Uterine fibroids (leiomyomas) !
Uterine fibroids are common non-cancerous growths of the uterine muscle; many cause no symptoms, others cause heavy periods, pelvic pressure or infertility.
Updated 2026-10-29
Structures involved
Tap one to see what it is and open it in 3D.
In biochemistry
In histology
In the clinical exam
Why it happens
- Naming tumours: -oma, carcinoma, sarcoma, and the misleading names
- Benign vs malignant tumours: the comparison table
- Actions of estrogen and progesterone
- Smooth muscle
What it is
Benign smooth-muscle tumours of the myometrium (leiomyomas), the most common pelvic tumour in women of reproductive age. Many cause no symptoms; others cause heavy menstrual bleeding, pelvic pressure or fertility problems.
Who gets it
Very common and more frequent with age during the reproductive years, and earlier and larger in women of African descent. Often found by chance on ultrasound. Worldwide they are a leading reason for hysterectomy; they usually shrink after menopause.
Causes
- Clonal growth from a single smooth-muscle cell of the myometrium
- Somatic gene changes (MED12 mutations are the most frequent)
- Growth driven by oestrogen and progesterone
- Excess extracellular matrix gives the firm, whorled texture
Risk factors
- Increasing age before menopause
- African descent
- Early menarche
- Nulliparity
- Obesity
- Family history of fibroids
Pathophysiology
Fibroids are well-defined, hormone-responsive masses with a pseudocapsule. Submucosal fibroids distort the cavity, enlarge the bleeding surface and impair contraction, so periods become heavy. Large fibroids press on the bladder, rectum or ureters. Outgrowing their blood supply, they can degenerate and cause acute pain (red degeneration in pregnancy).
Classification
- FIGO type 0: pedunculated, entirely inside the cavity (submucosal)
- FIGO types 1–2: submucosal, with less than half (1) or at least half (2) of the fibroid in the wall
- FIGO types 3–4: intramural; type 3 touches the endometrium, type 4 lies entirely in the wall
- FIGO types 5–7: subserosal; type 7 is pedunculated on the outer surface
- FIGO type 8: other sites (cervical, parasitic); hybrid fibroids are written as two numbers, e.g. 2–5
Symptoms and signs
- Heavy or prolonged menstrual bleeding
- Tiredness, pallor and breathlessness from iron-deficiency anaemia
- Pelvic pressure, bloating, a palpable mass; enlarged, firm, irregular uterus on exam
- Urinary frequency or retention, constipation
- Pelvic pain, painful periods (dysmenorrhoea) or dyspareunia
- Subfertility or pregnancy loss, mainly with submucosal fibroids; many have no symptoms
Diagnosis
- Clinical
- History of the bleeding pattern and bimanual exam: an enlarged, firm, irregular uterus.
- Tests
- Pregnancy test; full blood count and ferritin for anaemia; endometrial sampling when there is a risk of endometrial hyperplasia or cancer.
- Imaging
- Pelvic ultrasound (transvaginal and abdominal) first; saline infusion sonography or hysteroscopy to map submucosal fibroids; MRI before surgery or embolisation.
Differential diagnosis
- Adenomyosis
- Endometrial polyp
- Endometrial hyperplasia or cancer
- Uterine sarcoma (leiomyosarcoma)
- Ovarian mass
- Pregnancy
Goal of treatment
Control bleeding and correct anaemia, relieve pressure symptoms and protect fertility when desired. Fibroids without symptoms usually need only observation.
Treatment
- Follow-up
- Watchful waiting with periodic review for fibroids that cause no symptoms; they often shrink after menopause.
- Medical
- Bleeding control with antifibrinolytics or NSAIDs, and hormonal options such as a progestin-releasing intrauterine system or combined hormonal contraceptives; iron replacement for anaemia.
- Medical
- GnRH agonists or oral GnRH antagonists (often with add-back hormone therapy) reduce bleeding and size, for example before surgery; other hormonal agents vary by country.
- Procedure
- Uterine artery embolisation by interventional radiology; image-guided ablation (radiofrequency or focused ultrasound) in selected centres.
- Surgical
- Myomectomy when fertility is to be kept (hysteroscopic for types 0–2, laparoscopic or open for others); hysterectomy as definitive treatment when childbearing is complete.
Drugs for this condition
Complications
- Iron-deficiency anaemia
- Infertility or recurrent pregnancy loss
- In pregnancy: painful red degeneration, malpresentation, preterm birth, postpartum haemorrhage
- Urinary retention or hydronephrosis
- Torsion of a pedunculated fibroid
- Recurrence after myomectomy
Prognosis
Benign. Malignant change is very rare; leiomyosarcoma is regarded as a separate tumour. Symptoms usually ease after menopause, and new fibroids often appear after myomectomy.
Test yourself
Think of the answer, then tap the question to see it.
Which FIGO type of fibroid hangs on a stalk entirely inside the uterine cavity?
FIGO type 0: a pedunculated submucosal fibroid.
Which fibroid location is most linked to heavy bleeding and subfertility?
Submucosal fibroids (FIGO types 0–2), because they distort the uterine cavity.
What is red degeneration of a fibroid?
Haemorrhagic infarction of a fibroid, typically in pregnancy, causing acute pain and sometimes low-grade fever.
What is the first-line imaging test for suspected fibroids?
Pelvic ultrasound, ideally transvaginal.
Which operation removes fibroids while keeping the uterus?
Myomectomy: hysteroscopic for submucosal fibroids, laparoscopic or open for the rest.
Related conditions
- Endometriosis
- Postpartum haemorrhage
- Miscarriage (early pregnancy loss)
- Iron deficiency anaemia
- Adenomyosis
- Abnormal uterine bleeding
- Dysmenorrhoea
- Molar pregnancy (hydatidiform mole)
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Uterine Leiomyomata (StatPearls (NCBI Bookshelf), 2025).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.
