A new method using vaginal ultrasound and transfundal pressure to evaluate the asymptomatic incompetent cervix.

OBJECTIVE: To evaluate the ability of ultrasound with transfundal pressure to detect the incompetent cervix in pregnant women at risk for this condition.

METHODS: One hundred fifty pregnant women with no prior pregnancy losses were scanned transabdominally, and 31 asymptomatic pregnant women with a prior history of cervical incompetency or risk for this condition were scanned transvaginally. The control patients were scanned once between 16-24 weeks, and the patients at risk were studied 73 times between 8-25 weeks. After evaluating the cervix and its internal os, transfundal pressure was applied. Cervical cerclages were placed for cervical funneling and shortening in response to transfundal pressure or for a grossly incompetent cervix on ultrasound evaluation.

RESULTS: Transfundal pressure elicited no changes in the internal cervical os of the 150 control patients, of whom 141 delivered at term, two miscarried at 22 and 23 weeks, and seven delivered prematurely (4.7%). Fourteen of the 31 pregnancies at risk for cervical incompetency revealed opening of the internal os or descent of the fetal membranes with transfundal pressure. Thirteen of these 14 pregnancies were treated with cerclage, with nine (64%) proceeding to term, three (21%) delivering prematurely, and two (14%) aborting. The one patient who did not receive a cerclage also aborted. In six cases, the cervix and its internal os appeared normal but the membranes protruded into the endocervical canal in response to transfundal pressure.

CONCLUSION: Application of transfundal pressure during transvaginal ultrasound evaluation of the cervix and its internal os may assist in detecting the asymptomatic incompetent cervix.