Preinduction cervical assessment

Abstract

Systems of quantifying and scoring cervical factors have been sought for years to predict the duration of labor and to determine which patients may successfully and safely undergo induction of labor. Early methods of cervical assessment generally attempted to classify patients as having favorable or unfavorable cervices based on dichotomous variables. Since then, obstetricians have begun to appreciate the usefulness of having a single score derived from the degree of ripeness of several cervical characteristics. The scoring system that has become most prevalent is the Bishop score. This system and its modifications take into account the dilation, effacement, consistency, and position of the cervix in addition to the station of the presenting part. Many have evaluated and confirmed the validity of the Bishop score. Among the factors considered in assigning the score, the strongest association with successful labor seems to be with cervical dilation. The Bishop score has been criticized for not attributing more significance to cervical dilation. However, despite this criticism, none of the modifications to the original scoring system have been shown to improve predictability. More recently, the use of ultrasound assessment of the cervix has been suggested to improve prediction of the success of labor induction. However, convincing evidence that this technique provides significant additional information when compared to digital examination is lacking. The Bishop score would seem to be the best and most cost-effective method currently available to assess the cervix and predict the likelihood of success of labor induction and the duration of such an induction.