Endometrium and Myometrium Pathology
Key Takeaways
- Postmenopausal bleeding with endometrium >4–5 mm (no HRT) warrants tissue sampling per guidelines.
- Endometrial polyp appears as focal echogenic pedunculated lesion best seen with saline infusion or 3D.
- Leiomyomas (fibroids) classified by location: submucosal, intramural, subserosal—impact bleeding and fertility.
- Adenomyosis shows heterogeneous myometrium, cystic spaces, asymmetric wall thickening, and vascularity.
- Endometrial hyperplasia thickens endometrium with irregular texture—cannot reliably grade on ultrasound alone.
Quick Answer: Postmenopausal ET >4–5 mm (no HRT) → workup. Polyp = focal pedunculated echogenic mass. Fibroids by FIGO location. Adenomyosis = heterogeneous myometrium, myometrial cysts, asymmetric wall. US cannot exclude hyperplasia/cancer.
Endometrial Thickness: Measurement and Action
Transvaginal sagittal view: measure double-layer endometrium outer-to-outer at thickest point.
| Clinical Scenario | Typical Threshold |
|---|---|
| Postmenopausal bleeding, no HRT | >4–5 mm → biopsy/SHG |
| Postmenopausal on sequential HRT | Higher cutoff (~8 mm context) |
| Premenopausal | Cycle-day dependent—no universal cutoff |
Intracavitary fluid with thick endometrium in postmenopausal patient increases malignancy concern—urgent sampling indication on registry.
Worked Scenario: PMB With 7 mm Endometrium
Focal polypoid area within thickened lining. Correct recommendation: sonohysterography or endometrial biopsy—not "normal postmenopausal endometrium."
Endometrial Polyps
Focal echogenic pedunculated mass, may show vascular stalk on Doppler. Best delineated with sonohysterography (SHG) where polyp projects into saline-distended cavity.
Distinguish diffuse thickening (hyperplasia/cancer concern) from focal polyp.
Leiomyomas (Fibroids) — FIGO Location
| Location | Symptoms | FIGO Types (simplified) |
|---|---|---|
| Submucosal | Heavy bleeding, infertility, cavity distortion | 0–2 (intracavitary/submucosal) |
| Intramural | Bulk, pain | 3–4 |
| Subserosal | Pressure, torsion if pedunculated | 5–7 |
| Cervical/other | Variable | 8 |
Submucosal fibroids impact cavity most—best seen on SHG as broad-based filling defect.
Degeneration types: hyaline (common), cystic, red degeneration (pain in pregnancy—heterogeneous), calcific (shadowing limits posterior assessment).
Adenomyosis
Diffuse or focal disease features:
- Asymmetric myometrial thickening
- Hypoechoic islands, myometrial cysts
- Indistinct endo-myometrial junction
- Fan-shaped shadowing on 3D coronal
vs. fibroid: well-circumscribed, pseudocapsule, often shadowing from discrete mass.
Focal adenomyoma can mimic fibroid—MRI or expert ultrasound may differentiate for surgical planning.
Endometrial Hyperplasia and Cancer
Ultrasound shows irregular thick endometrium, increased vascularity, polypoid mass—cannot grade histology or stage depth on US alone. Biopsy required.
Tamoxifen users: subendometrial cystic spaces and heterogeneous lining—distinct from simple hyperplasia; biopsy per oncology guidelines.
Intrauterine Devices
Echogenic device in cavity; malposition if embedded in myometrium or low in cervix. Document on sagittal and transverse views.
Pyomyoma (Rare)
Infected fibroid—complex mass, fluid, fever postpartum or post-procedure—urgent communication.
Exam Traps
- Measuring single layer when protocol requires double
- Calling all thick postmenopausal endometrium polyps without focal vs diffuse distinction
- Submucosal fibroid missed on TA-only scan
- Adenomyosis called fibroid without junctional zone assessment
- Staging endometrial cancer depth on ultrasound alone
Endometrium questions tie numbers to clinical action—PMB thresholds and SHG indications appear repeatedly on RDMS GYN items.
