Uterine Leiomyoma

Uterine leiomyomas, commonly termed fibroids, are benign smooth muscle tumours arising from the myometrium. They are the commonest benign gynaecological tumour in women of reproductive age.

A substantial proportion of affected women are entirely asymptomatic. A meaningful minority have significant symptomatic burden, including heavy menstrual bleeding, pelvic pressure and, in some cases, reproductive implications.

Classification by anatomical location (submucosal, intramural or subserosal) is essential. It determines the pattern of symptoms and the range of appropriate treatment options.

Pathophysiology and classification

• Fibroids arise from clonal proliferation of myometrial smooth muscle cells, driven by genetic predisposition and hormonal influence. Growth is characteristically oestrogen and progesterone-dependent.
• This accounts for the tendency to grow during the reproductive years and regress after menopause, when circulating ovarian hormone production falls substantially.
• Anatomical classification reflects the relationship to the uterine wall and cavity. It directly informs the symptom pattern and the most appropriate treatment for an individual fibroid.
  • Submucosal fibroids project into and distort the endometrial cavity. Because of their direct relationship to the endometrium, they are particularly relevant to heavy menstrual bleeding and fertility impact.
  • Intramural fibroids lie predominantly within the myometrial wall. This is the commonest overall pattern.
  • Subserosal fibroids project outward from the external uterine surface. They are particularly relevant to bulk-related pressure symptoms rather than bleeding.
• Recognised risk factors include advancing reproductive age. Prevalence increases through the reproductive years before regression after menopause.
• African ancestry is associated with substantially increased prevalence, earlier age of onset, and generally larger fibroid size and number.
• Nulliparity and obesity are also risk factors. Obesity reflects increased peripheral oestrogen production through adipose tissue aromatisation.

• The great majority of fibroids, particularly smaller lesions, are entirely asymptomatic. They are identified incidentally on pelvic examination or imaging for an unrelated indication. Where symptoms occur, they relate directly to fibroid size, number and, critically, anatomical location.
• Heavy menstrual bleeding is the commonest symptomatic presentation. It is particularly associated with submucosal fibroids, given their direct relationship to and distortion of the endometrial cavity and surface.
• Larger fibroids of any location also increase the overall endometrial surface area, contributing to increased menstrual blood loss.
• Bulk-related symptoms are particularly associated with larger fibroids, particularly of subserosal or intramural location. They include pelvic pressure or a palpable abdominal mass. Depending on the direction of growth and resulting pressure effect, there may be urinary frequency (from bladder compression) or, less commonly, bowel symptoms.
• Reproductive implications are important for women of reproductive age with symptomatic or strategically located fibroids. They include a recognised association with infertility, particularly for submucosal fibroids given their direct impact on the endometrial cavity and implantation environment. They also include an increased risk of certain pregnancy complications, including miscarriage and preterm labour.
• Acute pain may reflect fibroid degeneration, particularly red or carneous degeneration. This can occur during pregnancy, as the rapid uterine growth outpaces the fibroid's blood supply.
• Acute pain may also reflect, uncommonly, torsion of a pedunculated subserosal fibroid. These are important, though generally self-limiting, acute presentations.

• Pelvic ultrasound, transabdominal or, for more detailed characterisation, transvaginal, is the standard first-line imaging investigation. It characterises fibroid number, size and anatomical location, directly informing management planning.
• Magnetic resonance imaging offers superior anatomical detail. It is particularly valuable for preoperative planning where surgical or interventional treatment is being considered. It also helps distinguish fibroids from other uterine pathology, including adenomyosis, where this remains uncertain on ultrasound alone.
• Saline infusion sonohysterography or hysteroscopy gives detailed assessment of submucosal fibroid characteristics and their relationship to the endometrial cavity. This directly informs suitability for hysteroscopic resection where that approach is being considered.
• Assess for anaemia, given the frequent association with significant, chronic heavy menstrual bleeding.
• Carefully exclude, clinically and where relevant histologically, the rare but important alternative diagnosis of uterine leiomyosarcoma. This malignant smooth muscle tumour can occasionally present with a superficially similar clinical picture. It is an uncommon, distinct diagnosis addressed with its own specific considerations. It does not typically arise through malignant transformation of a pre-existing benign fibroid.
• This is particularly relevant where a fibroid shows atypical, rapid growth, particularly in a postmenopausal woman.

• Asymptomatic fibroids identified incidentally require no specific treatment. Management comprises reassurance and, where relevant to size or characteristics, periodic clinical or imaging surveillance.
• Medical management of heavy menstrual bleeding associated with fibroids follows broadly similar principles to those addressed under the general management of heavy menstrual bleeding.
  • The levonorgestrel-releasing intrauterine system is a reasonable option for smaller fibroids without significant cavity distortion.
  • Tranexamic acid and nonsteroidal anti-inflammatory drugs provide symptomatic benefit.
  • Combined hormonal contraception is a further relevant option.
• Gonadotropin-releasing hormone agonist or, increasingly, the more convenient oral gonadotropin-releasing hormone antagonist combination formulations provide effective medical treatment for reducing fibroid size and associated bleeding.
• They are valuable as definitive medical management, or as preoperative treatment to reduce fibroid size and bleeding before planned surgery. Consider treatment duration carefully, given the hypoestrogenic adverse effects with more prolonged use.
• Hysteroscopic myomectomy is the preferred, minimally invasive surgical approach for symptomatic submucosal fibroids. It gives direct access to and resection of these cavity-distorting lesions. It effectively treats associated heavy menstrual bleeding while preserving the uterus and future fertility potential.
• Myomectomy via a laparoscopic or open approach, according to fibroid size, number and location, is the standard surgical treatment for symptomatic intramural or subserosal fibroids in women wishing to preserve their uterus and fertility potential. Individualise the approach to these factors.
• Uterine artery embolisation is an effective, uterus-preserving interventional radiological option. It is particularly relevant for women wishing to avoid surgery, or to preserve their uterus without an immediate fertility priority.
• It works by selective embolisation of the uterine arteries to induce fibroid infarction and subsequent shrinkage. Its impact on future fertility relative to myomectomy warrants full, individualised counselling.
• Hysterectomy is definitive, curative treatment. It is for women who have completed childbearing and whose symptoms are not adequately controlled with less invasive approaches, or for women with very large or numerous fibroids not amenable to more conservative surgery.
• Individualised counselling on the full range of treatment options underpins patient-centred management of this extremely common gynaecological condition. It should incorporate the woman's symptom burden, fibroid characteristics and fertility considerations.