Role of transvaginal ultrasonographic cervical assessment in predicting the outcome of induction of labor
Keywords:Cervical length, Induction of labor, Modified Bishop score, Transvaginal sonography
Background: Induction of labor is the most common intervention in modern obstetrics. The pre-induction ‘favourability’ of the cervix as assessed by the bishop score is very subjective. Transvaginal sonography appears to be a feasible alternative to the traditional bishop’s score. Aim of this study, was to compare cervical assessment by transvaginal sonography and digital examination in prediction of outcome of labor induction.
Methods: Three hundred women at term with maternal and foetal indications for labor induction were included in the study. Modified Bishop score was assessed by digital examination and the cervical length was measured by Transvaginal sonography (TVS). Successful labor induction was taken as a vaginal delivery within 24 hours from the start of induction. Data were analyzed using SPSS for Windows 15.0.
Results: Labour induction was successful in 81.33% of patients. Mean cervical length by digital examination was 2.6 cm, whereas the mean sonographic cervical length was 3.4cm. There was a significant difference of 0.8cm in mean cervical length measured by two methods (P=0.01). The best cut off point for predicting successful induction of labor was ≤3.4cm for sonographic cervical length (sensitivity 0.82, specificity 0.87, positive predictive value 0.77 and negative predictive value 0.25). The best cut off point for Modified Bishop score was 2 (sensitivity 0.95, specificity 0.93). The ROC curve showed that compared to TVS cervical length, Modified Bishop score was the best parameter for predicting successful induction of labor.
Conclusions: Transvaginal sonographic cervical length measurement can be used as an adjunct tool to the traditional Bishop score for predicting successful labor induction in high risk pregnancies.
Zhang J, Yancey MK, Henderson CE. U.S. National trends in labor induction.1989-1998. J Reprod Med. 2002;47:120-24.
Sharma SK, Nagpal M, Thukral CL. Evaluation of pre induction scoring by clinical examination vs transvaginal sonography. Int J Reprod Contracept Obstet Gynecol. 2017;6:228-31.
Bishop EH. Pelvic scoring for elective induction. Obstet Gynecol. 1964;24:266-8.
Bansiwal R, Rao R, Mishra N, Kapur V. Bishop score and transvaginal ultrasound for preinduction cervical assessment: a randomized clinical trial. Int J Reprod Contracept Obstet Gynaecol. 2013;2(4):611-5.
Buyer J, Papiernik E, Dreyfus J, Collins D, Wninisdoerffer B, Gueguen S. Maturation signs of the cervix and prediction of preterm birth. Obstet Gynecol. 1986;68:209-14.
Paterson-Brown S, Fisk NM, Edmonds DK, Rodeck CH. Preinduction cervical assessment by Bishop’s score and transvaginal ultrasound. Eur J Obstet Gynecol Reprod Biol. 1991;40:17-23.
Goldberg J, Newman RB, Rust PF. Interobserver reliability of digital and endovaginal ultrasonographic measurements. Am J Obstet Gynecol. 1997;177:853-8.
Lazanakis M, Marsh MS, Brockbank E, Economides DL. Assessment of the cervix in the third trimester of pregnancy using transvaginal ultrasound scanning. Eur J Obstet Gynecol Reprod Biol. 2002;105:31-5.
Anderson HF. Transvaginal and transabdominal ultrasonography of the uterine cervix during pregnancy. Am J Clin Ultrasound. 1991;19(2):77-83.
Reis FM, Gervasi MT, Florio P. Prediction of successful induction of labor at term: Role of clinical history, digital examination, ultrasound assessment of the cervix, and fetal fibronectin assay. Am J Obstet Gynecol. 2003;189:1361-67.
Park KH. Transvaginal ultrasonographic cervical measurement in predicting failed labour induction and caesarean delivery for failure to progress in nulliparous women. J Korean Med Sci. 2007;22:722-7.
Burnett JE. Preinduction scoring: An objective approach to induction of labor. Obstet Gynecol. 1996;28:479-83.
Elghorori MR, Hassan I, Dartey W, Abdel-Aziz E, Bradley M. Comparison between subjective and objective assessment of cervix before induction of labor. Obstet Gynecol. 2006;26(6):521-6.
Selhi M, Surapeni T. Preinductionsonographic measurement of cervical length: An adjunct to Bishop score? Amithyaa- Fernandez Hospital. 2010;1(2).
Chandra S, Crane JM, Hutchens D, Young DC. Transvaginal ultrasound and digital examination in predicting successful labor induction. Obstet Gynecol. 2001;98:2-6.
Rane SM, Pandis GK, Guirgis RR, Higgins B, Nicolaides KH. Preinductionsonographic measurement of cervical length in the prolonged pregnancy: the effect of parity in the prediction of induction to delivery interval. J Ultrasound in Obstet Gynaecol. 2003;22:40-4.
Uyar Y, Erbay G, Demir BG, Baytur Y. Comparison of the Bishop score, body mass index and transvaginal Cervical length in predicting the success of labor induction. Arch Gynaecol Obstet. 2009;280:357-62.
Yang SH, Roch CR, Kim JH. Transvaginal ultrasonography for cervical assessment before induction of labour. Am J Ultrasound Med. 2004;23:375-82.
Gonen R, Degani S, Ron A. Prediction of successful induction of labour: Comparison of transvaginal ultrasonography and Bishop score. Eur J Ultrasound 1998;7:183-7.
Bueno B, San Frutos L, Salazar F, Perez-Medina T, Engels V, Archilla B, et al. Variables that predict the success of labor induction. Acta Obstet Gynecol Scand. 2005;84:1093-97.
Ware V, Raynor BD. Transvaginal ultrasonographic cervical measurement as a predictor of successful labor induction. Am J Obstet and Gynecol. 2000;182:1030-32.
Gabriel R, Darnaud T, Chalot F, Gonzalez N, Leymarie F, Quereux C. Transvaginal sonography of the uterine cervix to labour induction. J Ultrasound Obstet Gynaecol. 2002;19:254-7.
Daskalakis G, Thomakos N, Hatziioannou L, Mesogitis S, Papantoniou N, Antasaklis A. Sonographic cervical length measurement before labour induction in term nulliparous women. J Foetal Diagn There. 2006;21:34-8.
Keepanasseril A, Suri V, Bagga R, Aggarwal N. Preinduction sonographic assessment of the cervix in the prediction of successful induction of labor in nulliparous women. Austral NZ J Obstet Gynaecol. 2007;47:389-93.