Bishop Score Calculator — Cervical Readiness for Labor Induction

How to Use This Calculator

1. Select scores for all 5 cervical components from the dropdown menus.
2. Total Bishop Score and cervical readiness appear instantly.
3. Induction Risk tab: enter score and parity to estimate C-section risk.
4. Scoring Guide tab: see ACOG thresholds and how many points remain to target.
5. Professional tier: add parity, GA, and prior cesarean for full induction plan.

Formula

Example

Frequently Asked Questions

• What is the Bishop Score and what does it measure? ▼
  The Bishop Score is a standardized pre-labor cervical assessment tool developed by Dr. Edward Bishop in 1964 to predict the success of labor induction. It quantifies the readiness of the cervix by scoring five components: cervical dilation (0–3 points), effacement (0–3 points), fetal station (0–3 points), cervical consistency (0–2 points), and cervical position (0–2 points), for a maximum possible score of 13. Each component reflects a different aspect of cervical and fetal preparation for labor. Dilation measures how open the cervix is; effacement reflects how thin/short the cervix has become; station indicates how far the fetal presenting part has descended into the pelvis; consistency describes whether the cervix feels firm, medium, or soft; and position refers to whether the cervix points posteriorly, mid-position, or anteriorly. A score of 0–5 indicates an unfavorable cervix where induction is likely to be unsuccessful without prior cervical ripening. Scores of 6–8 represent a moderately favorable cervix with variable success rates. A score of 8 or higher indicates a favorable, ripe cervix where induction success approaches that of spontaneous labor onset. Originally developed for multiparous women, lower thresholds (≥6) may apply to multiparas. The Bishop Score remains the most widely used cervical assessment tool in obstetrics and is referenced in all major induction guidelines.
• What Bishop Score is needed before inducing labor? ▼
  The threshold for acceptable Bishop Score before induction depends on clinical context and parity. ACOG (American College of Obstetricians and Gynecologists) Practice Bulletin 107 states that a Bishop Score ≥8 is generally associated with a successful induction with vaginal delivery rates similar to spontaneous labor. For nulliparous women, a score below 6 is associated with significantly elevated cesarean delivery risk (approximately 45–55% in some series) when oxytocin induction is attempted without prior cervical ripening. Cervical ripening should therefore be performed before induction when the Bishop Score is below 6 (or sometimes below 8 in nulliparas). Cervical ripening agents include pharmacological options — prostaglandin E2 (dinoprostone gel or insert) and misoprostol (PGE1) — and mechanical options such as Foley balloon catheter, double-balloon catheter, and osmotic dilators. Each increases the Bishop Score by several points over hours, allowing oxytocin induction to proceed with higher success rates. In post-term pregnancies (≥41–42 weeks), ACOG recommends offering induction regardless of the Bishop Score because of rising risks of stillbirth, meconium aspiration, and macrosomia. In these cases, cervical ripening is performed if needed and induction proceeds even from an unfavorable cervix due to clinical urgency.
• How do you perform cervical assessment for the Bishop Score? ▼
  Cervical examination for Bishop Score is performed with the patient in the dorsal lithotomy position during a digital vaginal examination, ideally with an empty bladder. Using a gloved hand, the examiner inserts two fingers through the vaginal introitus to reach the cervix. Dilation is assessed by estimating how many centimeters the cervical os admits — closed means no dilation, 1–2 cm, 3–4 cm, or ≥5 cm. Effacement is estimated as a percentage of the pre-labor cervical length (~3–4 cm) that has been taken up into the lower uterine segment: 0–30% means a thick, long cervix; ≥80% means a fully effaced, paper-thin cervix. Station is the relationship of the fetal presenting part to the ischial spines: -3 is floating above the spines and +2 is 2 cm below. Consistency is assessed by palpating the cervix against the posterior vaginal wall — firm (like a tip of nose), medium, or soft (like lips). Position refers to where the cervix points within the vagina — posterior toward the sacrum, mid-position, or anterior toward the pubic symphysis. Examination technique varies between providers, contributing to inter-examiner variability of 1–2 points. Sterile technique and limiting examinations are important to minimize infection risk, particularly with ruptured membranes.
• What is the difference between the Bishop Score and the Modified Bishop Score? ▼
  The original Bishop Score (1964) uses five components: dilation (0–3), effacement (0–3), station (0–3), consistency (0–2), and position (0–2), for a maximum of 13 points. The Modified Bishop Score, also called the Calder Score (published by Calder et al. 1974), recalibrates the station parameter and adjusts some scoring levels. In the Modified Bishop Score, fetal station uses a different scale (-5 to +5 or -3 to +3 depending on the version) and the station scoring is slightly different. The modified version also sometimes changes the effacement scoring. The key practical difference is that the Modified Bishop Score has a maximum of 12 points and uses slightly different thresholds. In clinical practice, both scores are used interchangeably in many institutions, and the choice depends on local protocol and training. Research comparing outcomes between the two versions shows broadly similar predictive value for successful induction. Some studies suggest the original Bishop Score is slightly superior for nulliparous women. The Modified Bishop Score is more commonly used in the United Kingdom and some European centers. For the purposes of most clinical decision-making, a score of ≥6–8 indicating a favorable cervix applies to both versions, with institutional protocols specifying which version is used.
• What are the indications and contraindications for labor induction? ▼
  Labor induction is indicated when the risks of continuing pregnancy exceed the risks of delivery. Common medical indications include: post-term pregnancy (≥41–42 weeks gestation), gestational hypertension or preeclampsia, gestational diabetes with suboptimal control, intrauterine growth restriction (IUGR) with abnormal Doppler studies, oligohydramnios, prelabor rupture of membranes (PROM) at term, chorioamnionitis, fetal demise, and maternal conditions such as antiphospholipid syndrome or renal disease. Elective induction at 39 weeks in low-risk women is supported by the ARRIVE trial (Grobman et al., NEJM 2018), which showed no increase in C-section rates and possible neonatal benefits. Absolute contraindications to induction include: placenta previa or vasa previa, prior classical uterine incision (vertical uterine incision), active herpes simplex infection, umbilical cord prolapse, and transverse fetal lie. Relative contraindications (requiring individualized risk-benefit analysis) include: prior low-transverse cesarean (TOLAC — trial of labor after cesarean is acceptable with informed consent at appropriate facilities), prior myomectomy entering the uterine cavity, grand multiparity (≥5 prior deliveries), and severe fetal compromise. Prostaglandins are generally avoided with a prior uterine scar due to elevated uterine rupture risk; mechanical methods are preferred.

Related Calculators