Uterine Fibroids (Leiomyomata) — Causes, Symptoms, Diagnosis & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Uterine fibroids (leiomyomata uteri, singular: leiomyoma) are benign monoclonal tumours arising from the smooth muscle cells (myocytes) of the uterine myometrium. They are the most common benign solid pelvic tumours in women — present in 70-80% of women by age 50, though only 25-50% cause significant symptoms requiring treatment. Despite their high prevalence, malignant transformation to leiomyosarcoma is extremely rare (estimated at 0.1-0.3% — and most studies suggest leiomyosarcoma arises de novo rather than from fibroids). Fibroids are classified by location within the uterine wall — a key determinant of symptoms: submucosal fibroids (beneath the endometrium — protruding into the uterine cavity — cause the most severe heavy menstrual bleeding and reproductive consequences despite being small); intramural fibroids (within the myometrial wall — most common — cause menorrhagia and bulk symptoms when large); and subserosal fibroids (on the outer uterine surface — predominantly cause pressure symptoms; when pedunculated, may undergo torsion). The FIGO leiomyoma classification (types 0-8) further categorises location precisely and guides treatment selection. Fibroids are oestrogen-dependent — they grow during reproductive years, enlarge during pregnancy, and typically regress after menopause. They are 2-3x more common, develop earlier, and are larger and more symptomatic in Black women — a significant racial health disparity requiring focused attention.

The exact initiating cause of fibroid development is incompletely understood, but genetic, hormonal, and local growth factor mechanisms all contribute. Genetic factors: 40-50% of fibroids have cytogenetic abnormalities — most commonly translocations involving HMGA2 (t(12;14)) and deletions of chromosome 7q. MED12 mutations (in approximately 70% of fibroids) and HMGA2 rearrangements drive the clonal expansion of a single myocyte into a fibroid. Hormonal dependency: fibroids express oestrogen receptor-alpha and progesterone receptor at higher levels than adjacent normal myometrium. Oestrogen promotes fibroid growth (fibroids rarely develop before menarche and always regress after menopause — hence GnRH analogues causing medical menopause shrink fibroids); progesterone drives fibroid proliferation in the luteal phase. Insulin-like growth factor (IGF-1) and transforming growth factor beta (TGF-beta) promote fibroid cell growth and extracellular matrix deposition. Risk factors for fibroid development: Black race (2-3x higher risk, earlier onset, larger fibroids — possibly related to genetic variants, hormonal differences, higher BMI rates, and chronic stress); early menarche (before age 10); nulliparity (pregnancy decreases risk — possibly protective from repeated differentiation of myometrial stem cells); obesity (increased peripheral oestrogen production from adipose tissue); hypertension; family history; and dietary factors (high red meat, low fresh fruit and vegetable consumption). Protective factors: multiple pregnancies; prolonged oral contraceptive use (modest); increasing parity.

Most fibroids are asymptomatic — discovered incidentally on pelvic ultrasound or at caesarean section. Symptomatic fibroids cause varying degrees of: Heavy menstrual bleeding (menorrhagia — the most common presenting complaint, particularly with submucosal or large intramural fibroids): soaking through pads and tampons in 1-2 hours, passing clots, prolonged periods (above 7 days), and resulting iron-deficiency anaemia (fatigue, breathlessness, pallor). Dysmenorrhoea (painful periods): from prostaglandin release from distorted endometrium and myometrial contractions against fibroids. Pressure and bulk symptoms from large fibroids: pelvic pressure or heaviness; urinary frequency and urgency (from bladder compression); urinary hesitancy and incomplete bladder emptying (from anterior fibroid pressure on the bladder outlet); constipation and bloating (from posterior fibroid compressing the rectum); and visible abdominal distension (very large fibroids can simulate a pregnancy — uterine fibroids can grow to fill the entire abdomen). Reproductive complications: submucosal fibroids significantly impair implantation and increase miscarriage rates; large intramural fibroids may reduce IVF success rates; fibroids can cause preterm labour, abnormal foetal presentation, obstructed labour, and post-partum haemorrhage in pregnancy. Pelvic pain: acute pain may occur from fibroid degeneration (red degeneration — particularly during pregnancy as fibroids rapidly enlarge); torsion of a pedunculated subserosal fibroid is a surgical emergency causing acute severe pain.

