1 Department of Obstetrics and Gynecology, The Jones Institute for Reproductive Medicine, Eastern Virginia Medical School, Norfolk, VA 23507, USA and 2 Hôpital de Nyon, Nyon and University Hospital Geneva, Geneva, Switzerland
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Abstract |
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Key words: intrauterine insemination/misoprostol/pregnancy/prostaglandin/vaginal
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Introduction |
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Intrauterine insemination (IUI) has an important role in the treatment of infertile couples. Although intracytoplasmic sperm injection (ICSI) has become a formidable treatment for patients with severe oligoasthenoteratozoospermia, there is a real role of IUI as a clinical treatment modality (Oehninger, 1996; Oehninger et al., 1997
). IUI involves the direct transfer of washed spermatozoa to the intrauterine space, thus by-passing potential vaginalcervical sperm barriers and increasing sperm concentration near the site of fertilization in the Fallopian tubes. It is known that painful uterine cramping occurs when PG from semen are placed in the intrauterine space. Consequently, semen preparation for IUI deliberately eliminates PG from the inseminate. In natural reproduction, spermatozoa migrate from the vagina into the cervical mucus, and thus leave naturally produced PG and other substances in the vagina. During standard IUI, these other seminal constituents (perhaps PG) are not present and therefore their positive effects on fertility are absent.
Misoprostol is a commercially available synthetic PG that is structurally related to PGE1 (Collins et al., 1985) and was used initially to prevent peptic ulcer disease induced by chronic ingestion of non-steroidal anti-inflammatory drugs (NSAID) (Dajani and Nissen, 1985
). Misoprostol has also been used extensively as an oral and intravaginal abortifacient, and most recently as a medical aid to evacuate early pregnancy failures in humans (Creinin and Darney, 1993
Peyron et al., 1993
). Misoprostol has also been used as a safe and inexpensive medication for cervical ripening and labour induction in human pregnancies (Sanchez-Ramos et al., 1997
).
Due to the reported safety, widespread commercial availability and relative similarity of misoprostol to PGE, the usefulness of vaginally placed misoprostol as adjunctive therapy at the time of IUI was investigated, and its tolerability and effects on clinical pregnancy rates assessed.
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Materials and methods |
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Infertility diagnoses were classified as: (i) male factor, if semen analyses revealed oligozoospermia (sperm concentration <20x106 spermatozoa/ml), asthenozoospermia (<50% progressively motile spermatozoa), and/or teratozoospermia [normal strict morphology 414%, thereby eliminating `poor prognosis' patients with <4% normal forms (Acosta and Kruger, 1996)]; (ii) endometriosis (minimalmild) confirmed by laparoscopic visualization and ablated by laser or electrocautery; (iii) polycystic ovarian syndrome (PCOS), when anovulatory cycles were coupled with any manifestation of hyperandrogenism with the exclusion of those with signs/symptoms of congenital adrenal hyperplasia or other endocrinopathies (Dunaif et al., 1987
; ACOG, 1995); (iv) oligo-ovulation or anovulatory cycles without signs or symptoms of hyperandrogenism and hypergonadotrophism; (v) tubal disease, when laparoscopy or hysterosalpingography (HSG) defined at least one abnormal Fallopian tube (in such cases, the disease was corrected by laparoscopy or laparotomy to the minimum end point of having at least one patent tube); (vi) uterine disease, abnormalities found on HSG (i.e. polyps or submucosal fibroids) with further hysteroscopic surgical correction; (vii) decreased ovarian reserve, those patients with cycle day 3 serum FSH concentrations
10 mIU/ml (MEIA; Abbott IMx-System®, Abbott Park, IL, USA) or a high oestradiol concentration (>90 pg/ml; MEIA); and (viii) unexplained infertility, as defined by the absence of abnormal results in the above diagnostic evaluations.
The decision to initiate IUI as a treatment for infertility was made by the attending physician. Subjects underwent one of the following treatments: natural cycle, clomiphene citrate, gonadotrophin or clomiphene/gonadotrophin stimulation. Natural cycles were used in a minority of cycles when mild spermatozoa or spermatozoacervical mucus problems were identified. Clomiphene citrate was used empirically or when anovulation was part of the infertility diagnosis, and was started at 50 mg/day and given on cycle days 59 or 37. The dosage was increased in subsequent cycles until ovulation was achieved, and was then repeated for up to four to six ovulatory cycles. IUI was offered only to those with ovulatory cycles while taking clomiphene. Ovulatory cycles were those defined as having either a positive urine luteinizing hormone (LH) kit test or those having ovulation trigger with human chorionic gonadotrophin (HCG) injection (as defined below).
