Chapter 44 - Pathology of the Ovaries

Clinical Applications of Sonography in Gynecology:

• Characterizes adnexal masses: Differentiates cystic, complex, or solid features.

• Evaluates abnormal uterine bleeding: Helps determine endometrial thickness and structure.

• Assesses infertility: Monitors ovulatory patterns and uterine/ovarian health.

• Monitors follicular development: Tracks growth during ovulation induction.

• Guides procedures: Used for transvaginal aspiration and biopsy.

• Screens for ovarian carcinoma: Assists in early detection.

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Imaging Approaches:

• Transabdominal sonography:

  • Provides a broad anatomical overview.

  • Useful for large masses or when transvaginal access is limited.

• Transvaginal sonography:

  • Offers superior resolution.

  • Better evaluates ovarian architecture, blood flow, and adnexal detail.

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Interpretation Considerations:

• Clinical correlation essential: Findings should be integrated with pelvic examination results.

• Requires collaboration: Effective communication between the referring physician and sonologist is crucial.

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Ovarian Dynamics and Tumor Formation:

• Women ovulate ~400 times during reproductive years.

• Approximately 250,000 follicles undergo stimulation over a lifetime.

• Ovaries are highly active organs and may develop 100+ tumor types (benign or malignant).

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Sonographic Descriptions of Masses:

• Masses are categorized as:

  • Cystic

  • Complex

  • Solid

• Sonographic diagnosis is suggestive but not definitive.

  • Final diagnosis is determined by pathology after surgical excision.

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Primary Role of Sonography:

• To identify abnormalities requiring surgical or medical management.

• While predictive, it is not conclusive without histological confirmation.

Pathology of the Ovaries INTRO

Ovary Overview:

• Paired, almond-shaped organs located on either side of the uterus, adjacent to the lateral pelvic walls.

• Shape: Ellipsoid.

• Orientation: Craniocaudal axis typically parallels the internal iliac vessels (used as a posterior reference point).

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Ovary Positioning Relative to Uterine Orientation:

• Normal (anteflexed midline uterus):
  Ovaries are lateral or posterolateral to the uterus.

• Laterally displaced uterus:
  The ipsilateral ovary may lie superior to the uterine fundus.

• Retroverted uterus:
  Ovaries are positioned laterally and superiorly, close to the uterine fundus.

• Enlarged uterus:
  Ovaries are often displaced superiorly and laterally.

• Post-hysterectomy:
  Ovaries are located more medially and directly above the vaginal cuff.
  May be found high in the pelvis or within the cul-de-sac.

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Imaging Considerations:

• Transvaginal limitations:
  Ovaries that are high or extremely lateral may fall outside the field of view, limiting visualization.

Anatomy of Ovaries

• Echotexture:

  • Homogeneous with a central echogenic medulla.

  • Peripheral anechoic/cystic follicles in the cortex.

• Variation with Age & Menstrual Cycle:

  • Appearance changes depending on hormonal phase and age.

Normal Ovarian Sonographic Features

1. Early Proliferative Phase:

• Multiple follicles begin developing.

• Growth continues until ~day 8–9.

• Stimulated by FSH and LH.

2. Ovulatory Phase:

• One dominant follicle emerges:

  • Grows to 2–2.5 cm.

  • May display cumulus oophorus: 1 mm mural protrusion (eccentric).

  • Sign of imminent ovulation—but not reliably seen.

• Other follicles regress (atresia).

• Follicular cyst forms if fluid in a nondominant follicle is not resorbed.

• Post-ovulation: dominant follicle may collapse, crenulate, or disappear.

• Fluid in the cul-de-sac is common post-ovulation (early luteal peak).

3. Luteal Phase:

• Corpus luteum develops:

  • Appears hypoechoic or isoechoic, often irregular with crenulated echogenic walls.

  • May contain low-level echoes.

  • Occasionally shows ring of fire on color Doppler.

  • Undergoes involution around day 8–9 post-ovulation if fertilization does not occur.

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Other Normal Findings:

• Echogenic Foci:

  • Small (1–2 mm), punctate, nonshadowing, and peripheral.

  • Likely from unresolved cyst walls (below US resolution).

  • Central foci may represent stromal response to past hemorrhage/infection.

  • No follow-up required unless suspicious features present.

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Postmenopausal Ovaries:

• Undergo atrophy; follicles disappear with age.

• Visualization is more challenging due to:

  • Reduced size

  • Absence of follicles

  • Bowel loops mimicking ovary—must check for peristalsis.

• Post-hysterectomy ovaries are also harder to detect:

  • Both transabdominal and transvaginal imaging improve detection rates.

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Ovarian Volume Assessment:

• Best indicator of size due to shape variability.

• Formula:
  Volume = 0.523 × length × width × height (prolate ellipse)

• Normal values (premenopausal):

  • Mean volume: 9.8 ± 5.8 mL

  • May be up to 22 mL

• Postmenopausal criteria:

  • Volume > 8 mL is abnormal.

  • Asymmetry: one ovary > 2× the volume of the other is concerning.

• 3D Ultrasound:

  • Allows precise measurement of ovarian long axis, stromal, and cystic components.

  • Provides enhanced volume accuracy.

Menstrual Cycle Phases (Sonographic Features):

• Oocyte maturation and ovulation are regulated by LH and FSH.

• Ovaries:

  • Produce androgens → converted to estrogens.

  • After ovulation, produce progesterone to support early pregnancy until placental hormone production (~10–12 weeks).

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Follicular Development and Cyst Formation:

• Typically, one follicle grows from ~3 mm to 24 mm over ~10 days during the mid- to late-follicular phase.

• After ovulation:

  • A corpus luteum forms.

  • If ovulation fails or the follicle doesn’t regress, a simple or complex cyst (1–10 cm) may remain.

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Functional Cysts:

• Include follicular cysts and corpus luteum cysts.

• Usually regress within 8 weeks.

• May cause pelvic discomfort or menstrual delay.

• Serial ultrasound helps track resolution.

• Surgical intervention considered if:

  • Cyst >6 cm and persists beyond 8 weeks.

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Management Option:

• Ultrasound-guided needle aspiration is a conservative option for recurrent simple cysts in selected cases.

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Sonographic Criteria for Simple Cysts:

• Thin, smooth walls

• Anechoic contents

• Posterior acoustic enhancement

→ Most are benign and functional in premenopausal women.

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Differential Diagnosis of Simple Adnexal Cysts:

• Functional cyst

• Paraovarian cyst

• Cystadenoma

• Cystic teratoma

• Endometrioma

• Rarely: Tubo-ovarian abscess

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Postmenopausal Considerations:

• Small anechoic cysts may occur and change in size over time.

• Serial sonography used to monitor.

• Surgery recommended for:

  • Cysts >5 cm

  • Cysts with internal septations or solid nodules

Ovarian Function Summary

• Definition:
  A simple cyst that hemorrhages or undergoes involutional changes can appear as a complex mass on ultrasound.

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Common Differential Diagnoses in Reproductive-Age Patients:

1. Ectopic Pregnancy

2. Endometriosis

3. Pelvic Inflammatory Disease (PID)

4. Dermoid cysts (mature cystic teratomas)

5. Other benign neoplasms

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Sonographic Characteristics of Complex Masses:

• Mixed echogenicity (both cystic and solid components)

• Possible presence of:

  • Internal echoes

  • Septations

  • Mural nodules

  • Fluid-fluid levels (especially with hemorrhage)

Complex Ovarian Masses: Overview

SOLID TUMORS