The aim of this study is to determine how the Bishop Score (BS) fares as a measurement tool.
The literature was reviewed to identify publications reporting the derivation and measurement properties of the BS. Its sensibility and reliability were assessed using 19/21 Feinstein principles and weighted kappa respectively.
BS was derived with the intention of selecting multiparous women most likely to have a vaginal birth within four hours of commencing induction of labor (IOL) based on a score ≥9, and not for predicting the success of IOL. With regard to sensibility, the score performed well on 12/19 attributes encompassing domains of purpose and framework, comprehensibility and ease of usage; moderately on 1/19 attribute related to face validity and poorly on 6/19 attributes related to replicability, suitability and content validity. Areas of greatest concern included omissions of important variables known to influence the success of IOL as well as inclusion and equal weighting of five highly correlated components. Kappa values varied between 0.35 and 0.69.
Although intended to be a discriminative index in multiparous women, BS is widely used as a prediction tool to determine the success of IOL in all women. Despite concerns regarding its derivation, sensibility and reliability, meta-analyses show that it is the best available tool to determine the success of IOL. With recent studies showing that cervical favorability is a poor determinant of the success of IOL, BS needs to be replaced by a prediction tool derived using sound statistical principles and validated in global settings.