Bishop Score Calculator
Bishop Score Calculator
Bishop’s 1964 pelvic score out of 13, from the original five items — and the honest part: its discrimination for successful induction is modest, around 0.68 to 0.80 in published areas under the curve, well short of what its ubiquity implies.
Bishop pelvic score
5 items, 0 to 13Dilatation 1 to 2 cm (1); effacement 40 to 50% (1); station minus 2 (1); consistency medium (1); position mid (1)
Scoring
Maximum 13. Bishop’s own paper named 9 or more as a high likelihood of successful induction
- the maximum is 13, not 15
- three items reach 3 and two reach 2. Consistency and position score 0 to 2 only, and the commonly quoted maximum of 15 comes from mis-tabulating those two as 0-to-3 items. If a score of 14 or 15 appears anywhere, the instrument has been mis-transcribed
- the derivation population
- Bishop’s method followed an analysis of 1,000 elective inductions, selected for MULTIPARITY, more than 36 weeks, a vertex presentation, a normal obstetric history and consent. The score is now applied to nulliparous women, medically indicated induction and preterm pregnancy, all outside it
- what it predicts, and how well
- modestly. Published areas under the curve for vaginal delivery after induction include 0.678, 0.69, 0.719 and 0.799; sensitivity and specificity pairs include 64% and 63%, 69% and 79%, and 87% and 60% at different cut-offs. Kolkman and colleagues found poor diagnostic accuracy for predicting caesarean delivery, Teixeira and colleagues positive associations, and a 2025 review of 36 studies declined to pool them
- versus cervical length
- comparisons go both ways: it outperformed cervical length in one cohort, was comparable in another (0.719 against 0.701) and neither was predictive in an unfavourable cervix in a third. Fetal head-perineum distance and IGFBP-1 have each beaten it in single studies
- the modified versions are different instruments
- the modified score replaces effacement with cervical length; Lange’s 1982 version doubles dilatation and drops consistency and position; Calder’s 1974 version alters three criteria; a simplified version uses only three items. This page implements the ORIGINAL 1964 five-item score, and a score quoted without its version is ambiguous
- a score is not a decision
- and not a probability for this patient. It states what was observed in a study population, not whether to induce or what will happen to this pregnancy
Worked example
Dilatation 1 to 2 cm (1); effacement 40 to 50% (1); station minus 2 (1); consistency medium (1); position mid (1)
1 + 1 + 1 + 1 + 1 = 5 points out of 13
5 sits in the 0 to 5 band, where the sources part company: one reproduction calls 0 to 5 unfavourable, another draws the line at 6 or less, a third at 4 or less. A score of 5 is unfavourable on two of those three readings
The simplified three-item subtotal is 1 + 1 + 1 = 3, and the two subjective items contribute 2 of the 5
Move dilatation to 3 to 4 cm and effacement to 60 to 70% and the total becomes 7 — favourable on one reading, unfavourable on another, unclassified on a third
Every item at its maximum gives 3 + 3 + 3 + 2 + 2 = 13. A score above 13 means consistency or position has been scored as a 0-to-3 item, the commonest transcription error in this instrument
At 9 points, the only threshold Bishop's paper named, the published areas under the curve still sit between 0.68 and 0.80 — better than chance, well short of decisive
Bishop’s 1964 five items
| Item | 0 | 1 | 2 | 3 |
|---|---|---|---|---|
| Dilatation | Closed | 1 to 2 cm | 3 to 4 cm | 5 to 6 cm |
| Effacement | 0 to 30% | 40 to 50% | 60 to 70% | 80% or more |
| Station | minus 3 | minus 2 | minus 1 or 0 | plus 1 or plus 2 |
| Consistency | Firm | Medium | Soft | not scored |
| Position | Posterior | Mid-position | Anterior | not scored |
What the score predicts, from the published evidence
| Study or source | Figure | Note |
|---|---|---|
| Bishop 1964 | a score of 9 conveys a high likelihood of successful induction | The only threshold in the original paper |
| Areas under the curve for vaginal delivery | 0.678, 0.69, 0.719, 0.799 | Four cohorts in a 2025 systematic review of 36 studies; no pooled estimate was attempted |
| Sensitivity and specificity at a cut-off above 4 | 69% and 79%; 87% and 60% in two cohorts | Different cohorts, different definitions of success |
| Sensitivity and specificity, unspecified cut-off | 64% and 63% | A third cohort |
| Kolkman et al. systematic review | poor diagnostic accuracy for predicting caesarean delivery | Contradicted by Teixeira et al., who reported positive associations |
| Versus transvaginal cervical length | 0.719 against 0.701 in one cohort; outperformed it in another; neither predictive in an unfavourable cervix in a third | No consistent winner |
| Simplified three-item version | a simplified score of 5 predicted vaginal delivery similarly to an original score above 8 | Dropping the two subjective items loses little |
A 1964 score for elective induction in multiparous women, and what has been found since
Edward Bishop’s pelvic score comes out of an analysis of 1,000 elective inductions at a single Philadelphia hospital in the early 1950s, and his selection criteria matter as much as his five items: multiparity, more than 36 weeks’ gestation, a vertex presentation, a normal previous and present obstetric history, and the patient’s consent. The score was built to time an elective induction in that population. It is now applied to nulliparous women, to medically indicated induction, and to preterm pregnancy, all of which are outside it — and most of the harm a clinical score does comes from use outside the population it was derived in.
