1 Center for Reproduction at Gramercy, MacGregor Medical Association, Houston, Texas, USA and 2 Department of Obstetrics and Gynecology, Nyon, Switzerland
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Abstract |
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Key words: clomiphene citrate/endometrial morphology/oligo-ovulation/vaginal estrogen/vaginal progesterone
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Introduction |
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Adverse effects of CC on the endometrium are likely to be the primary cause of the suboptimal pregnancy rates seen when ovulation is induced with CC. It has long been recognized that women who receive CC for ovulation induction demonstrate a delay in endometrial stromal development, resulting in out of phase endometrial biopsies performed in the late luteal phase. Specifically, 1012 days after ovulation, the predecidual changes induced by progesterone that characterize this later part of the luteal phase are lacking in a large fraction of women who used CC (Wentz, 1980; Cook et al., 1984
; Fritz et al., 1987
; Massai et al., 1993
). Moreover, studies of the endometrium after exposure to CC have shown a high incidence of histological features consistent with hypo-estrogenic effects (Bonda, 1992
), suggesting that the lack of progestational effects seen in the late luteal phase may stem from anti-estrogenic effects resulting in insufficient development of estrogen receptors (ER) and progesterone receptors (PR). Supporting this latter hypothesis were findings that supplementing the hormonal environment during the late luteal phase with exogenous progesterone did not normalize late luteal endometrial biopsies (de Ziegler and Bouchard, 1993
).
The purpose of this study was to examine the effects on endometrial morphology of a timed sequence of vaginal hormone supplementation (HS) with estradiol (E2) and progesterone gel following CC therapy and to determine if this regimen can correct the endometrial anomalies seen in CC cycles. We postulated that to restore normal endometrial morphology in CC cycles, it was first necessary to neutralize the anti-estrogenic effects of CC on the endometrium as soon as follicular maturation was initiated, i.e. on cycle day 8.
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Materials and methods |
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The protocol followed ethical guidelines established by the Declaration of Helsinki, revised 1983, and was approved by the Western Institutional Review Board. Each patient gave written informed consent.
Treatment design
All patients who met screening criteria underwent a transvaginal sonogram on day 2 or 3 of the menstrual cycle to rule out ovarian cysts, defined as any sonoluscent structure measuring >15 mm in mean diameter. Patients with a satisfactory ultrasound and negative serum pregnancy test were assigned, using a computer-generated random numbers table, to one of four treatment groups (Table I). Groups 1 and 2 received 50 mg oral CC (Serophene®; Serono Laboratories, Randolph, MA, USA) and groups 3 and 4 received 100 mg oral CC for 5 days starting 3 days after spontaneous or induced menses. Groups 2 and 4 also received HS with vaginal E2 0.1 mg twice daily (Estrace Cream®; Bristol Myers Squibb Company, Princeton, NJ, USA) and 90 mg/day of progesterone (1.125 g of vaginal progesterone gel, Crinone® 8%; Serono Laboratories).
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Hormonalendometrial analyses
To analyse serum concentrations of E2 and progesterone, a competitive chemiluminescent immunoassay was used (ACS-estradiol-6 and progesterone; Chiron Diagnostics, Medfield, MA, USA). The detection level for E2 was 10 pg/ml with inter-assay precision of 4.2%; the detection level for progesterone was 0.1 ng/ml, with inter-assay precision of 4.7%. Endometrial biopsies were interpreted and dated according to Noyes criteria (Noyes et al., 1950). Ten (± 1) days after ovulation predecidual changes of the endometrial stroma were expected. A delay >2 days in endometrial transformation was considered as abnormal and qualified as out of phase by reference to prior studies on luteal phase defect (Jones et al., 1970
; Kennan et al., 1989
).
Statistical analyses
Fishers's exact test was used to analyse differences in the endometrial biopsy data between groups. For comparisons of differences in ages, BMI, hormone measurements, day of LH peak, follicular recruitment and endometrial thickness between the four CC treatment groups, data were analysed using one-way analysis of variance (ANOVA) followed by Duncan's multiple comparison tests in those cases where overall treatment differences were significant (SuperANOVA; Abacus Concepts, Berkeley, CA, USA). A P value of < 0.05 was regarded as statistically significant.
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Results |
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The age and BMI were similar for all CC treatment groups with mean age (± SEM) of 30.8 ± 0.6 years (range 2638) and BMI of 28.3 ± 1.2 kg/m2 (range 1936) (F test, not significant). As shown in Table II, baseline endocrine parameters (LH, FSH, prolactin, DHEA-S, testosterone and TSH) were not different among the four groups.
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Discussion |
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Given its properties, it is reasonable to postulate that endometrial maturation is suboptimal secondary to the anti-estrogen effect of CC. Following the same principles, prior attempts have been made to co-administer an estrogen preparation in order to restore proper endometrial priming prior to exposure to endogenous and exogenous progesterone during the luteal phase (Yagel et al., 1992). Gerli observed that supplementing CC with exogenous estrogen increased endometrial thickness and decreased the risk of spontaneous abortion in oligomenorrhoeic women who used CC for ovarian stimulation (Gerli et al., 2000
). Adding support to this hypothesis, Hurd et al. demonstrated in a different trial that when CC was used for ovarian stimulation for IVFembryo transfer, luteal support with both E2 and progesterone significantly increased conception rates compared with no luteal support (Hurd et al., 1996
). Recognizing the need for proper E2 priming, we designed a study using hormonal supplementation with E2 and progesterone in order to correct the endometrial disorders that progesterone alone fails to achieve. Both hormones were administered vaginally in order to optimize endometrial concentrations, since evidence supports that vaginally administered E2 and progesterone result in higher endometrial concentrations of these hormones than when administered otherwise (Miles et al., 1994
; Bulletti et al., 1997
; Tourgeman et al., 1999
). Our results clearly showed that exogenous vaginal E2 and progesterone improved endometrial morphology of CC-treated patients.
Discrepancies exist, however, between various published reports on endometrial morphology in CC cycles, as some investigators have failed to observe any morphological abnormalities in the mid-luteal (Jones et al., 1970) or even in the late luteal phase (Lamb et al., 1972
; Hecht et al., 1990
). A likely explanation for this finding is that the markedly varying E2 levels which occur in ovarian stimulation cycles using CC may on occasion overcome the inherent anti-estrogenic properties of clomiphene on the endometrium. It is conceivable, however, that in some cycles where CC is used, suboptimal levels of E2 may not suffice in negating the effects of CC on the endometrium.
This study demonstrated that hormonal supplementation with vaginal E2 and progesterone resulted in in-phase endometrial development in 100% of women following CC-induced ovulation. Hence, our findings suggest that adding vaginal estrogen followed by progesterone supplementation to CC in ovulation induction regimens for oligo-ovulatory women is a valuable option for maximizing endometrial morphology without greatly increasing costs or monitoring for the patient.
Large scale studies using simplified derivatives of our sequential vaginal E2 and progesterone supplementation regimen for CC cycles should assess the practical value (in terms of pregnancy rates) of normalizing endometrial morphology with exogenous hormones.
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Acknowledgements |
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Notes |
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References |
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accepted on October 11, 2001.