Uterine Fibroids on Ultrasound — What a Scan Shows

Are fibroids sexually transmitted? No. Fibroids are not an infection and cannot be passed between people in any way. They are growths of your own uterine muscle, driven largely by hormones and genetics. Chlamydia and other sexually transmitted infections do not cause fibroids — that is a completely separate condition affecting different tissue, covered in our guide to pelvic infection. Nothing about having fibroids says anything about your sexual history.

Are fibroids cancerous? Almost never. Fibroids are benign, and having them does not raise your risk of developing cancer of the womb. A malignant muscle tumour of the uterus does exist but is genuinely rare, and rapid growth — particularly after menopause — is the feature that prompts closer assessment. If a scan raises that question, you will be referred rather than watched.

Did I cause them? No. Fibroids are not caused by diet, stress, contraception, or anything you did or failed to do. Risk is influenced by age, family history, ethnicity and hormonal factors — none of which is a choice.

Yes, occasionally — and since people search for exactly this, here is the honest picture rather than a reassuring one.

Very small fibroids may not be resolved, particularly a few millimetres across. A womb already enlarged by multiple fibroids can be difficult to assess completely, because the larger ones obscure what lies behind them — and counting becomes approximate. Scanning route matters: a transvaginal scan sees the cavity and smaller fibroids far better than scanning through the abdomen, while a very large fibroid uterus may actually need the abdominal view to capture its full extent. Both are often used together.

Submucosal fibroids are the ones where certainty matters most, because they drive bleeding and fertility problems — and they are also the ones where a standard scan can under-call the extent to which a fibroid indents the cavity. Where that distinction changes management, a saline infusion scan, hysteroscopy or MRI may be arranged through a gynaecologist. MRI is also used for surgical planning, where precise mapping is needed.

If your symptoms and your scan do not match — heavy bleeding with a scan reported as normal, for instance — that mismatch is worth raising with your GP rather than accepting. Other conditions, including other causes of heavy periods, may be responsible.

When to scan. There is no strict rule, but scanning in the first half of the cycle, soon after a period, generally gives the clearest view of the cavity when the lining is thin — useful when submucosal fibroids are the question. For simply confirming and measuring fibroids, timing matters much less.

Monitoring. Many fibroids need nothing more than periodic measurement to check they are stable, using consistent technique so that comparisons mean something. Our guide to monitoring fibroids covers how that works in practice.

Treatment is decided by symptoms rather than by the presence of fibroids, and is arranged through your GP or a gynaecologist. Options range from medication controlling bleeding, through procedures such as uterine artery embolisation, to surgical removal of fibroids or of the womb. Asymptomatic fibroids generally need no treatment at all — and a scan finding them is not, by itself, a reason to do anything.