Subserosal fibroids

Fibroids are non-cancerous growths that develop in or around the uterus (womb). Also known as myomas, leiomyomas or fibromas, they can occur singly or in large numbers. Fibroids are made up of muscle and fibrous tissues and vary in size – they can be as small as an apple pip, or as large as a grapefruit. There are different kinds, depending on where they are located.

  • intramural fibroids develop in the muscle wall of the uterus and are the most common type of fibroid
  • subserosal fibroids develop outside the uterus wall into the pelvis
  • submucosal fibroids develop in the muscle layer of the uterus and grow into the uterus
  • pedunculated fibroids are subserosal or submucosal fibroids which are attached to the womb with a narrow stalk of tissue

How common are fibroids?

Fibroids affect around 1 in 3 women during their life and are the most common non-cancerous tumours in women of childbearing age[1]Patient Info. Fibroids. Last accesses 2 Aug 17 Women are not always aware of them, with up to 25% of women being clinically diagnosed.9

They most commonly occur in women between the ages of 30-50, of Afro-Caribbean origin and in those who are overweight or obese. If you are extremely overweight, your risk of developing them is three times higher than average. Hereditary also plays a role. If your mother had fibroids, your risk of getting them is three times higher than average.

The good news is that the number of children you have decreases the risk of developing fibroids, with more children meaning a lower risk.


The exact cause of fibroids is not entirely clear. Hormones are known to play a part: the higher hormone levels, the faster they grow. They shrink during the menopause and/or if you take anti-hormone medication.


In general, fibroids are not dangerous. However, they can cause symptoms such as pressure on the bladder, lower back pain, pain during sex, period pain, bleeding between periods, and heavy bleeding.

Fibroids can also affect fertility as they can stop fertilised eggs embedding into the womb, so making it harder for you to get pregnant. If you do manage to get pregnant multiple fibroids can:

  • block the vagina meaning a caesarean may be necessary to deliver the baby
  • increase the risk of miscarriage 

If your fibroids deteriorate during pregnancy, pain and premature labour can occur.

Do you think you have fibroids? Then contact your GP. Read about how to get the most out of your GP appointment here.