Ovarian volume throughout life: a validated normative model

Abstract

The measurement of ovarian volume has been shown to be a useful indirect indicator of the ovarian reserve in women of reproductive age, in the diagnosis and management of a number of disorders of puberty and adult reproductive function, and is under investigation as a screening tool for ovarian cancer. To date there is no normative model of ovarian volume throughout life. By searching the published literature for ovarian volume in healthy females, and using our own data from multiple sources (combined n=59,994) we have generated and robustly validated the first model of ovarian volume from conception to 82 years of age. This model shows that 69% of the variation in ovarian volume is due to age alone. We have shown that in the average case ovarian volume rises from 0.7 mL (95% CI 0.4-1.1 mL) at 2 years of age to a peak of 7.7 mL (95% CI 6.5-9.2 mL) at 20 years of age with a subsequent decline to about 2.8 mL (95% CI 2.7-2.9 mL) at the menopause and smaller volumes thereafter. Our model allows us to generate normal values and ranges for ovarian volume throughout life. This is the first validated normative model of ovarian volume from conception to old age; it will be of use in the diagnosis and management of a number of diverse gynaecological and reproductive conditions in females from birth to menopause and beyond.

Figure 1. The validated model of log-adjusted ovarian volume throughout life.

The coefficient of determination indicates that 69% of the variation in human ovarian volumes is due to age alone. Colour bands indicate ranges within standard deviation from mean, within and standard deviations, and outside standard deviations.

Figure 2. Residual distribution for the validated model.

Residuals are the squared differences between data values and predicted values for that age.

Figure 3. Model validation analysis.

The tradeoff between overfit and underfit for one of the five cross-validation data splits. Models with degree less than 11 are unsuitable due to low ; models with degree greater than 17 are unsuitable due to larger differences between test and training mean-squared errors. The degree 14 model is optimal.

Figure 4. The normative validated model of ovarian volume throughout life.

The red line is predicted mean ovarian volume in millilitres for any age. Colour bands indicate ranges within standard deviation from mean, within and standard deviations, and outside standard deviations.

Figure 5. Model residuals for ages up to 10 years.

Residuals are the squared differences between data values and predicted values for that age.

Figure 6. Model residuals for ages between 10 and 30 years.

Residuals are the squared differences between data values and predicted values for that age.

Figure 7. Model residuals for ages over 30 years.

Residuals are the squared differences between data values and predicted values for that age.