OC17.02: Quantitative analysis of number and size of antral follicles: a comparison of real-time two-dimensional and automated three-dimensional ultrasound

Antral follicle counts are an important marker of ovarian reserve; however there is no consensus as to which follicles should be included in this count. Smaller antral follicles may be more indicative of the functional ovarian reserve as larger follicles are often atretic. This study was designed to compare real-time two-dimensional (2D) ultrasound to automated three-dimensional (3D) ultrasound for the measurement of antral follicle number and size. 26 subjects aged < 40 underwent transvaginal ultrasound in the early follicular phase of the menstrual cycle. A real-time 2D scan of both ovaries was performed and each antral follicle measured by taking the mean of two diameters. 3D datasets of both ovaries were then acquired and analysed using SonoAVC, shown to be a reliable method. The time taken to measure the size of all antral follicles in both ovaries was recorded in seconds for each technique. Antral follicles were grouped into 6 categories according to their relative size to reflect the current medical literature: 2.0–5.0 mm, 2.0–6.0 mm, 2.0–8.0 mm, 2.0–9.0 mm, 2.0–10 mm, and 1.0–10 mm. A paired t-test or Wilcoxon signed ranks test was used to analyse the data dependent on its distribution. The total AFC and number of follicles in all 6 categories were significantly lower with SonoAVC than with real-time 2D ultrasound (p < 0.05). SonoAVC measured more antral follicles measuring 1.0–1.99 mm than real-time 2D (P = 0.002) whilst, 2D measured more follicles measuring 3.0–3.99mm (P = 0.019) and 4.0–4.99mm (P = 0.013) than those measured with SonoAVC. The time taken to measure the number and size of the antral follicles was significantly less with sonoAVC than with the 2D technique (P < 0.001). Fewer antral follicles are evident with SonoAVC. The clinical value of this remains to be determined but the automated technique is significantly quicker than real-time 2D ultrasound which may overestimate the number and size of follicles.