Sonographic cervical assessment to predict the success of labor induction: a systematic review with metaanalysis.

Clinical and ultrasound parameters to predict the risk of cesarean delivery after induction of labor.

Objective. To investigate risk factors associated with postterm pregnancy and cesarean delivery following labor induction. Design. Population-based cohort study. Setting. Sweden. Population. From the Swedish Medical Birth Register, a total of 1,176,131 singletons births from gestational week 37 and onwards, between 1992 and 2006. Methods. Unconditional logistic regression analysis. Main outcome measures. Risk of postterm pregnancy (delivery at ≥42 weeks) and cesarean delivery following labor induction. Results. Among 1,176,131 births, 8.94% were delivered postterm. Compared to normal weight women, the risk of postterm pregnancy in obese women was almost doubled (adjusted OR: 1.63, 95% CI 1.59–1.67). The risk of postterm pregnancy increased with increasing maternal age and was higher among primiparous women. The risk of cesarean section (CS) following labor induction postterm, increased with maternal age and BMI, and was more than doubled among women 35 years and older (adjusted OR 2.28, 95% CI 2.0...

https://obgyn.onlinelibrary.wiley.com/doi/pdf/10.3109/00016349.2010.500009

Maternal risk factors for postterm pregnancy and cesarean delivery following labor induction.

Objectives To evaluate fetal head–perineum distance measured by ultrasound imaging as a predictive factor for induction of labor, and to compare this distance with maternal factors, the Bishop score and ultrasound measurements of cervical length, cervical angle and occiput position. Methods The study included 275 women admitted for induction of labor. The fetal head–perineum distance was measured by transperineal ultrasound imaging as the shortest distance from the outer bony limit of the fetal skull to the skin surface of the perineum. Cervical length and angle was measured by transvaginal ultrasound examination, and fetal head position was assessed by transabdominal ultrasound imaging. The Bishop score was assessed without knowledge of ultrasound measurements. Receiver–operating characteristics (ROC) curves were used for evaluation of the probability of a successful vaginal delivery. The time from induction to delivery was tested using Cox regression analysis with ultrasound measurements, parity and body mass index (BMI) as possible predictive factors. Results Areas under the ROC curve for prediction of vaginal delivery were 62% (95% CI, 52–71%) for fetal head–perineum distance (P = 0.03), 61% (95% CI, 51–71%) for cervical length (P = 0.03), 63% (95% CI, 52–74%) for cervical angle (P = 0.02), 61% (95% CI, 52–70%) for Bishop score (P = 0.03) and 60% (95% CI, 51–69%) for BMI (P = 0.05). The Cesarean delivery rate was 22% among nulliparous and 5% among parous women (P < 0.01). Parity, fetal head–perineum distance, cervical length and cervical angle were contributing factors predicting vaginal delivery within 24 h in a Cox regression model. Occiput posterior position had no significant predictive value. Conclusions Fetal head–perineum distance measured by transperineal ultrasound examination can predict vaginal delivery after induction of labor, with a predictive value similar to that of ultrasonographically measured cervical length and the Bishop score. However, we judge none of these methods used alone to be good enough in a clinical setting. Copyright  2008 ISUOG. Published by John Wiley & Sons, Ltd.

Ultrasound assessment of fetal head–perineum distance before induction of labor

Comparison of digital and ultrasonographic examination of the cervix in predicting time interval from induction to delivery in women with a low Bishop score.

BACKGROUND We evaluated the accuracy of the Bishop score in predicting the likelihood of successful labor induction (entry into active phase) in nulliparous and multiparous women. METHODS During an index year, all patients having induction of labor and a preinduction Bishop score were included in a standard protocol for cervical ripening and use of oxytocin. Receiver-operating characteristic (ROC) curves were constructed for Bishop scores (0 to 11) to predict abdominal delivery for failed induction (final cervical dilation <4 cm) versus vaginal delivery. RESULTS Parturients who had vaginal delivery (n = 253) and those in whom attempted induction failed (n = 38) did not differ significantly with respect to maternal demographics, length of gestation, Bishop score and its distribution, and infant birth weight. The area under the ROC curve did not differ significantly from the area under the nondiagnostic line. CONCLUSION The Bishop score appears to be a poor predictor of the outcome of labor induction.

John G. Morrison

Papers

Bishop score : A poor diagnostic test to predict failed induction versus vaginal delivery