A WOMAN’S GENITALS: THE UTERUS
The uterus is a pear-shaped, muscular organ about three inches long and two inches across at its widest part (the fundus). The pointed part of the pear shape points down into the top of the vagina and the body of the ‘pear’ lies above the vagina in the pelvis. In most women the uterus is angled slightly forwards but in about 20 per cent it is tipped backwards (retroverted). It used to be thought that women with retroverted uteri were more likely to be infertile but this is now known not to be so.
The uterus has a cavity lined with a special type of cellular tissue called endometrium. The narrow canal leading from the vagina to the cavity through the cervix is normally plugged up with mucus. Suffice it to say on this subject that when a woman is most likely to conceive (around the time of ovulation) her cervical mucus is most encouraging to sperms and that when this mechanism fails in some way, her partner’s sperms, however plentiful, may not get past the cervical mucus barrier.
At the sides of the top of the wide end of the uterus two tubes enter. These are the fallopian tubes that run from the ovaries to the uterus. Each fallopian tube is about four inches long and is thinner than the lead in a pencil. The tubes have very muscular walls lined with hair-like projections. Both walls and projections move in such a way as to waft ova (eggs) progressively along from the ovaries to the uterus. Cells lining the tubes produce substances that alter sperms so that they can fertilise an egg—indeed, fertilisation of an egg by a sperm occurs in one or other of the fallopian tubes. The open ends of the tubes are a collection apparatus which ensures that eggs are caught and channelled down into the fallopian tubes. There are numerous nervous, hormonal and chemical mechanisms at work in normal fallopian-tube functioning and we still know very little about exactly what goes on. But just as the structure and physiology of the fallopian tubes is vital to the downward passage of an egg, it is also important for the upward progress of the sperms. For one of many possible reasons an egg may remain in a fallopian tube once fertilised and the pregnancy develops there. This is called a tubal or ectopic pregnancy. An operation is needed at which the affected tube and the foetus are removed though surgeons try if possible to conserve the affected tube.
Perhaps the commonest condition affecting the uterus that we should consider in an article such as this is uterine fibroids. Although no one knows what causes them about one in five women suffer from them, even though they may not be aware of them. Common problems include heavy periods including flooding; painful periods; and infertility. The anaemia that the heavy periods cause may have to be treated, and operations include removing the fibroids themselves or even the whole uterus. Sometimes nothing need be done except to watch what happens over some months.
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