|Year : 2019 | Volume
| Issue : 2 | Page : 168-172
The role of ultrasound in the prediction of successful induction of labour
Sara Nejateslami Fard1, Mahsa Naemi1, Reihaneh Pirjani2, Vajiheh Marsoosi1
1 Department of Obstetrics and Gynecology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
2 Department of Obstetrics and Gynecology, Arash Women's Hospital, Tehran University of Medical Sciences, Tehran, Iran
|Date of Web Publication||8-May-2019|
Department of Obstetrics and Gynecology, Shariati Hospital, Tehran University of Medical Sciences, Tehran
Source of Support: None, Conflict of Interest: None
Background: So far, there has not been conducted the study in Iran about the role of ultrasound in the prediction of successful induction of labour. Therefore, the aim of this study was to investigate the role of sonographic parameters that may help clinicians to improve the prediction of the outcome of induction and need for ripening of cervix before induction. Materials and Methods: In this prospective study, the number of 298 singleton pregnancies that attended for the induction of labour at Shariati and Arash Hospitals in 2017 was evaluated. Immediately before the induction, transvaginal sonography was performed for the measurement of cervical length and posterior cervical angle, and a transabdominal scan was carried out to determine the position of the foetal occiput. Cox proportional hazard model was used for determination of the effects of independent predictor variables on the induction-to-delivery time. Results: The most common indication for the induction was movement reduction and prolonged pregnancy with 20.5% and 18.5% of cases, respectively. The mean of posterior cervical angle in patient delivered vaginally was 124 ± 18 and in patient delivered by caesarean section was 100 ± 26.5 (P < 0.001). The sensitivity, specificity, positive predictive value and negative predictive value of sonography compared Bishop score for the likelihood of vaginal delivery within 24 h and was 93.98%, 47.56%, 75% and 82.52%, respectively. Conclusion: The use of parameters of sonographic to predict the outcome of induction enables the clinician to present precise information to mothers and plan for the further management of the pregnancy.
Keywords: Induction, predictive value of tests, pregnancy, pregnancy outcome, ultrasonography
|How to cite this article:|
Fard SN, Naemi M, Pirjani R, Marsoosi V. The role of ultrasound in the prediction of successful induction of labour. Adv Hum Biol 2019;9:168-72
|How to cite this URL:|
Fard SN, Naemi M, Pirjani R, Marsoosi V. The role of ultrasound in the prediction of successful induction of labour. Adv Hum Biol [serial online] 2019 [cited 2020 Jul 3];9:168-72. Available from: http://www.aihbonline.com/text.asp?2019/9/2/168/257821
| Introduction|| |
Induction of labour is one of the most common obstetrical procedures. More than 22% of deliveries are conducted by induction of labour. The aim of induction of labour is a vaginal delivery safely for maternal and neonate. Induction of labour is widely used, it prevents from complications such as caesarean section, unfavourable cervix, prolonged labour, postpartum haemorrhage, traumatic birth and it improves health outcomes for maternal and their neonate.
A standard method to predict the safety and duration of induction labour is the Bishop score. However, this method of evaluation has been reported to be a poor predictor of labour in female planned for induction of labour and it is subjective. Ultrasonography has been proposed as a useful method to monitor the progression of labour and to predict the mode of delivery in different studies.,
The estimate of cervical length by transvaginal ultrasound before the induction of labour has also been suggested to predict successful induction of labour. However, a meta-analysis study by Verhoeven et al. in 2013 included 31 studies was presented that estimate of cervix length in labour only could be predicted the outcome of delivery after the induction of labour moderately. Another study by Yang in 2004 assessed that cervical length is a method of predictor successful for labour induction measured by transvaginal ultrasonography. It predicted more successful labour induction than the Bishop score.
Occiput posterior (OP) is the most common malposition in the labour, and its prevalence is 4%–10% during the second stage of labour and at delivery. It is associated with prolonged labour, third- and fourth-degree perineal lacerations, haemorrhage, chorioamnionitis and wound infection in postpartum. Akmal et al. reported that the risk of caesarean section can be estimated during the early stage of active labour by performing of sonographic determined occiput position.
