T. Alshawaf et al., ULTRASONIC MONITORING DURING REPLACEMENT OF FROZEN-THAWED EMBRYOS IN NATURAL AND HORMONE REPLACEMENT CYCLES, Human reproduction, 8(12), 1993, pp. 2068-2074
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.