KUMJ | VOL. 22 | NO. 2 | ISSUE 86 | APRIL - JUNE, 2024
Accuracy of Transvaginal Ultrasound Parameters and Bishop Score as Predictors of Successful Induction of Labor in Term High-Risk Pregnancy
Shakya S, Shrestha A
Abstract: Background
Induction is one of the most common interventions in obstetrics practice, accounting
for 1.4-35%. Cervical favorability is crucial for successful induction. The Bishop score
is simple and assesses preinduction cervical favorability based on five components.
However, it has high inter- and intra-observer variability. Alternative objective
methods are transvaginal ultrasound parameters (e.g., cervical length, width, and
funneling).
Objective
To assess and compare the predictive value of transvaginal ultrasound and bishop
score for vaginal delivery. In addition, the time interval from induction to delivery in
women undergoing induction of labor.
Method
This prospective cross-sectional study included 342 pregnant women, in whom
induction of labor was performed at 38-42 weeks of gestation. Cervical length,
funneling, and width from transvaginal sonography and bishop scores by digital
examination are assessed prior to induction in high-risk cases according to standard
protocol.
Result
In our study, both transvaginal cervical length and bishop score showed similar
predictors of successful labor induction, i.e., vaginal delivery. The ROC curve for
cervical length showed an optimal cut-off value of ≤ 32 mm, corresponding to a
sensitivity of 64.2% and a specificity of 60.0%, whereas the optimal cut-off value for
Bishop score was ≥ 5, with a sensitivity of 65.1% and a specificity of 62.0%. However,
cervical width and the presence of cervical funneling did not correlate. Both cervical
length and Bishop score had a significant correlation as predictors of successful
induction, with an OR of 0.93 (95% CI 0.91-0.96), an AOR of 0.96 (955 CI 0.9-0.99),
and an OR of 1.41 (95% CI 1.2-1.6) and an AOR 1.2 (95% CI 1.1-1.5), respectively.
Conclusion
Cervical length and bishop score are both good and equally predict of successful
induction of labor.
Keyword : Bishop score, Cervical length measurement, Labor induction, Obstetric delivery
