Causes of unexplained infertility
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.
1.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.
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.
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.