Infertility - Introduction

Pre-pregnancy advice

Normal Conception

Infertility Investigations

Causes And Management Of Infertility

Investigations need to be aimed at the basic functions necessary to conceive

1. Ovulation
2. Egg pick-up and transport along the fallopian tubes
3. Sperm production
4. Sperm delivery to the cervix by sexual intercourse at the right time, just before ovulation
5. Sperm penetration of and survival in receptive cervical mucus

The subsequent steps of fertilisation and implantation are generally out of reach of routine testing, except when necessary for in vitro fertilisation treatment (IVF or the "test-tube" method). Abnormalities of the uterus causing implantation failure are fortunately very uncommon. Although IVF treatment fails mostly at the stage of implantation, the cause seems to be due primarily to imperfect quality of the embryo, and of the egg or sperm in the first place (even though fertilisation occurred).

The term ovulation implies release of an egg from its growing fluid-filled follicle in the ovary. But the egg also needs to be fully mature, and that is directly related to the maturity of the growing follicle, which is reflected by the amount of hormones it produces: oestrogen before ovulation and progesterone afterwards. It is easiest to measure progesterone, about one week after ovulation, when it is at its peak.

The body temperature rises in response to progesterone and temperature charting each day has been the traditional test of ovulation, but is unreliable. That is partly because it can be difficult to interpret, and partly because it takes little rise in progesterone to induce the full rise in temperature that occurs after ovulation. The temperature reaches a plateau soon after it first goes up, but progesterone should keep on rising to much higher levels if there is a fully mature egg that is capable of leading to conception. A smaller rise shows the egg is not mature enough even though sufficient to shift the temperature.

It is important to appreciate that the timing of ovulation, and therefore the progesterone peak, is related to the following menstrual period, not to the last menstrual period. The normal time after ovulation to the following menstruation is about 2 weeks, therefore progesterone measurement must aim to be done about 7 days before the expected menstrual period. The traditional timing of the progesterone measurement on Day 21 (from the start of the menstrual cycle) is based on the average 28-day cycle, but is way out in a 35-day cycle (when it should be done on Day 28).

It is also important to appreciate, however, that the routine measurement of progesterone in women who have regular monthly menstrual cycles is of questionable value. Even if the levels are low in the first one or two cycles they will usually turn out to be normal in most cycles. Variation in the quality of ovulation between cycles is normal, and one has to test a lot of cycles to be sure of a persistent problem. Real, persistent ovulatory disorder causing infertility usually only occurs in women who have infrequent or absent menstrual periods, and they need special investigations of the cause.

Nevertheless, it is common practice to measure progesterone in 2 or 3 cycles because it is simple and seems reassuring. But remember: timing must be correct, and treatment is of no benefit unless a clearly persistent disorder is evident in many more cycles.

The passage of eggs is prevented by blockage of the fallopian tubes, but can also occur due to functional damage (i.e. preventing the tubes working) even if the tubes are open. The delicate fimbria may be damaged by inflammation and scarring, or the tubes may become fixed, interfering with picking up of the egg when it is released. Or the surface of the ovary may be obscured by adhesions (scar tissue, sometimes like curtains) preventing release of the egg to the tube.

X-ray pictures (called a hysterosalpingogram or HSG) can be taken after passing dye through the cervix to show up an outline of the inside of the uterus and tubes, but it cannot show adhesions outside the tubes and around the ovaries.

To see such adhesions and other conditions it is necessary to look directly using a narrow telescope passed through the umbilicus into the abdomen under anaesthetic (called laparoscopy). But that should not be done at an early stage of infertility unless there is a specific suggestion of likely damage. Such suggestion would come from a history of pelvic infection, complicated miscarriage or childbirth, abdominal conditions like appendicitis, and abdominal surgery. Also, a simple blood test for antibodies may suggest unsuspected infection in the past with Chlamydia, which is the commonest micro-organism causing sexually transmitted pelvic infection.

This is easily checked by laboratory counting of sperm numbers in a semen sample. Many sperm are abnormally formed or have lost their motility, and these must be excluded from the reckoning. Unfortunately sperm counting is only really useful if there is a severe defect and the counts are zero or extremely low, because it can tell little about sperm function (i.e. how they work), which is what really matters. Some men with normal sperm counts in semen are infertile, and some with low counts are fertile.

The first natural test of sperm function - before being able to reach and fertilise the egg - is for the sperms to escape from the seminal fluid and penetrate cervical mucus, and to survive there for 24 hours or more.

Mucus is not a simple fluid but a complex tissue network which sperms have to work hard to penetrate. Testing penetration of the mucus therefore tests similar characteristics of the sperm to those required for fertilisation (i.e. penetration of the egg). Many other and more complex tests can be undertaken but tests of sperm-mucus penetration are a good start.

The postcoital test (PCT) involves examining a small sample of cervical mucus under a microscope for the presence of swimming sperm about 12 hours after intercourse (coitus). The mucus is collected very simply, rather like cervical smear testing. It is of key importance, however, that the mucus is collected at the right time, as described below, or it will not be a proper test of either sperm or mucus.

Semen and mucus can also be collected separately and sperm penetration (or "invasion") tested in the laboratory. This is less relevant than the PCT for assessing natural fertility, but it can be useful in special circumstances, and is sometimes done first. Again, mucus timing is of key importance.

Mucus receptivity is also tested along with sperm function by the PCT or invasion test. But for these tests to be valid, for either the sperm or mucus, the mucus must be collected at the right time of the cycle, ideally one or two days before ovulation. That is when the mucus is at its best, stimulated by oestrogen hormone from the fully mature egg follicle. It is then most copious, stretchy, slippery and looks clear, just like the raw "white" of a hen's egg .

The mucus surge, just before ovulation, usually only lasts 2-3 days and most women can learn to recognise it themselves. It may be noticed without looking specially for it, or on a tissue wiped over the entrance to the vagina, or between two fingers introduced into the vagina and then opened and closed like a scissor action to gather the mucus. The mucus surge usually occurs 12-14 days from the start of the menstrual period in women with 28-day cycles, but earlier or later accordingly in women with shorter or longer cycles (as pointed out earlier in regard to the timing of ovulation).

See also:

• Infertility - Introduction
• Pre-pregnancy advice
• Normal Conception
• Fertility Investigations
• Causes And Management Of Infertility

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