Endometrial dating and determination of the window of implantation in healthy fertile women

Objective: To reassess endometrial morphological criteria of normality identifying the best morphological and molecular "implantation window" indicators in normal women. Design: Prospective clinical study. Setting: Assisted reproductive unit. Patient(s): Fourteen healthy volunteers. Intervention(s): Blood sampling for LH, E-2, and progesterone (P4) determinations. Daily vaginal ultrasounds. Two endometrial biopsies per volunteer, 7 days apart, during luteal phase. Main Outcome Measure(s): Endometrial dating, pinopodcs formation, immunohistochemical determination of integrins (alpha v beta 3, alpha 4 beta 1), leukemia inhibitory factor (LIF), interleukin-1 receptor type I (IL-1R tI), mouse ascites Golgi (MAG), the transmembrane mucin (MUC-1), and p4 receptor expression. Result(s): In 26 of 28 biopsies observers agreed; in two biopsies there was a discrepancy (difference of 72 hours). With use of LH peak, 24 of 26 samples were in phase, and 2 were 3 days behind. Pinopodes appeared on days 20-21 and persisted through day 28 in small groups or larger areas. beta 3 Integrin was highly expressed in luminal and glandular epithelium from day 22 through 28; 48 hours thereafter pinopodes appeared. alpha 4 Subunit exhibited luminal epithelium reaction positivity on days 22-23 and glands on days 18-23. LIF and IL-1R tI showed weak, erratic expression. MAG antibodies showed luminal epithelium expression up to day 22 and glands up to day 25. MUC-1 showed positivity during the whole luteal phase. P4 receptors were positive through day 20 and at the end of the luteal phase. Conclusion(s): The three most cited markers that frame the window of implantation do not correlate in our material. Pinopodes are present from day 20 on; beta 3 and alpha 3 integrin subunits indicate a window opening on days 22-23. (C) 2000 by American Society for Reproductive Medicine.