In order to investigate the cause of infertility, a detailed history taking and physical examination is first carried out. A number of investigations are then performed. The most common causes of infertility are:

Ovulation Disorders

At least 20% of cases are due to an ovulatory problem. As mentioned in the Fertility / Infertility section, for a pregnancy to occur, it is necessary for the ovary to produce an oocyte (egg). In most women, one egg is released from the ovary each month, usually between the 13th and 15th day of a 28 day cycle. The cycle length is calculated by counting from the first day of menstrual bleeding in one month to the first day of the next episode of bleeding. Usually this will be from 25-35 days, but if the cycle is longer than this, or very irregular, then this suggests that there may be a problem with ovulation.

Apart from the regularity of the menstrual cycle, other factors suggest that ovulation is occurring normally. These include lower abdominal pain and an increase in the amount of cervical mucus around the expected time of ovulation. However, these are not sensitive predictors of ovulation, and frequently other methods are used to be sure that ovulation is normal.

The most accurate test to confirm that ovulation has taken place is a blood test taken after the expected time of ovulation (mid-luteal phase progesterone). A basal body temperature (BBT) chart may also be used as a retrospective check on ovulation, but this is not as sensitive as a progesterone assay. Further blood tests including the measurement of levels of hormones (FSH, LH, E2) and other factors (e.g. thyroid hormone and prolactin) may be necessary if an ovulation problem is suspected. Ultrasound of the female pelvis may also be needed. On ultrasound, the uterus and ovaries are seen clearly, and the growth of the egg-containing follicles can be measured.

Some of the common causes of ovulation problems include:

• Polycystic Ovarian Syndrome (PCOS, where the female partner may have infrequent menstruation, increased body weight and/or body hair, many small follicles in the ovaries and abnormal hormone levels or abnormal blood sugar or insulin levels)
• hyperprolactinaemia (where the breast milk secreting hormone is abnormally high - this can be due to a small benign hormone-secreting tumor in the pituitary gland)
• extremes of body weight
• stress
• premature failure of the ovaries

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Semen Abnormalities

Male problems account for up to 30% of infertility. The major problems include defects in sperm production or failure of sperm transport. The sperms are produced in the testes, stored in the epididymis (coiled channels surrounding the testis), and then transported via the vas deferens during sexual intercourse. Factors including hereditary causes, smoking, alcohol, frequent saunas, varicose veins (congested veins) in the scrotum, undescended testes, genital tract surgery and infection may lead to sperm abnormalities. The male may produce a normal volume of fluid in the ejaculate, but microscopic examination may reveal a problem with the number of sperm produced, the motility of the sperm or in the number of sperm having a normal appearance.

As an initial investigation, the male partner will be asked to provide a semen sample for analysis. It is recommended that the couple abstain from intercourse for 2 days before the sample is collected. The sample is best analyzed in the laboratory within 60 minutes of production. The count, motility and normal appearance or shape of the sperm will be assessed (against World Health Organization (WHO) criteria). At least two abnormal semen analyses performed on separate occasions 3 months apart are necessary to make a firm diagnosis of male factor infertility.

In some cases, further investigations including hormonal tests, microbiological assessment of the semen and imaging of the male genital tract may be indicated. In addition, genetic evaluation may be advised for some infertile men who have a severe sperm abnormality. Some men have abnormalities in the number of chromosomes (karyotype) or abnormalities in the structure of the male chromosome (Y-chromosome microdeletion). These genetic tests are often advised in men with a sperm count of less than 5 million per mL.

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Tubal Damage / Obstruction

20-25% of cases of infertility are associated with tubal problems. Fallopian tubes may be damaged by previous pelvic infection or surgery, ectopic pregnancy or endometriosis. Silent pelvic infection is also not uncommon. Women may develop blocked tubes without having had a history of any past illness.

The methods to assess tubal- peritoneal problem are hysterosalpingogram (HSG), laparoscopy with dye study or sonohysterography. An HSG may be used for assessment of tubal patency in patients at low risk of tubal disease. However, laparoscopy with dye study is the preferred work-up particularly when there is a strong suspicion of peritoneal pathology such as pelvic adhesions or endometriosis.

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Endometriosis

15% of cases of infertility are due to endometriosis. Endometriosis is a condition where the tissue that makes up the uterine inner lining is present in places outside of the uterine cavity. Although woman with endometriosis may feel pain during menstruation (dysmenorrhoea) or sexual intercourse (dyspareunia) , some women have no symptoms at all. The exact cause of this condition is unclear. In its least serious form, it appears as a few darks spots lying on the surface of the pelvis in areas adjacent to the uterus. When the disease is more advanced, ovarian cysts (endometrioma or chocolate cyst) containing chocolate like material may be present, and adhesions may form in the pelvis. In its mild form, no one is sure exactly how the disease causes infertility. It may be due to a problem of the fallopian tube picking up the egg and transporting the eggs or sperm down the tube, or there may be a hormonal type effect. When endometriosis is severe, there may be adhesions in the pelvis which prevent the fallopian tube from collecting the egg at the time of ovulation. Endometriosis can only be seen on laparoscopy. Ultrasound is unable to pick up endometriosis unless there is an ovarian endometrioma.

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Unexplained Infertility

While one third of couples may have more than one cause of infertility, about 10% of couples does not have any obvious cause and all investigations are normal. This is known as unexplained infertility. In young women with unexplained infertility of less than 3 years of duration, a spontaneous pregnancy rate of up to 60% is observed even without treatment. However, if the couple is still unable to conceive after 3 years, the spontaneous conception rates drop significantly to less than 10% per year.

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Other Causes

Coital problems, immunological problems (such as the presence of antisperm antibodies in the cervical mucus) or congenital abnormalities of the uterus (womb) are other uncommon causes that may also contribute to infertility. Congenital uterine anomalies are usually diagnosed using a hysterosalpingogram (HSG) or a hysteroscopy.

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