Comprehensive Notes: Pathology of the Uterus (Vagina, Cervix, Endometrium)

THE VAGINA

• Anatomy overview

  • Vagina runs anterior and caudal from the cervix, located between the urinary bladder (anterior) and rectum (posterior).
  • Relationships shown: Anterior fornix, posterior fornix, cervix, urethra, bladder, rectum, pouch of Douglas.
  • Location clinically: Visualized on imaging and palpation; serves as a conduit between external genitalia and uterus.

• Gartner's Duct Cyst

  • Most common cystic lesion in the vagina.
  • Size descriptors (example from slide): Vol = $1.59\,\text{cm}^3\,, D1=1.68\,\text{cm}, D2=0.75\,\text{cm}, D3=2.41\,\text{cm}$.
  • Pathogenesis notes: No Mullerian inhibiting substance (MIS) or androgens involved in formation.
  • Developmental origin (schematic): Bladder, gonads (female duct/Müllerian), male duct/Wolffian, urogenital sinus; MIS androgens influence determine whether a Gartner duct cyst forms or not.
  • Clinical relevance: Recognized as the most common vaginal cystic lesion.

• Imperforate hymen and vaginal obstruction

  • The most common congenital abnormality of the female genital tract.
  • Obstruction can cause accumulation of fluid (hydrocolpos), blood (hematocolpos), or pus (pyocolpos).
  • Imaging/clinical correlation: Obstruction leads to distention of vagina and uterus; May present in adolescence with cyclic symptoms.

• Hematocolpos (example case)

  • 12-year-old with hematocolpos: blood in the vagina due to obstruction.

• Vaginal masses and imaging roles

  • Solid masses in the vagina are rare.
  • Sonography is not used for diagnosing vaginal carcinoma, but can aid in staging.
  • Most vaginal cancers are vaginal adenocarcinoma or rhabdomyosarcoma; solid mass may show necrosis.

• Translabial or transperineal sonography technique

  • Useful visualization of vagina and cervix.
  • Recommended probe: 5.0- to 7.5-MHz sector or curvilinear transducer.
  • Procedure: Covered with sterile probe cover and applied to vestibule of vagina in sagittal plane; partial bladder filling can aid visualization of the cervical area.
  • Imaging planes: Rotation obliquely counterclockwise yields coronal images and defines a second plane.
  • Patient positioning: Hips elevated (similar to transvaginal approach) helps displace pelvic gas and improves anatomy identification.
  • Limitations and workarounds: Elevation of hips, better perineal probe application, or orientation changes can overcome limitations.

• The vaginal cuff

  • Seen in hysterectomy patients post-surgery.
  • Upper size limit of normal vaginal cuff is $2.1\,\text{cm}$.
  • A cuff larger than normal or with well-defined mass or high echogenic areas warrants suspicion for malignancy, especially in patients with prior cancer history.
  • Nodular areas in vaginal cuff may reflect post-radiation fibrosis.

• Rectouterine recess (Pouch of Douglas)

  • The most posterior and inferior reflection of the peritoneal cavity; located between rectum and vagina.
  • Frequently a site for intraperitoneal fluid collections.
  • TVS can detect as little as $5\,\text{mL}$ of fluid.
  • Normal fluid in the cul-de-sac can be seen during all phases of the menstrual cycle in asymptomatic women.
  • Pathologic collections may be associated with ascites, blood from ruptured ectopic pregnancy, hemorrhagic cyst, or pus from infection.
  • Pelvic abscesses and hematomas can occur in the cul-de-sac.

THE CERVIX

• Anatomy and position

  • The cervix lies posterior to the bladder, between the lower uterine segment and vaginal canal.
  • The cervical canal extends from the internal os (joins the uterine cavity) to the external os (projects into the vaginal vault).
  • The cervix comprises the cylindrical portion of the uterus that enters the vagina and measures $2\text{-}4\,\text{cm}$ in length.
  • After examining the uterine cavity, the probe should be slowly pulled back to image internal and external os.

