Bishop score, also Bishop's score, is a pre-labour scoring system to assist in predicting whether induction of labour will be required.[1] It has also been used to assess the odds of spontaneous preterm delivery.[2]
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The total score is achieved by assessing the following five components on vaginal examination: The Bishop score grades patients who would be most likely to achieve a successful induction. The duration of labor is inversely correlated with the Bishop score; a score that exceeds 8 describes the patient most likely to achieve a successful vaginal birth. Bishop scores of less than 6 usually require that a cervical ripening method be used before other methods.
They can be remembered with the mnemonic: Call PEDS For Parturition = Cervical Position, Effacement, Dilation, Softness; Fetal Station.
Each components is given a score of 0-2 or 0-3. The highest possible score is 13.
| Parameter\Score | 0 | 1 | 2 | 3 | Description |
|---|---|---|---|---|---|
| Position | Posterior | Intermediate | Anterior | - | The position of the cervix varies between individual women. As the anatomical location of the vagina is actually downward facing, anterior and posterior locations relatively describe the upper and lower borders of the vagina. The anterior position is better aligned with the uterus, and therefore there is an increased likelihood of spontaneous delivery. |
| Consistency | Firm | Intermediate | Soft | - | In primigravid women the cervix is typically tougher and resistant to stretching, much like a balloon that has not been previously inflated. Furthermore, in young women the cervix is more resilient than in older women. With subsequent vaginal deliveries the cervix becomes less rigid and allows for easier dilation at term. |
| Effacement | 0-30% | 31-50% | 51-80% | >80% | Effacement is a measure of stretch already present in the cervix. It is analogous to stretching a rubber band; as the rubber band is stretched further, it becomes thinner. This is affected by individual variation and previous surgery such as loop excision for cervical dysplasia or cancer. |
| Dilation | 0 cm | 1–2 cm | 3–4 cm | >5 cm | Dilation is a measure of the diameter of the stretched cervix. It complements effacement, and is usually the most important indicator of progression through the first stage of labour. |
| Fetal station | -3 | -2 | -1, 0 | +1, +2 | Fetal station describes the position in of the fetus' head in relation to the distance from the ischial spines, which can be palpated deep inside the posterior vagina (approximately 8–10 cm) as a bony protrusion. Negative numbers indicate that the head is further inside, above the ischial spines. |
A score of 5 or less suggests that labour is unlikely to start without induction. A score of 9 or more indicates that labour will most likely commence spontaneously.[3]
A low Bishop's score often indicates that induction is unlikely to be successful.[4] Some sources indicate that only a score of 8 or greater is reliably predictive of a successful induction.
According to the Modified Bishop's pre-induction cervical scoring system, effacement has been replaced by cervical length in cm, with scores as follows- 0>3 cm, 1>2 cm, 2>1 cm, 3>0 cm.[5]
Another modification for the Bishop's score is the modifiers. Points are added or subtracted according to special circumstances as follows:
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