Uterine Fibroids (Leiomyoma) — Causes, UAE, Myomectomy & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Uterine fibroids (leiomyomata or myomata) are benign monoclonal smooth muscle tumours arising from the uterine myometrium, with variable amounts of fibrous connective tissue. They are the most common pelvic tumours in women — present histologically in approximately 70% of Caucasian women and 80% of Black women by age 50. Although the majority are asymptomatic and discovered incidentally, symptomatic fibroids affect 20-25% of reproductive-age women and are the most common indication for hysterectomy in the UK. Fibroids are classified by location: intramural (within the myometrial wall — most common, 70%); submucosal (protruding into the uterine cavity — most symptomatic, causing heavy bleeding and impairing implantation); subserosal (protruding outward from the uterine surface — cause bulk symptoms); and pedunculated (attached by a stalk — subserosal or submucosal). The FIGO classification (type 0-8) further characterises submucosal extent. Fibroids vary enormously in size — from millimetres to over 20 cm — and may be solitary or multiple. Malignant transformation to leiomyosarcoma is rare (incidence estimated at less than 1 in 1,000 fibroids).

Fibroids are hormone-dependent tumours — they arise from a single smooth muscle cell that undergoes somatic mutation and is subsequently stimulated to grow by oestrogen and progesterone. Genetic factors: somatic mutations in MED12 (70% of fibroids), HMGA2 (chromosome 12 rearrangement), and COL4A5-COL4A6 deletions are commonly identified. Fibroid development requires postpubertal oestrogen exposure and is accelerated during pregnancy (human placental lactogen) and inhibited after menopause. Risk factors: Black/African-Caribbean ethnicity (2-3 times higher incidence than Caucasian, earlier onset by 5-10 years, larger and more numerous fibroids — possibly related to vitamin D deficiency, hair relaxer exposure, and differences in oestrogen metabolism); nulliparity (pregnancy appears to reduce fibroid risk — fibroids regress post-partum); early menarche (longer oestrogen exposure); obesity (adipose tissue converts adrenal androgens to oestrone via aromatase — higher circulating oestrogen); hypertension (independent risk factor — mechanism unclear); alcohol consumption; dietary red meat; high stress. Protective factors: multiparity; oral contraceptive pill (reduces fibroid risk with long-term use); smoking (reduces circulating oestrogen — not recommended as a preventive strategy); vegetable-rich diet; vitamin D sufficiency (inverse association in observational studies).

Heavy menstrual bleeding (HMB): the most common presenting symptom — caused primarily by submucosal fibroids (type 0-2) which distort the endometrial cavity, impairing normal haemostasis, increasing vascular surface area, and impairing myometrial contraction after menstruation. HMB causes iron deficiency anaemia (fatigue, pallor, palpitations, breathlessness) in a significant proportion of women. Pelvic pain and pressure: constant pelvic heaviness or pressure from large fibroids; acute severe pain from fibroid degeneration (red degeneration in pregnancy — central haemorrhagic infarction of a rapidly growing fibroid; torsion of pedunculated fibroid). Dysmenorrhea: particularly with submucosal fibroids — prostaglandin excess and impaired uterine contraction cause painful periods. Bulk symptoms: urinary frequency and urgency from bladder compression (large anterior fibroids); constipation or tenesmus from rectal compression (posterior fibroids); abdominal distension or a palpable pelvic mass. Reproductive effects: submucosal fibroids impair embryo implantation, causing recurrent implantation failure and miscarriage; large intramural fibroids may impair sperm transport or distort the uterine cavity affecting implantation. Obstetric complications: malpresentation, preterm labour, placental abruption, and increased caesarean section rate. Abdominal examination: uterine enlargement ('fibroids = irregular lumpy enlargement analogous to 12-, 16-, 20-week gravid uterus size').

History: menstrual pattern (HMB, cycle length, clot passage, flooding), pelvic pain, bulk symptoms, fertility plans, and previous treatments. Pelvic examination: uterine size, shape, consistency, and mobility (fibroids cause firm, irregular uterine enlargement — 'knobbly' uterus); occasionally fibroid palpable suprapubically. Transvaginal ultrasound (TVUS): first-line imaging — identifies fibroid number, location (intramural, submucosal, subserosal), size, and uterine volume; FIGO classification of submucosal extent (type 0 = fully intracavitary, type 1 = over 50% intracavitary, type 2 = under 50% intracavitary). Three-dimensional ultrasound: better characterises uterine cavity distortion for fertility planning. Saline infusion sonography (SIS/sonohysterography): instillation of saline into the uterine cavity to separate cavity walls — improves detection of submucosal fibroids and polyps. MRI pelvis: gold standard for pre-surgical fibroid mapping — accurately identifies fibroid number, size, location, vascularity, and their relationship to the endometrial cavity and uterine serosa; essential for planning myomectomy and uterine artery embolisation. Hysteroscopy: direct visualisation of uterine cavity — diagnoses and simultaneously treats submucosal fibroids (hysteroscopic resection). Blood tests: FBC (anaemia from HMB); ferritin (iron stores); pregnancy test; endometrial biopsy (pipelle) to exclude endometrial pathology in women over 40 or with intermenstrual bleeding.

