THE NATURAL-HISTORY OF A POSITIVE RESPONSE TO TRANSFUNDAL PRESSURE INWOMEN AT RISK FOR CERVICAL INCOMPETENCE

OBJECTIVE: Our purpose was to observe the evolution of the endocervica l canal length in women at risk for cervical incompetence after a posi tive response to transfundal pressure. STUDY DESIGN: Ten women at risk for cervical incompetence had a midtrimester cervical evaluation with transvaginal ultrasonography and transfundal pressure. With a transva ginal probe, the endocervical canal length was first measured. Transfu ndal pressure was then applied and the endocervical canal length was r emeasured. All patients had a positive response to transfundal pressur e as defined by a decrease in endocervical canal length after applicat ion of transfundal pressure. At the initial evaluation the digital exa mination of the cervix had revealed a closed and long cervix in all 10 cases. In 9 of the 10 patients repeat examinations were performed unt il the endocervical canal length progressively shortened to <10 mm or the digital examination revealed a dilated cervix. The endocervical ca nal lengths after application of transfundal pressure from the first a nd last examination were compared. One patient was lost to follow-up, but the obstetric outcome was available. RESULTS: The median time inte rval between the first and final examination was 7 (2 to 20) days in 9 of the patients. The median (range) gestational age at the first and final examination was 19.0 (15 to 22) weeks (n = 10) and 20.5 (18 to 2 4) weeks (n = 9), respectively. There was significant shortening of th e endocervical canal length from the first to the last examination; 12 .2 (4 to 20) mm (n = 10) versus 0.0 (0 to 9.5) mm (n = 9), p = 0.008. Six patients had membranes at the external cervical os before applicat ion of transfundal pressure at the last examination. The one patient l ost to ultrasonographic follow-up had a pregnancy loss at 23 weeks of gestation, 6 weeks after a positive response to transfundal pressure. CONCLUSION: In patients at risk for cervical incompetence, shortening of the endocervical canal length in response to transfundal pressure r equires treatment with a cervical cerclage because it is associated wi th progressive cervical changes over 1 to 3 weeks.