Endometrial Dating Method Detects Individual Maturation Sequences During the Secretory Phase

Area of Science:

• Reproductive endocrinology
• Histopathology
• Assisted reproductive technologies

Background:

• Precise endometrial dating is crucial for optimizing embryo transfer timing.
• Current histological methods may lack the precision needed for individual assessment.
• Immunohistochemistry offers a potential advancement in endometrial receptivity analysis.

Purpose of the Study:

• To evaluate a novel immunohistochemical method for precise endometrial dating.
• To determine if this method improves the accuracy of timing embryo transfers.
• To compare immunohistochemical dating with traditional Noyes criteria.

Main Methods:

• A novel method combining menstrual cycle days, Noyes criteria, and immunohistochemistry (estrogen receptor, progesterone receptor, Ki-67).
• Analysis of 217 endometrial biopsies from 151 subfertile patients during the secretory phase (days +5 to +10 post-ovulation/progesterone).
• Assessment of endometrial maturation and comparison with clinical timing.

Main Results:

• Individual endometrial maturation varied, with an average deviation of 1.68±1.67 days.
• Histological maturation showed a delay of approximately 2 days compared to clinical days post-ovulation.
• The immunohistochemical method revealed that 8 days are needed for histological mid-secretory phase, not the expected 6 days.

Conclusions:

• Endometrial maturation to the mid-secretory phase requires 8 days, a finding observed in both fertile and subfertile patients.
• The novel immunohistochemical method is superior to Noyes criteria alone for endometrial dating.
• This advanced method provides a more accurate basis for determining optimal embryo transfer timing.