The significance of transvaginal ultrasonographic evaluation of the cervix in women treated with emergency cerclage

OBJECTIVE: Our purpose was to determine whether perioperative transvaginal ultrasonographic evaluation of the incompetent cervix treated with emergency cerclage is predictive of pregnancy outcome. STUDY DESIGN: Twenty-nine women who underwent emergency cerclage at 16 to 26 weeks of gestation had transvaginal ultrasonographic evaluation of the cervix within 48 hours before and after surgery and at least three times thereafter until 28 weeks of gestation. The following measurements were obtained: (1) funnel width, (2) funnel length, (3) endocervical canal length, (4) the distance between the internal and external os, (5) upper cervix (length of closed endocervical canal above the cervical cerclage), (6) lower cervix (endocervical canal length below suture), and (7) cervical index (1 + Funnel length/Endocervical canal length). Values are reported as the median in millimeters, and statistical analysis was performed by use of the Mann-Whitney U test, Wilcoxon signed-lank test, Spearman rank correlation, 2 x 2 contingency tables, and multiple regression analysis with significance set at p < 0.05. RESULTS: Cerclage procedures resulted in significant improvement in postoperative median measurements of funnel width (15 vs 4.0 mm, p < 0.0001), funnel length (29 vs 3 mm, p < 0.0001), and endocervical canal length (2 vs 27 mm, p < 0.0001). There was a significant relationship between gestational age at delivery and the following measurements: preoperative funnel width (r = -0.51, p = 0.007), postoperative endocervical canal length (r = 0.39, p = 0.04), length of the lower cervix (r = 0.39, p = 0.038), and the cervical index (r = -0.39, p = 0.038). An upper cervical length <10 mm was a good predictor of delivery before 36 weeks of gestation, sensitivity 85.7% (12/14), specificity 66.7% (10/15), positive predictive value 70.6% (12/17), negative predictive value 83% (10/12), and Fisher's exact p = 0.008. Postoperatively all patients had upper cervical lengths <10 mm by 28 weeks of gestation. Preoperative digital assessments of cervical dilatation before surgery did not correlate with gestational age at birth (r = -0.031, p = 0.36). CONCLUSIONS: In cases of cervical incompetence treated with emergency cerclage, perioperative transvaginal ultrasonographic assessment of the cervix reveals that the procedure results in improved ultrasonographic status of the cervix and that the ultrasonographic cervical findings before and after surgery correlate with pregnancy outcome.