The Bishop score is a tool healthcare professionals use to assess the readiness of the cervix for labor. It helps predict the likelihood that inducing labor will lead to a successful vaginal birth. Developed by Dr. Edward Bishop, this scoring system evaluates specific physical changes in the cervix and the position of the baby’s head. By assigning points to these factors, providers can get a standardized view of how prepared the body is for the labor process, particularly when considering a medical induction.
How the Bishop Score is Calculated
The total Bishop score is determined by assessing five distinct components during a pelvic exam, with each factor receiving a point value that contributes to a final sum. The total possible score is 13.
One of the primary factors is cervical dilation, which measures how open the cervix is in centimeters. A closed cervix receives 0 points, while a cervix that is 5 to 6 centimeters dilated would receive 3 points.
Cervical effacement, or the thinning of the cervix, is also measured. It is recorded as a percentage. A cervix that is 0% to 30% effaced scores 0 points, while one that is over 80% effaced earns 3 points.
The consistency and position of the cervix are also evaluated. A firm cervix, which may feel like the tip of a nose, scores 0 points, whereas a soft cervix gets 2 points. Similarly, the cervix moves from a posterior (backward-facing) position to an anterior (forward-facing) one as labor approaches; an anterior position receives 2 points.
Finally, fetal station assesses how low the baby’s head has descended into the pelvis in relation to bony landmarks called the ischial spines. A higher position, denoted with negative numbers like -3, scores 0 points. As the baby descends to a lower position, such as +1 or +2 station, it receives 3 points, indicating closer proximity to birth.
Interpreting the Score
A higher score suggests that the body is more prepared for labor and that an induction is more likely to be successful. The total score helps healthcare providers communicate a standardized assessment of the situation.
A score of 8 or higher is considered “favorable.” This indicates that the cervix is ripe and that labor may begin spontaneously soon. If an induction is needed, a score in this range suggests a high probability that it will proceed smoothly and result in a vaginal delivery.
Conversely, a score of 6 or less is “unfavorable.” This means the cervix is not yet ready for labor, and an induction started without any cervical preparation is less likely to be successful. Scores in the intermediate range, such as 7, can represent a gray area where the success of an induction may be less predictable.
Role in Deciding on Labor Induction
The Bishop score serves as a practical guide for healthcare providers when creating a plan for labor induction. It helps determine the most appropriate course of action based on the cervix’s state.
When the score is low or unfavorable (6 or less), a provider may recommend cervical ripening methods before proceeding with induction. This involves using medications, such as prostaglandins, or mechanical methods, like a balloon catheter, to help the cervix soften, thin out, and open. This preparatory step can significantly increase the chances of a successful induction.
If the Bishop score is high or favorable (8 or more), it suggests the cervix is already prepared for labor. In these cases, a provider might decide to proceed directly with labor induction methods, such as administering Pitocin, without prior cervical ripening.