Uterine fibroids

What are Fibroids?

Fibroids are the most common benign (non-cancerous) tumour in women, affecting up to 60% of women by the time they reach the age of 40. Fibroids can vary in size, number and location. Each fibroid grows from a single cell and is stimulated by the female hormone oestrogen, continuing to grow under the influence of oestrogen until the menopause when they slowly start to shrink back. Fibroids can be more likely if a family member is also known to be affected.

Fibroids can often cause no symptoms, but in some patients they may. These can include:

  • Heavy menstrual bleeding (menorrhagia)
  • Miscarriage
  • Infertility
  • Abdominal pain and distention
  • Increased urinary frequency due to pressure on the bladder

Fibroids and Infertility

Women with fibroids are 50% less likely to conceive naturally than women without fibroids. The size, location and number of fibroids can all increase the effect on infertility, and the type of fibroids that have the greatest effect are ones that distort the uterine cavity (known as submucosal fibroids).

There are several theories why fibroids decrease fertility; these include:

  • They cause abnormal uterine contractions which affect the transport of the sperm and early embryo.
  • They prevent the implantation of the embryo in the uterine cavity because they cause the lining to be abnormal and distorted.
  • They disrupt the blood flow to the embryo during the early stages of development and cause general alterations in the blood supply to the uterus.
  • They press on the fallopian tubes causing a blockage and preventing the sperm from reaching the egg for fertilisation.