Uterine Fibroids (Leiomyoma)
Summary
Uterine Fibroids (Leiomyomas) are benign monoclonal tumours arising from the smooth muscle cells of the myometrium. They are the most common pelvic tumour in women, affecting 20-40% of women of reproductive age, and up to 70-80% of Afro-Caribbean women. Growth is Oestrogen and Progesterone dependent; thus, they enlarge during pregnancy and shrink after menopause. [1,2]
Clinical Pearls
Submucosal is the Bleeder: The tiny fibroid poking into the cavity (Submucosal) causes torrentially heavy periods (Menorrhagia), whereas the massive football-sized fibroid on the outside (Subserosal) might be completely asymptomatic or just cause bloating. Size doesn't correlate with bleeding; location does.
Red Degeneration: A classic exam scenario. A pregnant woman presents with acute severe abdominal pain, vomiting, and low-grade fever. The fibroid has outgrown its blood supply and infarcted. Management is Conservative (Analgesia/Rest). Surgery (Myomectomy) is dangerous in pregnancy due to haemorrhage risk.
Sarcomatous Change: Malignant transformation to Leiomyosarcoma is extremely rare (less than 0.1%). However, suspect it if a fibroid grows rapidly in a post-menopausal woman (when it should be shrinking).
Risk Factors
- Ethnicity: 3x higher risk in Black women. Present earlier and grow larger.
- Age: Peak incidence 30-50 years.
- Nulliparity: Pregnancy is protective (remodelling).
- Obesity: Increased peripheral aromatization of androgens to oestrogens.
- Early Menarche / Late Menopause: Increased lifetime oestrogen exposure.
Classification (FIGO System)
Based on location relative to the uterine wall:
- Submucosal (Type 0, 1, 2): Project into uterine cavity. Associated with Heavy Menstrual Bleeding (HMB) and Infertility.
- Intramural (Type 3, 4, 5): Within the myometrium.
- Subserosal (Type 6, 7): Project outwards. Can become pedunculated. Associated with pressure symptoms.
Histology
- Whorled bundles of smooth muscle cells separated by connective tissue.
- Often have a "pseudocapsule" (compressed myometrium) allowing easy shelling out during surgery.
| Condition | Features |
|---|---|
| Fibroid | Firm, irregular midline mass. Moves with cervix. |
| Ovarian Cyst | Separate from uterus. Cystic feel. Can be mobile. |
| Adenomyosis | "Boggy", tender, uniformly enlarged uterus. |
| Pregnancy | Soft, smooth enlargement. Amenorrhoea. |
| Endometrial Cancer | Post-menopausal bleeding. Risk factors. |
Symptoms
Examination
Imaging
- Transvaginal Ultrasound (TVUS): First line. High sensitivity. Maps location/size.
- MRI Pelvis: Gold standard for mapping prior to surgery (Myomectomy/UAE) or distinguishing form Adenomyosis/Sarcoma.
- Hysteroscopy: Consults the cavity. Essential for submucosal fibroids.
Lab
- FBC: Check for Iron Deficiency Anaemia.
Management Algorithm
SYMPTOMATIC FIBROIDS
↓
IMPACT ON FERTILITY?
┌───────────┴───────────┐
YES NO
↓ ↓
SURGICAL MEDICAL FIRST
(Myomectomy) (Control symptoms)
↓ ↓
- Hysteroscopic 1. LNG-IUS (Mirena)
(Submucosal) 2. Tranexamic Acid + NSAIDs
- Laparoscopic 3. COC Pill / POP
(Intramural) ↓
SYMPTOMS PERSIST?
↓
INTERVENTIONAL
┌───────────┴───────────┐
SURGERY RADIOLOGY
(Hysterectomy) (Uterine Artery
(Myomectomy) Embolisation)
1. Medical Management (Symptom Control)
- Mirena IUS: First line for HMB if cavity not distorted.
- Tranexamic Acid: For bleeding.
- GnRH Analogues (Goserelin): Induces "medical menopause". Used for 3-6 months pre-op to shrink fibroids and correct anaemia. Not for long term use (Bone density loss).
2. Uterine Artery Embolisation (UAE)
- Interventional Radiology procedure. Particles injected to block fibroid blood supply -> Infarction/Shrinkage.
- Pros: Avoids major surgery, uterus preserved.
- Cons: Severe pain for 24h (Post-embolisation syndrome). Risk to future fertility (ovarian supply damage).
3. Surgical Options
- Hysteroscopic Resection: For submucosal fibroids < 3cm. (TCRP / MyoSure). Day case.
- Myomectomy (Open/Lap): Removal of fibroids, repairing uterus. Preserves fertility. Risk of bleeding / adhesions / C-Section needed for future birth.
- Hysterectomy: Definitive cure.
4. New Agents
- Rylogo (Relugolix): Oral GnRH antagonist combination therapy. New NICE approved option for moderate/severe symptoms.
- Red Degeneration: In pregnancy.
- Torsion: Of a pedunculated subserosal fibroid (Acute pain).
- Expulsion: Of a stalked submucosal fibroid through cervix (Labour-like pain).
- Malignancy: Leiomyosarcoma (Rare).
- Benign. Treatable.
- Recurrence after Myomectomy is ~15-30%.
- Shrink after menopause.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| HMB | NICE NG88 (2018) | Mirena 1st line. UAE should be offered as uterus-sparing option. |
| Fibroids | RCOG Green-top | Management of Red Degeneration. |
Landmark Evidence
1. Emyoma Trial
- Compared UAE vs Myomectomy. UAE had shorter hospital stay and faster recovery but higher re-intervention rate.
What are fibroids?
They are balls of muscle that grow in the wall of the womb. They are usually non-cancerous (benign). They are incredibly common - by age 50, about 70-80% of women have them.
Why do I have heavy periods?
If a fibroid grows just under the lining of the womb, it increases the surface area that bleeds each month and stops the womb muscle from clamping down to stop the bleeding.
Do I need surgery?
Not always. If they aren't causing problems, we leave them alone. If you have heavy bleeding, we can try tablets or a coil first. If you want children, we are careful to choose treatments that protect the womb.
Will they turn into cancer?
The risk is extremely small (less than 1 in 1000).
Primary Sources
- NICE. Heavy menstrual bleeding: assessment and management (NG88). 2018.
- Stewart EA. Uterine fibroids. N Engl J Med. 2015.
Common Exam Questions
- Diagnosis: "Pregnant, acute pain, mass?"
- Answer: Red Degeneration.
- Treatment: "1st line for fibroid HMB?"
- Answer: Mirena IUS (if no distortion).
- Complication: "Rapid growth in 60yo?"
- Answer: Suspect Leiomyosarcoma.
- Anatomy: "Submucosal vs Subserosal?"
- Answer: Submucosal bleeds; Subserosal presses.
Viva Points
- GnRH Analogues: Why only short term? Because they cause menopausal side effects (Hot flushes) and Osteoporosis (Bone thinning) due to low oestrogen.
- UAE vs Myomectomy: Discuss fertility. Myomectomy preferred if fertility is main goal. UAE has higher miscarriage risk.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.