Tests on the woman
To begin it will be necessary to assess whether the woman is ovulating. Ovulation (the release of a mature egg from an ovary) ought to occur once in every menstrual cycle. Cycles may vary in length, normally lasting 26 to 30 days, although a longer or shorter cycle can still be ovulatory and therefore will not be a problem. Whatever the length of cycle, ovulation always occurs about 14 days before the start of the next menstruation. The couple may be asked to chart whether it occurs, by taking the woman’s temperature each morning as soon as she wakes. This is called basal body temperature (BBT) and it normally fluctuates from day to day. However, just before ovulation it will drop, and on ovulation it will rise by about 0.5°C. By carefully keeping a record of each morning’s temperature, after six months or so, the couple will be able to tell whether ovulation has occurred or not. If there is no such variation, or if it happens in only certain months, ovulation is not happening or is spasmodic. Another test for ovulation is to examine the mucus or natural fluids in the vagina. All women have secretions which are usually white in colour and of a viscous consistency. These act as a cervical plug to bar bacteria from the uterus and to act as a barrier to sperm at times in the month when their presence would be unnecessary. However, four days before ovulation, vaginal secretion changes, becoming thin and watery. If you placed a sample between your fingers and pulled them apart, the fluid would stretch between them. Microscopic channels are now formed in this mucus to encourage the passage of sperm rather than form a barrier. Under the microscope these channels can be seen to form patterns like those of a fern leaf, hence this test is also called the ‘fern test’.
To make sure that ovulation has occurred, the doctor may take a blood sample at this time and a week later. If the level of progesterone* is higher in the second sample, this would indicate not only that ovulation is occuring but also that the woman’s body is preparing to allow a fertilized egg to implant in her womb.
Tests on the man
The most important steps in the evaluation of maleare examination of the semen and of a specimen of the tissue of the testes. The first of these is commonly known as a ‘sperm count’, which is conducted in order to determine whether the man is producing viable sperm, although the actual number or concentration of sperm present is only one of the factors taken into consideration. Analysis of a semen sample not more than a few hours old assesses the number of sperm per millilitre of semen, the total volume of the ejaculate, the consistency of the fluid, the shape and appearance of the sperm, and their liveliness or ‘motility’. Normal limits are wide and a combination of factors is used to indicate sub , including: a total volume of less than one millilitre of semen, less than 40 per cent total motility, less than 60 per cent normal in form, and less than 20 million sperm per millilitre of semen. Obviously, a combination of negative factors offers less hope for the man’s .
For comparison, approximate figures for an average ejaculate are a volume of three millilitres, 30 to 40 million sperm per millilitre, not more than 25 per cent dead or immobile, and 10 per cent misshapen with two heads or twin tails.
Obviously, the lower the proportion of viable sperm, the slighter the chance of a pregnancy.
In addition to the above, especially when the results of these seem to be normal, observation is also made of thyroid, adrenal and pituitary function.
The couple may be asked to co-operate in a postcoital test. In this, the woman reports for a vaginal examination within a few hours of having had intercourse, and without disturbing the semen within her. A sample of the mucus plugging the cervix will reveal whether her mucus is acting as a barrier, whether her partner’s sperm are motile enough, or even whether the chemical balance within her vagina acts as a natural spermicide and kills her partner’s sperm.