Treatment depends on symptom severity, fibroid location and size, fertility plans, and patient preference. Expectant management: appropriate for asymptomatic or minimally symptomatic fibroids — most fibroids are stable or slow-growing and regress after menopause. Medical management (symptom control): levonorgestrel intrauterine system (Mirena IUD): reduces HMB by 80-90%; effective only when fibroids do not significantly distort the uterine cavity — FIGO type 0-1 fibroids often prevent proper fitting; first-line for HMB without significant cavity distortion. Tranexamic acid 1 g TDS for the first 4 days of menstruation reduces blood loss by 30-50%. NSAIDs (mefenamic acid, ibuprofen) reduce blood loss and pain. GnRH agonists (goserelin 3.6 mg SC monthly, leuprorelin 3.75 mg IM monthly): reduce fibroid volume by 35-65% within 3-6 months by inducing pseudomenopause; used pre-operatively to reduce uterine size and blood transfusion requirement; not suitable for long-term use due to bone mineral density loss. Ulipristal acetate (selective progesterone receptor modulator — SPRM): intermittent courses (5 mg daily for 3 months) — withdrawn from routine use in UK due to rare serious hepatotoxicity, pending safety review. Mifepristone (antiprogesterone) is an alternative SPRM. Surgical management: Hysteroscopic resection (TCRF): for symptomatic submucosal fibroids (FIGO type 0-2) — treats the fibroid through the cervix without incision; highly effective for HMB; day-case procedure; fertility-preserving. Myomectomy: surgical removal of fibroids while preserving the uterus — laparoscopic (fibroids under 10 cm), open (abdominal — for large, multiple, or posteriorly located fibroids). Recommended for women wishing to preserve fertility. Uterine artery embolisation (UAE): interventional radiology procedure — bilateral uterine artery occlusion with polyvinyl alcohol particles causes fibroid infarction and shrinkage; reduces fibroid volume by 50-70%; effective for HMB; avoids surgery; not recommended for women desiring future pregnancy (reduced ovarian reserve risk, increased placental complications). Focused ultrasound surgery (HIFU/MRgFUS): high-intensity focused ultrasound to ablate fibroid tissue — non-invasive, outpatient; for select patients. Hysterectomy: the only definitive treatment — removes all fibroids and prevents recurrence; laparoscopic or abdominal; appropriate for women who have completed childbearing and desire permanent resolution.

Heavy menstrual bleeding causing severe iron deficiency anaemia: the most common complication — haemoglobin can fall to 6-7 g/dL or below, causing disabling fatigue, dyspnoea on minimal exertion, palpitations, pallor, and reduced work capacity; requires concurrent iron supplementation (ferrous sulfate 200 mg TDS) and management of the fibroid cause. Urinary complications from large fibroids: urinary retention from bladder neck compression (acute retention is a urological emergency); obstructive hydronephrosis from ureteric compression by cervical or large intramural fibroids — causing chronic obstructive nephropathy and renal impairment; recurrent UTIs. Fibroid degeneration: hyaline degeneration (most common — gradual replacement by fibrous tissue); red degeneration in pregnancy (haemorrhagic infarction from vascular compromise — causes acute severe pain, fever, and uterine tenderness in the second trimester; managed conservatively with analgesics); torsion of pedunculated fibroid — acute severe pain requiring emergency surgery. Infertility and recurrent miscarriage: submucosal fibroids (FIGO type 0-2) significantly impair IVF outcomes — removal (myomectomy or hysteroscopic resection) is recommended before ART. Fibroid recurrence after myomectomy: 20-50% recurrence rate by 5 years — cumulative over time.

No primary preventive strategy exists for fibroid formation, but modifiable risk factors can be addressed. Maintain a healthy weight: obesity increases fibroid risk through elevated circulating oestrogen (aromatase activity in adipose tissue) — maintaining a BMI under 25 is associated with lower fibroid incidence. Regular physical activity is associated with reduced fibroid risk in observational studies — likely mediated through lower oestrogen levels and improved insulin sensitivity. Diet: observational studies suggest that a diet rich in fruit and vegetables, particularly green vegetables and citrus (vitamin C), is associated with lower fibroid risk; reduce red meat and high-fat dairy; alcohol reduction is recommended. Vitamin D: Black women have higher fibroid prevalence and higher rates of vitamin D deficiency — supplementation may be beneficial (RCTs ongoing). For women with existing fibroids and fertility goals: watchful waiting is appropriate for asymptomatic or minimally symptomatic fibroids that do not distort the uterine cavity; submucosal fibroids should be resected before IVF (hysteroscopic resection improves implantation rates). Post-surgical surveillance: regular TVUS after myomectomy to monitor for recurrence, particularly in women not yet pregnant.

See a GP for: heavy menstrual bleeding (soaking a pad or tampon every hour or less, passing large clots, flooding to clothing or bedding) — this requires assessment for anaemia and investigation for underlying cause including fibroids; pelvic pain, pressure, or a feeling of fullness in the lower abdomen; urinary frequency or urgency not caused by infection; and bloating or a visible abdominal swelling. Seek urgent GP or A&E review for: acute severe pelvic pain with fever (possible fibroid degeneration or torsion); urinary retention (inability to pass urine with full bladder); and signs of severe anaemia with symptoms at rest (pallor, extreme fatigue, breathlessness at rest). Women investigating infertility or recurrent miscarriage should specifically request a transvaginal ultrasound to evaluate for submucosal fibroids — the most important treatable uterine cause of implantation failure and early pregnancy loss. Any unexpected postmenopausal uterine mass requires urgent gynaecological review — though leiomyosarcoma is rare, the diagnosis must be excluded.