Ultrasound anatomy in reproductive age
During the reproductive period, the ultrasound appearance of the uterine adnexa has strictly defined physiological parameters. The ovaries are defined as ovoid-shaped structures characterized by medium echogenicity. It should be noted that adjacent structures—the fallopian tubes—are normally not visualized at all on transvaginal ultrasound (TVUS) (they become visible only when exudate accumulates).
A key element of a normal ovary is its follicular apparatus. Small hypoechoic (dark) inclusions are clearly visualized at the periphery of the organ during scanning. These are antral follicles, whose normal diameter is 2–3 mm. Their number can reach up to ten.
An important diagnostic criterion is ovarian volume. In women of reproductive age, it is not a static value and varies within a fairly wide range—from 3.2 to 12.3 cm³. The exact value directly depends on the current phase of the menstrual cycle. Any disproportionate increase in volume or change in the normal ovoid structure indicates the development of a pathological process (e.g., oophoritis).
Dynamic monitoring and age-related changes
Performing dynamic ultrasound echography allows the gynecologist to evaluate physiological processes in detail. Thanks to dynamic ultrasound, the physician can:
- track how the dominant follicle develops step-by-step;
- reliably record the moment of ovulation;
- monitor the stage of formation and development of the corpus luteum.
With the onset of postmenopause, the sonographic appearance changes radically. During the first year after the cessation of menstruation, the ovarian volume decreases significantly and is normally no more than 3 cm³. Its internal structure completely loses the follicular apparatus, becoming homogeneous (uniform), and the overall echogenicity of the tissue increases noticeably.
Blood flow evaluation and 3D modeling
For an in-depth study of physiological changes throughout the cycle, standard scanning is supplemented with color Doppler mapping (CDM) and pulsed-wave Doppler (PD), which are most commonly performed via the transvaginal approach.
The evaluation of intraovarian hemodynamics is based on the analysis of maximum systolic and diastolic blood flow velocity curves. The main calculated parameters are:
- RI — resistance index;
- PI — pulsatility index;
- S/D — systolic-diastolic ratio.
Deviation of these parameters from normative values indicates pathology. Studying blood flow is extremely important for detecting neoangiogenesis (formation of new blood vessels), which accompanies tumor growth. For example, in malignant ovarian neoplasms, the most informative marker is a drop in RI below 0.4.
To obtain the most detailed information, three-dimensional (3D) ultrasound is used. This advanced technique has an important advantage: it constructs an image simultaneously in three mutually perpendicular planes (which is physically unavailable in classical 2D ultrasound). This allows for an extremely precise evaluation of the internal structure of the organ and the architecture of its vascular bed.
Class and exam questions
What should the normal size of follicles be on ultrasound?
Up to 10 antral follicles are identified at the periphery of a normal ovary (appearing as hypoechoic inclusions), and their normal diameter ranges from 2 to 3 mm.
How does the structure of the ovary change in postmenopause?
In the first year of postmenopause, the organ's volume decreases to 3 cm³, and the follicular apparatus completely disappears. The structure becomes homogeneous, and tissue echogenicity increases.
Are the fallopian tubes visible on a normal ovarian ultrasound?
No, normally the fallopian tubes are not visualized on transvaginal ultrasound. They become visible only when pathology develops, such as the accumulation of fluid or pus within them.
What is dopplerography used for during adnexal examination?
It helps evaluate physiological changes in blood flow across cycle phases and detect pathological neoangiogenesis in tumors (in malignant processes, the RI drops below 0.4).
What else to study on this topic
- Changes in ovarian structure in oophoritis and involvement in tubo-ovarian masses
- Ultrasound signs of hydrosalpinx and pyosalpinx
- Dynamics of the M-echo (endometrium) in various phases of the menstrual cycle
- CT signs of pelvic inflammatory disease
- Application of hysterosalpingo-contrast sonography (HyCoSy) to create an acoustic window
- Fitz-Hugh-Curtis syndrome as a complication of pelvic infections
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