GENERAL GYNECOLOGY Is ovarian volume estimation reliable when compared with true volume? Gurkan Bozdag, MD; Mehmet Coskun Salman, MD; Sezcan Mumusoglu, MD; Zuhal Yapici, MD; Serdar Gunalp, MD OBJECTIVE: We aimed to evaluate the agreement of 2-dimensional (2D) and 3-dimensional (3D) ultrasonography (USG) with true ovarian volume (OV), as calculated precisely after oophorectomy. STUDY DESIGN: A total of 46 ovaries from 30 patients were prospectively enrolled. Preoperatively, all ovaries were assessed by 2D and 3D USG for volume estimation and results were compared with true OV that was calcu- lated with Archimedes’ principles following oophorectomy. RESULTS: The correlation coefficients of 2D and 3D USG with true OV were similar (0.65 vs 0.67, respectively). The mean bias (upper and lower limits of agreement) between 2D and true OV was 1.41 (–3.84 to 6.66) mL. The respective figure for 3D and true OV were 0.33 (– 4.71 to 5.37) mL. While estimation by 2D USG brought 18% larger, 3D USG re- vealed 11% smaller values than the true OV. CONCLUSION: Three-dimensional OV estimation might present im- provement in means of lower mean bias than 2D USG. Key words: agreement, correlation, formula, ovarian volume, ultrasonography Cite this article as: Bozdag G, Salman MC, Mumusoglu S, et al. Is ovarian volume estimation reliable when compared with true volume? Am J Obstet Gynecol 2012;206:44.e1-4. T he validity of ovarian volume (OV) has been commonly investigated in reproductive endocrinology and gyne- cologic oncology. According to the avail- able data, the main associated conditions in which the value of OV has been inves- tigated are: (1) ovarian cancer screening with or without biochemical markers, 1 (2) definition of polycystic ovary appear- ance, 2,3 and (3) prediction of ovarian reserve. 4 Traditionally, 2-dimensional (2D) trans- vaginalultrasonography (USG) is generally the first choice device for calculating OV. In this approach, after scaling all 3 dimen- sions of the ovary via USG, a mathematical formula is used that assumes the ovary is prolate-ellipsoid in shape, which is probably not valid in real life. In fact, OV determined by USG was found to be at least 27% smaller than the true volume, which is subsequently calcu- lated postoperatively in patients un- dergoing oophorectomy for cryopreser- vation. 5 Although 3-dimensional (3D) USG and magnetic resonance imaging have been assumed to enhance the detec- tion of polycystic ovaries, 3 there is a pau- city of data regarding their relevance in determining true OV. In this prospective study, we aimed to analyze the validity of preoperative 2D and 3D USG in determining OV, when compared to true volume, as calculated after oophorectomy. MATERIALS AND METHODS A total of 30 consecutive patients who were scheduled for any gynecologic sur- gery and were willing to enroll in the study were prospectively recruited. Only those ovaries assumed to be normal after both USG and the entire operation were analyzed (n = 46). Of the 30 women, with the exception of 1 who underwent vaginal hysterectomy and unilateral sal- pingo-oophorectomy, the remaining pa- tients were treated with total abdominal hysterectomy and unilateral or bilateral salpingo-oophorectomy. The reasons for hysterectomy were myoma (n = 14), ovarian pathology (n = 6), both myoma and ovarian pathology (n = 2), endome- trium cancer without ovarian involvement (n = 2), endometrial hyperplasia (n = 2), persistent premenopausal bleeding (n = 2) or postmenopausal bleeding (n = 1), and stress incontinence (n = 1). Any ova- ries bearing a follicle 10 mm in diameter or cyst noticed either under USG (n = 8 ovaries, having any degree of echogenicity) or during the surgery (n = 6 ovaries) were excluded. All 2D and 3D examinations with en- docavitary probe (5-9 MHz) were per- formed by a single physician (Z.Y.) at a maximum of 24 hours prior to the oper- ation with Voluson e (GE Healthcare, Is- tanbul, Turkey). The 2D OV was esti- mated with 3 available dimensions, namely maximal longitudinal (a), an- teroposterior (b), and transverse (c) di- ameters, as previously reported. 3,5-8 The 3D OV was processed at the same visit with virtual organ computer-aided anal- ysis imaging program using plane A and 60-degree rotational steps. Following oophorectomy with lapa- rotomy, the true OV was calculated im- mediately in the operating room by dif- ferent physicians (G.B. or M.C.S.) who were blinded to estimations of the ob- server performing the USG assessment. Initially, a sterile sperm tube was filled with 0.9% sodium chloride (NaCl) up to From the Department of Obstetrics and Gynecology, Hacettepe University School of Medicine, Hacettepe, Ankara, Turkey. Received Jan. 3, 2011; revised May 31, 2011; accepted July 13, 2011. The authors report no conflict of interest Reprints: Gurkan Bozdag, MD, Department of Obstetrics and Gynecology, Hacettepe University School of Medicine, Sihhiye, 06100, Ankara, Turkey. gbozdag@hacettepe.edu.tr. 0002-9378/$36.00 © 2012 Mosby, Inc. All rights reserved. doi: 10.1016/j.ajog.2011.07.020 Research www. AJOG.org 44.e1 American Journal of Obstetrics & Gynecology JANUARY 2012