Bishop Score
Predicts whether successful vaginal delivery is likely or labor needs to be induced based on the original and the modified versions.
Bishop score is used in obstetrics and gynecology to assess whether labor is likely to be successful or if intervention is required. It is based on five factors: cervical dilation, effacement, station, consistency, and position. There is also a modified Bishop score that includes additional factors such as prior vaginal deliveries, preeclampsia, postdates pregnancy, nulliparity, and premature or prolonged rupture of membranes.Each factor is assigned a point value based on the severity.
For example, a cervical dilation of 3-4 cm receives 2 points, while a dilation of closed receives 0 points. The total score is then used to predict the likelihood of a successful vaginal delivery. Scores above 9 indicate a high likelihood of successful vaginal birth, scores between 5 and 9 carry both indication of induced or spontaneous labor, and scores below 5 indicate that intervention with a cervical ripening method is likely to be required to induce labor.
About Bishop score
This is a score used to determine the possibility of successful vaginal delivery or the need for induced labor.
In some cases, this pelvic or cervix score helps calculate pre-term delivery odds. This model was created in the early 60s by Dr. Edward Bishop.
There are two circulating versions of the score, the original one and a modified one, the items of which can be found in the table below, along their weight in the total score:
| Bishop score items | Answer choices (points) |
| Dilation (cm) | Closed (0) 1 – 2 cm (1) 3 – 4 cm (2) +5 cm (3) |
| Effacement (%) | 0 – 30% (0) 40 – 50% (1) 60 – 70% (2) 80% (3) |
| Station | -3 (0) -2 (1) -1, 0 (2) +1, +2 (3) |
| Consistency | Firm (0) Medium (1) Soft (2) |
| Position | Posterior (0)¨C11CMid (1)¨C12CAnterior (2) |
| Additional items (featured in the modified Bishop score): | |
| Prior vaginal deliveries | Each pregnancy counts as 1 point in score |
| Select what other characteristics may apply: | Preeclampsia (1)¨C13CPostdates pregnancy (-1)¨C14CNulliparity (-1)¨C15CPremature or prolonged rupture of membranes (-1) |
Cervical dilation for delivery is at 10 cm. Minor dilation occurs in some cases days or even weeks before start of labor.
Cervical effacement represents the degree of softening and thinning of the cervix, measured during cervical exam.
Normally effaced cervix is classed as 0%. 50% effacement is when the cervix is half of its original thickness. Vaginal delivery occurs at 100% cervical effacement.
Fetal station describes the descent of the baby into the pelvis. An imaginary line drawn between the two extremities of the pelvic bones is used to assess the fetal position.
When the baby is above the line this marks minus station. When the baby is below the line, this marks plus station.
Score interpretation
As a pre-labor scoring system, the Bishop score offers information as to whether medical inducement of labor is required.
The scores range from 13 to 0, although the latter is highly unlikely. The sum of points awarded to each of the pregnancy associated factors is interpreted as follows:
■ Scores above 9 points indicate high likelihood of successful vaginal birth.
■ Scores between 5 and 9 carry both indication of induced or spontaneous labor. In these cases, the outcome is dependent on other patient factors such as regular contractions or membrane rupture presence.
■ Scores below 5 indicate that intervention with a cervical ripening method is likely to be required to induce labor.
There is a correlation between Bishop scores and caesarean rates. These values differ for first time mothers and women with past vaginal deliveries:
| Bishop score | First time mother (nulliparous) | Past vaginal delivery (multiparous) |
| 0 – 3 | 45% | 7.70% |
| 4 – 6 | 10% | 3.90% |
| 7 – 10 | 1.40% | 0.90% |
Original source
Bishop EH. Pelvic Scoring For Elective Induction. Obstet Gynecol. 1964; 24:266-8.
Other references
1. Laughon SK. et al. Using a Simplified Bishop Score to Predict Vaginal Delivery. Obstet Gynecol. 2011; 117(4): 805–811.
2. Crane JM. Factors predicting labor induction success: a critical analysis. Clin Obstet Gynecol. 2006; 49(3):573-84.
