Fibroids: what they are, how they are found and when they need treatment

What fibroids are, and where in the womb they grow

Fibroids are benign (non-cancerous) lumps of muscle and fibrous tissue that grow in the wall of the womb (uterus). There may be one or several, from a few millimetres to many centimetres across.

Where a fibroid sits shapes its symptoms. Some grow within the muscle wall, some bulge outwards from the surface of the womb, occasionally on a stalk, and some push into the cavity where the lining sheds each month; these are the type most linked with heavy bleeding and difficulty conceiving.

Fibroids depend on the hormones oestrogen and progesterone, so they appear during the years of periods and usually become smaller after the menopause. Their cause is not fully understood; they become more common with age and often run in families.

The symptoms fibroids can cause, and why many women have none

Fibroids often cause no symptoms at all and come to light by chance on a scan. When they do cause trouble, it is usually one of these:

• Heavy or long periods, sometimes with clots or flooding, which can lead to anaemia and leave you tired or short of breath.
• Pressure from a larger fibroid: passing urine often, constipation, a swollen tummy or a feeling of fullness low in the pelvis.
• Pain in the pelvis or lower back, or pain during sex.

Many women with fibroids conceive without difficulty. Fibroids that distort the cavity are linked with difficulty conceiving and with miscarriage, so their position matters when a pregnancy is planned. In pregnancy they usually cause no problems, though one can become painful, and a large or low-lying fibroid can affect the baby’s position or the birth plan.

Bleeding between periods, after sex or after the menopause is not typical of fibroids and needs checking in its own right.

How fibroids are found: examination and scans

A larger fibroid can sometimes be felt during an examination, but the main test is an ultrasound scan, which shows how many fibroids there are, their size and where they sit.

The scan is often done over the tummy and with a slim probe in the vagina. If an internal scan is not suitable for you, for example if you have not been sexually active, say so; a scan over the tummy is used instead.

If a fibroid may be inside the cavity, hysteroscopy, in which a fine telescope is passed through the cervix, can look at it directly. A blood count checks for anaemia.

Why many fibroids need no treatment, and what comes before surgery

Fibroids that cause no symptoms, or symptoms that do not bother you, usually need no treatment, though a repeat scan may be suggested. Since fibroids generally get smaller after the menopause, women nearing it sometimes choose to wait.

When fibroids cause heavy periods, NICE guidance puts medicines and other non-surgical options ahead of surgery for most women. For smaller fibroids that leave the cavity’s shape unchanged, the usual heavy-period medicines apply: a hormonal coil, tranexamic acid or anti-inflammatory painkillers during the period, the combined pill or progestogen tablets. Side effects include irregular spotting with hormonal treatments and stomach upset with painkillers.

Medicines that lower hormone levels for a time, such as GnRH analogues, can shrink fibroids and reduce bleeding. Because they cause menopause-like effects such as hot flushes and, with longer use, bone thinning, they are often given for a limited period, for example before an operation. Fibroids tend to grow again once they stop.

Procedures and operations for fibroids, and their risks

If medicines have not helped enough or you prefer not to take them, other treatments are considered. The choice depends on your symptoms, the size, number and position of the fibroids, whether you want to keep your womb or have a pregnancy, and how you weigh the risks:

• Hysteroscopic removal: fibroids inside the cavity are removed through the cervix, with no cut on the tummy. Risks include bleeding, infection and, rarely, damage to the womb wall or absorption of too much of the fluid used during the procedure.
• Uterine artery embolisation: through a thin tube in an artery in the groin or wrist, a radiologist blocks the fibroids’ blood supply with tiny particles so they shrink, keeping the womb. Pain in the following days is common; risks include infection, discharge and, occasionally, an earlier menopause, and less is known about pregnancy afterwards.
• Myomectomy, removing the fibroids but keeping the womb, by keyhole or open surgery: risks include heavy bleeding needing a transfusion, infection and scar tissue, and rarely the womb has to be removed to stop the bleeding. Fibroids can grow again, and the scar is considered when planning a later birth.
• Hysterectomy, removing the womb: periods and fibroid bleeding stop, and it ends the possibility of pregnancy. It is major surgery, with risks including bleeding, infection, bladder or bowel injury and blood clots.