A study showed that in women undergoing induction of labour, the posterior cervical angle is better than the Bishop score in the prediction of the outcome of labour. So far, the study in Iran has not been conducted about the role of ultrasound in the prediction of successful induction of labour. Therefore, the aim of this study was to investigate the role of sonographic parameters that may help clinicians to improve the prediction of the outcome of induction and need for ripening of cervix before the induction.
| Materials and Methods|| |
Study design and setting
This study was a prospective study of 298 singleton pregnancies that attended for induction of labour at Shariati and Arash Hospitals (Tehran-Iran) in 2017. The ethical committee clearance number in this study was 9211290024.
Patients with pervious caesarean delivery, any contraindication to delivery, nonvertex presentation and multiple pregnancies were excluded from the study. Cephalic presentation for live foetuses, first pregnancy and undergoing induction of labour at 35–42 weeks of gestation were considered as inclusion criteria. All participants completed the written consent and accepted to participate in the study.
We performed transvaginal sonography (TVS) immediately before induction for the measurement of cervical length and posterior cervical angle. In continuation, a transabdominal scan was done to determine the position of the foetal occiput. Afterward, a trained midwife evaluated the Bishop score. It should be noted that she was not aware of the sonographic findings. Bishop score is a scoring system in pre-labour for predicting whether induction of labour will be required as well as to assess the likelihood of spontaneous preterm delivery.
The ultrasound transducer was placed transversely in the suprapubic region of the maternal abdomen to determine the foetal head position. The landmarks depicting foetal position were the foetal orbits for OP position, the midline cerebral echo for occiput transverse (OT) positions and cerebellum or occiput for occiput anterior (OA) position.
The findings for each patient were drown in a circle within a page, like a clock, with 24 divisions, and the position was described as anterior (OA) if the occiput was between 09.30 and 02.30 h, transverse (OT) if between 02.30 and 03.30 h, or 08.30 and 09.30 h and posterior (OP) if between 03.30 and 08.30 h.
The induction was started after vaginal examination and Bishop score determination. Misoprostol was prescribed for cases with Bishop score <5 and oxytocin for inappropriate contractions of uterus and Bishop score ≥5. Amniotomy was performed when cervix ≥4 cm.
We used a researcher-made checklist including participations age, weight, height, body mass index (BMI), gestational age at induction, maternal age, foetal weight, cervical length, posterior cervical angle, occiput position, induction to delivery time, Bishop score and delivery type.
Qualitative data were presented with frequency and percentage, and quantitative variables were presented with mean ± standard deviation. Normality of data was assessed with the Kolmogorov–Smirnov test. The mean comparisons of investigated variables between groups were assessed through the Student's t-test. Cox proportional hazard (PH) model was used for determination of the effects of independent predictor variables on the induction-to-delivery time. Schoenfeld's residual test was used to test the PHs' assumption. Times that exceeded 24 h or which resulted from caesarean sections were considered as censored.
For different probability cutoffs, the sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) were calculated. In the comparison of the receiver operating characteristics curves, the area under the curve is usually the best discriminator.
All the analyses were done using SPSS (version 23) (SPSS Inc., Illinois, USA). P < 0.05 was considered as statistically significant.
| Results|| |
In the present study, we assessed 298 patients undergoing induction of labour. The demographic and clinical characteristics of study populations are presented in [Table 1]. The mean age of participations was 27.08 ± 5.85 years. About 58.1% of them were obese, and membrane status in 259 (86.9%) of them were intact. Bishop score in 43.8% of them were 4 and only in two patients were 9. Type of induction for nearly half of them was oxytocin followed by misoprostol for 44% of cases. The preinduction position of the foetal occiput was OA in 105 (35.2%) of cases, OT in 11 (37.2%) and OP in 82 (27.5%). Delivery type in 59.1% of them was normal vaginal delivery (NVD).
The most common indication for induction was movement reduction and prolonged pregnancy with 20.5% and 18.5% of cases, respectively, and antepartum haemorrhage with the 2% of cases had the lowest frequency.
