To discuss the accuracy of three-dimensional (3D) sonography in diagnosing arcuate uterus and septate uterus and propose a quantitative indicator in distinguishing arcuate uterus and septate uterus.

Ninety-six patients with suspected congenital uterine malformation underwent 3D sonography to assess uterine anomalies at Obstetrics and Gynecology Hospital of Fudan University from August 2011 to March 2013. Uterine coronal section was reconstructed and measured in omni view imaging mode of 3D sonography. Then qualitative diagnosis and categorization was done. The results were compared with diagnosis of hysteroscopy, hysteroscopy combined with laparoscope to determine the sensitivity, specificity, positive predictive values, negative predictive values and total accuracy of 3D sonography in diagnosing arcuate uterus, partial and complete septate uterus respectively. The variable was created in coronal section of uterus constructed through 3D imaging mode to differentiate arcuate uterus from septate uterus.

There were 33 cases (34.4%, 33/96) of arcuate uterus, 54 cases (56.2%, 54/96) of partial septate uterus and 9 cases (9.4%, 9/96) of complete uterus in 96 cases diagnosed by 3D sonography. The accuracy of 3D sonography in diagnosing arcuate uterus and septate uterus was 86.5%. We concluded that 3D sonography had 100% sensitivity, 82.9% specificity, 60.6% positive predictive value and 100% negative predictive value in the diagnosis of arcuate uterus. The sensitivity of 3D sonography for diagnosis of partial septate uterus was 80.6%, the specificity was 100%, the positive predictive value was 100%, and the negative predictive value was 69.1%. The sensitivity, specificity, positive and negative predictive values of 3D sonography for detecting complete septate uterus were all 100%. The ratio of depth of uterine internal indentation and depth from uterine fundus to the top of internal indentation was more than 50% for septate uterus, while less than 50% for most of the arcuate uterus.

The diagnostic efficiency of 3D sonography in specific uterine malformation is different. The new quantitative indicator maybe helpful in improving the accuracy of 3D sonography in diagnosing arcuate uterus and septate uterus.