What are fibroids

Uterine leiomyomata, often referred to as fibroids, are tumours of the uterus (womb). They are very common and can be asymptomatic. Fibroids tend to be multiple and can be situated inside the cavity of the uterus, in the wall or outside (see diagram). In some cases, they can grow to a very large size.

No one knows why they develop, but it is well established that the female hormone oestrogen makes them enlarge; this is why fibroids are usually diagnosed when women are in their 30's and 40's, and why they shrink after the menopause.