Bishop Score for Vaginal Delivery and Induction of Labor

Introduction

The Bishop score is a quick assessment of how ready the cervix is for labor. It’s used most often to decide whether to induce labor and how. Dr. Edward Bishop, an obstetrician, introduced it in 1964. Before labor starts, the cervix softens, thins, opens, and moves forward, a process called ripening. The Bishop score turns those changes into a single number. A higher score means the cervix is more “favorable,” and induction is more likely to lead to a vaginal birth. It remains one of the most widely used tools in labor and delivery.

What it assesses

During a vaginal exam, the clinician rates five features of the cervix and the baby’s position:

How it’s scored

The five scores are added for a total from 0 to 13. Dilation, effacement, and station each range from 0 to 3, and consistency and position each range from 0 to 2.

Results and Interpretation

1. Bishop Score (≤5 pts): Suggests unfavorable cervix. Induction may be necessary for successful vaginal delivery.

   1. Labor is unlikely to start without induction.

   2. Induction with an unfavorable cervix is associated with a longer labor and a higher likelihood of cesarean delivery

   3. Cervical ripening agents are often considered.

   4. Success rates tend to vary based on indication for induction and weeks gestation.

2. Bishop Score (6-7 pts): Does not definitively predict whether or not induction will be successful. Consider induction or augmentation of labor based on clinical judgment.

   1. The success of induction is less predictable; clinical judgement, parity, and the overall obstetric picture should guide management.

   2. Success rates tend to vary based on indication for induction and weeks gestation.

3. Bishop Score (≥8 pts): Suggests spontaneous vaginal delivery is more likely and augmentation or induction may be unnecessary.

   1. The cervix is favorable.

   2. The probability of vaginal delivery after induction is similar to that after spontaneous labor.

   3. Success rates tend to vary based on indication for induction and weeks gestation.

For patients: A low Bishop score doesn’t mean you can’t have a vaginal birth. It usually means your cervix needs some help softening and opening first, which is a routine part of many inductions.

Limitations

The Bishop score depends on a manual exam, so different clinicians may score the same patient differently. It was originally developed in women who had given birth before, so it’s less predictive for first pregnancies. Some practices also use ultrasound measurement of cervical length alongside it. It’s one factor in planning an induction, together with the reason for induction, the pregnancy’s progress, and the patient’s preferences.

BISHOP EH. PELVIC SCORING FOR ELECTIVE INDUCTION. Obstet Gynecol. 1964 Aug;24:266-8.