The mechanism of hydrosalpinx in embryo implantation.

BACKGROUND: Hydrosalpinx adversely affects embryo implantation and contributes to poor implantation rates post embryo transfer. Embryo transport depends on concomitant intrauterine fluid motion induced by uterine wall motility, the result of spontaneous myometrial contractions towards the fundus. METHODS AND
RESULTS: The uterine dynamics of five patients with hydrosalpinx were recorded and analysed by image-processing techniques: the frequency was higher while the amplitudes and passive widths were lower compared with healthy volunteers. The existing peristaltic activity should have induced intrauterine fluid flow; however, the recordings failed to show the expected transport of fluid bolus. This observation was supported by mathematical simulations based on the hypothesis that fluid accumulation in the Fallopian tube of a patient with hydrosalpinx increases tubal pressure and thereby induces a pressure gradient between the fundus and the cervix. This pressure gradient acts adversely to the cervix-to-fundus intrauterine peristalsis and generates reflux currents that may thrust embryos away from the implantation site.
CONCLUSIONS: The reflux phenomenon could explain the reduced implantation rate associated with hydrosalpinx. Resolution of the issue of whether the removal of a Fallopian tube with hydrosalpinx should be undertaken for improving IVF pregnancy rates should be accompanied by prospective randomized clinical trials.