Statistical analysis
All statistical descriptions and analyses were conducted using SPSS
Statistics 17.0 (IBM, Chicago, IL, USA). The one-sample
Kolmogorov-Smirnov test was first applied to check normal distribution.
Continuous measurements are presented as mean± standard deviation (SD),
median (minimum-maximum) and 95% medical reference range. Mean±1.96SD
and P2.5-P97.5 were defined as 95% reference range for the normally
distributed data (lateral indentation angle, cornual angle, lateral
indentation depth and uterine cavity surface area) and non-normally
distributed data (endometrial thickness, uterine cavity length, uterine
cavity width and internal os width), respectively. Regression analyses
were used to screen the factors that influence the area of uterine
cavity. Variables with univariate P≤0.1 were included in the multiple
linear regression model for simple linear regression analysis.
Statistical significance was set at P < 0.05.