Journal of Ultrasound in Medicine, Vol 14, Issue 10 719-724, Copyright © 1995 by American Institute of Ultrasound in Medicine
Monitoring the effacement of the uterine cervix by transperineal sonography: a new perspective
M. Zilianti, A. Azuaga, F. Calderon, G. Pages and G. Mendoza
Maternidad Concepcion Palacios, Departamento de Investigaciones Cientificas, Caracas, Venezuela.
The objective of this study is to monitor the process of effacement of the
uterine cervix and demonstrate that transperineal sonography is the
appropriate technique for this purpose. Eighty-six patients with normal,
term pregnancies were studied at the beginning of labor. Transperineal
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 cervical os. When the
funneling process reached the lower end of the cervix, both orifices fused,
completing the process of effacement. The dilatation of the external os,
which remained stationary during initial phase, increases very quickly once
the effacement has been completed. Transperineal sonography efficiently
imaged the changes described here.
