Uterine fibroids

Notes

Introduction

Ureterine fibroids (leiomyomas) are benign tumours that arise from the muscle layer of the uterus termed the myometrium.

Fibroids are the most common type of pelvic tumour in women and usually arise in women of child-bearing age. Uterine fibroids may be asymptomatic or present with a variety of symptoms including bleeding (i.e. Menorrhaga), pelvic pain or infertility. 

Epidemiology

They are the most common type of pelvic tumour and leading cause of hysterectomy. 

The exact epidemiology of uterine fibroids is difficult to assess as many women are asymptomatic. In general, the incidence of uterine fibroids increases with age until the menopause, peak incidence occurs in women in their 40s and they are more common in black women.

Aetiology & pathology

Fibroids are a hormone driven growths, which are maintained by high levels of oestrogen and progestogens.

The importance of this hormonal-mediated growth is best represented by the age of onset of fibroids. Uterine fibroids do not occur in pre-pubescent girls and the overall prevalence of fibroids progressively increases towards menopause.

Fibroids are very similar to the normal muscular myometrium and they may occur anywhere within it. Depending on the location of fibroids, they may be classified as subserosal, intramural or submucosal.

Risk factors

The risk of developing fibroids is decreased by pregnancy and reduces further with every subsequent pregnancy. There are several risk factors that increase the chances of a female developing fibroids.

  • Early age of puberty
  • Increasing age
  • Obesity
  • Ethnicity (e.g. black females).

Clinical features

Uterine fibroids have an unpredictable natural history and a large majority are identified incidentally on pelvic imaging.

If present, women may suffer from the following clinical features:

  • Menorrhagia
  • Abdominal swelling
  • Pelvic pain
  • Dyspareunia
  • Dysmenorrhoea
  • Urinary/bowel symptoms.

In some cases, fibroids may undergo ‘red degeneration’ during pregnancy. Red degeneration is the result of rapid enlargement and the fibroid subsequently outgrows its blood supply. This can lead to acute severe abdominal pain. Another causes of severe abdominal pain associated with uterine fibroids is torsion of a pedunculated fibroid.

 

Diagnosis & investigations

A pelvic ultrasound is considered the first-line investigation for evaluation of uterine fibroids.

Fibroids are often asymptomatic or cause menorrhagia in females. Therefore, they are commonly diagnosed incidentally or when investigating menorrhagia that is not responsive to medical therapy. A transvaginal ultrasound is the modality of choice, but a transabdominal ultrasound can also be used. In clinical practice, the main reason for requesting a pelvic ultrasound is identification of a pelvic mass or menorrhagia that is not responsive to conventional treatment.

Other investigations that can be completed in the work up of uterine fibroids include full blood count (assess for anaemia), plevic MRI and hysteroscopy if there is concern about intramucosal fibroids. Pelvic MRI is the best imaging modality to assess fibroids and it is useful at differentiating between leiomyomas, adenomyosis (endometrial tissue in the myometrium), and adenomyomas (benign tumour variant of adenomyosis). However, its use is usually restricted to complicated cases or operative planning because of the ease and high sensitivity (95-100%) of ultrasonography. 

 

Management

The management of fibroids depends on the presenting symptoms of the patient.

Menorrhagia is the most common problem associated with fibroids, and thus, management focuses on the treatment of heavy periods.

Treatment options for menorrhagia include the intra-uterine contraceptive system (IUS), non-steroidal anti-inflammatory drugs (NSAIDs), tranexamic acid and the combined oral contraceptive pill. 

In cases of menorrhagia not responsive to medical therapy, or where fibroids are causing significant pain or mass effect, surgical intervention with myomectomy or hysterectomy are options. 

Complications

The main complications associated with uterine fibroids can be divided into pregnancy and non-pregnancy related.

Pregnancy-related complications

  • Infertility (distortion of uterine cavity)
  • Malpresentation
  • Placental abruption
  • Intrauterine groth restriction
  • Preterm labour

Non-pregnancy-related complications

  • Prolapsed fibroid
  • Anaemia (i.e. menorrhagia)
  • Endocrine effects (polycythaemia, hypercalcaemia, hyperprolactinaemia)

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