Unexplained infertility
Encyclopedia
Unexplained infertility is infertility
that is idiopathic
in the sense that its cause remains unknown even after an infertility work-up
, usually including semen analysis
in the man and assessment of ovulation and fallopian tubes in the woman.
such as decreased maternal immune tolerance towards the embryo may also be a possible explanation.
s, and, if this has not resulted in pregnancy, it appears most useful to subsequently perform in vitro fertilization (IVF) in 6 menstrual cycles.
The administration of clomiphene citrate is intended to achieve ovulation induction
or ovarian hyperstimulation. However, it may result in multiple pregnancy, which ensuing increased risks and morbidity. Human chorionic gonadotropin
(hCG) is given to trigger ovulation, and the intrauterine insemination is performed within 2 days of hCG administration.
Infertility
Infertility primarily refers to the biological inability of a person to contribute to conception. Infertility may also refer to the state of a woman who is unable to carry a pregnancy to full term...
that is idiopathic
Idiopathic
Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...
in the sense that its cause remains unknown even after an infertility work-up
Work-up
In chemistry, work-up refers to the series of manipulations required to isolate and purify the product of a chemical reaction.Typically, these manipulations include:* quenching a reaction to deactivate any unreacted reagents...
, usually including semen analysis
Semen analysis
A semen analysis evaluates certain characteristics of a male's semen and the sperm contained in the semen. It may be done while investigating a couple's infertility or after a vasectomy to verify that the procedure was successful. It is also used for testing donors for sperm donation, in stud...
in the man and assessment of ovulation and fallopian tubes in the woman.
Possible causes
In unexplained infertility abnormalities are likely to be present but not detected by current methods. Possible problems could be that the egg is not released at the optimum time for fertilization, that it may not enter the fallopian tube, sperm may not be able to reach the egg, fertilization may fail to occur, transport of the zygote may be disturbed, or implantation fails. It is increasingly recognized that egg quality is of critical importance and women of advanced maternal age have eggs of reduced capacity for normal and successful fertilization. Also, polymorphisms in folate pathway genes could be one reason for fertility complications in some women with unexplained infertility. Aberrant reproductive immunologyReproductive immunology
Reproductive immunology refers to a field of medicine that studies interactions between the immune system and components related to the reproductive system, such as maternal immune tolerance towards the fetus, or immunological interactions across the blood-testis barrier...
such as decreased maternal immune tolerance towards the embryo may also be a possible explanation.
Prevalence
In the US, up to 20% of infertile couples have unexplained infertility.Management
The most efficient management of unexplained infertility appears to be administration of clomiphene citrate and performance of intrauterine insemination (IUI) during 3 menstrual cycleMenstrual cycle
The menstrual cycle is the scientific term for the physiological changes that can occur in fertile women for the purpose of sexual reproduction. This article focuses on the human menstrual cycle....
s, and, if this has not resulted in pregnancy, it appears most useful to subsequently perform in vitro fertilization (IVF) in 6 menstrual cycles.
The administration of clomiphene citrate is intended to achieve ovulation induction
Ovulation induction
Ovulation induction is the stimulation of ovulation by medication. It is usually used in the sense of stimulation of the development of ovarian follicles to reverse anovulation or oligoovulation, but can also be used in the sense of triggering oocyte release from relatively mature ovarian follicles...
or ovarian hyperstimulation. However, it may result in multiple pregnancy, which ensuing increased risks and morbidity. Human chorionic gonadotropin
Human chorionic gonadotropin
Human chorionic gonadotropin or human chorionic gonadotrophin is a glycoprotein hormone produced during pregnancy that is made by the developing embryo after conception and later by the syncytiotrophoblast .. Some tumors make this hormone; measured elevated levels when the patient is not...
(hCG) is given to trigger ovulation, and the intrauterine insemination is performed within 2 days of hCG administration.