Uterine Fibroids (Leiomyoma)

Leiomyomas are benign, monoclonal smooth-muscle tumours of the myometrium and are the commonest benign solid tumour of the female genital tract. They are oestrogen- and progesterone-dependent, hence grow in the reproductive years and regress after menopause. NEET PG loves the classification (FIGO), degeneration types, USG features, and the myomectomy-vs-hysterectomy-vs-UAE decision tree.

Definition & basic facts

A fibroid (leiomyoma, fibromyoma, myoma) is a well-circumscribed, pseudo-encapsulated tumour arising from a single neoplastic smooth-muscle cell of the myometrium. The "capsule" is actually compressed surrounding myometrium and areolar tissue — this potential plane is what allows enucleation during myomectomy.

• Most common in 35–45 years; lifetime prevalence up to 70–80% (often asymptomatic).
• More frequent and more aggressive in Afro-Caribbean women, present earlier, larger.
• Monoclonal origin; cytogenetic abnormalities in ~40% (translocations involving HMGA2 at 12q14, MED12 mutations are the commonest somatic mutation).

High-yield: Fibroids are oestrogen AND progesterone dependent. They have a higher concentration of oestrogen and progesterone receptors than surrounding normal myometrium, which is why anti-progestins (ulipristal, mifepristone) and GnRH analogues shrink them.

Classification

By anatomical location

Type	Location	Key clinical point
Intramural	Within myometrial wall (commonest)	Bulk symptoms, may distort cavity
Submucosal	Project into endometrial cavity	Most symptomatic → heavy menstrual bleeding, infertility, recurrent miscarriage
Subserosal	Project outward beneath serosa	Pressure symptoms; may be pedunculated
Pedunculated	On a stalk (subserosal or submucosal)	Torsion (subserosal); fibroid polyp / inversion risk (submucosal)
Cervical	In cervix (1–2%)	Surgically difficult, distorts ureters/bladder
Broad ligament / intraligamentary	Between leaves of broad ligament	Mimics adnexal mass; ureter at risk
Parasitic	Detached, derives blood supply from omentum/other organ	Rare

High-yield: Intramural is the commonest type overall; submucosal is the most symptomatic (menorrhagia, infertility) even when small.

FIGO PALM-COEIN sub-classification (frequently tested)

FIGO type	Description
0	Pedunculated intracavitary (submucosal)
1	Submucosal, <50% intramural
2	Submucosal, ≥50% intramural
3	Contacts endometrium, 100% intramural
4	Intramural
5	Subserosal ≥50% intramural
6	Subserosal <50% intramural
7	Subserosal pedunculated
8	Other (cervical, parasitic)

High-yield: Types 0, 1, 2 are amenable to hysteroscopic resection. Type 0 = entirely intracavitary on a stalk.

Pathology & degenerations

Macroscopically: firm, whorled, white cut surface. Microscopically: interlacing bundles of smooth muscle with a "fascicular/whorled" pattern; spindle cells with cigar-shaped nuclei.

Because fibroids outgrow their blood supply, they undergo degeneration:

Degeneration	Notes / association
Hyaline	Commonest degeneration overall; homogeneous eosinophilic change
Cystic	Liquefaction following hyaline; postmenopausal
Red (carneous)	Commonest in pregnancy (esp. 2nd trimester); aseptic infarction → acute pain, low-grade fever, localised tenderness, leucocytosis. Managed conservatively (analgesia, rest)
Calcific	"Womb stone"; postmenopausal; whorled calcification on X-ray
Fatty	Rare
Myxomatous / mucoid	Soft
Sarcomatous (malignant)	<0.1–0.5%; suspect if rapid growth, esp. postmenopausal

High-yield (very frequently asked): Commonest degeneration = hyaline. Commonest degeneration in pregnancy = red (carneous) degeneration → presents with acute abdominal pain + low-grade fever, treated conservatively.

High-yield: Atrophy (not degeneration) is the change after menopause/GnRH analogues — fibroids shrink due to oestrogen withdrawal.

Sarcomatous change is rare. Malignant transformation of a benign fibroid is debated; most leiomyosarcomas arise de novo. Suspect malignancy with: rapid growth, postmenopausal enlargement, growth on GnRH therapy. Histology: >10 mitoses/10 HPF, cytological atypia, coagulative tumour cell necrosis (Stanford criteria) define leiomyosarcoma.

Clinical features

Up to 50–80% are asymptomatic. When symptomatic:

Menstrual: Heavy menstrual bleeding (HMB / menorrhagia) is the commonest symptom, especially with submucosal fibroids. Mechanisms: increased endometrial surface area, impaired uterine contractility, venous congestion, ulceration over submucosal fibroids. Intermenstrual bleeding is NOT typical — investigate for other causes.

