A meta-analysis of the therapeutic role of oil soluble contrast media at hysterosalpingography: a surprising result?

OBJECTIVE: To evaluate the therapeutic effect of oil-soluble contrast media compared with water-soluble contrast media after hysterosalpingography (HSG) in infertile couples. DESIGN: Meta-analysis of four randomized clinical trials (RCTs) and six nonrandomized controlled studies evaluating pregnancy rates after the use of oil- or water-soluble contrast media during HSG. SETTING: Institute of Epidemiology and Health Services Research, Leeds, United Kingdom. PATIENTS: Four identified RCTs studied 800 patients and six nonrandomized studies comprised an additional 1,806 patients, all experiencing primary or secondary infertility. INTERVENTION: Hysterosalpingography as part of infertility investigation. MAIN OUTCOME MEASURE: Pregnancy rates after HSG. RESULTS: Pregnancy rates were significantly higher in the oil-soluble contrast media group compared with the water-soluble contrast media group in the RCTs. Inclusion of the six nonrandomized studies did not alter this conclusion. This apparent benefit was greatest for patients with unexplained infertility. CONCLUSIONS: Oil-soluble contrast media have a therapeutic effect compared with water-soluble media and this effect is greatest for patients who have been diagnosed as having unexplained infertility. New techniques for the evaluation of tubal patency support the hypothesis that tubal "plugs" may be involved in proximal tubal blockage.