Teach me fibroids fr
Reading File
Finding Sources
Finding Sources
Reading File
Reading File
Reading File
Reading File
Reading File
Finding Sources
Reading File
Finding Sources
Reading File
Reading File
Finding Sources
Loading Image
Finding Sources
Reading File
Reading File
I now have comprehensive material. Let me compile the full teaching answer.
Uterine Fibroids (Leiomyomas) - Full Breakdown
What Are They?
A uterine fibroid (leiomyoma, myoma) is a benign monoclonal smooth muscle tumor arising from the myometrium. They are the most common tumor in women, present in up to 40% of reproductive-age women and up to 70-80% by age 50. They are also the most common reason hysterectomy is performed (~240,000 per year in the US).
- Robbins, Cotran & Kumar Pathologic Basis of Disease, p. 937
- Berek & Novak's Gynecology, p. 497
Pathogenesis & Molecular Biology
Fibroids are monoclonal tumors - each one arises from a single smooth muscle cell. Key molecular points:
| Feature | Detail |
|---|---|
| MED12 mutation | Found in ~70% of fibroids. MED12 encodes a subunit of the Mediator complex, which bridges transcription factors to RNA polymerase |
| HMGC / HMGIY | Rearrangements of chromosomes 12q14 and 6p; these encode chromatin-regulating DNA-binding factors |
| Fumarate hydratase (FH) | Germline mutations cause HLRCC syndrome (hereditary leiomyoma + renal cell carcinoma); somatic FH mutations occur in sporadic fibroids too |
| Hormonal dependence | Require estrogen AND progesterone for growth; shrink after menopause; can grow rapidly in early pregnancy |
Fibroids contain large aggregations of extracellular matrix - collagen, elastin, fibronectin, and proteoglycan - in addition to smooth muscle. This explains their firm, rubbery texture.
Risk Factors
| Factor | Effect |
|---|---|
| Black/African American race | 2.9x higher risk vs. white women; earlier onset, more numerous, larger, more symptomatic |
| Family history | 2.5x increased risk in first-degree relatives |
| Obesity | 21% increased risk per 10 kg weight gain; obesity raises biologically available estrogen via increased androgen-to-estrone conversion + decreased SHBG |
| Nulliparity | Increasing parity is protective - postpartum uterine remodeling may cause fibroid involution |
| Red meat/processed meat diet | Associated with increased risk |
| Physical activity | Women with >7 hrs/week of exercise significantly less likely to have fibroids |
| OCP use | No definitive relationship with fibroid formation or growth |
- Berek & Novak's Gynecology, p. 500-502
Classification - FIGO System
The FIGO system categorizes fibroids 0-8 based on location relative to the endometrium and serosa:
| Type | Location | Surgical Approach |
|---|---|---|
| 0 | Intracavitary (pedunculated, entirely in cavity) | Vaginal or hysteroscopic |
| 1 | Submucosal, <50% in myometrium | Hysteroscopic |
| 2 | Submucosal, ≥50% in myometrium | Hysteroscopic or open/lap |
| 3 | Abuts endometrium, no intracavitary component | Open or laparoscopic |
| 4 | Entirely intramural | Open or laparoscopic |
| 5 | Subserosal, ≥50% intramural | Open or laparoscopic |
| 6 | Subserosal, <50% intramural | Open or laparoscopic |
| 7 | Pedunculated subserosal (stalk-attached) | Open or laparoscopic |
| 8 | Extrauterine (cervical, parasitic, broad ligament) | Open or laparoscopic |
Transmural fibroids span both surfaces and are described with both relationships (e.g., "2-5").
- Sabiston Textbook of Surgery, p. (Table 120.5)
- Berek & Novak's Gynecology, p. 506
Morphology (What They Look Like)
Gross:
- Sharply circumscribed, discrete, round, firm, gray-white tumors
- Classic whorled pattern of smooth muscle bundles on cut section
- Range from tiny nodules to massive pelvic tumors
- Large tumors may develop areas of yellow-brown to red softening (degeneration)
Microscopic:
- Bundles of smooth muscle cells resembling normal myometrium
- Uniform cells with oval nucleus, long bipolar cytoplasmic processes
- Scarce mitotic figures (key differentiator from leiomyosarcoma)
- Variants include: leiomyoma with bizarre nuclei, cellular leiomyoma - both benign if low mitotic index
Rare variants:
-
Intravenous leiomyomatosis - extends into vessels, may reach vena cava/right atrium; considered benign
-
Disseminated peritoneal leiomyomatosis - multiple peritoneal nodules; benign despite appearance
-
Robbins, Cotran & Kumar, p. 937
Symptoms
Most fibroids are asymptomatic. When symptomatic, location matters more than size:
| Symptom | Mechanism / Notes |
|---|---|
| Abnormal uterine bleeding (menorrhagia) | Submucosal fibroids are most responsible - distort endometrial cavity |
| Pelvic pressure / bulk symptoms | Large or multiple fibroids pressing on adjacent structures |
| Urinary frequency | Bladder compression |
| Constipation | Posterior fibroid pressure on rectum |
| Dysmenorrhea / dyspareunia | Broad ligament or cervical fibroids |
| Acute pelvic pain | Degeneration (loss of blood supply) or torsion of pedunculated fibroid |
| Infertility / recurrent miscarriage | Submucosal fibroids have the strongest effect; intramural may slightly reduce fertility |
| "Fibroid expulsion" pain | A submucous pedunculated fibroid causes uterine contractions like labor, with cramping + hemorrhage |
There is no strong correlation between the degree of pain and fibroid volume or number. Do not assume a large fibroid = more pain.
