Thickness of fetal membranes: A possible ultrasound marker for preterm delivery

BACKGROUND: Urocortin is a neuropeptide produced by the human endometrium and has biological effects putatively important for promoting blastocyst implantation. We measured urocortin concentrations in samples of endometrial wash fluid collected from women with unexplained infertility who underwent intrauterine insemination (IUI). METHODS: Patients 28-42 years of age (n = 71) were consecutively enrolled after a complete clinical evaluation. Endometrial wash fluid was retrieved before IUI, at the time of ultrasound evaluation of endometrial thickness. Urocortin concentrations were assayed with a specific ELISA. RESULTS: After IUI, 28 patients (39%) became pregnant. Urocortin concentrations were significantly higher in women who became pregnant than in those who did not (0.38 microg/L vs 0.13 microg/L, P <0.0001). At a cutoff of 0.321 microg/L, urocortin results were positive in 61% [95% confidence interval (CI), 41%-78%] of women who had successful implantation and negative in 98% (95% CI, 88%-99.6%) of those who did not. The pregnancy rate for women with urocortin concentrations >0.32 microg/L was 94%, which differed significantly (P <0.05) from the overall pregnancy rate of 39% in the study population. CONCLUSIONS: Urocortin is measurable in endometrial wash fluid, and its concentrations before IUI are higher in women who subsequently achieve pregnancy. These data suggest that the probability of having a successful pregnancy-producing IUI may be better estimated by measuring urocortin in endometrial wash fluid.