• Nabothian cysts

  • Benign cervical cysts, generally < $2\,\text{cm}$, can be multiple.
  • Result from obstructed dilated endocervical glands due to chronic inflammation; usually asymptomatic.

• Cervical polyps

  • May present with irregular bleeding.
  • Benign hyperplastic protrusions of endocervical or ectocervical epithelium.
  • Chronic inflammation is a likely etiologic factor.
  • May be pedunculated (projecting from cervix) or broad-based.
  • Ultrasound visualization may be variable depending on location.
  • Sonohysterography with fluid infusion enhances visualization.
  • More common in late middle age.

• Cervical myoma (fibroid)

  • Small percentage occur in the cervix.
  • In small tumors, patients may be asymptomatic; as they enlarge, can cause bladder or bowel obstruction.
  • May be pedunculated and prolapse into the vaginal canal.

• Cervical stenosis

  • Acquired obstruction of the cervical canal at internal or external os.
  • Causes include radiation therapy, prior cone biopsy, postmenopausal cervical atrophy, chronic infection, laser or cryosurgery, cervical carcinoma.
  • In postmenopausal patients, stenosis may be asymptomatic but can produce a distended, fluid-filled uterus.
  • In premenopausal patients, may present with abnormal bleeding, oligomenorrhea/amenorrhea, cramping, dysmenorrhea, or infertility.

• Cervical carcinoma

  • Detected primarily via screening (Pap smears); many early lesions are asymptomatic.
  • Advanced cervical cancer usually clinically evident.
  • Squamous cell carcinoma is the most common type.
  • Precursors are cervical dysplasias classified as mild, moderate, or severe.
  • Affects women of menstrual age; clinical presentation includes vaginal discharge or bleeding.
  • Sonographic findings can include retrovesical mass, ureteral obstruction, or bladder invasion.

PATHOLOGY OF THE UTERUS

• General anatomy and imaging context

  • The uterus lies in the true pelvis between the urinary bladder anteriorly and the rectosigmoid colon posteriorly.
  • Uterine position is variable and changes with bladder and rectal distention.
  • The body of the uterus may lie obliquely to either side of midline.
  • TVS is excellent for assessing retroverted/retroflexed uterus due to proximity of the fundus to the posterior surface.
  • Size and shape of a normal uterus vary with age, hormonal status, and parity.
  • 3D reconstruction of uterus and endometrium is recommended when possible (AIUM guidelines).

• Anomalies and variations of the uterus

  • DES exposure: T-shaped uterus caused by in utero exposure to diethylstilbestrol.
  • Agenesis (uterine agenesis/aplasia): complete absence of vagina, cervix, uterus, and fallopian tubes due to bilateral arrest of Müllerian development; associated with MRKH syndrome.
  • Uterine duplication variants: didelphic uterus with two uteri and two cervices (double uterus).
  • Bicornuate uterus: two horns with a single cervix or rudimentary septum may be present; diagnosis aided by imaging.
  • Septated uterus: most common Müllerian anomaly; septum fails to dissolve after fusion of Müllerian ducts.
  • Distinguishing bicornuate vs septate: 3D imaging or detailed ultrasound techniques; use of color Doppler at the fundus can help (two sets of arcuate arteries suggest bicornuate; one set around the outer edge suggests sep­tate).

• Vaginal anomalies (Müllerian/urogenital sinus origins)

  • Congenital vaginal anomalies can include vaginal atresia, vaginal septa, vaginal duplication, or other Müllerian/urogenital sinus malformations.

• Differential considerations for an enlarged uterus

  • pregnancy, postpartum state, leiomyoma (fibroids), adenomyosis, bicornuate or didelphic uterus.
  • Uterine tumor considerations include leiomyoma and carcinoma.

