- BACKGROUND: There has been debate in the literature for more than 40 years as to whether flushing of the Fallopian tubes enhances fertility and whether this presumed therapeutic effect is greater with oil-soluble media than with water-soluble media. A meta-analysis of the therapeutic role of oil-soluble contrast media at hysterosalpingography was published in March 1994 (Watson 1994). This Cochrane Review is an expansion and update of that overview. OBJECTIVES: To evaluate the effect of flushing the Fallopian tubes with oil- or water-soluble contrast media on subsequent pregnancy rates in infertility patients. SEARCH STRATEGY: 1. For randomised controlled trials (RCTs): we searched the Cochrane Subfertility Review Group specialised register of controlled trials. 2. For non-randomised controlled studies: Medline and manual search of eight relevant journals. SELECTION CRITERIA: Six RCTs and six non-randomised controlled studies. In two studies tubal flushing was compared with no treatment-controls. Eleven studies, comprising a total of 2635 subjects, compared oil- with water-soluble media. DATA COLLECTION AND ANALYSIS: Independently by first 2 authors for: 1. Methodological trial characteristics 2. Characteristics of participants 3. OUTCOMES: the main studied outcome was pregnancy rate per patient MAIN RESULTS: In comparison with no treatment, a significant benefit on pregnancy rates was seen by flushing the tubes with oil-soluble media (OR 1.80, 95% CI 1.29-2.50) but not with water-soluble media (OR 0.87, 95% CI 0.50-1.52). In the direct comparison of oil- and water-soluble media the former lead to significantly higher pregnancy rates (OR 1.92, 95% CI 1.60-2.29). The treatment effect appeared similar in RCTs and non-RCTs. Subgroup analysis suggested the therapeutic benefit was greatest for patients suffering from unexplained infertility and least for those with tubal factor infertility. REVIEWER'S CONCLUSIONS: Flushing of the tubes with oil-soluble media increases subsequent pregnancy rates in infertility patients. The hypothesis that tubal "plugs" are a cause of proximal tubal occlusion and that oil-soluble media may flush them out, is supported by new techniques such as falloposcopy. Clinicians should consider flushing the tubes with OSCM before contemplating more invasive therapies.