The Bishop score (Bishop EH, Obstet Gynecol 1964) is a standard assessment of cervical readiness for labor and the likelihood of successful induction. It includes 5 parameters from vaginal examination: cervical dilatation, effacement (or length), consistency, position, and fetal head station. Each parameter is scored 0–3 points (position is scored 0–2), for a total of 0–13.
Interpretation: ≥ 8 indicates a favorable ("ripe") cervix, with a likelihood of successful induction (vaginal delivery within 24–48 hours) of approximately 95%; 6–7 is borderline; ≤ 5 indicates an "unripe" cervix, often requiring cervical ripening beforehand (prostaglandins, balloon catheters).
The score is used to guide decisions on induction method and to predict outcome. WHO (2018) recommends the Bishop score as the standard assessment before amniotomy, oxytocin, or prostaglandin use.
When to use
Before elective or emergency labor induction — a mandatory assessment.
Selecting the method of cervical ripening (mechanical — balloon catheter; pharmacologic — misoprostol/dinoprostone).
Predicting duration of labor and risk of cesarean delivery.
Counseling the patient on delivery strategy in post-term pregnancy.
Parameters in detail
Cervical dilatation
Cervical dilatation: 0 — closed, 1 — 1–2 cm, 2 — 3–4 cm, 3 — ≥ 5 cm.
39-week pregnant patient, post-term pregnancy, induction planned. Vaginal examination: dilatation 1 cm, effacement 30%, fetal head at −2 station, cervix of medium consistency, mid position.
Calculation
Dilatation 1 cm (1) + effacement 30% (0) + station −2 (1) + medium consistency (1) + mid position (1) = 4 points.
Interpretation and management
Bishop 4 — "unripe" cervix. Management: cervical ripening before induction. Options: intravaginal misoprostol 25 µg every 4 hours (max. 6 doses) or Foley balloon catheter (mechanical ripening, 12 hours). Repeat Bishop assessment after 12–24 hours; once ≥ 7 is reached, proceed with amniotomy + oxytocin. Counsel the patient on the possible duration of the process (up to 48 hours) and the risk of cesarean delivery (higher with a low initial Bishop score).
Limitations and cautions
Subjectivity in assessing effacement and consistency — inter-rater reproducibility is moderate.
In multiparous women, induction success is higher for the same Bishop score — the scale does not directly account for parity.
Does not account for a uterine scar (prior cesarean) — a contraindication to certain ripening methods.
Modified versions (Simplified Bishop with 3 parameters) are simpler but less accurate.
At what Bishop score can induction be started without prior ripening?
≥ 7 — amniotomy plus oxytocin is usually sufficient. At 6, decisions are individualized, often with light ripening.
Can the score be used after a prior cesarean scar?
The score itself — yes. But ripening methods are limited: prostaglandins are contraindicated (risk of uterine rupture), a mechanical balloon is acceptable, and oxytocin should be used with caution.
What counts as "complete effacement"?
The cervix reaches the level of the lower uterine segment — the external and internal os merge. On the Bishop score this corresponds to ≥ 80% (3 points).
Does the Bishop score change during labor?
Yes, dynamic reassessment is important. Progression of the Bishop score in the first 12 hours of induction is a favorable prognostic sign.
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Aleksandr A. Aulov
Physician, internal medicine, Sechenov School — independent medical education platform.
Calculators are compiled from the original publications and current clinical guidelines. Interpretation thresholds follow the source study unless stated otherwise.
This calculator is intended for healthcare professionals. Do not use it for self-diagnosis or self-treatment. Management decisions are made by the treating clinician based on the full clinical picture of the individual patient.
Last clinical review: April 28, 2026 ·
Author: Aleksandr A. Aulov,
MD, internal medicine ·
Primary source: Bishop EH. Obstet Gynecol 1964; 24: 266-268