• Leiomyomas (fibroids)

  • Most common gynecologic tumors; occur in ~$20 ext{-}30\%$ of women >30 years.
  • More common in African American women.
  • Histology: composed of spindle-shaped smooth muscle cells in a whorled pattern; variable fibrous tissue; potential for various histologic subtypes due to degeneration.
  • Clinically: uterine enlargement, profuse/prolonged bleeding, pelvic pain; may cause infertility by distorting endometrial cavity or fallopian tubes.
  • Growth patterns by location:
  • Submocousal: protrudes into endometrial cavity; heavy bleeding, infertility; may erode into cavity.
  • Intramural: within myometrium; can enlarge and press on adjacent organs; most common location.
  • Subserosal: arise from myometrium and project extrinsic (exophytic); may compress adjacent structures.
  • Hormonal dynamics: estrogen-dependent; size may increase during pregnancy; often little change during pregnancy; rarely grow in postmenopausal women unless supplemented with hormones; rapid growth in postmenopausal patients on hormone replacement therapy is concerning for neoplasm.
  • Clinical manifestations: irregular bleeding patterns (menometrorrhagia), pelvic pressure, pain.
  • Role in infertility: may distort endometrial cavity or fallopian tubes.
  • Imaging features: may appear as well-defined hypoechoic/complex masses within the uterus on ultrasound; may be pedunculated.
  • Treatment options:
  • For infertility or submucosal fibroids: myomectomy is often the treatment of choice.
  • For heavy bleeding: hormonal suppression, endometrial ablation, uterine artery embolization (UAE), high-intensity focused ultrasound (HIFU).

• Uterine calcifications

  • Most commonly due to calcifications within leiomyomas.
  • Less commonly due to arcuate artery calcifications at the periphery of the uterus.
  • Calcifications can indicate underlying disease such as diabetes mellitus, hypertension, or chronic renal failure.

• Adenomyosis

  • Ectopic occurrence of endometrial tissue within the myometrium; more common in the posterior aspect.
  • Benign disease.
  • Can be diffuse or focal; diffuse causes bulky, globally enlarged uterus; focal adenomyosis is adenomyoma.
  • Sonographic pattern: bulky uterus with thickened posterior myometrium; indistinct endometrium–myometrium border in involved areas; myometrial cysts; occasionally a focal lesion resembling a mass.
  • Epidemiology: about 60% of women with adenomyosis experience abnormal uterine bleeding (hypermenorrhea, menorrhagia, irregular, acyclic bleeding).
  • Symptoms: pelvic pain, dysmenorrhea, heavy bleeding.
  • Pathophysiology and imaging notes: islands of endometrial tissue within myometrium produce hemorrhage; lesions described as Swiss cheese or honeycomb pattern; lesions may be small beyond the resolution of ultrasound; posterior acoustic enhancement is more prominent due to fluid content.

• Arteriovenous malformations (AVMs) of the uterus

  • Vascular plexus of arteries and veins without intervening capillary network; rare; usually involve the myometrium.
  • Etiology: congenital or acquired (trauma, surgery, gestational trophoblastic disease).
  • Clinical presentation: menorrhagia with blood loss and anemia in women of childbearing age.
  • Critical diagnosis: dilation and curettage can cause catastrophic hemorrhage if AVMs are present.
  • Sonographic features: serpiginous, anechoic tubular spaces with areas of color aliasing; spectral Doppler shows high-velocity, low-resistance arterial flow with concurrent high-velocity venous flow and arterial component.

• Uterine leiomyosarcoma

  • Rare, solid tumor arising from myometrium or endometrium; most often located in the fundus.
  • Demographics: most common in women aged 40–60 years.
  • Clinical behavior: rapid growth.
  • Rare pediatric variant: sarcoma botryoides (grapelike clusters of tumor mass).
  • Ultrasound features: may resemble fibroids or endometrial carcinoma; can be solid or mixed solid/cystic.
  • Red flag: rapid enlargement in peri-/postmenopausal age raises concern for malignancy.

