What does a normal transvaginal pelvic ultrasound with dominant follicles noted on each ovary indicate for fertility?

Interpretation of Normal Transvaginal Pelvic Ultrasound with Dominant Follicles

A normal transvaginal pelvic ultrasound with dominant follicles on each ovary indicates normal ovulatory function and suggests good fertility potential. 1

Understanding Dominant Follicles and Their Significance

Dominant follicles are a normal finding on transvaginal ultrasound (TVUS) and represent the development of mature follicles that will eventually release an egg during ovulation. Their presence on both ovaries indicates:

• Active follicular development
• Normal ovarian function
• Potential for ovulation
• Good ovarian reserve

The presence of dominant follicles differs significantly from polycystic ovary morphology (PCOM), which is characterized by multiple small follicles (typically ≥20 follicles measuring 2-9mm) and/or increased ovarian volume (≥10ml). 1, 2

Ultrasound Assessment of Normal Ovaries

When evaluating a transvaginal ultrasound showing dominant follicles:

• Dominant follicles: Typically measure >10mm in diameter and indicate approaching ovulation 1, 2
• Normal ovarian volume: Generally <10ml per ovary 1, 2
• Follicle distribution: In normal ovaries, follicles are fewer in number and may include a dominant follicle, versus the peripheral "string of pearls" pattern seen in PCOM 3
• Endometrial appearance: Should also be assessed, as a three-layer endometrial pattern is consistent with normal hormonal stimulation 1, 4

Fertility Implications

The presence of dominant follicles on both ovaries suggests:

1. Normal ovulatory function: The development of dominant follicles indicates the ovaries are responding appropriately to hormonal signals 1

2. Good fertility potential: Dominant follicles suggest eggs are maturing properly and have the potential to be released during ovulation 2

3. Absence of PCOS indicators: The finding differs from polycystic ovary morphology, which would show numerous small follicles (≥20) measuring 2-9mm 1, 2

Important Considerations and Potential Pitfalls

• Timing of ultrasound: The presence of dominant follicles is dependent on the menstrual cycle phase. Ideally, ultrasound for fertility assessment should note the timing relative to the last menstrual period 1

• Follicle size interpretation: Dominant follicles typically reach 18-25mm before ovulation. The exact size of the dominant follicles should be noted as it helps determine proximity to ovulation 2

• Bilateral dominant follicles: While normal, the presence of dominant follicles on both ovaries simultaneously could potentially indicate hyperovulation, which might increase the chance of fraternal twins if conception occurs 1

• Ultrasound technique matters: Transvaginal ultrasound with high-frequency transducers (≥8MHz) provides the most accurate assessment of follicular development 1, 5

When Further Evaluation May Be Needed

Despite normal findings, additional evaluation might be warranted if:

• There is a history of irregular menstrual cycles
• Clinical signs of hyperandrogenism are present
• Infertility persists despite normal ultrasound findings
• Other reproductive hormones are abnormal

In these cases, a comprehensive fertility workup may be indicated, including hormonal assessment and potentially hysterosalpingography to evaluate tubal patency. 1