Review article
UNEXPLAINED INFERTILITY
Miro Kasum
; Department of Gynaecology and Obstetrics, Clinical Hospital Center, Medical School University of Zagreb, Croatia
Abstract
Unexplained infertility refers to the absence of a definable cause for a couple’s failure to achieve pregnancy after 12 months of attempting conception despite a thorough evaluation. Currently, a thorough evaluation tipically ¬includes documentation of: adequate ovulation, tubal patency, normal uterine cavity, normal semen analysis and adequate ovarian oocyte reserve. Although the exact etiology of unexplained infertility is unknown, several possibilities have been proposed. Subtle changes in follicle development, ovulation, and in luteal phase have been reported in some women. In other couples, the male partner’s semen analysis shows sperm concentration and motility at the lower end of the normal range. Many cases of unexplained infertility are probably caused by the presence of multiple factors (egg, female partner over 37 years of age, male partner with low normal semen parameters), each of them on their own do not significantly reduce fertility, but can reduce the pregnancy rate combined. Couples with unexplained infertility also had a higher rate of complete fertilization failure, subtle functional abnormalities in oocyte and/or sperm function and reduced oocyte fertilization and embryo cleavage rates compared to couples in whom tubal factor is the cause. It has been suggested that the term unexplained infertility is unsustainable, as condition such as endometriosis, tubal infertility, premature ovarian ageing and immunological infertility tend to be misdiagnosed as unexplained infertility. Despite improved diagnostic techniques, the average incidence of unexplained infertility has been reported to be approximately 15% among infertile couples, and varies from 0% to 37%. Unexplained infertility represents the single most frequent female infertility diagnosis, with a reported prevalence of approximately 25%–30% of all infertilities. Idiopathic male infertility is responsible for 40%–50% of all male infertility. The management of couples with unexplained infertility usually starts with treatments that consume few resources (life style changes, expectant management, timed intercourse, intrauterine insemination, clomiphene plus insemination) and moves sequentialy to treatments requiring proportionaly greater resources (gonadotropin injections plus insemination or in-vitro fertilization). Lifestyle changes may increase the pregnancy rate slightly. Approximately 1 to 3 per cent of couples with unexplained infertility become pregnant each month. Expectant management may be an option for the female partner less than 32 years of age, but not for the women over 37 years of age since their pregnancy rate is less than 1 percent per cycle. Useful treatments include insemination, clomiphene, clomiphene plus insemination, gonadotropin injections, gonadotrophin injections plus insemination and in-vitro fertilization. Intrauterine insemination was associated with a 5 percent per cycle pregnancy rate and the pregnancy rate per cycle was 9,5 percent for clomiphene plus insemination. A combined approach using both gonadotrophin injection and insemination reported the pregnancy rates between 9,5 and 26 percent. After failure of up to three cycles of the use of gonadotrophin injections plus insemination, this treatment should be limited because most pregnancies will occur in the first three cycles. In-vitro fertilization appears very useful for treatment of unexplained infertility because of 20 to 40 percent per cycle pregnancy rates. Patients who have total failure of fertilization after conventional in-vitro fertilization procedure are generally treated by means of intracytoplasmatic sperm injection in future cycles. The approach to the treatment of unexplained infertility should balance the efficacy, cost, safety, and risks of various treatment alternatives and individual treatment steps should be recommended for no more than three to six months.
Keywords
idiopatska neplodnost; endometrioza; imunološka neplodnost; starenje jajnika; tubarna neplodnost
Hrčak ID:
23512
URI
Publication date:
1.12.2007.
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