• Endometrium: thickness measurement and normal variations

  • Endometrium is the hypoechoic layer of the inner myometrium surrounding the endometrium; it thickens and increases in reflectivity through the menstrual cycle and sheds during menses.
  • In preovulatory and postovulatory periods (roughly days 2–5 and days 21–28), an inner hypoechoic edema layer appears.
  • Endometrium should be measured perpendicular to the long axis of the uterus; calipers placed at the maximum anterior–posterior diameter of the outer borders.
  • The echogenic halo surrounding the endometrium should not be included in measurement as it represents the inner compact layer of the myometrium.
  • Any fluid present should not be included in endometrial measurements.
  • AIUM 2009 pelvic sonography guidelines recommend 3D reconstruction of uterus and endometrium when feasible.
  • Endometrial thickness norms vary by phase and patient; if measurements exceed thresholds, further evaluation is warranted.

• Endometrial pathologies and related imaging/diagnostic considerations

  • Endometrial hyperplasia
  • The most common cause of abnormal uterine bleeding.
  • Associated with unopposed estrogen stimulation.
  • Can be a precursor to endometrial carcinoma.
  • Sonographic finding: abnormal thickening of the endometrium; threshold values roughly > $14\text{ mm}$ typically prompts biopsy; on estrogen replacement therapy (HRT), threshold may be > $15\text{ mm}$.
  • Endometrial hyperplasia: clinical notes
  • Postmenopausal women with thickened endometrium may require biopsy; prior to menopause, large thickening can be associated with infertility or abnormal bleeding.
  • Endometrial hyperplasia: terminology and text
  • Long endometrium and proliferative patterns described; 3-line proliferative phase vs secretory endometrium depicted to illustrate cycles.
  • Endometrial polyps
  • May be asymptomatic or cause uterine bleeding.
  • Histology: overgrowths of endometrial tissue covered by epithelium.
  • Sonographic appearance: nonspecific thickening or a round echogenic mass within the endometrial cavity; can be pedunculated or broad-based or have a thin stalk.
  • More common in perimenopausal and postmenopausal women; menstruating women may have menometrorrhagia or infertility.
  • Endometritis
  • Infection within the endometrium; thickening or fluid may indicate infection.
  • Typically associated with PID, postpartum state, or instrumentation of the uterus.
  • In pelvic infection, uterus may serve as conduit for infection to tubes and adnexa.
  • Postpartum risk factors include prolonged labor, vaginitis, PROM, or retained products of conception.
  • Clinical feature: intense pelvic pain.
  • Sonographic findings: prominent or irregular endometrium with some endometrial fluid; pus may appear as echogenic debris within the cul-de-sac; enlarged ovaries with multiple cysts due to periovarian inflammation.
  • Tubo-ovarian complex and abscess progression
  • Worsening endometritis may dilate the fallopian tubes into fluid-filled, folded tubular structures with well-defined walls.
  • Periovarian adhesions may fuse inflamed tube and ovary.
  • Advanced progression forms a tubo-ovarian abscess: complex multilo­culated mass with septations, irregular shaggy margins, and scattered internal echoes.
  • Intrauterine synechiae (Asherman’s syndrome)
  • Endometrial adhesions occurring after uterine curettage or pelvic surgery; may cause infertility or recurrent pregnancy loss.
  • Sonographic signs: bright echoes within the endometrial cavity.
  • Best seen in the secretory phase when endometrium is more hyperechoic or in a gravid uterus as a hyperechoic band traversing anterior–posterior.
  • Endometrial carcinoma
  • The most common gynecologic malignancy in North America; most common in postmenopausal patients.
  • Clinical presentation often vaginal bleeding; however only a minority of postmenopausal bleeding cases are cancer.
  • Risk factors: replacement estrogen therapy; in premenopausal women, anovulatory cycles and obesity also contribute.
  • Early change: thickened endometrium.
  • Sonographic findings: thickened endometrium (> $4 ext{--}5\text{ mm}$ is suspicious for cancer). Myometrial invasion is a key diagnostic criterion; invasion shows as irregular central endometrial interface with echogenic/hypoechoic invasion patterns and infiltration of hyperdense structures in myometrium.
  • Hydrometra or hematometra can result from endometrial cancer obstructing the canal.
  • Halo (subendometrial halo) presence usually indicates superficial invasion; obliteration of halo suggests deeper invasion.