The cervical length measured by TVS was significantly shorter in the patient delivered vaginally, compared with patient those delivered by caesarean section (18 ± 5.7) versus (29.5 ± 11) mm, respectively (P < 0.001). The Bishop score was significantly higher in the patients delivered vaginally, compared with patients delivered by caesarean section (5.8 ± 2.3) versus (4.7 ± 7), respectively (P < 0.001). The position of the occiput in delivery time in 52 (17.4%) patients was OP that only 12 of them (6.8%) were vaginally. The mean of posterior cervical angle in patient delivered vaginally was 124 ± 18 and in patient delivered by caesarean section was 100 ± 26.5 (P < 0.001). [Table 2] has been showed indications for Induction of labour.
The results of the unavailable and multivariable analysis using the Cox's PHs' model have been demonstrated in [Table 3]. Based on the results, Cox PH model for OA and OT indicated that in the patients with the BMI ≥30 kg/m2, the risk of the time of induction-to-delivery within 24 h is 1.36 fold higher (adjusted hazard ratio: 1.36 [95% confidence interval: 1.08, 1.81], P = 0.061). In related with OP, none of the variables were not had the significant effect on the time of induction-to-delivery within 24 h.
|Table 3: The results of univariate and multivariate Cox proportional hazards|
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The sensitivity, specificity, PPV and NPV of sonography compared Bishop score for the likelihood of vaginal delivery within 24 h and was 93.98%, 47.56%, 75% and 82.52%, respectively [Table 4].
|Table 4: Comparison of sonography diagnostic values versus Bishop score for the likelihood of vaginal delivery within 24 h|
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| Discussion|| |
The present study reported that the most of indication for induction was movement reduction and prolonged pregnancy with 20.5% and 18.5% of cases, respectively, and antepartum haemorrhage with the 2% of cases had the lowest frequency. Furthermore, the Cox PH model for OA and OT indicated that in the obese patients, the risk of the time of induction-to-delivery within 24 h was 1.36 fold higher. In related with OP, none of the variables were not had the significant effect on the time of induction-to-delivery within 24 h. This study showed that the sensitivity, specificity, PPV and NPV of sonography compared Bishop score for the likelihood of vaginal delivery within 24 h and was 93.98%, 47.56%, 75% and 82.52%, respectively.
Rane et al. in 2004 explained that assessment of cervical length, posterior cervical angle and occiput position by preinduction sonographic is better than the Bishop score in the prediction of outcome of delivery in women undergoing induction of labour. The estimation of sonographic sensitivity in the prediction of caesarean and the likelihood of vaginal delivery during 24 h was better than of the Bishop score by 20%. The posterior cervical angle prepares an accurate measure of the position of the cervix. If this angle is <120°, it indicates prolonged labour. In the prediction of the outcome of induction, sonographic parameters were better than Bishop Score. This study is in line with the present study.
Popowski et al. in France in 2015 showed the effect of foetal head position in labour by ultrasound on maternal and neonatal outcome and mode of delivery. The findings showed that rate of operative delivery increased by digital vaginal determination of foetal occiput positions in ultrasound examination without decreasing maternal and neonatal morbidity, and it in 35% of cases was incorrect. While Akmal et al. showed that the risk of caesarean section can be estimated by sonographic determined occiput position.
A study in 2004 showed that cervical length measurement by transvaginal sonographic and modified Bishop's score were significantly related to successful induction of labour. Moreover, 83.7% of the women delivered vaginally and 39.3% of the women delivered by caesarean section had corrected Bishop's score >5. This study confirmed the present study. Other study showed that transvaginal sonographic is superior to Bishop Score in predicting successful induction of labour.
| Conclusion|| |
The use of parameters of sonographic to predict the outcome of induction enables the clinician to present precise information to mothers and plan for the further management of the pregnancy.
This study was supported by Tehran University of Medical Sciences (TUMS). We gratefully acknowledge the kind support of the participants for their precious collaboration in this study as well as staffs of Shariati and Arash Hospitals.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]