Introduction
Transvaginal three-dimensional ultrasound (3D-US) has been used widely in gynecological field ,especially in classification of the uterine malformations(1,2) and diagnosis of uterine adhesion(3,4), which has shown satisfactory concordance with other “gold standard” examinations, such as laparoscopy and hysteroscopy(5,6) and hysterosalpingography(7). The advantage largely arises from its ability to reconstruct the coronal plane of the uterus, which allows for visualization of the outer and inner contour of the uterine walls yielding accurate measurement of the sub-septation length and cavity width(8,9,10). To distinguish between normal uterus cavity and Mullerian duct anomalies or uterine adhesion, a coronal plane would be useful in demonstrating their distinguishing features. Normal uterus was defined as any uterus having either straight or curved fundal and interostial lines but with the internal or external indentation at the fundal midline not exceeding 50% of the uterine wall thickness(11). Internal shape of endometrial cavity, uterine contour, fundal indentation, and septal length can be accurately demonstrated using real-time 3D-US .
Uterine synechiae or adhesions have a significant adverse effect on fertility. The degree of adhesion can be mild, moderate, or severe according on whether adhesions involve one-fourth, one-half, or over three-fourths of the uterine cavity(12). 2D ultrasound may present a diagnostic clue to adhesions within the endometrial cavity through the presence of bands seen within the endometrial echo, particularly with the aid of sonohysterography. However, the true narrowing or “bands” adherent across the cavity is usually well deli­neated on the coronal plane on 3D imaging and 3D-US can predict adhesions and cavity damage with greater accuracy than hysterosalpingogram(13) and obliteration (undetectable endometrium) in 3D-US showed 100% sensitivity to diagnose uterine adhesion(3). According to our experience, shape and area of uterine cavity in the coronal section of the uterus is very important information to distinguish between normal uterus cavity and uterine adhesion(14), just as it plays an important role in evaluating the endometrial cavity post-septal resection or metroplasty(15). So, We propose that it is very necessary to determine a “normal” and more specific uterine cavity using real-time 3D-US measurements in the coronal view, which could help us to determine the degree of uterine adhesion, to judge whether a certain intrauterine device is suitable or not, to calculate the ratio of normal and abnormal uterine cavity in some gynecological diseases, et al.
The purpose of this study was to evaluate uterine cavity measurements in adult women of childbearing age who have normal uterine cavity confirmed by hysteroscopy and to confirm the range of “normal uterine cavity”. It may be a basic research for the clinical application of uterine cavity morphological measurements to judge some gynecological diseases.