The importance of sonographic endometrial parameters in influencing success following embryo transfer in the modern era and therapeutic options--part 1: the importance of late proliferative phase endometrial thickness.

PURPOSE: To evaluate the importance in the modern era of either too thin or too thick of an endometrium in the late proliferative phase on success following embryo transfer.
METHODS: Pregnancy rates following fresh embryo transfer in cycles using controlled ovarian hyperstimulation and following donor egg or frozen embryo transfers using artificial estrogen-replaced cycles according to endometrial thickness were determined.
RESULTS: A thin endometrium has a negative impact on success following embryo transfer but improvement in IVF technology makes this confounding variable much less important than in the early days of IVF. Too thick of an endometrium does not seem to negatively impact success.
CONCLUSIONS: Treatment options, e.g., low-dose aspirin, sildenafil or vaginal estradiol are of marginal value in improving endometrial thickness or outcome. For those with a good frozen embryo program the best option may be to cryopreserve all embryos and transfer in a subsequent graduated estrogen/progesterone replacement cycle.