• Tamoxifen and endometrium

  • Tamoxifen is a nonsteroidal anti-estrogen used in breast cancer therapy (adjuvant setting) and has estrogen receptor antagonistic effects in some tissues but partial agonist effects in others (endometrium).
  • Effects on endometrium include irregular fluid-filled uterine cavity and potential endometrial pathology even in postmenopausal women.
  • Case example: irregular endometrial cavity in an 86-year-old patient on hormonal therapy after breast carcinoma.

• Postmenopausal vaginal bleeding (PMVB)

  • PMVB defined as vaginal bleeding after at least 12 months of period cessation.
  • Common causes: estrogen therapy, endometrial atrophy (most common without HRT), endometrial carcinoma, cervical carcinoma, estrogen-producing ovarian tumor.

• Postmenopausal endometrium imaging and guidelines

  • Endometrium thickness measurement is a key diagnostic metric; ultrasound features are used to triage biopsy decisions.
  • Endometrium and tamponade are assessed with SIS (sonohysterography) to distend the uterine cavity with saline for better visualization of endometrial pathology.

• Sonohysterography (Saline Infused Sonography, SIS)

  • Valuable for evaluating abnormally thickened endometrium and causes of infertility by distending the endometrial cavity with saline to distinguish growths and abnormalities.
  • Premenopausal timing: typically performed in mid-cycle, usually days 6–10.
  • Rationale for SIS use: prevents displacing early pregnancy and reduces artifact from stagnant blood.
  • In women with irregular cycles, perform soon after cessation of bleeding when possible.
  • In postmenopausal women, can be performed anytime or shortly after a monthly bleed if on sequential hormone therapy.

• Endometrial thickness measurement specifics (imaging technique)

  • Measure perpendicular to the long axis of the uterus.
  • Calipers placed at the maximum anterior–posterior diameter of the outer borders.
  • Exclude the hyperechoic inner myometrial halo and any fluid in measurement.
  • 3D reconstruction of uterus and endometrium recommended when possible.

• Practical imaging notes

  • 3D sonography and coronal views can improve visualization of uterine anatomy (especially for anomalies).
  • 3D reconstruction is recommended by AIUM 2009 pelvic sonography guidelines where available.

• Case-based/illustrative items and prompts

  • Didelphic uterus: imaging and measurement approaches may be assessed via case questions.
  • Symptom-causing benign fibroid treatment choice and rationale may be asked in exams.

• Quick differential reminders

  • For thickened endometrium: consider hyperplasia, polyps, endometritis, adhesions, retained products, trophoblastic disease, carcinoma.
  • For endometrial fluid: consider endometritis, retained products, pelvic inflammatory disease, cervical obstruction, tamoxifen effects.
  • For endometrial shadowing: consider gas from abscess, intrauterine device, calcified fibroids or vessels, retained products.

• Summary of commonly tested entities

  • Vagina: Gartner’s duct cyst; imperforate hymen; vaginal cuff assessment.
  • Cervix: Nabothian cysts; cervical polyps; cervical myomas; cervical stenosis; cervical carcinoma and precursors.
  • Uterus: anomalies (agenesis, didelphic, bicornuate, septate, DES effect); fibroids (submucosal, intramural, subserosal) and their management; calcifications; adenomyosis; AVMs; leiomyosarcoma.
  • Endometrium: hyperplasia, polyps, endometritis, synechiae, carcinoma; Tamoxifen effects; PMVB.
  • Imaging strategies: TVS, transperineal/translabial approaches, SIS, 3D ultrasound, color Doppler for vascular anomalies.

CASE STUDY AND PRACTICAL APPLICATIONS

• Practical scan technique reminders

  • When scanning for didelphic uterus or complex Müllerian anomalies, leverage 3D imaging to visualize two horns and vascular patterns.
  • For suspected postmenopausal bleeding with thick endometrium, consider SIS and biopsy if thickness exceeds thresholds, especially if > $14 ext{ mm}$ (unopposed estrogen) or > $15 ext{ mm}$ with hormone therapy.

