Establishing the intercycle variability of three-dimensional ultrasonographic predictors of ovarian reserve.

Objective: To estimate the intercycle variability of antral follicle counts (AFCs) and ovarian volume, as measured by using three-dimensional ultrasound, and to compare these to the variation in basal FSH levels.

Design: Prospective study.

Setting: University-based assisted conception unit.

Patient(s): One hundred women undergoing two cycles of assisted reproductive technology.

Intervention(s): Transvaginal three-dimensional ultrasound assessment and venepuncture in the early follicular phase of the menstrual cycle, immediately before assisted reproductive technology.

Main Outcome Measure(s): Intercycle variability of AFC, ovarian volume, and basal FSH.

Result(s): The limits of agreement between cycles were +4.03 and -3.71 for AFC, +2.67 and -3.03 cm(3) for ovarian volume, and +4.36 and -4.52 IU/L for FSH levels. The AFC showed the least degree of variation, with a range of 0.48 times its own mean, in contrast to corresponding values of 0.73 and 1.29 for ovarian volume and basal FSH levels, respectively. The intraobserver variability for AFC and ovarian volume and the intraassay variability for FSH were 0.37, 0.17, and 0.42 times the mean of those respective variables.

Conclusion(s): The AFC demonstrates a lower intercycle variability than do ovarian volume and basal FSH level. The observed intercycle variability of the AFC may primarily be caused by observer variability, and the true biological variation may be minimal.