Bishop Score
On this page
Direct answer
The Bishop score is an obstetric scoring system that assesses cervical readiness for induction of labour using five parameters: dilatation, effacement, station, consistency and position. Each parameter scores 0 to 3 or 0 to 2, giving a maximum of 13. A score of 8 or more predicts a favourable cervix in which induction is likely to succeed, while a low score means cervical ripening is usually needed first.
What you must remember
- Dilatation: a closed os scores 0, 1 to 2 cm scores 1, 3 to 4 cm scores 2, and 5 cm or more scores 3.
- Effacement: 0 to 30 per cent scores 0, 40 to 50 per cent scores 1, 60 to 70 per cent scores 2, and 80 per cent or more scores 3.
- Station: minus 3 scores 0, minus 2 scores 1, minus 1 or 0 scores 2, and plus 1 or plus 2 scores 3.
- Consistency: firm scores 0, medium scores 1 and soft scores 2.
- Position: posterior scores 0, mid-position scores 1 and anterior scores 2.
- Favourable cervix: a total of 8 or more predicts a higher chance of successful induction, while a total of 6 or less suggests an unfavourable cervix.
- Modified scores: some units replace effacement with cervical length or drop items, so the version used and its cut-offs should always be stated.
Scoring the cervix one parameter at a time
A clinician scores the cervix on digital vaginal examination, and each item is added in a fixed order. The walk-through below follows the order most textbooks and viva answers use.
- Dilatation. A closed os scores 0, 1 to 2 cm scores 1, 3 to 4 cm scores 2, and 5 cm or more scores 3.
- Effacement. Shortening of 0 to 30 per cent scores 0, 40 to 50 per cent scores 1, 60 to 70 per cent scores 2, and 80 per cent or more scores 3.
- Station. The head level at minus 3 scores 0, the score rises through minus 2 (1) and minus 1 or 0 (2), and plus 1 or plus 2 scores 3.
- Consistency. A firm cervix scores 0, a medium cervix scores 1, and a soft cervix scores 2.
- Position. A posterior cervix scores 0, a mid-position cervix scores 1, and an anterior cervix scores 2.
- Total and interpret. The five scores add up to a maximum of 13, and the total is read against the cut-offs for induction. Scores of 6 or less generally point to ripening first, while 8 or more suggests the cervix is ready for oxytocin.
Where the exam tries to catch you
Examiners test whether the candidate knows the direction of each item and what the total means for the plan.
- Trap: confusing effacement with cervical length Correct: effacement is the percentage of cervical shortening on examination, and cervical length is a separate ultrasound measure used only in some modified versions.
- Trap: believing a high Bishop score guarantees vaginal delivery Correct: the score predicts a favourable cervix and induction success, but it does not replace assessment of the pelvis or the fetal condition.
- Trap: inducing with oxytocin straight away after a score of 4 Correct: a low score means the cervix is unfavourable, so ripening with a prostaglandin or a mechanical method is usually needed first.
Frequently asked questions
What is the maximum possible Bishop score?
The maximum Bishop score is 13. Dilatation, effacement and station each score up to 3, while consistency and position each score up to 2. A total of 13 signals a highly favourable cervix for induction.
Which Bishop score suggests a favourable cervix for induction?
A Bishop score of 8 or more is generally taken to suggest a favourable cervix, in which induction with oxytocin is likely to succeed. Scores of 6 or less usually indicate an unfavourable cervix that needs ripening first. The exact cut-off depends on the protocol in use.
Which parameter of the Bishop score measures descent of the fetal head?
Station measures the descent of the presenting part relative to the ischial spines, and it is the parameter that reflects head descent. Station of minus 3 scores 0, while plus 1 or plus 2 scores 3. Station is assessed on digital vaginal examination, not by ultrasound.
How does the modified Bishop score differ from the original?
The modified Bishop score differs because cervical length, usually measured by ultrasound, replaces effacement in some versions. Some units also drop or change other items, so the cut-offs differ. The version used should always be named when a score is recorded.
Why does a low Bishop score matter in labour induction?
A low Bishop score matters because an unfavourable cervix makes induction with oxytocin more likely to fail or take longer. It usually prompts cervical ripening with a prostaglandin or a mechanical method before oxytocin is started. This lowers the chance of a prolonged induction that ends in caesarean section.