Last updated on June 9, 2021 at 16:21
Definition and epidemiology
Leiomyomas, often called uterine fibroids due to their fibrous consistency due to their collagen content, is a benign smooth muscle neoplasm of the myometrium. They are never malignant.
It’s a very common condition, affecting around 6/10 women. It’s mostly asymptomatic and those who are asymptomatic do not require treatment.
The underlying cause is not known, but some risk factors are:
- Age – risk increases with age
- Oestrogen and hormone treatment
- Does not increase the risk for new leiomyomas, but for the growth of those already present
- Black ethnicity
- Family history
Some protective factors are also known:
- Oral contraceptive pills (either decrease the risk or have no effect on it)
- High parity
Leiomyomas originate from a single cell. They are hormone responsive, responding to oestrogen and progesterone, which may allow them to grow quite large.
They are well-circumscribed with a pseudocapsule, round, pearly white, firm, and rubbery. As they outgrow their own blood supply, infarct or degeneration can occur which may cause pain.
Leiomyomas are classified according to their location.
- Subserosal leiomyoma
- Grows outward toward the abdominal cavity
- Covered by serosa
- Can grow big without causing symptoms
- May compress bladder or rectum
- Intramural leiomyoma
- Grow inside the wall of the uterus
- Rarely grow big
- Submucosal leiomyoma
- Grow underneath the mucosal layer
- Distorts the uterine cavity
- Isthmic leiomyoma
- Grow close to the opening of the fallopian tube
- May cause infertility
- Broad ligament leiomyoma
- Grow inside the broad ligament of the uterus
- Difficult to remove due to the nearby vessels
- Cervical leiomyoma
- Grow in the cervix
- Difficult to remove due to the thin wall of the cervix and that it’s hard to reach
Submucosal and subserosal leiomyomas may be pedunculated, in which case they’re only attached to the uterine wall by a small stalk, making them easy to remove. However, the pedunculated submucosal type may prolapse through the cervix, causing acute pain.
Submucosal and intramural leiomyomas may cause lower abdominal pain, dysmenorrhoea and bleeding disorders like hypermenorrhoea, or metrorrhagia.
Because they distort the uterine cavity, submucosal leiomyomas can also lead to infertility or spontaneous abortion. Also, if the uterus contains multiple leiomyomas, which altogether distort its structure, infertility may also occur.
Large anterior subserosal leiomyomas may compress the bladder and cause urinary urgency. Large posterior subserosal leiomyomas may compress the rectum, causing faecal urgency or constipation.
Leiomyomas can cause acute pelvic pain if they are degenerated (necrosis) or if they prolapse.
Diagnosis and evaluation
On physical examination uterine enlargement and irregular contour can be palpated, sometimes described as lumpy, bumpy, and enlarged uterus.
If the physical examination is positive, imaging should be performed. The first line choice is saline-infusion sonography, which is the ultrasound examination after saline infusion into the uterine cavity.
If the patient is asymptomatic, we only perform observation and follow-up.
If the patient is symptomatic, we have three options:
- Uterine artery embolization
- Medical treatment
- Hormonal therapy – GnRH agonists which reduce oestrogen
- Ulipristal acetate (although it may cause liver damage and so it’s currently under investigation)
- Surgical treatment
- Myomectomy if the woman wants future pregnancy
- Hysterectomy if not
- (Open surgery, hysteroscopic, or laparoscopic)
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