Tehran University of Medical Sciences Journal of Family and Reproductive Health 1735-8949 20 2 2026 09 13 101 107 Mina Jafarabadi Vali-E-Asr Reproductive Health Research Center, Family Health Research Institute, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran Mitra Alizadeh Vali-E-Asr Reproductive Health Research Center, Family Health Research Institute, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran Elahe Rezayof Vali-E-Asr Reproductive Health Research Center, Family Health Research Institute, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran Leila Sahebi Vali-E-Asr Reproductive Health Research Center, Family Health Research Institute, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran Yas Goudarzi Farzanegan 1, National Organization for Development of Exceptional Talents, Tehran, Iran 2026 06 13 2026 07 11 Objective: Given the invasive and costly nature of reference diagnostic methods like hysteroscopy , this study aimed to compare the diagnostic accuracy and the dimensional measurement agreement of uterine cavity lesions between two-dimensional saline infusion sonography (2D SIS) and three-dimensional saline infusion sonography (3D SIS) against the gold standard of hysteroscopy and histopathology. Materials and methods: This cross-sectional study was conducted on 283 female patients who were candidates for hysteroscopy. Prior to surgery, all patients underwent blinded evaluations via 2D SIS and 3D SIS performed by experienced radiologists, and the type, number, location, and size of the lesions were recorded. Subsequently, all patients underwent diagnostic hysteroscopy and tissue sampling for pathological evaluation as the gold standard. Diagnostic performance metrics were calculated, and the dimensional agreement of the lesions between the modalities was statistically evaluated using the Intraclass Correlation Coefficient (ICC) and Bland-Altman analysis. Results: The mean age of the patients was 35.9 ± 8.1 years. Histopathological examination confirmed endometrial polyps in 20.5% and leiomyomas in 17.3% of the patients. Compared to 2D SIS, 3D SIS demonstrated higher sensitivity (83.15% vs. 78.65%), higher specificity (93.30% vs. 91.75%), and higher overall diagnostic accuracy (90.11% vs. 87.63%). In the dimensional agreement analysis, 3D SIS showed an excellent correlation (ICC = 0.927) and a negligible mean systematic error (mean bias: -0.26 mm; 95% limits of agreement: -7.77 to 7.25 mm) compared to hysteroscopy. In contrast, 2D SIS systematically overestimated lesion dimensions compared to hysteroscopy (mean bias: 2.21 mm) and exhibited the widest limits of agreement when compared with 3D SIS (-8.76 to 13.70 mm). Conclusion: 3D SIS is an accurate, non-invasive tool that lacks systematic bias in measuring uterine tumors, offering superior performance compared to the 2D SIS method. Given its high overall accuracy, 3D SIS can be utilized as a reliable first-line diagnostic tool, significantly reducing the necessity for unnecessary diagnostic hysteroscopies and the associated financial burdens on the healthcare system. https://jfrh.tums.ac.ir/index.php/jfrh/article/view/3771 https://jfrh.tums.ac.ir/index.php/jfrh/article/download/3771/760