Uterine fibroids, also known as leiomyomas are benign smooth muscle tumours of the uterus. They are the most common pelvic tumour in women, occurring in 20-40% of women, and even more common in black women (50%).
Incidence increases with age until menopause with peak incidence in women in their 40s.
Pathophysiology
Fibroids arise from the myometrial layer of the uterine body. Sometimes they may arise from the cervix even. There aetiology is not completely understood but it is believed that they arise from a single mutated smooth muscle cell that has abnormal growth.
Abnormal vaginal bleeding accompanies uterine fibroids. It is believed that this due to distortion of the endometrial lining. They can disrupt the menstrual flow → dysmenorrhoea.
If the fibroid is large enough, it can lead to mass effect on surrounding organs such as the bowel or bladder → frequency, urgency, incontinence and constipation.
Their growth is sensitive to oestrogen and change in size throughout the menstrual cycle. During pregnancy, with increased oestrogen they can grow and outstrip their blood supply which causes them to degenerate (we will discuss this at the end).
🔢 Classification
They can be classified anatomically by their location in the uterine wall:
- Intramural - this is the most common one. It is confined to the myometrium.
- Submucosal - develops underneath the endometrium and protrudes into the uterine cavity.
- Subserosal - forms below the serosal layer and grows in the serosal layer of the uterus.
Both the submucosal and subserosal forms may become pedunculated as they form a stalk.
⚠️ Risk factors
- Increasing age - risk increases with age during reproductive years (up until menopause).
- Early menarche - if menarche before age 11.
- Nulliparity
- Obesity
- Diabetes
- Hypertension
- Afro-Carribean and Asian ethnicity
- Family history
😷 Presentation
The majority of women are asymptomatic and they are discovered incidentally.
Typical symptoms that may present are:
- Menorrhagia - may cause fatigue due to iron deficiency anemia.
- Dysmenorrhoea - painful cramping before or during menstruation.
- Pelvic pain or pressure as well as abdominal distension
- Urinary frequency, urgency and incontinence/retention
- Constipation
- Dyspareunia
- Subfertility - this is due to its obstructive effect.
- Solid suprapubic mass or enlarged uterus - may be felt on examination.
🔍 Investigations
🥇 A transvaginal ultrasound or transabdominal ultrasound may be used if the uterus is palpable, or if the history and exam suggest a pelvic mass.
An FBC may be used to assess for iron deficiency anaemia.
MRI may be used to assess the fibroid for surgery.
🧰 Management
Asymptomatic fibroids require no management.
Menorrhagia management
<3 cm in diameter:
- 🥇 Levonorgestrel intrauterine system (LNG-IUS) - this is the first-line treatment, however, it cannot be used if there is distortion of the uterine cavity.
- 🥈 Non-hormonal treatments:
- Tranexamic acid
- NSAIDs such as mefenamic acid.
- 🥈Hormonal treatments:
- Combined oral contraceptive
- Oral progestogen
- Injectable progestogen
🥇 If it is >3cm in diameter → tranexamic acid or NSAIDs are the first-line options.
Shrinking fibroids:
- 🥇 GnRH analogues such as zolidex can be used. They work by suppressing ovulation and thus reduce oestrogen induced growth. But they can only be used for 6 months due to the risk of osteoporosis.
- Ulipristal acetate - can be used if surgery is not suitable or has failed but its use is restricted due to risk of liver toxicity.
There are 4 options for surgery:
- Myomectomy - removal of the fibroid from the uterine wall. It is fertility-sparing and uterus preserving. It is done abdominally, hysteroscopically (especially if submucosal) or laparoscopically.
- Uterine artery embolisation - done with interventional radiology. Access is gained via the femoral artery.
- Hysterectomy
- Hysteroscopic endometrial ablation
- Fibroids >3cm
- With significant symptoms to consider other management options
- If hysteroscopy is needed
- If primary care treatment options have failed
🚨 Complications
- Subfertility
- Iron deficiency anaemia
- Malignant changes to leiomyosarcoma (<0.1%)
- Torsion of pedunculated fibroid
- Red degeneration
This is when there ischaemia, infarction and necrosis of the fibroid due to impaired blood supply. It mainly occurs in the second/third trimester of pregnancy. It occurs due to rapid enlargement in pregnancy with the oestrogen present. It then outgrows the blood supply and strips it away.
It presents with pain, low-grade fever, tachycardia and vomiting. Remember to look out for this on exam questions