New insights into the mechanisms underlying hydrosalpinx fluid formation and its adverse effect on IVF outcome

The adverse effects of hydrosalpinx on the outcome of IVF have been well documented; however, the causes for impaired implantation in patients with hydrosalpinx are poorly understood. Hydrosalpinx fluid has been shown to be toxic to mouse embryos but not human embryos, and this has become a topic of intense debate. An understanding of the mechanisms underlying hydrosalpinx formation following pelvic inflammatory disease appears to be essential in elucidating the causes for reduced implantation in hydrosalpinx patients and providing more rational treatments. This review discusses the mechanisms underlying hydrosalpinx formation and its adverse effect on IVF outcome, with new insights into possible involvement of Fallopian tube epithelial transporters and ion channels, particularly the cystic fibrosis transmembrane conductance regulator (CFTR). Possible links between Chlamydia trachomatis in pelvic inflammatory disease and the subsequent CFTR-mediated events in hydrosalpinx formation leading to infertility in hydrosalpinx are proposed. The causes of reduced implantation, particularly in patients with visible hydrosalpinges shown on ultrasound scanning, are re-examined in light of these possible mechanisms.