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Uterus Ultrasound

Uterine ultrasound is the primary imaging modality for evaluating gynecological pathology due to its excellent visualization of anatomy, real-time assessment of the endometrium, lack of ionizing radiation, and cost-effectiveness in resource-limited settings[cite: 1]. While powerful, it remains operator-dependent and has limitations in evaluating deep myometrial invasion compared to MRI[cite: 1].

Uterine Anatomy

Layers of the Uterus

  • Endometrium: The inner mucosal layer; its echogenicity varies with the menstrual cycle.
  • Myometrium: The middle muscular layer, exhibiting homogeneous mid-level echogenicity.
  • Serosa: The outer layer, visualized as a thin hyperechoic line.

Normal Measurements

  • Nulliparous: 6-8 cm length, 3-5 cm width, 2-3 cm AP.
  • Multiparous: 8-10 cm length, 4-6 cm width, 3-5 cm AP.
  • Postmenopausal: $\le 6$ cm length, $\le 2$ cm AP (without HRT).
  • Endometrial thickness: Varies by cycle phase (4-16 mm) and is $\le 4$ mm in postmenopausal patients.
Normal uterus sagittal
Midline sagittal view showing normal endometrial stripe, myometrium, and cervix.
Proliferative phase
Proliferative phase endometrium with a triple-layer appearance.
Secretory phase
Secretory phase endometrium with thick, uniform hyperechoic appearance.

Clinical Indications

  • Common Indications: Abnormal uterine bleeding, pelvic pain, suspected fibroids or adenomyosis, infertility, and postmenopausal bleeding[cite: 1].
  • Clinical Scenarios: Evaluation of bulk symptoms from fibroids, dysmenorrhea in adenomyosis, endometrial cancer screening, and congenital anomalies[cite: 1].

Scanning Technique

  • Preparation: Full bladder for transabdominal scans; empty bladder for transvaginal scans.
  • Approach: Perform systematic sagittal and transverse sweeps. The optimal time for endometrial assessment is during days 5-10 of the menstrual cycle.
  • Equipment: Use curvilinear transducers (3-5 MHz) for transabdominal imaging and endovaginal transducers (5-9 MHz) for TVS.

Pathological Findings

Uterine fibroid
Well-defined hypoechoic fibroid with posterior acoustic shadowing.
Adenomyosis
Diffuse uterine enlargement with heterogeneous myometrium and cysts.
Endometrial polyp
Focal endometrial thickening with a feeding vessel (pedicle sign).
Endometrial cancer
Thickened, irregular endometrium with increased chaotic vascularity.
Uterus didelphys
Uterus didelphys showing two separate cavities and two cervices.
Retained products
Heterogeneous endometrial mass with vascularity post-delivery.

References

  1. American College of Radiology (ACR). (2023). ACR Appropriateness Criteria® Abnormal Uterine Bleeding. Journal of the American College of Radiology, 20(1S), S78-S92.
  2. Salen, P., et al. (2023). Gynecologic Ultrasound (4th ed.). Elsevier.
  3. European Society of Urogenital Radiology (ESUR). (2022). Guidelines on Gynecological Ultrasound. European Radiology, 33(3), 261-279.
  4. Timor-Tritsch, I. E. (2023). Uterine Ultrasound. In: Rumack, C. M., & Levine, D. (Eds.), Diagnostic Ultrasound (6th ed., pp. 112-128). Elsevier.
  5. African Society of Uroradiology (ASUR). (2023). Consensus Guidelines on Gynecological Ultrasound in African Populations. African Journal of Radiology, 28(1), 45-60.