Pressure/bulk: Urinary frequency, retention (cervical/anterior), hydroureter, constipation, mass per abdomen, "feeling of weight."

Pain: Usually painless. Pain suggests red degeneration, torsion of pedunculated fibroid, or expulsion of submucosal polyp (colicky). Dysmenorrhoea if submucosal.

Reproductive: Subfertility (esp. submucosal/cavity-distorting), recurrent miscarriage. Pressure on bladder → frequency.

Signs: Firm, irregular, non-tender mass arising from pelvis, moving with the cervix (uterine origin), mass that you "cannot get below."

High-yield: A pelvic mass that moves with the cervix and you cannot get below = uterine origin (fibroid). Anaemia from chronic HMB is the commonest complication.

Fibroids & pregnancy

Most fibroids do not affect pregnancy, but high-yield associations:

• Red degeneration (2nd/3rd trimester) — acute pain, fever, vomiting; conservative management.
• Increased risk of: miscarriage, malpresentation (esp. with lower-segment/cornual fibroids), preterm labour, obstructed labour (cervical/lower segment), PPH (atony), placental abruption, IUGR.
• Torsion of pedunculated fibroid, especially puerperium.
• Most fibroids do not significantly increase in size during pregnancy contrary to old teaching; one-third may grow in the first trimester.
• Myomectomy during caesarean is generally avoided (haemorrhage risk) — exception: pedunculated subserosal fibroid.

Diagnosis & investigations

Step-wise approach: History (HMB, bulk) → bimanual exam (firm irregular uterus) → transvaginal USG (investigation of choice / first line) → saline infusion sonohysterography or hysteroscopy for submucosal mapping → MRI for surgical planning / adenomyosis differentiation.

USG (TVS) — investigation of choice:

• Well-defined, hypoechoic (sometimes heterogeneous) rounded mass, may have shadowing.
• Calcification = posterior acoustic shadowing.
• Doppler: peripheral / circumferential ("ring") vascularity (vs central vascularity of adenomyosis/malignancy).

Saline infusion sonography (SIS) / hysteroscopy: Best for assessing submucosal fibroids and cavity distortion before fertility surgery.

MRI: Most accurate for number, size, location; distinguishes fibroid from adenomyosis; mandatory before uterine artery embolisation; helps flag sarcoma (though imperfect).

Others: Haemoglobin (anaemia), thyroid/coagulation if HMB workup; CA-125 may be mildly raised (non-specific).

Feature	Fibroid	Adenomyosis
Borders	Well-defined, pseudocapsule	Ill-defined
Uterus	Asymmetrical, lumpy	Symmetrically bulky, globular
Tenderness	Non-tender	Tender (esp. premenstrual)
Junctional zone (MRI)	Normal	Thickened >12 mm
Doppler	Peripheral vascularity	Diffuse/central
Parity	Any	Multiparous, 40s

Management

Management depends on symptoms, size, location, age, and fertility wishes. Asymptomatic small fibroids → expectant management with periodic review.

Medical management

Medical therapy controls symptoms / shrinks fibroids temporarily (often pre-operative), but fibroids regrow on stopping treatment.

Drug class	Examples	Mechanism / use
GnRH agonists	Leuprolide, goserelin	Down-regulate pituitary → hypo-oestrogenism → shrinkage. Best for pre-operative shrinkage + correcting anaemia. Limited to 3–6 months (bone loss); add-back therapy.
GnRH antagonists	Relugolix, elagolix (with add-back)	Rapid suppression, oral, no flare
SPRM (anti-progestin)	Ulipristal acetate	Shrinks fibroids, controls bleeding (liver toxicity concerns limit use)
LNG-IUS (Mirena)	—	Controls HMB if cavity not distorted; does not shrink fibroid
Tranexamic acid / NSAIDs	—	Symptomatic bleeding control, non-hormonal
Progestins / COCs	—	Cycle control; modest

High-yield: GnRH agonist is the drug of choice for pre-operative size reduction and anaemia correction, given for ~3 months before myomectomy/hysterectomy. Causes a temporary menopausal state and shrinks fibroid by 35–50%.

Surgical management

Myomectomy — removal of fibroids preserving uterus. Procedure of choice for women desiring fertility.

• Hysteroscopic myomectomy: FIGO 0,1,2 submucosal fibroids (<3–4 cm, <50% intramural ideal). Watch for fluid overload/hyponatraemia with hypotonic distension media.
• Laparoscopic / open (abdominal) myomectomy: intramural/subserosal.
• Risks: recurrence (15–30%), adhesions, uterine rupture in future pregnancy (→ many advise elective LSCS), haemorrhage.

Hysterectomy — definitive treatment; for women with completed family, symptomatic, or large fibroids.

