LAUSR

Background To determine differences in endometrial cavity anteroposterior diameter, thickness, volume, and diameter lines of uterine body and thickness, and volume of upper, middle, and lower regions of the endometrium in infertile women using a new method for three-dimensional (3D) reconstruction based on two-dimensional (2D) ultrasound images. Methods This retrospective cross-sectional study included a total of 81 infertile women, who underwent 2D ultrasound standard examination. We created 3D models of the uterine body, endometrial cavity, and endometrium based on 2D ultrasound images. The parameters that were measured and analyzed in a 3D plane included volume and diameter lines of endometrial cavity, surface area, thickness, volume, and diameter lines of uterine body, and surface area, thickness, and volume of upper, middle, and lower region of the endometrium. These parameters were used for comparisons between normal and arcuate uterus, between non-pregnant and pregnant infertile women, and between nulliparous and multiparous infertile women. The differences between the different regions of the endometrium and the correlations between age and the parameters were also determined in this study. Results Endometrial cavity length, and middle and lower regions of the endometrial volume in the normal uterus were 39.63±7.61 mm, 1,307.92±1,034.40 mm3, and 653.98±460.41 mm3, respectively. For arcuate uterus, these parameters were 32.96±4.69 mm, 539.89±298.94 mm3, and 347.90±129.61 mm3, respectively. The parameters were significantly higher in normal uterus compared with arcuate uterus (P=0.000, 0.001, and 0.006, respectively). Upper, middle, and lower regions of endometrial thickness in normal uterus were 7.79±3.26, 8.18±3.33, and 6.41±2.60 mm, respectively. Both upper and middle regions of endometrial thickness were significantly greater than the lower regions of endometrial thickness with P=0.009 and P=0.001, respectively. Correlation analysis revealed that age positively correlated with volume of upper endometrial regions (r=0.274, P=0.028). Conclusions This study provides references for the volume and thickness of the endometrium in the different anatomical regions of normal and arcuate uterus. Age mainly affects the upper region of the endometrium. The 3D measurement provides a precise way to quantify the morphological parameters of gynecological diseases.