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.
PMID 1550160 1550160 DOI 10.1016/0002-9378(92)91358-h 10.1016/0002-9378(92)91358-h
Cite this article
Joffe, G. M., Del Valle, G. O., Izquierdo, L. A., Gilson, G. J., Smith, J. F., Chatterjee, M. S., & Curet, L. B. (1992). Diagnosis of cervical change in pregnancy by means of transvaginal ultrasonography. American journal of obstetrics and gynecology, 166(3), 896-900. https://doi.org/10.1016/0002-9378(92)91358-h
Joffe GM, Del Valle GO, Izquierdo LA, Gilson GJ, Smith JF, Chatterjee MS, et al. Diagnosis of cervical change in pregnancy by means of transvaginal ultrasonography. Am J Obstet Gynecol. 1992;166(3):896-900. doi:10.1016/0002-9378(92)91358-h
Joffe, Gary M., et al. "Diagnosis of cervical change in pregnancy by means of transvaginal ultrasonography." American journal of obstetrics and gynecology, vol. 166, no. 3, 1992, pp. 896-900.
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.
Although shortened cervical length has been consistently associated with spontaneous preterm birth, it is not known when in gestation this risk factor becomes apparent. To determine whether sonographic cervical findings between 16 weeks' and 18 weeks 6 days' gestation predict spontaneous preterm birth and whether serial evaluations up to 23 weeks 6 days' gestation improve prediction in high-risk women. DESIGN, SETTING, Blinded observational study performed between March 1997 and November 1999 at 9 university-affiliated medical centers in the United States in 183 women with singleton gestations who previously had experienced a spontaneous birth before 32 weeks' gestation. Certified sonologists performed 590 endovaginal sonographic examinations at 2-week intervals. Cervical length was measured from the external os to the functional internal os along a closed endocervical canal. Funneling and dynamic cervical shortening were also recorded. Spontaneous preterm birth before 35 weeks' gestation, analyzed by selected cutoff values of cervical length. Forty-eight women (26%) experienced spontaneous preterm birth before 35 weeks' gestation. A cervical length of less than 25 mm at the initial sonographic examination was associated with a relative risk (RR) for spontaneous preterm birth of 3.3 (95% confidence interval [CI], 2.1-5.0; sensitivity = 19%; specificity = 98%; positive predictive value = 75%). After controlling for cervical length, neither funneling (P =.24) nor dynamic shortening (P =.054) were significant independent predictors of spontaneous preterm birth. However, using the shortest ever observed cervical length on serial evaluations, after any dynamic shortening, the RR of a cervical length of less than 25 mm for spontaneous preterm birth increased to 4.5 (95% CI, 2.7-7.6; sensitivity = 69%; specificity = 80%; positive predictive value = 55%). Compared with a single cervical measurement at 16 weeks' to 18 weeks 6 days' gestation, serial measurements at up to 23 weeks 6 days significantly improved the prediction of spontaneous preterm birth in a receiver operating characteristic curve analysis (P =.03). Cervical length assessed by endovaginal sonography between 16 weeks' and 18 weeks 6 days' gestation, augmented by serial evaluations, predicts spontaneous preterm birth before 35 weeks' gestation in high-risk women.
The role of the cervix in the pathogenesis of premature delivery is controversial. In a prospective, multicenter study of pregnant women, we used vaginal ultrasonography to measure the length of the cervix; we also documented the incidence of spontaneous delivery before 35 weeks' gestation. At 10 university-affiliated prenatal clinics, we performed vaginal ultrasonography at approximately 24 and 28 weeks of gestation in women with singleton pregnancies. We then assessed the relation between the length of the cervix and the risk of spontaneous preterm delivery. We examined 2915 women at approximately 24 weeks of gestation and 2531 of these women again at approximately 28 weeks. Spontaneous preterm delivery (at less than 35 weeks) occurred in 126 of the women (4.3 percent) examined at 24 weeks. The length of the cervix was normally distributed at 24 and 28 weeks (mean [+/- SD], 35.2 +/- 8.3 mm and 33.7 +/- 8.5 mm, respectively). The relative risk of preterm delivery increased as the length of the cervix decreased. When women with shorter cervixes at 24 weeks were compared with women with values above the 75th percentile, the relative risks of preterm delivery among the women with shorter 1.98 for cervical lengths at or below the 75th percentile (40 mm), 2.35 for lengths at or below the 50th percentile (35 mm), 3.79 for lengths at or below the 25th percentile (30 mm), 6.19 for lengths at or below the 10th percentile (26 mm), 9.49 for lengths at or below the 5th percentile (22 mm), and 13.99 for lengths at or below the 1st percentile (13 mm) (P < 0.001 for values at or below the 50th percentile; P = 0.008 for values at or below the 75th percentile). For the lengths measured at 28 weeks, the corresponding relative risks were 2.80, 3.52, 5.39, 9.57, 13.88, and 24.94 (P < 0.001 for values at or below the 50th percentile; P = 0.003 for values at the 75th percentile). The risk of spontaneous preterm delivery is increased in women who are found to have a short cervix by vaginal ultrasonography during pregnancy.
Fifty-one consecutive twin pregnancies studied prospectively were compared with 153 consecutive control twin gestations that were concurrently delivered, but chosen retrospectively. Study patients were managed by a protocol that used weekly ultrasound surveillance combined with clinical assessment. Control subjects were not managed by protocol or ultrasound surveillance. Seven of 51 study patients (13.7%) were diagnosed as having cervical incompetency before 30 weeks' gestation (range 18-28 weeks, mean 24). In comparison, 14 of 153 controls (9.2%) delivered before 30 weeks' gestation (range 18-29 weeks, mean 25). The mean cervical length, dilatation, and membrane herniation (funneling) at diagnosis were 1.9, 2.2, and 3.6 cm, respectively, for patients with cervical incompetency. There was a significant difference in perinatal mortality. All study twins survived, whereas nine control subjects delivered at a mean gestational age of 22.7 weeks, with a loss of 17 infants. Life table analysis demonstrated that a significantly greater proportion of controls delivered very low birth weight, premature twins. The use of ultrasound and clinical criteria to select patients for cerclage placement helped prevent birth of the youngest and smallest twins and significantly decreased perinatal mortality in the study group. Routine cerclage placement is not recommended for twin gestations, but multifetal gestations may benefit from ultrasound surveillance for cervical incompetency.