Diagnosis of cervical change in pregnancy by means of transvaginal ultrasonography.

There are no absolute objective diagnostic criteria for cervical incompetence. Abdominal and endovaginal ultrasonographic assessment of endocervical length, both of which have been associated with technical problems, have been used to establish the diagnosis. Cervical cerclage may be useful in preventing silent cervical dilatation; however, no prospective trials with and without cerclage have been performed when endocervical shortening has been demonstrated by ultrasonography.