Bishop score, also Bishop's score, also known as cervix score is a pre-labor scoring system to assist in predicting whether induction of labor will be required. It has also been used to assess the likelihood of spontaneous preterm delivery. The Bishop Score was developed by Professor Emeritus of Obstetrics and Gynecology, Dr. Edward Bishop, and was first published in August 1964.
The total score is calculated by assessing the following five components on manual vaginal examination by a trained professional:
- Cervical dilation in centimeters
- Cervical effacement as a percentage
- Cervical consistency by provider assessment/judgement
- Cervical position
- Fetal station, the position of the fetal head in relation to the pelvic bones
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 (pharmacologic or physical, such as a foley bulb) be used before other methods.
They can be remembered with the mnemonic: Call PEDS For Parturition = Cervical Position, Effacement, Dilation, Softness; Fetal Station.
The examiner assigns a score to each component of 0 to 2 or 0 to 3. The highest possible score is 13 and the lowest possible score is 0.
|Cervical position||Posterior||Middle||Anterior||–||The position of the cervix changes with menstrual cycles and also tends to become more anterior (nearer the opening of the vagina) as labour becomes closer.|
|Cervical consistency||Firm||Medium||Soft||–||In primigravid women, the cervix is typically tougher and resistant to stretching, much like a balloon that has not been previously inflated (it feels like the bottom of a chin). With subsequent vaginal deliveries, the cervix becomes less rigid and allows for easier dilation at term.|
|Cervical effacement||0-30%||40-50%||60-70%||80+%||Effacement translates to how 'thin' the cervix is. The cervix is normally approximately three centimetres long, as it prepares for labour and labour continues the cervix will efface till it is 'fully effaced' (paper-thin).|
|Cervical dilation||Closed||1–2 cm||3–4 cm||5+cm||Dilation is a measure of how open the cervical os is (the hole). It 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 of the fetus's head in relation to the distance from the ischial spines, which are approximately 3-4 centimetres inside the vagina and are not usually felt. Health professionals visualise where these spines are and use them as a reference point. Negative numbers indicate that the head is further inside than the ischial spines and positive numbers show that the head is below the level of the ischial spines.|
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A Bishop's score 6 or less often indicates that induction (e.g., with controlled-release prostaglandin E2/prostin gel [Cervidil], intravaginal gel [Prostin], intracervical gel [Prepidil]) is unlikely to be successful. Some sources indicate that only a score of 8 or greater is reliably predictive of a successful induction.
Modified Bishop score
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 for >3 cm, 1 for >2 cm, 2 for >1 cm, 3 for >0 cm. Cervical length may be easier and more accurate to measure and have less inter-examiner variability.
Another modification for the Bishop's score is the modifiers. Points are added or subtracted according to special circumstances as follows:
- One point is added to the total score for:
- 1. Existence of pre-eclampsia
- 2. Each previous vaginal delivery
- One point is subtracted from the total score for:
- 1. Postdate/post-term pregnancy
- 2. Nulliparity (no previous vaginal deliveries)
- 3. PPROM; preterm premature (prelabor) rupture of membranes
- Bishop, Edward H. (August 1964). "Pelvic Scoring for Elective Induction". Obstetrics & Gynecology. 24 (2): 266–268. PMID 14199536.
- Newman RB, Goldenberg RL, Iams JD, et al. (September 2008). "Preterm Prediction Study: Comparison of the Cervical Score and Bishop Score for Prediction of Spontaneous Preterm Delivery". Obstet Gynecol. 112 (3): 508–15. doi:10.1097/AOG.0b013e3181842087. PMC 2728002. PMID 18757646.
- AGOS-Edward H. Bishop
- Tenore J (2003). "Methods for cervical ripening and induction of labor". Am Fam Physician. 67 (10): 2123–8. PMID 12776961. (Incomplete) Free Text.
- Dutta DC. Text Book of Obstetrics. 6ed. New Central Book Agency. 2001. ISBN 978-81-7381-142-5.