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Transvaginal sonographic cervical length for the prediction of spontaneous preterm birth in twin pregnancies: a systematic review and metaanalysis

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Objective

To assess the accuracy of transvaginal sonographic cervical length (CL) in predicting spontaneous preterm birth in women with twin pregnancies.

Study Design

Systematic review and metaanalysis of predictive test accuracy.

Results

Twenty-one studies (16 in asymptomatic women and 5 in symptomatic women) with a total of 3523 women met the inclusion criteria. Among asymptomatic women, a CL ≤20 mm at 20-24 weeks' gestation was the most accurate in predicting preterm birth <32 and <34 weeks' gestation (pooled sensitivities, specificities, and positive and negative likelihood ratios of 39% and 29%, 96% and 97%, 10.1 and 9.0, and 0.64 and 0.74, respectively). A CL ≤25 mm at 20-24 weeks' gestation had a pooled positive likelihood ratio of 9.6 to predict preterm birth <28 weeks' gestation. The predictive accuracy of CL for preterm birth was low in symptomatic women.

Conclusion

Transvaginal sonographic CL at 20-24 weeks' gestation is a good predictor of spontaneous preterm birth in asymptomatic women with twin pregnancies.

Section snippets

Materials and Methods

This systematic review was conducted following a prospectively prepared protocol and reported using recently recommended guidelines for systematic reviews of diagnostic test accuracy.6

Results

The searches produced 1027 citations of which 314 were considered relevant (Figure 1). In all, 293 studies were excluded, the main reasons being the inclusion of only singleton pregnancies (37%), not a test accuracy study (27%), and the lack of original data (24%). A total of 21 studies, including 3523 women with twin pregnancies,18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 met the inclusion criteria of which 15 (3001 women) provided data for metaanalyses.

Comment

This systematic review and metaanalysis gives the strongest evidence to date that transvaginal sonographic measurement of CL at 20-24 weeks of gestation is a good predictor of spontaneous preterm birth in asymptomatic women with twin pregnancies. A CL ≤20 mm predicts spontaneous preterm birth at <32 and <34 weeks of gestation, whereas a CL ≤25 mm predicts preterm birth at <28 weeks of gestation. A “normal” CL, however, was less accurate in predicting the absence of preterm birth because the

Acknowledgments

We are very grateful to Dr Percy Pacora for his assistance in obtaining the articles. We would like to thank Dr Nathan Fox for assistance in providing unpublished data from his study and for clarification of other queries.

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    This research was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services.

    Reprints not available from the authors.

    Cite this article as: Conde-Agudelo A, Romero R, Hassan SS, et al. Transvaginal sonographic cervical length for the prediction of spontaneous preterm birth in twin pregnancies: a systematic review and metaanalysis. Am J Obstet Gynecol 2010;203:128.e1-12.

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