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Unexplained Infertility

Unexplained infertility is that infertility cause is remaining unknown even after the all checkup of infertility. Doctor will prescribe all tests like semen analysis to known male factor, ultrasound, and blood test to female. But all these test reports are normal and the reason of infertility is still unsuspected. So, this is called unexplained infertility. Unexplained infertility abnormalities are likely to be present but not detected by recent methods. Possible problems could be that the egg is not released at right time of 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 zygote may be disturbed, or implantation fails. It is increasingly recognized that egg quality is of critical importance and women of advance maternal age have eggs of reduced capacity for normal and successful fertilization. Reproductive immunology such as decreased maternal immune tolerance towards the embryo may also be possible explanation. However, a growing body of evidence suggests that epigenetic modifications in sperm may be partially responsible. 

Causes of unexplained infertility

  1. Anatomical abnormalities

It used to be thought that a retroverted uterus was a cause of infertility, but this is no longer taken to be the case.  The sperm cannot reach to the cervix due to the position of cervix is abnormal. It is also possible that there may be failures in the mechanism in the mouth of the fallopian tubes which allows them to pick up the egg.  Abnormal levels of hormones called prostaglandins, which are responsible for making the muscles contract, may interfere with the passage of the egg in the tube.  High prostaglandin levels are usually associated with endometriosis, and this condition is likely to be detected.  Large multiple fibroids can interfere with the process of reproduction by making the womb unreceptive to a fertilized egg.  Scar tissue can also result in damage to the fallopian tubes.

Diagnosis of the cause of infertility, investigations should include vaginal ultrasound scans and also hysteroscopy.  Vaginal ultrasound will pick up abnormalities within the womb and abnormalities with the ovaries, which would otherwise be missed by a laparoscopy.   Hysteroscopy should be performed at the same time as a laparoscopy so that any problems within the womb, which could cause infertility, may be detected.

  • Abnormal development of the follicle and of ovulation

In few women the egg may be released from the follicle in which it develops before it is properly mature or it may not be released at all formed to cyst.

  • Abnormal eggs

It would appear that a very small number of cases of unexplained infertility are due to the persistent production of abnormal eggs.  These may have a deformed structure or chromosomal abnormalities.

  • Trapped eggs

In some cases it would appear that eggs are produced, and mature correctly within the follicle.  This goes on to become a “corpus luteum” but without first bursting to releasing the egg.  The egg is therefore effectively “trapped” inside the unbroken “corpus luteum”.

  • Luteal phase abnormalities

The most important of all causes of “unexplained” infertility.  This is where the part of the cycle that follows after the egg has been released from the ovary, is abnormal in some way.

After releasing the egg, the follicle which contained it in the ovary goes on to become the “corpus luteum”.  The corpus luteum produces the hormone called progesterone.  Progesterone is essential for preparing the lining of the womb to implant the fertilized egg in uterus, and for continue the pregnancy for several weeks.

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.  Problems during this phase of the cycle are known as “Luteal phase defects”, and can be investigated either by carefully examining samples from the lining of the womb which is called endometrial biopsy) or by monitoring the progesterone output by taking a number of blood samples on different days after ovulation so that the progesterone level in them can be measured. Problems in the luteal phase may also occur as a result of abnormal levels of the hormone prolactin.

Treatment of unexplained infertility

  • Treatment with intrauterine insemination (IUI) alone did not raise this conception rate significantly.
  • Treatment of unexplained infertility with Clomid plus IUI increases chance of conception per cycle.
  • Treatment with gonadotropin injections + IUI raises the conception rate even further to 17 percent per treatment cycle.
  • Lastly, in vitro fertilization (IVF) conception rates for unexplained infertility are typically among a center's highest, usually at least 50 percent with the transfer of two embryos.

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