The decision to initiate gonadotrophins or clomiphene/gonadotrophin combined ovarian stimulation with IUI treatment was usually made after previous treatments with clomiphene citrate coupled with IUI had failed to produce pregnancy. When the decision was made to start ovarian stimulation/IUI, purified FSH (Metrodin® or Fertinex®; Serono Labs Inc., Norwell, MA, USA) or recombinant FSH (Gonal-F®; Serono) was initiated on day 3 of a spontaneous menstrual cycle or induced menstrual bleeding. Cycles were monitored with serial serum oestradiol and LH concentrations, as well as ovarian follicular size determinations by ultrasound. No cycles employed pituitary desensitization with gonadotrophin-releasing hormone agonist (Dodson et al., 1991). Cycles began with 12 ampoules of gonadotrophin and continued on a step-down fashion, depending on patient response. Patients without PCOS were started with 23 ampoules [human menopausal gonadotrophin (HMG), FSH or combined] and followed in a step-down fashion via individualized protocols. Some cycles in patients with PCOS (n = 67) utilized the combination of clomiphene and gonadotrophins, and in these cases clomiphene 100 mg was taken daily from cycle day 3 to day 7; initiation of daily gonadotrophin injections was on cycle day 9. The starting dose of clomiphene would vary depending on three differing predicted ovarian responses to stimulation (high responders with 50 mg/day, normal responders with 100 mg/day, and low responders with 150 mg/day). Ovulation was triggered by i.m. injection of 10 000 IU of HCG when the lead follicle(s) reached a diameter of 1820 mm for clomiphene/FSH cycles. IUI was then performed ~36 h later. Patients were counselled on the risks of multiple gestation when more than one mature follicle was triggered, and our defined stimulation technique generally resulted in one to three mature follicles per cycle. Although rare, cycles with more than three mature follicles were not cancelled.
Semen samples for IUI were collected and prepared by sperm washing (human tubal fluid and 0.2% human serum albumin; Irvine Scientific, Santa Ana, CA, USA), and with further processing by the use of gradient centrifugation (Percoll or ISolate®) in cases of leukospermia (white blood cell concentration >1x106/ml with negative semen cultures) or positive antisperm antibodies (via direct immunobead testing) (Irianni et al., 1993; Ombelet et al., 1997
). Donor sperm cases were included (see Table IV
). IUI was performed using a UnisemTM intrauterine cannula (Unimar®; Cooper Surgical, Shelton, CT, USA) or ShepardTM intrauterine insemination catheter (Cook®, Spencer, IN, USA) in cases of stenosis. All patients utilising gonadotrophins (including clomiphene/gonadotrophin cycles) had luteal support with vaginal progesterone suppositories (50 mg daily) starting 48 h post insemination. Luteal support was continued until serum or urinary pregnancy evaluation ~16 days after IUI, and when pregnant, through gestational week 10.
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Pregnancy determinations were made by HCG titre evaluation at ~16 days post insemination. Positive pregnancy tests were further followed by transvaginal ultrasonography at 46 weeks from insemination. Those with gestational sacs with cardiac activity were defined as clinical pregnancies.
Statistical analysis
Pregnancy rates in PGE1 and placebo cycles were compared using Cox proportional hazards regression with the AndersonGill counting process notation to account for repeated cycles of some patients (Anderson and Gill, 1982; Fleming and Harrington, 1991). Patients may have multiple events as well as cycle-dependent covariates. Differences in patient demographic and clinical variables between PGE1 and placebo cycles were analysed using a generalized estimating equation (GEE) approach to clustered data (Diggle et al., 1994
).
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Results |
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No significant differences were noted between the active treatment and placebo cycles regarding subjective side effects, complications and pain variables (Table V), and none of these variables was associated with pregnancy. The placebo group showed a non-significant increased pain score on the day of IUI (1.4 versus 1.1) and day post IUI (0.8 versus 0.6). Complications occurred in six (2%) cycles in the active treatment regimen [severe pelvic pain (n = 4) and fever >100.4°F (n = 2)] and in two (1%) cycles in the placebo group (severe pain). All but one of the pain episodes occurred >2 h post IUI, and were completely resolved within 48 h. One case occurred immediately from the time of IUI, even before suppository placement. All fevers resolved within 24 h, and none required antibiotic use. Vaginal spotting after IUI occurred in 23 (9%) active treatment cycles versus 15 (6%) in the placebo group. Pregnancy information was not available from three IUI cycles due to lack of follow-up and inability to contact the subjects, and therefore were not included in the analysis.
