Eighty per cent of female sterility cases are due mainly to these causes:
- Advanced age: as previously mentioned, we know that from 35 years of age the reproductive potential drops and that after 40 years of age the possibility of pregnancy per month is less than 10%.
- Tubo-peritoneal Factor: when the Fallopian Tubes have any kind of lesion.
- Anovulation: when the ovum is not released by the ovary, whether because it was not fully formed or because it is not mature enough. Polycystic Ovary Syndrome patients are included in this group.
- Endometriosis: when the uterine tissue is outside the uterus.
- Other risk factors: Myomas. Sexually transmitted diseases. Chronic diseases such as diabetes, cancer, thyroid disease, asthma or depression. Intake of medication such as antidepressants or steroids. Obesity with a Body Mass Index > 30 or underweight by over 25%.
Problems with ovulation are the most frequent cause for female infertility (25%) and are produced as a consequence of hormonal imbalances or the incorrect development of the ovaries. It is one of the causes for sterility with the best prognosis, once the diagnosis and treatment are established. Approximately 35% of women experience anovulation at some time during their lives. The origin for this hormonal disorder may be in the hypothalamus, pituitary gland, or in the ovary itself. Among the determining factors for this situation are: stress, significant weight gain or loss, excessive production of prolactin (the hormone responsible for producing breast milk) and polycystic ovaries, which are particularly important due to their complexity and frequency.
There is a strong relationship between endometriosis and sterility, because 10% of women suffer from it and 35% of sterile women have it.
Endometriosis appears when the tissue that normally lines the uterus appears in other organs: ovaries, Fallopian tubes, bowel, bladder, peritoneum and, sometimes, in organs further away such as the lungs. It can affect all menstruating women, even the youngest.
It is important to highlight that most women suffering from endometriosis have symptoms such as increasingly painful menstruation (dysmenorrhoea) which generally does not respond to the usual treatment, menstruations that are abnormal in intensity (whether heavy or light), sterility and pain during sexual intercourse (coitalgia). It can also cause blood cysts in the ovaries, also called chocolate cysts because of their brownish appearance.
Diagnosis can be made only by means of direct visualisation of the lesions, which in some cases are very small in size, and they can be identified only by means of laparoscopy.
It is not clear why slight to moderate endometriosis is associated with sterility, but it has been suggested that the effect on the tubes’ functionality is caused by the inflammatory and wound-healing component of the endometrial tissue. However, the presence of a family hereditary factor and the possibility of poor oocyte quality are also common.
Surgical treatment by laparoscopy (diathermy/argon/exeresis) improves the patient's fertility. This is not the case in the use of medication, which is more useful for the treatment of pain.
About 20% of women have polycystic ovaries (PCO). The term PCO refers to the appearance of the ovary in ultrasound scans, because an increase in the number of small cysts (antral follicles) on the ovary surface can be observed. However, there are a great many women with PCO who have no problems in ovulating and getting pregnant.
However, some women who have this characteristic ultrasound scan pattern also have the condition known as Polycystic Ovarian Syndrome (PCOS). In these women, the hormonal disorder causes irregular menstrual cycles or even a lack of menstruation (amenorrhoea); therefore they will have problems in getting pregnant, due to their lack of ovulation. To better understand the process, we must consider that a normal woman usually experiences ovulation 12 times a year. If menstruation appears every three months, in theory there will be only four ovulations a year, and even though menstruation occurs, there may often be anovulation, so this problem will probably appear throughout the year.
The first step for treatment normally involves restoring normal weight and doing physical exercise, if it is associated with being overweight or hypertension. If normalisation of menstrual cycles and ovulation is not achieved, the next step is medical treatment to normalise the hormonal functions and stimulate ovulation. Ovarian drilling (making small holes in the ovary surface by using heat or laser) may also be considered to improve the ovarian hormonal microenvironment. In our group, this is considered to be the last option; the IVF cycles are considered first.
Around 25% of female sterility cases are due to a tubal factor, meaning a disorder of the Fallopian tubes. In normal conditions, the tubes behave like a fishing rod, picking up the ovum released during ovulation, transporting spermatozoa towards the ovum and carrying the already fertilized ovum to the uterus. Damage to the tubes, whether partial because of an adherence or complete (tubal obstruction), will prevent this transfer and therefore fertilisation will not occur.
Tubal damage can occur due to infections rising from the uterine cervix or uterus towards the tubes (Pelvic Inflammatory Disease, PID), or else per continuum from the abdominal cavity, e.g. an appendicitis. The germs most frequently involved in PID are Gonorrhoea, Chlamydia and other pathogens that produce an inflammatory reaction causing an anomalous wound-healing which prevents the proper functioning of the tubes. It is estimated that, with one episode of acute pelvic disease, there will be a 30% chance of sterility. With two, there will be 50%, and with three, up to 70%.
Another type of factor causing tubal blockage is previous pelvic surgery, which may have produced adherences on the tubes or endometriosis.
Besides the impossibility of pregnancy, the tubo-peritoneal factor is frequently related to ectopic pregnancy, which is when the embryo does not reach the uterine cavity due to alterations in the diameter and the inside of the tube which prevents it from being transported appropriately.
If liquid builds up in the tube (hydrosalpinx), this becomes a potential source for chronic infections. Hydrosalpinx exeresis is recommended before carrying out an IVF cycle, because the liquid can also be detrimental to embryo implantation.
The most effective reproductive treatment, more than tubal microsurgery, is complex ART techniques such as IVF/ICSI.