Assessing cervical readiness for labor in term pregnancies
Predicting the likelihood of successful vaginal delivery following induction of labor
Determining whether cervical ripening agents (e.g., prostaglandins) are needed prior to oxytocin administration
Target Population
Originally validated for multiparous, term women considering elective induction. Now broadly used for indicated inductions (e.g., hypertension, FGR) in both nulliparous and multiparous populations.
Section 2
Formula & Logic
Scoring Variables
Dilation (cm)
0 (0) | 1–2 (1) | 3–4 (2) | ≥5 (3)
Effacement (%)
0–30% (0) | 40–50% (1) | 60–70% (2) | ≥80% (3)
Station (cm)
-3 (0) | -2 (1) | -1 or 0 (2) | +1 or +2 (3)
Consistency
Firm (0) | Medium (1) | Soft (2)
Position
Posterior (0) | Mid (1) | Anterior (2)
Simplified Bishop Score (The "New" Standard)
Research suggests that only 3 variables (Dilation, Effacement, and Station) are as predictive as the full 5-variable score. A Simplified Bishop Score ≥ 5 is considered favorable for induction.
Mnemonic
"Call PEDS For Parturition": Cervical Position, Effacement, Dilation, Softness (Consistency), and Fetal Station.
Section 3
Pearls/Pitfalls
The Nulliparous Threshold
For first-time mothers (nulliparous), a higher Bishop Score (≥8) is typically required to predict a successful induction compared to multiparous patients (≥6).
Clinical Pearls
Cervical length via ultrasound < 25-30mm is equivalent to a "favorable" Bishop score.
A low score (<6) does not mean a vaginal delivery is impossible; it simply means the induction will take longer (frequently >24 hours) and likely requires ripening.
The digital exam should be performed between contractions for the most accurate assessment of station and dilation.
Known Limitations
High inter-observer variability (±1 cm difference in dilation/station is common).
Poor correlation with successful induction in obese patients (BMI >30).
Does not account for fetal weight or position (occiput posterior/transverse).
Section 4
Next Steps
Score ≥ 8 — Favorable Cervix
01
High probability of successful vaginal delivery with induction
02
Cervical ripening agents are generally unnecessary
03
Induction of labor using oxytocin and/or amniotomy is appropriate
Score ≤ 6 — Unfavorable Cervix
01
Cervical ripening is indicated prior to standard labor induction
Consider pharmacological methods (e.g., prostaglandins like misoprostol or dinoprostone)
04
Re-assess the Bishop score after the ripening intervention
Section 5
Evidence Appraisal
Derivation Study
Pelvic scoring for elective induction.
Bishop EH. • Obstet Gynecol.. 1964;Aug;24:266-8. Evaluated 500 multiparous women at term to find objective, standardized criteria to replace subjective "gut feelings" about induction readiness.
Section 6
Literature
Dr. Edward Bishop
Developed by Dr. Edward Bishop in 1964. He sought to create a standardized point system to replace subjective clinical intuition when determining if a woman was ready for elective induction of labor.
