infertility

infertility may be primary or secondary. Primary infertility is when no pregnancy has ever occurred. Secondary infertility is when there have been one or more pregnancies but a further pregnancy has proved impossible. It has been estimated that the chances of conception for a given couple having regular sexual intercourse without any contraception are 80% and 90% after 12 months and 18 months respectively. It is therefore usual to begin investigations after one year. At this time some problems may be discovered and it should be possible, the basic tests having been done, to offer a realistic prognosis and a possible treatment outline. It is important to discover if there are any obvious abnormalities because with the new methods of treatment that have become available over the last twenty years it is frequently possible to offer real hope of success.

Female physiology

The Fallopian tubes lead from the ovaries, where the eggs are made, to the uterus. Each month, around 12–14 days from the last menstrual period, an egg (ovum) is released from the ovary. The ovum passes down the tube and its passage is facilitated by the moving cilia of the lining cells, which waft the ovum along. If intercourse occurs around this time the sperm swims up through the uterus to the tube and one of them joins the egg in the tube. The fertilized egg then continues down the tube to the uterus which has been prepared by hormones to receive the egg.

Causes of infertility

Unexplained	27%
Male factor	24%
Anovulation	21%
Tubal factors	14%
Endometriosis	6%
Sexual dysfunction	6%
Mucus hostility	3%

Unexplained infertility

is not easy to define. The more investigations that a clinic is able to perform the lower is the incidence of unexplained infertility. Hopefully some time in the future all will be explained.

Male infertility

It is not always recognized how commonly the male partner is the infertile one. The average amount of seminal fluid ejaculated each time is 2–5 ml. Persistent low volume may indicate an abnormality. If the number of sperm is less than 10 million/ml this makes fertilization less likely. The mobility of the sperm is also a factor, as is the ability of the sperm to penetrate the egg. These factors can all be tested in the laboratory. An important cause of reduced sperm numbers is a history of mumps, as the testicles are damaged in some cases.

Anovulation

means that for some reason no ovum is produced in each menstrual cycle.

Tubal factors

The main tubal factor is blockage, which may result from infection from sexually transmitted disease or a previous miscarriage. The blockage prevents the union of sperm and ovum so that no pregnancy occurs. Sometimes, although the tube may not be blocked, the cilia, which assist the passage of the ovum down the tube, are damaged so that the ovum gets stuck in the tube and union with the sperm does not occur. Sometimes the sperm does manage to fertilize the stuck egg and this results in a pregnancy occurring in the tube — an ectopic pregnancy. As this pregnancy grows the tube may rupture, with serious consequences due to bleeding into the abdominal cavity.

Endometriosis

is a condition where, for unknown reasons, portions of the lining of the uterus grow in other parts of the pelvis such as the ovaries. The reason why this causes infertility is not clear.

Sexual dysfunction

occurs sometimes due to psychological factors that prevent proper intercourse.

Mucus hostility

means that the secretion from the neck of the womb (cervix) is abnormal, and kills the sperm so that they cannot travel through the uterus to the tubes.

Investigations

At an infertility clinic both partners are given a full physical examination and a detailed medical history is taken.

In the male a good proportion of infertility is due to deficiencies in semen, so a proper seminal examination is essential. This involves measurement of the volume of the ejaculate — the sperm count — which should be 20 million/ml or more; the swimming ability of the sperm; and the numbers of abnormal forms present. A history of mumps or sexually transmitted disease or genital trauma are important, as are previous hernia operations. A social history of drug and alcohol intake may be relevant, as may occupations involving working at extremes of temperature or at altitude. Physical examinations may reveal some testicular or penile abnormality.

There is still controversy as to what constitutes normal semen. With modern methods of assisted reproduction many men with very low sperm counts can produce enough sperm which can be used to fertilize eggs ‘in vitro’ (IVF). Our ideas as to what constitutes an infertile male have radically altered in the last twenty years.

In the case of the female partner the occurrence of ovulation can be tested by Basal Body Temperature measurement (the temperature rises 1 degree following ovulation in the second half of the menstrual cycle) and by measurement of the female hormones, oestrogen and progesterone. The use of ultrasound can visualize the ovum in the ovary, and taking a sample of the lining of the uterus can show whether or not the uterus is being prepared properly in each cycle for reception of a fertilized ovum. Assessment of the state of the tubes can be achieved by injecting dye through the cervix. This fills the uterine cavity, and, with the use of a small telescope (laparoscope) inserted into the abdomen, dye will be seen flowing from the tubal opening at the ovary if the tube is patent. If no dye is seen the tube is blocked. A newer method, falloscopy, involves the introduction of a tiny telescope (falloscope) into the tube through the tubal opening in the uterus and allows evaluation of the state of the tubal lining — so important for the transport of the egg. The mucus at the cervix can be sampled and tested to see if it kills sperm; if it does, there are methods of avoiding this.

A small telescope (hysteroscope) can also be used to examine the inside of the uterus to see if there any abnormalities of shape and to exclude the presence of tumours. All these tests are available at properly equipped infertility centres.

A history of pelvic infection may be relevant — perhaps after a miscarriage or previous abdominal operation, or due to sexually transmitted disease. An abnormal menstrual history may suggest a hormonal disturbance. Previous use of hormonal contraception (the Pill) can result in anovulation, and use of the intrauterine device can cause infection and blocked tubes.

The success of infertility treatment varies enormously depending on the cause. In the most favourable cases treatment may be 90% successful. In cases it may be quite unsuccessful. Nowadays, with proper investigation and treatment the results are incomparably better than a quarter of a century ago.

Malcolm Macnaughton

See also assisted reproduction; fertility; impotence; menstrual cycle; ovum; pregnancy; testis.