Objective: To determine the impact of oil-based versus water-based contrast on pregnancy and live birth rates ≤5 years after hysterosalpingography (HSG) in infertile women. Design: A 5-year follow-up study of a multicenter randomized trial. Setting: Hospitals. Patient(s): Infertile women with an ovulatory cycle, 18–39 years of age, and having a low risk of tubal pathology. Intervention(s): Use of oil-based versus water-based contrast during HSG. Main Outcome Measure(s): Ongoing pregnancy, live births, time to ongoing pregnancy, second ongoing pregnancy. Result(s): A total of 1,119 women were randomly assigned to HSG with oil-based contrast (n = 557) or water-based contrast (n = 562). After 5 years, 444 of 555 women in the oil group (80.0%) and 419 of 559 women in the water group (75.0%) had an ongoing pregnancy (relative risk [RR] 1.07; 95% confidence interval [CI] 1.00–1.14), and 415 of 555 women in the oil group (74.8%) and 376 of 559 women in the water group (67.3%) had live births (RR 1.11; 95% CI 1.03–1.20). In the oil group, 228 pregnancies (41.1%) were conceived naturally versus 194 (34.7%) pregnancies in the water group (RR 1.18; 95% CI 1.02–1.38). The time to ongoing pregnancy was significantly shorter in the oil group versus the water group (10.0 vs. 13.7 months; hazard ratio, 1.25; 95% CI 1.09–1.43). No difference was found in the occurrence of a second ongoing pregnancy. Conclusion(s): During a 5-year time frame, ongoing pregnancy and live birth rates are higher after tubal flushing with oil-based contrast during HSG compared with water-based contrast. More pregnancies are naturally conceived and time to ongoing pregnancy is shorter after HSG with oil-based contrast. Clinical Trial Registration Number: Netherlands Trial Register (NTR) 3270 and NTR6577(www.trialregister.nl).
Bibliographical noteThe authors thank all participating women, the hospitals and their staff, the research nurses and the staff of the nationwide consortium for women’s health research (NVOG Consortium; www.zorgevaluatienederland.nl) for logistic support; and H2Oil study group collaborators Nan van Geloven, Jos W.R. Twisk, Peter M. van de Ven, and Peter G.A. Hompes for their contributions to this study.
- Female infertility
- oil-based contrast medium
- ongoing pregnancy
- water-based contrast medium