Division of Reproductive Medicine and Gynecologic Endocrinology, Department of Gynecology and Obstetrics, University Clinic, Ratzeburger Allee 160, 23538 Lübeck, Germany
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Abstract |
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Key words: cetrorelix/clomiphene/COS/friendly IVF/GnRH antagonist
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Introduction |
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CC is cheap and simple to administer. It has been in use for four decades and is still the first-line therapy in normogonadotrophic anovulatory women. The combination of CC treatment in the early follicular phase and subsequent, overlapping, gonadotrophin stimulation has been a standard therapy in the past (Quigley, 1984; Lehmann et al., 1988
). Due to the synergistic effect of these compounds the amount of gonadotrophin required is lower and so are the costs (Ronen et al., 1988
; Tummon et al., 1992
). In addition the gonadotrophins counteract the detrimental effects of the CC to the endometrium (Ronen et al., 1988
). Due to the high rate of premature LH surges, and therefore the high cancellation rate, this stimulation regimen was abandoned when GnRH agonists were introduced in IVF.
This study was designed to investigate the possibility of using CC in combination with gonadotrophins in a prospective GnRH antagonist protocol. More specifically, it was carried out to evaluate the equivalence of rFSH and HMG with regard to the rate of HCG administration.
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Materials and methods |
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Inclusion and exclusion criteria
Healthy female partners of infertile couples were included after having given written informed consent. They were between 1839 years of age at the time of screening with normal menstrual cycles with a range of 2435 days and an intra-individual variation of 3 days. All had a normal uterus, confirmed by ultrasound. Exclusion criteria were a previous IVF procedure, presence of polycystic ovarian syndrome, corpus luteum insufficiency, impaired ovarian function, severe endometriosis, submucosal uterine myoma, or a FSH level 10 IU/l at screening. The exclusion criterion of no previous IVF cycles, which was valid for stimulation protocols 1 and 2 (see below), was changed during the course of the study. In stimulation protocols 3 and 4 (see below) patients could be included, if they did not have a history of more than three IVF attempts.
Stimulation protocols
The stimulation procedure was changed three times. Finally, four different stimulation protocols were analysed. Stimulation protocol 1 (group 1): from cycle day 2 or 3 (treatment day 1) 100 mg CC p.o. was administered once daily for 7 days. On treatment day 6 ovarian stimulation was initiated with three ampoules of HMG (Menogon®, Ferring Arzneimittel GmbH, Kiel, Germany) or rFSH (Gonal F®, Serono International S.A., Geneva, Switzerland) according to randomization. From treatment day 8 up to and including the day of HCG the gonadotrophins were adjusted to individual patients ovarian response. From treatment day 6 up to and including the day of HCG administration 0.25 mg cetrorelix (Cetrotide®, Serono International S.A.) was injected s.c. each day. 10000 IU HCG was administered when at least one follicle had reached 18 mm diameter. All cycles were carried out using ICSI to allow rating of oocyte maturity. Embryo transfer was performed 48 h after oocyte retrieval.
Due to the occurrence of premature LH surges, the stimulation protocol was modified three times. A premature LH surge was defined as LH >10 IU/l and progesterone >1 ng/ml, as was done in all prospective randomized studies with antagonists (Albano et al., 2000; The European Orgalutran® Study Group et al., 2000
). The procedures were amended as follows (Figure 1
).
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Broca-index
The Broca-index was calculated as weight/(height100)xf (f = 0.85) (Roche Lexikon Medizin, 1999).
Clinical pregnancy
A clinical pregnancy was confirmed in case of positive fetal heartbeats in transvaginal sonography 2835 days after embryo transfer.
Statistics
Statistical analysis was carried out using the ClopperPearson-test with double-sided 95% confidence interval. A P-value of < 0.05 was considered to be statistically significant. The data are presented as means with SD.
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Results |
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Due to the occurrence of premature LH surges the stimulation protocol was modified three times. The results are presented exclusively for the different treatment groups (groups 14). Oocytes were obtained from all patients with a premature LH surge. In one of these patients, however, no fertilization was achieved. COS had to be cancelled before the HCG injection in four patients. In 12 cases total fertilization failure was found and in one additional case treatment failure was reported without any further comments (Table I).
