Uterine Fibroids are benign tumours arising from the smooth muscle and connective tissue of the uterus. They are also known as leiomyomas or myomas and are among the most common structural abnormalities of the uterus, particularly during the reproductive years. Fibroids can occur as a single lesion or as multiple tumours and vary greatly in size, ranging from very small nodules to masses large enough to enlarge the uterus substantially.
They are hormonally responsive, with growth influenced by ovarian steroid hormones and local molecular signalling. Most are non-cancerous and remain benign, and a fibroid itself is not generally considered a precursor that routinely transforms into uterine cancer. Their clinical importance depends primarily on location, size, number and symptoms rather than simply their presence.
Fibroids are commonly classified according to their relationship with the uterine wall. Intramural fibroids develop predominantly within the muscular wall, submucosal fibroids project towards or into the uterine cavity, and subserosal fibroids project outward from the uterus. Some can extend on a stalk and are described as pedunculated.
Location strongly influences symptoms: lesions distorting the uterine cavity are particularly associated with heavy menstrual bleeding and can interfere with implantation or fertility, while larger outward-growing lesions may produce pelvic pressure or urinary and bowel symptoms. The anatomical classification is therefore more clinically useful than simply describing a fibroid as large or small. Imaging, particularly pelvic ultrasound, is commonly used to establish the number, size and location of lesions.
Many Uterine Fibroids are asymptomatic and discovered incidentally. When symptoms occur, heavy or prolonged menstrual bleeding is a major manifestation and can lead to iron-deficiency anaemia. Pelvic pressure, lower abdominal discomfort, back pain, urinary frequency, constipation and abdominal enlargement can occur when fibroids become sufficiently large or strategically positioned. Some individuals experience painful menstruation or pain during sexual activity.
Symptoms do not always correlate directly with the total number of fibroids because a relatively small lesion projecting into the uterine cavity can produce substantial bleeding, while a larger lesion elsewhere may cause few symptoms. Rapid changes in symptoms or postmenopausal growth warrant careful evaluation because the differential diagnosis changes with age and reproductive status.
The development of Uterine Fibroids is influenced by genetic, hormonal and cellular factors. Fibroid cells arise from a smooth-muscle cell that undergoes abnormal clonal proliferation, followed by production of substantial extracellular matrix. Oestrogen and progesterone contribute to the growth environment, helping explain why fibroids commonly enlarge during reproductive life and may shrink after menopause when ovarian hormone levels decline. Genetic alterations within fibroid tissue are common, and different fibroids in the same uterus can have different molecular characteristics. Risk varies among populations, and factors associated with increased occurrence include age during reproductive years, family history and several metabolic or hormonal influences. Their biology is therefore more complex than the simplistic idea that fibroids are merely caused by excess hormones.
Diagnosis usually relies on pelvic imaging, with ultrasound commonly providing the initial assessment. More detailed imaging, such as magnetic resonance imaging, can map large or numerous fibroids and assist with treatment planning, particularly before procedures intended to preserve the uterus. Hysteroscopy can directly visualise lesions projecting into the uterine cavity and may allow treatment of selected submucosal fibroids. Blood tests may be used to investigate consequences such as anaemia but do not diagnose a fibroid itself. When abnormal uterine bleeding occurs, clinicians must also consider other causes rather than automatically attributing all bleeding to known fibroids. Tissue examination is generally obtained when a lesion is removed rather than through routine biopsy of every fibroid.
Management ranges from observation to medication, minimally invasive procedures and surgery. Asymptomatic fibroids often need no treatment beyond appropriate clinical monitoring. Heavy menstrual bleeding can sometimes be controlled with medicines that reduce bleeding or alter hormonal activity, while pain may respond to appropriate analgesic strategies. Uterine artery embolisation reduces blood supply to fibroid tissue and can shrink lesions, while focused ultrasound techniques are available in selected settings. Surgical options include myomectomy, which removes fibroids while retaining the uterus, and hysterectomy, which removes the uterus and provides definitive treatment when fertility preservation is not required. Treatment selection depends on symptoms, fibroid location and size, age, reproductive goals, comorbidities and the individual's preferences.
Fibroids can affect fertility, pregnancy and reproductive planning, but their presence does not automatically cause infertility. Submucosal lesions and fibroids that substantially distort the uterine cavity have a stronger relationship with impaired implantation and certain reproductive outcomes than many fibroids located elsewhere. During pregnancy, fibroids may remain stable, enlarge or undergo degenerative changes that cause pain, while their location and size can sometimes influence obstetric management. Fibroids can also complicate delivery in selected circumstances, particularly when they obstruct the birth canal or affect uterine anatomy. Because fertility goals can influence whether the uterus should be preserved and which procedures are appropriate, reproductive planning is an important component of treatment discussions.
The term fibroid can sound alarming because it denotes a tumour, but Uterine Fibroids are overwhelmingly benign and are biologically distinct from malignant uterine tumours. A major misconception is that every fibroid requires removal; many cause no symptoms and can safely be observed. Another misconception is that hysterectomy is the only definitive treatment, whereas several uterus-preserving and minimally invasive options exist for selected patients.
Conversely, treatment is not always necessary merely to reduce the measured size of a fibroid if symptoms are minimal. The condition is significant because heavy menstrual bleeding, anaemia, pressure symptoms and reproductive effects can substantially affect quality of life, while modern imaging and multiple treatment strategies allow management to be tailored to the anatomical and reproductive circumstances of the individual.