Premenopausal Abnormal Uterine Bleeding
Premenopausal abnormal uterine bleeding evaluation uses ultrasound for structural causes: polyps, submucosal fibroids, adenomyosis, endometrial hyperplasia. Endometrial thickness alone is less predictive premenopausally—correlate with cycle day and focal vs diffuse findings. Intracavitary fluid with polypoid mass warrants SHG or hysteroscopy referral.
Endometrial Cancer Sonographic Features
Suspicious findings include heterogeneous thick endometrium, irregular vascularity, polypoid mass, and loss of endo-myometrial interface. Cervical involvement may show bulky cervix or fluid. Ultrasound cannot stage depth of invasion reliably—MRI and biopsy required. Never report "benign polyp" when solid vascular mass effaces junctional zone.
Fibroid Degeneration Patterns
| Degeneration | Ultrasound Clues | Clinical Context |
|---|---|---|
| Hyaline | Common; minimal change | Asymptomatic |
| Cystic | Fluid spaces within fibroid | Rapid growth |
| Red | Heterogeneous, painful | Pregnancy, postpartum |
| Calcific | Shadowing | Postmenopausal |
Red degeneration in pregnancy causes acute pain—fibroid may appear heterogeneous with increased vascularity peripherally. Distinguish from adnexal torsion clinically.
FIGO Fibroid Classification (Exam Recognition)
Type 0–2 submucosal (intracavitary, <50% intramural, ≥50% intramural). Type 3–4 intramural. Type 5–7 subserosal. Type 8 other (cervical, parasitic). Submucosal types most impact fertility and bleeding—best evaluated with SHG.
Adenomyosis vs Fibroid: Practical Distinction
Fibroid: discrete mass, pseudocapsule, often shadowing, well-circumscribed. Adenomyosis: diffuse asymmetric thickening, myometrial cysts, indistinct junctional zone, fan-shaped shadowing on 3D coronal. Focal adenomyoma mimics fibroid—MRI helps pre-surgical planning.
Tamoxifen-Related Endometrial Changes
Tamoxifen causes subendometrial cystic spaces and heterogeneous endometrium without necessarily indicating hyperplasia. Oncology protocols guide biopsy thresholds—sonographer documents findings; oncologist manages sampling. Do not apply simple postmenopausal 4–5 mm rule without clinical context.
Intrauterine Synechiae (Asherman)
Intrauterine adhesions appear as echogenic bands crossing cavity—best seen on SHG where bands bridge fluid-filled space. History of D&C, infection, or postpartum curettage supports diagnosis. Causes infertility and amenorrhea—refer for hysteroscopic evaluation.
SHG Indications
Sonohysterography delineates submucosal fibroids and polyps in saline-distended cavity—use when PMB with focal thickening or infertility with normal 2D stripe.
Postmenopausal Bleeding Threshold
ET >4–5 mm without HRT in postmenopausal bleeding prompts biopsy or SHG—registry items tie number to action. Diffuse thickening differs from focal polyp on imaging and management.
Adenomyosis Registry Clues
Adenomyosis shows heterogeneous myometrium, myometrial cysts, and blurred junctional zone—unlike circumscribed fibroid with pseudocapsule. Submucosal fibroid distorts cavity and causes abnormal bleeding—best seen on SHG as broad-based filling defect.
FIGO Location and Symptoms
Submucosal fibroids (FIGO 0–2) most impact fertility and bleeding. Intramural fibroids cause bulk symptoms. Red degeneration in pregnancy appears heterogeneous and painful. Endometrial hyperplasia cannot be graded on ultrasound alone—biopsy required.
IUD and Cavity Assessment
Document IUD position on sagittal and transverse views. Malposition into myometrium or low cervix requires follow-up. Intracavitary fluid with thickened postmenopausal endometrium is an urgent sampling indication on registry clinical stems.
In a postmenopausal patient with vaginal bleeding not on hormone therapy, endometrial thickness greater than approximately 4–5 mm typically prompts:
Adenomyosis on ultrasound is suggested by:
Submucosal leiomyomas are clinically significant because they:
Endometrial polyps are often best confirmed with: