A comparison of two- and three-dimensional ultrasonographic methods for evaluation of ovarian follicle counts and classification of polycystic ovarian morphology

Follicle counts differ by ultrasonographic method. Counts by two-dimensional real-time ultrasonography may be problematic given its propensity to misclassify polycystic ovaries.

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VOLUME 115, ISSUE 3, P761-770, MARCH 01, 2021


Heidi Vanden Brink, Ph.D., Adrienne J. Pisch, B.S., Marla E. Lujan, Ph.D. 



To determine the level of agreement across assessments of follicle number per ovary (FNPO) and classifying of polycystic ovarian morphology (PCOM; FNPO ≥25) with the use of various real-time (RT) and off-line two-dimensional (2D) and three-dimensional (3D) ultrasonographic methods.


Method comparison study.


University-based clinical research unit.


Sixteen women with and without PCOM.


Thirty-two ovaries were analyzed with the use of eight ultrasonographic methods: 2D-Grid (reference method), 2D-RT, 2D-RT with Grid, multiplanar view (MPV), MPV-RT, tomographic ultrasound imaging (TUI), TUI-RT, and semiautomated volume calculation (SonoAVC).

Main Outcome Measure(s)

FNPO, PCOM status, and time to obtain FNPO. Clinical feasibility, defined as the time taken to obtain FNPO, also was evaluated.


2D-RT overestimated FNPO versus 2D-Grid (3 ± 9 follicles) owing to overcounting in non-PCOM ovaries (6 ± 6 follicles). However, systematic bias was not detected when a grid overlay was incorporated (2D-RT with Grid). SonoAVC underestimated FNPO (−3 ± 5 follicles), particularly in PCOM ovaries (−4.1 ± 5.0 follicles). No bias in FNPO was detected between MPV, TUI, or TUI-RT versus 2D-Grid. 2D-RT significantly misclassified ovaries as PCOM. All methods except MPV took less time to complete FNPO assessments compared with 2D-Grid.


Variability in FNPO across ultrasonographic methods limits their interchangeable use, particularly when a precise metric is needed. 2D-RT may be problematic owing to its propensity to misclassify PCOM. 2D-RT with Grid and MPV-RT could represent clinically feasible alternatives to obtain FNPO and classify PCOM. Efforts to reduce variation in FNPO will clarify the relevance of PCOM in women’s health.

Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders.