Sonographic detection of cervical incompetence.

The diagnosis of cervical incompetence is based primarily on prior obstetrical history and clinical findings. Sonographic evaluation of the cervix and lower uterine segment does offer an objective means of establishing this diagnosis during gestation. Bulging of the membranes into a partly dilated cervical canal seems to be the most reliable sign of cervical incompetence. Standardization of the scanning techniques and large prospective studies will be necessary in order to determine the value of this diagnostic tool.