Significance of transvaginal sonographic assessment of cervical length before induction of labour

Shreya M. S., Savitha C.


Background: The traditional method of predicting whether an induced labor will result in successful vaginal delivery is based on pre-induction favourability of cervix as assessed by bishop score. However, this method is limited by subjectivity and reproducibility and though done in all the patients prior to induction of labour, several studies have demonstrated poor correlation between Bishop score and outcome of labor. Currently assessment of cervical status by sonographically at term in induction of labor is most accurate and highly reproducible compared to Bishop score.

Methods: This study was carried out in a tertiary care teaching institute in Karnataka. 180 pregnant women at or beyond 37weeks who were planned for induction, Bishop score assessment of cervix and cervical assessment by ultrasound such as cervical length (CL) was done one day prior to induction. Induction was with 0.5mg PGE2gel. Maximum 3 induction were carried out over a period of 24hrs. Primary outcome of the study was the onset of active labor.

Results: Amongst 160 pregnant women who were induced (20 women were excluded has they underwent LSCS for some other reasons during latent phase) cervical length by sonography <2cm were 14 none had failed induction. Amongst 180 pregnant women who were induced cervical length <2cm in 14 all had Bishop score >4.

Conclusions: Transvaginal sonographic measurement of cervical length was evaluated in predicting response to induction. CL <2cm was associated with greater incidence of successful labor induction. These results show the CL has significant role in predicting outcome of labor.


Bishop score, Cervical length, Induction of labor, Transvaginal sonography

Full Text:



Royal College of obstetrics and Gynecologists (RCOG). Induction of labour. Evidence based clinical guide line number 9. London: RCOG clinical support unit. 2001.

Martin J A, Hamilton B E, Sutton PD, et al. Births: Final data for 2002. NATL Vital Stat Rep. 2003;52:1.

Anish K, Vanita S, Rashmi B, Aggarwal N. Pre-induction sonographic assessment of the cervix in the prediction of successful induction of labour in nulliparous women. Australian New Zealand J Obstet Gynaecol. 2007;47:389-93.

Saanchez-Ramos L, Delke. Induction of labour and pregnancy termination for fetal anomaly. James DK, Steer PJ, Weiner CP, Gonik B. High risk pregnancy - management options, 3rd ed. W.B. Saunders, London; 2006:1392-495.

Arulkumaran S, Gibb DM, TambyRaja RL, Heng SH, Ratnam SS. Failed induction of labour. Aust. NZ J Obstet Gynecol. 1985;25:190-193

Baacke KA, Edward RK. Pre-induction cervical assessment. Clin Obstet Gynecol. 2006;49:564

Pandis G, Papageorghiou AT, Ramanathan VG, Thompson MO, Nicolaides KH. Pre-induction sonographic measurement of cervical length in prediction of successful induction of labour. Ultrasound Obstet Gynecol. 2001;18:623-28.

Jackson GM, Ludmir J, Bader TJ. The accuracy of digital examination and ultrasound in the evaluation of cervical length. Obstet Gynecol. 1992;79:214-8.

Dhall K, Mittal SC, Kumar A. Evaluation of pre-induction scoring systems. ANZJ Obstet Gynecol. 1987;27:309-11.

Friedman EA, Niswander KR, Bayonet- Rivera NP, Sachtleben MR. Relationship of prelabor evaluation to inducibility and the course of labor. Obstet Gynecol. 1996;28:459-501.

Bouyer J, Papiernik E, Dreyis J, Collin D, Winisdoerffer B, Gueguen S. Maturation signs of the cervix and prediction of preterm birth. Obstet Gynaecol. 1986;68:209-14.

Chandra S, Crane JAI, Hutchens D. Transvaginal ultrasound and digital examination in predicting successful labour induction. Obstet Gynecol. 2001;98(1):2-6.

Gabriel R, Darnaud T, Chalot F, Gonzalez N, Leymarie F, Quereux C. Transvaginal sonography of the uterine cervix prior to labour induction. Ultrasound Obstet Gynecol. 2002;19:254-7.

Daskalakis G, Thomakos N, Hatziioannou L, Mesogitis S, Papantoniou N, Antsaklis A. Sonographic cervical length measurement before labour induction in term nulliparous women. Fetal Diagn Ther. 2006;21(1):34-8.

Rane SM, Pandis GK, Guirgis RR, Higgins B, Nicolaides KH. Pre-induction sonographic measurement of cervical length in prolonged pregnancy: the effect of parity in the prediction of induction to delivery interval. Ultrasound Obstet Gynecol. 2003;22(1):40-8.

Yang SH, Roh CR, Kim JH. Transvaginal ultrasonography for cervical assessment before induction of labour. J Ultrasound Med. 2004;23(3):375-82.

Rane SM, Guirgis RR, Higgins B, Nicolaides KH. The value of ultrasound in the prediction of successful induction of labour. Ultrasound Obstet Gynecol. 2004;24:538-549.

Boozarjomehri F, Timor-Tritsch I, Chao CR, Fox HE. Presence of cervical wedging is associated with shorter duration of induced labor. Am J obstet Gynecol. 1994;171:1081-7.

Gomez Laencina AM, Sanchez FG, Gimenez JH, Martinez MS, Valverde Martinez JA, Vizcaino VM. Comparison of ultrasonographic cervical length and Bishop in predicting successful labour induction. Acta Obstet Gynecol Scand. 2007;86(7):799-804.

Tan PC, Vallikkannu N, Suguna S, Quek KF, Hassan J. Transvaginal sonographic measurement of cervical length versus Bishop’s score in labour induction at term: tolerability and prediction of cesarean delivery. Ultrasound Obstet Gynecol. 2007;29(5):568-73.

Watson WJ, Stevens D,Welter S, Day D. Factors predicting successful labour induction. Obstet Gynecol. 1996;88:990-2.

Gonen R, Degani S, Ron A. Prediction of successful induction of labour: comparison of transvaginal ultrasonography and the Bishop score. Eur J Ultrasound. 1998;7:183-7.

Ware V, Raynor D. Transvaginal ultrasonographic cervical measurement as a predictor of successful labour induction. Am J Obstet Gynecol. 2000;182:1030-2.