Fibroid Degeneration Types
When fibroids outgrow their blood supply, they degenerate:
| Type | Appearance / Notes |
|---|---|
| Hyaline | Most common; fibrotic change |
| Cystic | Liquefaction of hyaline areas |
| Myxoid | Mucoid degeneration |
| Red (carneous) | Common in pregnancy; hemorrhagic infarction; causes acute pain |
| Calcific | Dystrophic calcification, often postmenopausal |
Diagnosis
| Modality | Use |
|---|---|
| Pelvic exam | Enlarged, irregular, firm, non-tender uterus. Works well even for BMI >30 |
| Pelvic ultrasound | First line; differentiates fibroids from adnexal masses; less good for submucosal |
| Saline infusion sonography (SIS) | Better for submucosal fibroids |
| MRI | Gold standard for mapping - most precise for number, size, and position including cavity proximity |
| Hysteroscopy | Directly visualizes and allows treatment of submucosal fibroids |
A definitive diagnosis of submucous fibroids requires SIS, hysteroscopy, or MRI. - Berek & Novak's Gynecology, p. 506
Fibroids & Fertility
A critical clinical pearl:
-
Submucosal fibroids - reduce fertility; removal increases fertility
-
Subserosal fibroids - do NOT affect fertility; removal does NOT increase fertility
-
Intramural fibroids - may slightly reduce fertility; removal does NOT clearly increase fertility
-
Berek & Novak's Gynecology, p. 497
Fibroids in Pregnancy
Most fibroids do not grow during pregnancy despite the hormonal milieu. Complications are possible:
- Increased risk of cesarean section (23% vs 12%)
- Increased risk of preterm delivery (~19% vs 13%)
- Placenta previa (3.5% vs 1.8%)
- Postpartum hemorrhage (8.3% vs 2.9%)
- Fetal malpresentation, uterine inertia
- Red degeneration - painful but self-limiting, treated conservatively
Uterine rupture after myomectomy: Risk during trial of labor is ~0.47% (similar to post-cesarean). Risk is higher if laparoscopic myomectomy was done without proper multilayered closure.
- Berek & Novak's Gynecology, p. 513
- Creasy & Resnik's Maternal-Fetal Medicine
Management
Watchful Waiting
- Appropriate for asymptomatic or mildly symptomatic women
- As women approach menopause, watchful waiting is reasonable - fibroids shrink after menopause and bleeding stops
Medical Treatment
| Drug | Mechanism | Notes |
|---|---|---|
| GnRH agonists (leuprolide) | Hypoestrogenic state causes fibroid shrinkage | Short-term only (bone loss); used preop to shrink fibroids |
| GnRH antagonists (elagolix, relugolix) | Same but oral; given with add-back estradiol + norethindrone to preserve bone | Elagolix 300 mg BID, relugolix 40 mg OD |
| Mifepristone (anti-progesterone) | Reduces fibroid size and symptoms | 5 mg/day x 6 months or 10 mg/day x 3 months; benefits often transient |
| Ulipristal acetate (SPRM) | Selective progesterone receptor modulator | 5-10 mg/day x 13 weeks |
| NSAIDs (naproxen, mefenamic acid) | Symptomatic relief of pain/heavy bleeding | |
| Combined OCPs / progestins / LNG-IUS | Reduce bleeding | Do not significantly shrink fibroids |
Surgical Treatment
| Procedure | Indication | Notes |
|---|---|---|
| Hysteroscopic myomectomy | Submucosal fibroids (Type 0, 1, 2) | Preserves fertility; preferred for cavity fibroids |
| Laparoscopic myomectomy | Subserosal / intramural, fertility-preserving | Needs meticulous multilayer closure |
| Abdominal myomectomy | Large/multiple fibroids, fertility desired | Safe alternative to hysterectomy even for very large uteri |
| Hysterectomy | Definitive; for women not desiring fertility | Can be abdominal, vaginal, or laparoscopic |
| Uterine artery embolization (UAE) | Good option when surgery not desired | Myomectomy has better outcomes than UAE for fertility; 17.5% need subsequent hysterectomy after UAE |
| Focused ultrasound surgery (FUS) | Noninvasive; for selected patients | |
| Laparoscopic radiofrequency ablation | Minimally invasive option |
Power morcellation during laparoscopic myomectomy is restricted due to risk of disseminating occult malignancy.
- Goldman-Cecil Medicine, p. treatment section
- Sabiston Textbook of Surgery, Table 120.5
Malignant Transformation
Transformation to leiomyosarcoma is extremely rare (roughly 1 in 1000-1500 women under 45). Fibroids are not premalignant lesions. A rapidly enlarging uterus almost never indicates sarcoma in a premenopausal woman - sarcomas are more typical in postmenopausal women presenting with pain and bleeding.
Quick Summary Table
| Feature | Key Point |
|---|---|
| Most common tumor in women | Up to 80% by age 50 |
| Origin | Monoclonal smooth muscle cell |
| Key mutation | MED12 (~70%) |
| Hormone dependence | Estrogen + progesterone; shrink after menopause |
| Most symptomatic location | Submucosal (menorrhagia, infertility) |
| Best imaging | MRI for mapping; U/S for initial eval |
| Fertility impact | Only submucosal removal clearly improves fertility |
| Degeneration in pregnancy | Red (carneous) degeneration - painful, conservative |
| Malignant transformation | Extremely rare |
| Definitive treatment | Hysterectomy; fertility-sparing = myomectomy |
Sources used:
- Robbins, Cotran & Kumar Pathologic Basis of Disease, p. 937
- Berek & Novak's Gynecology, pp. 497-513
- Sabiston Textbook of Surgery, Table 120.5
- Goldman-Cecil Medicine, treatment section
- Creasy & Resnik's Maternal-Fetal Medicine
Try again
Asking for Preferences
This is a shared conversation. Sign in to Orris to start your own chat.