Two mechanical points before the evidence. The maximum is 13, not 15: dilatation, effacement and station each reach 3, consistency and position only reach 2, and the 15 that circulates comes from mis-tabulating those two. And the modified versions are different instruments — cervical length substituted for effacement, or dilatation double-weighted with consistency and position dropped, or a simplified three-item form. This page implements the original 1964 five-item score, and a Bishop score quoted without its version is ambiguous.
Then the honest part. For the outcome the score is actually used to predict — vaginal delivery after induction — published areas under the curve cluster between 0.678 and 0.799: better than chance, a long way from decisive. A 2025 systematic review of 36 studies declined to pool them for heterogeneity and noted that the two existing meta-analyses disagree, Kolkman and colleagues finding poor diagnostic accuracy for predicting caesarean delivery where Teixeira and colleagues reported positive associations. Comparisons with transvaginal cervical length go both ways, and the simplified three-item version performs about as well as the full five. None of that makes the score useless — a structured examination recorded the same way by everyone has value independent of its discrimination — but it should be read as one input among several. A score is not a diagnosis, and a risk from a cohort is not a probability for this pregnancy. This page computes a number, or applies published criteria, and names the body that publishes them. It renders no clinical decision: nothing here says whether this fetus is growth restricted, whether a scan should be repeated, whether labour should be induced or when a pregnancy should be delivered. An obstetric measurement is read alongside the whole clinical picture — history, serial trend, the other biometry — and never instead of it. It supports a clinician’s judgement rather than replacing it.
Frequently asked questions
What is the maximum Bishop score?
13. Dilatation, effacement and station each score 0 to 3; consistency and position score 0 to 2. The maximum of 15 quoted in some summaries comes from mis-tabulating consistency and position as 0-to-3 items. A total above 13 means the instrument has been transcribed wrongly.
What Bishop score is favourable?
The sources disagree, which is the most useful thing to know. Bishop’s own paper named 9 or more as a high likelihood of successful induction. Other reproductions give 8 or more as favourable with 6 or less unfavourable, or 7 or more as generally favourable, or 0 to 5 as unfavourable. A score of 7 is classified three ways.
How well does the Bishop score predict a successful induction?
Modestly. Published areas under the curve for vaginal delivery after induction include 0.678, 0.69, 0.719 and 0.799. Kolkman and colleagues found poor diagnostic accuracy for predicting caesarean delivery; Teixeira and colleagues found positive associations; a 2025 review of 36 studies declined to pool them.
Which version does this page use?
The original 1964 five-item score, out of 13. The modified Bishop score replaces effacement with cervical length; Lange and colleagues’ 1982 version doubles dilatation and drops consistency and position; Calder’s 1974 version changes three of the criteria; and a simplified version uses only dilatation, effacement and station. They give different numbers on the same cervix.
Was the score derived in nulliparous women?
No. Bishop’s selection criteria were multiparity, more than 36 weeks, a vertex presentation, a normal obstetric history and consent, in women selected for elective induction. Nulliparity is one of the characteristics that later modified versions subtract a point for, which is itself an acknowledgement that the original does not fit that group.
Related calculators
References
- Bishop EH. Pelvic scoring for elective induction. Obstet Gynecol. 1964;24:266-8.
- Kolkman DGE, Verhoeven CJM, Brinkhorst SJ, et al. The Bishop score as a predictor of labor induction success: a systematic review. Am J Perinatol. 2013;30(8):625-30.
- Michail A, Fasoulakis Z, Domali E, Daskalakis G, Antsaklis P. Role of the Bishop score in predicting successful induction of vaginal delivery: a systematic review of current evidence. Cureus. 2025;17(7):e87467.
- Perinatology.com. Bishop Score Calculator, citing Bishop EH 1964, ACOG Practice Bulletin No. 107 (2009) and Laughon SK, et al. Obstet Gynecol. 2011;117(4):805-11.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/