A method to visualize 3-dimensional anatomic changes in the cervix during pregnancy: a preliminary observational study.

OBJECTIVE

The purpose of this study was to develop a method to visualize 3-dimensional (3D) anatomic changes in the cervix and lower uterine segment during the antepartum period.

METHODS

An observational study of patients with both uncomplicated and complicated pregnancies was performed. To visualize 3D anatomic changes, solid models were constructed from 3D sonographic data. Model construction followed a 3-step protocol. First, 3D transvaginal sonographic data of the cervix and lower uterine segment were obtained. Second, sonographic data were exported to a medical image-processing program, which was used to align 3D sonographic data obtained from a single patient at different time points. Last, sonographic data were used to guide construction of solid models using mechanical design software. Anatomic changes were visualized by comparing solid models constructed from sonographic data obtained at different time points.

RESULTS

From 16 patients who consented, 5 patients were selected for this study. Two to 4 models were derived from each of the 5 patients at 15 to 38 weeks' gestation. To show anatomic changes in the cervix and lower uterine segment, solid models from different time points in the same patient were superimposed. A total of 16 solid models were constructed. In addition, 3D changes associated with second-trimester cervical failure and successful therapeutic cerclage were shown.

CONCLUSIONS

A method to visualize 3D cervical changes is presented, revealing complex anatomic changes in the lower uterine segment, cervical stroma, and cervical mucosa as pregnancy progresses.