowed us to assess the effect of tubal flushing versus no tubal flushing over a 6-month period, as well as time to conception after immediate versus delayed flushing over a period of 12 months. We aimed to recruit 554 participants.

Participants/materials, setting, methods

We included ovulatory infertile women (18-39 years), who were advised expectant management based on a favorable prognosis for natural conception (Hunault prediction-model). The study has two primary endpoints, time to conception leading to live births (I) within 6 months, and (II) over a 12-month period. Here we report on conception within 6 months leading to ongoing pregnancy. Live birth data will be available at the 2024 ESHRE meeting. Analyses were done according to intention-to-treat principle.

Main results and the role of chance

Between August 2019 and May 2023, we randomized 577 women (287 allocated to the immediate HSG and 290 allocated to the delayed HSG group). Mean (±sd) female age was 30.0±3.6 years and median duration of infertility was 17.0 months.

In the immediate HSG group, 239 women had an HSG after a median duration of 0.7 months after randomization, while in the delayed group 83 women had an HSG within 6 months (median time to HSG: 5.2 months after randomization).

Conception leading to ongoing pregnancy within 6 months occurred in 90 women (32.5%) in the immediate HSG group and 91 women (33.2%) in the delayed HSG group (HR: 0.96; 95% CI: 0.72-1.29). Conception leading to any pregnancy within 6 months occurred in 119 women (43.0%) in the immediate HSG group and 104 women (38%) in the delayed HSG group (HR: 1.16; 95% CI: 0.89-1.51).

The median time to conception leading to ongoing pregnancy was 2.4 months in the immediate HSG group and also 2.4 months in in the delayed HSG group.

Limitations, reasons for caution

This study was limited to women with unexplained infertility with favorable natural conception chances (&gt;30%). In this abstract, we only report time to ongoing pregnancy and not time to pregnancy leading to live birth. Data on conception leading to live births will be available at the 2024 ESHRE meeting.

Wider implications of the findings

In women with unexplained infertility and a favorable prognosis to conceive, early tubal flushing with oil-based contrast during HSG does not increase live birth rates nor reduce time to pregnancy within six months as compared to tubal flushing delayed by six months.

Trial registration number

EU clinical Trials Register, no: 2018-004153-25 AND Clinicaltrials.gov, ID: NCT05608590