Role of Bishop score and cervical length by transvaginal ultrasound in induction of labour in primigravidae

Abstract

Aim: To evaluate the role of Bishop score, cervical length by transvaginal ultrasound in predicting the success of induction of labour. Method: It is a prospective study done at Government general Hospital, Kurnool, Andhra Pradesh, India over a period of one year from May 2008 to April 2009. Hundred primigravidae with 37 to 42 weeks of gestation who underwent induction of labour for different indications were taken. Bishop score followed by cervical length in centimeters by transvaginal ultrasound were assessed in all patients. Results: Bishop score of 5 and cervical length by transvaginal ultrasound of 2.8 cm are considered as cutoff values. Bishop score ≤ 5, cervical length above > 2.8 cm are considered unfavorable. Among the women with Bishop score ≤ 5, 62.5% of women had vaginal delivery within 24 hours. In women with Bishop score > 5, 78.5% had successful induction. When cervical length is considered, among the women with cervical length > 2.8cm, 48.9% had successful induction, whereas in women with cervical length ≤ 2.8 cm 84% had successful induction. Whereas when both Bishop score and cervical length are considered when both factors unfavorable, 40.62% women had successful induction. In women with Bishop score ≤ 5 and cervical length ≤2.8 cm, 79.48% had successful induction. Among the women with Bishop score > 5 and cervical length ≤2.8 cm, 72.2% had successful induction. When Both factors are favourable 90.9% of them had successful induction. Conclusion: Bishop score when complimented with cervical length by transvaginal ultrasound could predict the success of induction of labour better compared with assessment by Bishop score alone.