To evaluate the feasibility of the use of serial ultrasound measurements of cervical length, membrane protrusion, and dilatation to discriminate between the competent and the incompetent cervix, 107 at-risk patients and 30 control subjects were examined prospectively. Patients were divided into five groups based on treatment and method of diagnosis. Epidemiologic, ultrasound, and outcome data were analyzed. Means and standard deviations for ultrasound measurements were established. Highly significant differences between all prediagnostic and postdiagnostic-pretreatment measurements were found (p less than 0.001). Highly significant differences were also found between all postdiagnostic-pretreatment and postdiagnostic-posttreatment measurements (p less than 0.001). No significant differences between prediagnostic and postdiagnostic-posttreatment measurements were noted. The incidence of preterm delivery was significantly higher among untreated diagnosed patients (p less than 0.01). By combined clinical and ultrasound criteria 51 patients (47.7%) were identified as not having cervical incompetency. Fifty-six patients (52.3%) were diagnosed.
PMID 3513583 3513583 DOI 10.1016/0002-9378(86)90598-3 10.1016/0002-9378(86)90598-3 Michaels et al. 1986, Michaels 1986
Cite this article
Michaels, W. H., Montgomery, C., Karo, J. J., Temple, J. G., Ager, J., & Olson, J. M. (1986). Ultrasound differentiation of the competent from the incompetent cervix: prevention of preterm delivery. American journal of obstetrics and gynecology, 154(3), 537-546. https://doi.org/10.1016/0002-9378(86)90598-3
Michaels WH, Montgomery C, Karo JJ, Temple JG, Ager J, Olson JM. Ultrasound differentiation of the competent from the incompetent cervix: prevention of preterm delivery. Am J Obstet Gynecol. 1986;154(3):537-546. doi:10.1016/0002-9378(86)90598-3
Michaels, William H., et al. "Ultrasound differentiation of the competent from the incompetent cervix: prevention of preterm delivery." American journal of obstetrics and gynecology, vol. 154, no. 3, 1986, pp. 537-546.
Our purpose was to determine whether perioperative transvaginal ultrasonographic evaluation of the incompetent cervix treated with emergency cerclage is predictive of pregnancy outcome. 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-rank test, Spearman rank correlation, 2 x 2 contingency tables, and multiple regression analysis with significance set at p < 0.05. 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 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). 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.
We sought to determine the predictive accuracy for preterm delivery of transvaginal ultrasonography of the cervix between 14 and 24 weeks' gestation in high-risk patients and to determine whether cerclage prevents preterm delivery in patients with ultrasonographic cervical changes. Patients with asymptomatic singleton pregnancies at high risk for preterm delivery were followed prospectively from 14 weeks' to 23 weeks 6 days' gestation with transvaginal ultrasonography of the cervix. The subgroup of patients with either a cervical length of <25 mm or funneling of >25% or both was offered McDonald salvage cerclage, which was performed at the discretion of the patient and the obstetrician. The 2 groups (with and without cerclage) were compared for the primary outcome of preterm delivery at <35 weeks' gestation. One hundred sixty-eight women were followed, including 97 (58%) with >/=1 prior 14- to 34-week preterm deliveries. Of 63 (37. 5%) patients identified as having cervical changes, 23 (37%) had preterm delivery; of 105 patients with no cervical changes, 8 (8%) had preterm delivery (relative risk, 4.8; 95% confidence interval, 2. 3-10.1). The sensitivity, specificity, and positive and negative predictive values of either a short cervix of <25 mm or funneling of >25% or both were 74%, 70%, 37%, and 92%, respectively. Of 63 pregnancies in which there were cervical changes, 39 underwent cerclage and 24 did not. These 2 groups were similar for demographic characteristics, risk factors, and transvaginal ultrasonographic cervical length and funneling but dissimilar for gestational age at identification of cervical changes (18.3 vs 21.2 weeks' gestation in the groups with and without cerclage, respectively; P <.001). Multivariate logistic regression analysis after adjustment for gestational age at cervical changes showed no difference in the rate of preterm delivery between the groups with and without cerclage (odds ratio, 1.1; 95% confidence interval, 0.3-4.6). Stratified analysis of patients identified between 18 and 24 weeks revealed 22 pregnancies with cerclage and 22 pregnancies without cerclage, which was similar for all characteristics studied. The incidence of preterm delivery remained similar (27% vs 23%, respectively; P =.7), as did days from cervical changes to delivery (111 vs 96, respectively; P =.2). Transvaginal ultrasonography of the cervix between 14 and 24 weeks' gestation is a good predictor of preterm delivery in high-risk pregnancies. Cerclage may not prevent preterm delivery in patients identified to be at high risk for this outcome by transvaginal ultrasonography.
Our goal was to study the effect of therapeutic McDonald cerclage on cervical length with the use of transvaginal ultrasonography. Cervical length was measured serially in singleton pregnancies in which there were doubts regarding cervical competence. When shortening of the cervix was substantial before 27 weeks' gestation a McDonald cerclage was applied. Wilcoxon signed rank test was used, and 1-tailed P <.05 was considered significant. In the 34 pregnancies studied, the mean cervical length measured at a mean gestational age of 14 weeks had decreased significantly (P <.0001) from 42 mm (95% confidence interval 38-47) to 21 mm (95% confidence interval 19-23) at a mean gestational age of 20 weeks 5 days, when a cerclage was applied. After the cerclage the mean cervical length increased significantly (P <.0001) to 34 mm (95% confidence interval 30-38) at a mean gestational age of 22 weeks 1 day (95% confidence interval 21 weeks 1 day-23 weeks 2 days). Therapeutic McDonald cerclage results in a longer cervical length as measured by 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.