ULTRASONIC MONITORING DURING REPLACEMENT OF FROZEN-THAWED EMBRYOS IN NATURAL AND HORMONE REPLACEMENT CYCLES

We evaluated the results of cryopreserved/thawed embryo replacement (F ER) to determine if the outcome following transfer in a natural cycle in a defined group was different to that from a hormone replacement cy cle, and also to assess vaginal ultrasonographic features that assist in predicting the timing of the transfer. At the London Fertility Cent re, 149 consecutive FER cycles were studied retrospectively. Women wit h proven ovulation and regular cycles were included during natural cyc les (n = 77). The hormone replacement cycle group included women with anovulation, irregular cycles and older women (n = 72). In the natural cycle group, transfer was performed following positive urinary lutein izing hormone (LH) surge and confirmation of ovulation by ultrasonogra phy. With the hormone replacement therapy group, gonadotrophin-releasi ng hormone analogue was used to induce pituitary down-regulation, oest radiol valerate was supplemented followed by regular ultrasound monito ring, and FER 2 days following the initiation of progesterone, which w as started once adequate endometrial development was noticed on ultras onography. The pregnancy and ongoing/delivery rates were analysed in r elation to the treatment cycle, age, number and quality of embryos tra nsferred. Ultrasonographic features were examined to evaluate their re lationship with the outcome of treatment. The results showed that no d ifference existed between natural and hormone replacement cycles in pr egnancy rates per cycle (26 and 25%), ongoing/delivery rate (20.8% in both groups), and implantation rate (10.3 and 10.6%). Pregnancy rates were not influenced by the number of embryos transferred, stage at whi ch the embryos were cryopreserved, or whether they were extra embryos from in-vitro fertilization/embryo transfer, or gamete intra-Fallopian transfer. The pregnancy rate was low (7.4%) if the embryos had less t han three blastomeres and if the fragmentation was >50% (0% pregnancy rate). With hormone replacement cycles, age did not influence the outc ome, and women 40 years and older had a pregnancy rate of 29.4% per cy cle. No pregnancies resulted in the natural cycle group if the maximum follicular diameter was >22 mm before ovulation. When poor endometria l development was noted (thickness <8 mm and grade C) no pregnancy res ulted from FER in natural or hormone replacement cycles. The pregnancy rates were higher when the endometrium was greater-than-or-equal-to 8 mm thickness and grade B (42.4%) or grade A (21.2%). We concluded tha t FER outcomes in natural cycles were similar- to those arising with h ormone replacement therapy provided good selection criteria were used, and vaginal ultrasonography can assist in timing the day of replaceme nt and identify cases to be cancelled before the transfer.