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Discussion |
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With a starting dose of 150 IU FSH the number of ampoules was ~18 per stimulation cycle. Though having a tendency to be lower, the gonadotrophin dose was not substantially different from those reported in the large phase III studies carried out according to the multiple-dose antagonist protocol (Albano et al., 2000). Lowering the daily gonadotrophin dose to 75 IU should be attempted to decrease the absolute gonadotrophin dose. However, the gonadotrophin dose is 50% lower than the amount required in the long protocol (Felberbaum and Diedrich, 1998
).
The different stimulation protocols (groups 14) lead to similar clinical results. So the reduction of CC stimulation days and gonadotrophin dose did not have a negative influence on the treatment outcome. Although there was only one patient with a premature LH surge where the oocytes could not be fertilized, the percentage of premature LH surges was unacceptably high for clinical practice. In group 3 there was a trend towards fewer premature LH surges, although this was not significant. It appears that reducing the duration of CC treatment and the starting dose of gonatrophins was a step in the right direction to reduce the amount of ampoules needed. However, these modifications were not sufficient to prevent a premature LH surge, as clearly demonstrated in group 4.
With only one grade II OHSS in the HMG group the side-effects of this regimen are comparable with those in the multiple-dose antagonist protocol (Ludwig et al., 2000).
To our knowledge, there is only one other study (Fiedler et al., 2001) dealing with the combination of Cetrotide and clomifene citrate. Fiedler and co-workers used CC with HMG or rFSH in 586 IVF cycles and did not conduct the study in a prospective randomized manner. A total of 295 cycles were performed with and 291 without additional administration of a GnRH antagonist. Pregnancy rates were similar with (23%) and without (21%) an antagonist treatment. LH serum levels were not provided by the authors, therefore the rate of premature LH surges cannot be assessed.
Despite the benefits of the presented co-administration of gonadotrophins and CC, the rate of premature LH surges remains a major drawback. This rate might be explained by the physiological mechanism, that the addition of CC with anti-estrogen effects leads, on the hypothalamic level, to the release of more native GnRH by the hypothalamus. An increased sensitivity of the pituitary for GnRH as a direct effect of the CC (Emons et al., 1986) could be another possible explanation for our results. Thus CC pretreated rat pituitary cell cultures required higher GnRH antagonist doses to suppress LH than CC untreated cultures (unpublished data).
The elevated rate of premature LH surges can be explained by an incompletely blocked pituitary due to an increased release of GnRH by the hypothalamus and an increased sensitivity of the pituitary for GnRH. Thus, increasing the daily dose of cetrorelix from 0.25 to 0.5 mg could overcome the problem of premature LH surge. On the other hand, a single dose of 3 mg Cetrotide in such a protocol might be an acceptable approach to prevent the premature LH surge. In the study by Zhioua and co-workers, 15 patients were treated using CC/HMG and a single dose of 3 mg Cetrotide on stimulation day 8 (Zhioua et al., 2000). No premature LH surge occurred. The pregnancy rate was 26.6%. Due to the small patient number this preliminary finding has to be confirmed in a greater number of patients.
The presumption of a not fully blocked pituitary, i.e. a partially susceptible pituitaryovary feedback loop, offers an explanation for the slightly elevated number of LH surges in patients treated with rFSH. In this patient group estrogen levels throughout the stimulation tended to be lower than in the HMG group, although this finding was not significant. Thus the negative feedback of the estrogen on the endogenous LH production of the not adequately blocked pituitary was weaker in the rFSH group, which might explain the elevated number of LH surges in this patient group.
In conclusion, soft stimulation protocols are a promising approach in assisted reproduction treatments. Nevertheless they have to be applied with caution until the problem of the premature LH surge has been overcome. Until a more reliable protocol can be established, this method of ovarian stimulation should only be done within prospective, clinical studies to avoid disadvantages for the treated patients. So far soft stimulation protocols do not have economic advantages when compared with the single or the multiple dose antagonist protocol. So defining a minimal effective gonadotrophin dose should be a main objective for future studies.
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Notes |
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References |
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Submitted on January 18, 2002; resubmitted on February 7, 2002; accepted on March 28, 2002.