Uterine Artery Embolisation (UAE):

• Interventional radiology occludes both uterine arteries with PVA particles → fibroid infarction/shrinkage.
• Good for: women wanting uterine preservation but not necessarily future fertility, poor surgical candidates.
• Avoid / contraindicated: desire for future fertility (relative — pregnancy outcomes uncertain), pedunculated subserosal fibroids (risk of detachment), suspected malignancy, active infection, large fibroid >10 cm.
• Complication: post-embolisation syndrome (pain, fever, nausea), premature ovarian failure.

MRI-guided focused ultrasound (HIFU): Non-invasive thermal ablation for selected fibroids.

High-yield decision flow: Asymptomatic → observe. Symptomatic + wants fertility → myomectomy. Symptomatic + family complete → hysterectomy. Wants uterus preserved, not fertility / unfit → UAE. Submucosal (FIGO 0–2) → hysteroscopic resection. Pre-op anaemia/large → GnRH agonist first.

Indications for treatment / surgery

• Significant menorrhagia → anaemia
• Pressure symptoms (urinary, bowel)
• Rapidly increasing size / postmenopausal growth (rule out sarcoma)
• Subfertility/recurrent miscarriage with cavity-distorting fibroid
• Pain (degeneration, torsion)
• Diagnostic uncertainty (cannot exclude ovarian tumour)

Complications

• Anaemia (commonest) from chronic HMB
• Torsion of pedunculated fibroid → acute abdomen
• Red degeneration (pain, especially pregnancy)
• Infection / suppuration (submucosal, after instrumentation)
• Pressure: hydroureter/hydronephrosis, retention
• Inversion of uterus by submucosal fibroid polyp being expelled
• Pseudo-Meigs / polycythaemia (rare paraneoplastic erythropoietin)
• Malignant change (leiomyosarcoma) — rare
• Obstetric complications (above)

Key differentials

• Adenomyosis (symmetrical bulky tender uterus, thickened junctional zone)
• Ovarian tumour / cyst (mass separate from uterus, can get below it on exam)
• Pregnancy (always exclude with βhCG in reproductive age)
• Leiomyosarcoma (rapid growth, postmenopausal)
• Endometrial polyp (focal intracavitary lesion on SIS)
• Pelvic kidney / full bladder (imaging clarifies)

Recently asked / exam angle

• Commonest type of degeneration → Hyaline. In pregnancy → Red (carneous) degeneration (classic clinical vignette: 2nd trimester pain + low-grade fever, manage conservatively).
• Most symptomatic fibroid = submucosal, even when small → menorrhagia + infertility.
• Investigation of choice = TVS/USG; MRI before UAE; SIS/hysteroscopy for submucosal mapping.
• Drug for pre-operative shrinkage = GnRH agonist (leuprolide); shrinks 35–50%, max 3–6 months due to bone loss.
• FIGO 0/1/2 → hysteroscopic resection; type 0 = pedunculated intracavitary.
• UAE contraindicated in pedunculated subserosal fibroids and when fertility strongly desired.
• MED12 mutation = commonest somatic mutation; HMGA2 (12q14) rearrangement.
• Myomectomy → future pregnancy: risk of uterine rupture → consider elective LSCS.
• Pelvic mass moving with cervix + cannot get below = uterine fibroid.
• Watch the fluid overload/hyponatraemia answer in hysteroscopic myomectomy.

Mnemonic for fibroid symptoms — "BLEED & PRESS": Bleeding (menorrhagia), Lump (mass), Enlargement, Effect on fertility, Dysmenorrhoea; PRESS = pressure on bladder/bowel/ureter.

Mnemonic for degeneration order: "Hyaline Cysts Run Cold Fat" → Hyaline → Cystic → Red → Calcific → Fatty.

Rapid revision

1. Fibroid = commonest benign solid genital tract tumour; oestrogen + progesterone dependent; regresses after menopause.
2. Commonest type = intramural; most symptomatic = submucosal.
3. Commonest degeneration = hyaline; in pregnancy = red (carneous) → conservative management.
4. MED12 is the commonest somatic mutation; HMGA2 / 12q14 rearrangement.
5. Commonest symptom = heavy menstrual bleeding; commonest complication = anaemia.
6. Investigation of choice = transvaginal USG; MRI for planning/before UAE; SIS/hysteroscopy for submucosal.
7. USG: hypoechoic, peripheral ("ring") Doppler vascularity.
8. GnRH agonist = drug for pre-op shrinkage + anaemia correction (3–6 months, bone loss limits).
9. Myomectomy for fertility; hysterectomy is definitive; UAE for uterine preservation without fertility.
10. FIGO 0,1,2 submucosal → hysteroscopic resection; beware fluid overload/hyponatraemia.
11. UAE contraindicated in pedunculated subserosal fibroids & desired fertility; post-embolisation syndrome.
12. Rapid growth/postmenopausal growth → suspect leiomyosarcoma (>10 mitoses/10 HPF, atypia, necrosis).