[Quality of endometrial preparation]

Area of Science:

• Reproductive Medicine
• Gynecology
• Obstetrics

Background:

• The gold standard for endometrial preparation involves sequential estrogen (E2) and progesterone (P4) administration.
• Endometrial thickness assessment using 3D ultrasound or VOCAL system is common, but predictive value is limited to 6 mm.
• Doppler ultrasound for blood flow evaluation has not definitively improved prediction of uterine receptivity.

Purpose of the Study:

• To review current understanding of endometrial preparation for embryo transfer.
• To highlight the significance of uterine contractions and progesterone timing for implantation.
• To discuss ongoing debates regarding progesterone maintenance post-pregnancy.

Main Methods:

• Literature review of established and emerging techniques in endometrial preparation.
• Analysis of ultrasound parameters (thickness, volume, blood flow) for predicting pregnancy.
• Evaluation of the role of uterine contractions and progesterone administration timing.

Main Results:

• Endometrial thickness has limited predictive value for pregnancy success.
• Doppler ultrasound has not proven effective in assessing uterine receptivity.
• Uterine contractions at embryo transfer negatively impact implantation; early progesterone initiation promotes quiescence.

Conclusions:

• Endometrial preparation protocols require optimization beyond simple thickness measurements.
• Progesterone administration timing is crucial for achieving uterine quiescence and improving implantation rates.
• Further research is needed to clarify optimal progesterone duration for maintaining pregnancy.