Impact of right–left differences in ovarian morphology on the ultrasound diagnosis of polycystic ovary syndrome

Right–left differences in ovarian morphology can impact the ultrasound diagnosis of polycystic ovary syndrome. Use of follicle number per ovary, even if in a single ovary, is recommended.

Volume 112, Issue 5, Pages 939–946


Brittany Y. Jarrett, Ph.D., Heidi Vanden Brink, M.Sc., Eric D. Brooks, M.D., Kathleen M. Hoeger, M.D., Steven D. Spandorfer, M.D., Roger A. Pierson, Ph.D., M.S., Donna R. Chizen, M.D., Marla E. Lujan, Ph.D., M.Sc.



To assess right–left differences in ultrasonographic markers of ovarian morphology and determine the impact on the diagnosis of polycystic ovarian morphology (PCOM).


A cross-sectional study of data collected from 2006 to 2018.


Academic clinical research centers.


Women with polycystic ovary syndrome (PCOS; n = 87) and controls (n = 67).



Main Outcomes Measure(s)

Follicle number per ovary (FNPO), follicle number per cross-section (FNPS), and ovarian volume (OV) were assessed in both ovaries using transvaginal ultrasonography. PCOM was identified based on recent international consensus guidelines or proposed diagnostic thresholds.


Overall, mean right–left differences were two follicles for FNPO, one follicle for FNPS, and 2 mL for OV. FNPO showed the strongest correlation between ovaries. Its assessment in a single ovary did not impact the diagnosis of PCOM in women with PCOS. However, there were differences in the probability of unilateral versus bilateral PCOM based on FNPS and OV in both groups.


FNPO is the most reliable unilateral marker of PCOM in light of right–left differences in ovarian morphology. Use of FNPS or OV to define PCOM is discouraged when only one ovary is visualized.

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