Pelvic ultrasound (transvaginal and transabdominal): the first-line imaging — identifies fibroid number, size, location, and relationship to the endometrial cavity; transvaginal ultrasound is superior for visualising the uterine cavity and identifying submucosal fibroids; highly accurate for fibroids above 1 cm. Saline infusion sonohysterography (SIS/SHG): instillation of saline into the uterine cavity during transvaginal ultrasound — greatly improves characterisation of submucosal and intracavitary fibroids; helps distinguish fibroids from endometrial polyps; required before planned myomectomy or reproductive treatment. Hysteroscopy: direct visualisation of the uterine cavity — diagnostic and therapeutic (hysteroscopic myomectomy for submucous fibroids); identifies intrauterine pathology including fibroids, polyps, and endometrial abnormalities. MRI pelvis: the gold standard for fibroid mapping — identifies the number, precise location (including relationship to endometrial cavity and serosa), size, and characteristics of all fibroids (including distinguishing adenomyosis from fibroids — important in treatment planning); essential before uterine artery embolisation (UAE) and high-intensity focused ultrasound (HIFU); provides information on fibroid vascularity useful for planning GnRH analogue therapy. Blood tests: FBC (haemoglobin — assess anaemia from menorrhagia); ferritin (iron stores); endometrial biopsy/hysteroscopy if endometrial pathology suspected (postmenopausal bleeding, thickened endometrium).

Treatment is required only for symptomatic fibroids; asymptomatic fibroids in women not planning pregnancy need monitoring but not treatment. Medical management of heavy menstrual bleeding: levonorgestrel intrauterine system (LNG-IUS — Mirena): reduces menstrual blood loss by up to 90% — highly effective for heavy periods from intramural or subserosal fibroids but not effective for distorted uterine cavities with significant submucosal fibroids. Combined oral contraceptives (COC): reduce blood loss and dysmenorrhoea. Tranexamic acid (antifibrinolytic — 1 g three times daily during menstruation): reduces blood loss by 50% — symptom relief only, no effect on fibroid size. Non-steroidal anti-inflammatory drugs (NSAIDs — mefenamic acid, ibuprofen): reduce blood loss and dysmenorrhoea. Hormonal fibroid-specific medical therapy: GnRH analogues (leuprolide, goserelin, nafarelin): induce a temporary, reversible menopause state — oestrogen suppression causes fibroid shrinkage by 35-65% over 3-6 months; used pre-operatively to reduce fibroid size, improve haemoglobin, and facilitate surgery; not suitable for long-term use (bone loss, menopausal symptoms) without oestrogen add-back therapy. Ulipristal acetate (Esmya — selective progesterone receptor modulator): reduces heavy bleeding and shrinks fibroids (now withdrawn in EU pending ongoing liver toxicity concerns — check current national guidelines). Relugolix-oestradiol-norethindrone acetate (Myfembree) and elagolix-oestradiol-norethindrone (Oriahnn): oral GnRH antagonist combinations with add-back therapy — approved for heavy menstrual bleeding from uterine fibroids in premenopausal women, addressing the bone loss issue of plain GnRH analogues; given as single daily oral tablet. Surgical treatment: Hysteroscopic myomectomy: resection of submucosal fibroids (FIGO types 0-2) via hysteroscope — outpatient procedure, no incision, very rapid recovery; gold standard for submucosal fibroids. Laparoscopic or open (abdominal) myomectomy: surgical removal of intramural and subserosal fibroids while preserving the uterus — preferred in women desiring future pregnancy; laparoscopic approach preferred for smaller or fewer fibroids; open myomectomy for multiple or large fibroids. Hysterectomy: definitive, curative treatment — removes all fibroids permanently; appropriate for women who have completed their family and have severe symptoms; total hysterectomy (uterus and cervix); can be performed laparoscopically, abdominally, or vaginally. Uterine artery embolisation (UAE): interventional radiology procedure — femoral artery catheterisation under fluoroscopic guidance; embolisation of both uterine arteries with PVA particles cutting blood supply to fibroids, causing ischaemic infarction; 70-85% of women have significant symptom improvement at 1 year; fibroid volume reduces 40-70%; preserves the uterus; suitable for women who do not desire future fertility (pregnancy after UAE is possible but outcomes data is less robust than after myomectomy). High-intensity focused ultrasound (HIFU/MRgFUS — MRI-guided focused ultrasound): non-invasive ablation of fibroid tissue using focused ultrasound waves under MRI guidance; suitable for selected fibroids (anterior wall, adequate distance from bowel, limited overall fibroid burden); outpatient procedure; good symptom relief in selected patients; available in specialist centres.

Iron-deficiency anaemia (the most common complication — from severe menorrhagia; affects up to 30% of women with symptomatic fibroids; causes fatigue, breathlessness, reduced exercise tolerance, and cognitive impairment; requires concurrent iron supplementation and treatment of the underlying fibroid). Subfertility and reproductive complications (submucosal fibroids significantly impair implantation and increase miscarriage risk; intramural fibroids above 4-5 cm reduce IVF implantation rates; during pregnancy, fibroids cause preterm labour, red degeneration pain, abnormal foetal presentation, and post-partum haemorrhage). Urinary and bowel complications (large fibroids compress the bladder causing urinary frequency, urgency, and incomplete emptying; posterior fibroids compress the rectum causing constipation; ureteric compression may cause hydronephrosis). Torsion of a pedunculated subserosal fibroid (acute severe pain — laparoscopic surgical emergency). Psychological impact (chronic pain, heavy bleeding, and fertility anxiety associated with significant depression, anxiety, and reduced quality of life — particularly in younger and Black women with more severe disease).

Fibroids cannot be reliably prevented — genetic and racial susceptibility are the dominant risk factors. Modifiable risk factors where evidence exists: maintaining a healthy weight (obesity increases fibroid risk through elevated oestrogen levels from adipose tissue aromatisation — weight loss in obese women may modestly reduce fibroid growth); increasing dietary fruit and vegetable consumption (inverse association with fibroid risk — particularly cruciferous vegetables and vitamin D-rich foods); reducing red and processed meat consumption. Vitamin D deficiency is associated with higher fibroid incidence — supplementation is under investigation but not yet proven preventive. Monitoring asymptomatic fibroids: women with known fibroids not requiring treatment should have annual or biennial ultrasound to monitor for significant growth; rapid growth (volume doubling time below 6 months in a postmenopausal woman) raises concern for leiomyosarcoma and should prompt surgical evaluation. Any fibroid growth after menopause (when fibroids normally regress with oestrogen decline) requires urgent investigation. During reproductive years, most fibroids are stable or grow slowly — significant growth during pregnancy is common and generally does not require intervention.

See a GP or gynaecologist promptly for: heavy periods that are affecting quality of life, sleep, or causing symptoms of anaemia (fatigue, breathlessness, pallor); pelvic pain, pressure, or a feeling of pelvic fullness; visible abdominal swelling; urinary frequency or urgency; or difficulty conceiving. See a gynaecologist urgently for: sudden severe pelvic pain (possible fibroid degeneration, torsion of pedunculated fibroid, or other acute gynaecological emergency); heavy menstrual bleeding with dizziness, severe pallor, or very rapid pad soaking. Seek emergency care for: acute severe abdominal pain with collapse or signs of haemorrhage. All women with postmenopausal bleeding should be urgently assessed by a gynaecologist — fibroids are a recognised cause but endometrial cancer must be excluded. Women undergoing IVF with known fibroids should have pre-IVF fibroid assessment — submucosal fibroids significantly reduce implantation success and should be removed before IVF when possible.