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Discussion |
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PG are known to enhance sperm transport and increase the fertilization rate in rabbits (Mandl, 1972). Novel animal studies involving the use of intrauterine PGE infusion have resulted in the maintenance of corpora luteal function and stimulation of progesterone production, ensuring uterine receptivity for pregnancy (Thibodeaux et al., 1992
).
Human in-vitro research has shown that PGE induces a relaxation response on the non-pregnant human uterine and Fallopian tube smooth muscle, whereas PGF has been shown in vitro to create a contractile response. The in-vivo effects from both PG are stimulatory on the myometrium (Ingelman-Sundburg, 1968; Coutinho and Maia, 1971
). Moreover, it has also been shown that PGE is more potent than PGF on myometrial response and that both PG inhibit tubal motility, thus suggesting that the relaxation of the tubal isthmus is a prerequisite for sperm penetration into the Fallopian tube (Coutinho and Maia, 1971
). Additional effects such as immunosuppression afforded by seminal PG has been shown both in vivo and in vitro, suggesting an attenuated female immunological response to spermatozoa (Skibinski et al., 1992
). Strikingly PGE, but not PGF, has been shown to improve significantly the ability of human spermatozoa to penetrate zona-free hamster oocytes (Aitken and Kelly, 1985
).
Human in-vivo research has shown the potential benefit of vaginally placed PG in the assistance of reproductive success. In 1959, it was noted that the most common reaction to intravaginal administration of seminal fluid was contraction of the uterine corpus, with relaxation of the cervical canal (Karlsson, 1959). Enhanced passage of spermatozoa through cervical mucus has been noted in the in-vivo use of PG (Eskin et al., 1973
). Additionally, intravenous injection of PGE1 has been shown to stimulate contractility of the non-pregnant human uterus, assisting sperm movement to the Fallopian tubes (Roth-Brandel et al., 1970
). Cervical relaxation, improved spermatozoamucus penetration, enhanced uterine contractility, tubal relaxation, and improved spermatozoazona binding all appear to be related to the normal deposition of PGE into the female reproductive tract.
Misoprostol [(±)-methyl-11, 16-dihydroxy-16-methyl-9-oxoprost-13-E-en-1-oate] is a synthetic PG structurally related to PGE1 (Collins et al., 1985
). The compound was used initially to prevent peptic ulcer disease induced by the chronic ingestion of NSAID. Since its commercial introduction, misoprostol has been reported as an effective oral and intravaginal abortifacient, and most recently as a medical aid to evacuate early pregnancy failures in humans (Creinin and Darney, 1993
; Peyron et al., 1993
). Misoprostol has also been shown to be an effective agent for cervical ripening and labour induction (Sanchez-Ramos et al., 1997
).
Due to these favourable effects of PG in regard to the potentiation of fertilization, the utility of augmenting IUI with vaginally placed PGE1 analogue (misoprostol) was investigated with regard to pregnancy success and complications. A significant increase was found in the pregnancy rates of women undergoing ovarian stimulation with clomiphene citrate, and there was a trend toward increasing pregnancy rates both in natural cycles and in women where gonadotrophins were used for stimulation, when vaginal misoprostol was placed at the time of insemination.
The positive effect of vaginal misoprostol leading to an improved clinical pregnancy rate is not clearly understood. As mentioned previously, the known effects of PGE on increasing myometrial contractility, potential relaxation of tubal isthmus, improved spermatozoonoocyte binding/penetration and attenuation of the female immune response to spermatozoa may all facilitate fertilization potential. It is not understood why a statistically significant increased pregnancy rate was found in the clomiphene/gonadotrophin-only stimulated cycles, and not in the natural, gonadotrophin-only cycles or combination clomiphene/gonadotrophin cycles. Due to this large study cohort involving a predominance of clomiphene cycles, it is speculated that the improved clinical pregnancy rate would eventually be seen in all groups (power limiting) if numbers of cycles were increased. The precise physiological mechanism(s) of how misoprostol leads to improved clinical pregnancy rates requires further research.
The findings presented here support the hypothesis that vaginal PG are important in assisting the process of human fertilization and establishment of pregnancy. However, a causal link remains to be established and further studies are needed to determine the precise role of PG in early human reproductive events.
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Notes |
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4 Present address: Atlanta Center for Reproductive Medicine, Woodstock, GA 30189, USA
5 To whom correspondence should be addressed at: Florida Institute for Reproductive Medicine, 836 Baptist Medical Center Pavilion, Jacksonville, FL 32207, USA. E-mail: sambrown99{at}yahoo.com
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Submitted on June 19, 2000; accepted on September 28, 2000.