• Key clinical decision points

  • A rapidly enlarging fibroid in a peri/postmenopausal patient warrants evaluation for leiomyosarcoma.
  • Abnormal uterine bleeding in a postmenopausal patient on tamoxifen requires careful evaluation for endometrial pathology, including hyperplasia or carcinoma.
  • AVMs are high-risk lesions; avoid curettage and consider targeted imaging and management.

• Images and interpretation prompts (as seen in slides 26–27)

  • Visual recognition prompts (e.g., identifying didelphic uterus on imaging) emphasize measuring and characterization of uterine anatomy.

• Reference measurements and thresholds (summary)

  • Normal vaginal cuff: up to $2.1\,\text{cm}$.
  • Endometrium thickness thresholds: suspicious typically > $4 ext{--}5\,\text{mm}$; higher thresholds in postmenopausal patients or with risk factors (e.g., >$14\,\text{mm}$ for hyperplasia biopsy; >$15\,\text{mm}$ on HRT).
  • Uterine dimensions vary with age, parity, and hormonal status; multiparity can increase size by roughly $1.0\text{ to }2.0\,\text{cm}$ over time.

• Important clinical correlations

  • Postpartum infection risk factors and imaging findings.
  • Clinical significance of endometrial invasion by carcinoma and how ultrasound signs of invasion guide staging.
  • The role of hormonal regimens in the endometrial pathology risk profile (estrogen alone vs combined estrogen/progestin vs sequential regimens).

• Quick reference glossary

  • Hydrometra: accumulation of serous fluid in the uterus due to obstruction.
  • Hematometra: accumulation of blood in the uterus due to obstruction.
  • Pyometra: accumulation of pus in the uterus due to obstruction or infection.
  • Hematometrocolpos: collection of menstrual blood in the uterus and vagina due to obstruction.
  • Hydrometrocolpos: accumulation of mucus/serous fluid in the uterus and vagina.
  • Synechiae: intrauterine adhesions (Asherman’s syndrome).

• Ethical and practical implications

  • Early detection of endometrial carcinoma through Pap screening is limited; imaging plays a critical role in evaluation of abnormal bleeding in high-risk populations (postmenopausal, tamoxifen users).
  • Management of fibroids and adenomyosis requires balancing fertility desires, symptom burden, and risks of invasive procedures.
  • AVMs pose a high risk of catastrophic hemorrhage; accurate diagnosis is crucial to avoid unsafe interventions.

IMAGING AND DIAGNOSTIC GUIDELINES SUMMARY

• Transvaginal ultrasound (TVS) is the primary modality for baseline assessment of uterine and endometrial pathology; transabdominal approaches complement TVS where needed.
• Translabial/transperineal ultrasound is a useful alternative when transvaginal access is limited or for certain neonatal/pediatric assessments.
• 3D ultrasound and coronal views enhance evaluation of uterine anomalies and endometrial assessment; recommended by AIUM guidelines when feasible.
• Sonohysterography (SIS) enhances endometrial cavity visualization by distending with saline, improving detection of polyps, submucosal fibroids, and hyperplasia; premenopausal timing is typically mid-cycle; postmenopausal timing can be flexible depending on clinical context.

Notes on terminology used in slides:

• Hydrometra: fluid in uterus due to obstruction.
• Hematometra: blood in uterus due to obstruction.
• Hydrometrocolpos/Hematometrocolpos: fluid/blood in uterus and vagina after obstruction.
• Pyometra: pus in uterus.

Quick reference: common pathologies at a glance

• Vagina: Gartner’s duct cyst; imperforate hymen causing hydrocolpos/hematocolpos/pyocolpos.
• Cervix: Nabothian cysts; cervical polyps; cervical myoma; cervical stenosis; cervical carcinoma and precursors.
• Uterus: Müllerian anomalies (agenesis, didelphic, bicornuate, septate, DES exposure T-shaped uterus); fibroids (submucosal, intramural, subserosal); adenomyosis; AVMs; leiomyosarcoma.
• Endometrium: hyperplasia, polyps, endometritis, synechiae, carcinoma; tamoxifen effects; PMVB; SIS utility.