Recently, many researches suggested that 2D US is insufficient for defining the true sagittal plane of uterine cervix. When the cervix is bent or curved, it is difficult to get a perfect sagittal section but rather mid oblique image by 2D US. Only 3D US allows us to evaluate the cervix in the coronal section and reproduce images in many cut. Coronal section of the cervix is especially useful in evaluating cervical funneling. Diagnosing internal orifice dilatation, asymmetrical, flattened or fissure-like cervices is possible. 3D US favors a more detailed study of cervical anatomy and biometry than 2D US. Cervical evaluation by 3D multiplanar sections can be added in the screening for preterm labor.

Three-dimensional (3D) imaging combined with power Doppler, theoretically provides the possibility to assess the volume and quantify the power Doppler signal in the whole target organ, whereas, information from 2D US on vascularization and blood flow is restricted to a single subjectively chosen 2D plane. The measurement of cervical indices is reproducible and may be used in clinical practice and research to determine the changes of the cervical morphology and vascularization in pregnancy. Consequently, further studies of 3D ultrasound imaging of the cervix in pregnancy and clinical correlations to obstetrical events are required for better understanding the physiology and functional pathophysiology of the cervix during pregnancy.