MONITORING THE EFFACEMENT OF THE UTERINE CERVIX BY TRANSPERINEAL SONOGRAPHY - A NEW PERSPECTIVE

The objective of this study is to monitor the process of effacement of the uterine cervix and demonstrate that transperineal sonography is t he appropriate technique for this purpose. Eighty-six patients with no rmal, term pregnancies were studied at the beginning of labor. Transpe rineal sonography was performed in transverse and longitudinal planes. After the initial examination, patients were reexamined several times during a 1 to 4 hour period. We observed a progressive shortening of the canal and the synchronous opening of a funnel-shaped internal cerv ical os. When the funneling process reached the lower end of the cervi x, both orifices fused, completing the process of effacement. The dila tation of the external os, which remained stationary during initial ph ase, increases very quickly once the effacement has been completed. Tr ansperineal sonography efficiently imaged the changes described here.