Apart from being terribly frustrating, unexplained infertility means that treatment is not directed at any known cause. Approximately 60% of couples with unexplained infertility of less than 3 years duration will fall pregnant in the next 3 years without any treatment at all. Recent analysis of all the studies of clomiphene (A fertility drug (trade name Clomid) that is used to stimulate ovulation and that has been associated with multiple births) has not found it to be beneficial.
One useful treatment option is ovarian stimulation combined with a direct insemination of prepared and ‘optimised’ sperms from the partner.
Possible causes of unexplained infertility are as follows:
Tubal abnormalities: It is possible that there may be a subtle defect in the mechanism by which the fimbria "pick up" the egg during ovulation; or else the cilia in the tube may not be functioning properly.
Abnormal eggs: A very small number of cases of unexplained infertility could be due to the persistent production of abnormal eggs. These eggs may have a deformed structure or chromosomal abnormalities.
Trapped Eggs: In some cases, it appears that eggs are produced and matured correctly within the follicle, which then goes on to become a corpus luteum without, however, first bursting to release the egg. The egg is therefore effectively "trapped" inside the unbroken corpus luteum - and this is called a luteinized unruptured follicle (LUF) syndrome.
Luteal phase abnormalities: The luteal phase is that part of the cycle which follows after the egg has been released from the ovary. This phase may be inadequate in some way, and this is called a luteal phase defect.
The corpus luteum produces the hormone called progesterone, which is essential for preparing the endometrium to receive the fertilized egg. Several things can go wrong with progesterone production: the rise in output can be too slow; the level can be too low; or the length of time over which it is produced can be too short. Another possibility is a defective endometrium that does not respond properly to the progesterone.
Luteal phase defects can be investigated either by a properly timed endometrial biopsy or by monitoring the progesterone output by taking a number of blood samples on different days after ovulation and measuring the progesterone level in them.
Immunological Factor: The immune system can react against the man’s own sperm, and, as a result, kill them, immobilize them, or make them stick together. Women can also develop an immune reaction to the sperm, with the same result, thus preventing the sperm from reaching the egg. It is also possible that women can develop antibodies against the coating of their own eggs (the zona pellucida), and these can prevent sperm from binding to the zona.
Infections: Infection by certain disease particles has been shown to be responsible for some cases of unexplained infertility. A disease particle called "T-strain mycoplasma" may be present in a quantity that is not enough to show up in a clinical examination, but which, nevertheless, can cause infertility.
Inability of sperm to penetrate eggs: There is evidence to show that some men’s sperm, although apparently adequate in every other way, are unable to get into the egg to fertilize it. The only way to make this diagnosis is by IVF; if donor sperm can fertilize the wife’s eggs but the husband’s sperm fail to do so, then the diagnosis is confirmed.
Psychological factors: Studies on infertile groups of men and women have produced contradictory findings about the importance of psychological factors in causing infertility. Emotional disturbances, undoubtedly, appear to be of some significance. Such a possibility is perfectly reasonable - after all, the whole hormonal cycle, with its delicate adjustments, is controlled by the brain. This is an area which needs further investigation, but it really is a "chicken and egg" kind of problem. Remember, it is much more common for the infertility to cause emotional stress, rather that for the emotional disturbance to result in infertility!
Remember, you still have a fairly good chance of getting pregnant on your own without any treatment at all!
The duration of infertility is important.
The longer the infertility, the less likely the couple is to conceive on their own. After 5 years of infertility, a couple with unexplained infertility has less than a 10% chance for success on their own.
One study showed that for couples with unexplained infertility of over 3 years duration, the cumulative conception rate after 24 months of attempting conception without any treatment was 28%. This number was found to be reduced by 10% for each year that the female is over 31.
Treatment for unexplained infertility
Ovarian stimulation and/or intrauterine insemination.
Intrauterine insemination vs. timed intercourse.
This has been studied and a slight improvement found for insemination. However, the difference was not large enough to be statistically significant.
Clomiphene citrate
3-6 months of treatment might improve fertility by as much as 2 times as compared to no treatment. This is a very low level infertility treatment. Infertility specialists do not usually recommend this level of treatment for women over the age of 35-37. Some do not use it on any couples with unexplained infertility.
Injectable gonadotropins plus intrauterine insemination
Several studies showed improved pregnancy rates with this treatment as compared to no treatment.
Injectable gonadotropins plus intercourse.
This is less extensively studied. It is not yet known whether the ovarian stimulation and the insemination have independent beneficial effects or whether their beneficial effects are only seen when they are used in combination.
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