RESEARCH ARTICLE |
https://doi.org/10.5005/jp-journals-10016-1325 |
A Study of Transvaginal Cervical Length Measurement at Term in the Prediction of Labor Outcome
1Department of Obstetrics and Gynaecology, Government Medical College, Tiruvallur, Tamil Nadu, India
2Department of Obstetrics and Gynaecology, Government Vellore Medical College, Vellore, Tamil Nadu, India
3Department of General Medicine, Saveetha Medical College, Chennai, Tamil Nadu, India
Corresponding Author: Padmalatha Dakshnamurthy, Department of Obstetrics and Gynaecology, Government Medical College, Tiruvallur, Tamil Nadu, India, Phone: +91 9841696797, e-mail: endork7@gmail.com
Received on: 08 July 2023; Accepted on: 08 August 2023; Published on: 25 November 2023
ABSTRACT
Background: The cervix and the changes it undergoes in pregnancy play an important role in the initiation and progress of labor.
Materials and methods: The period of study was from January to December 2022 for a period of one year. A total of 370 low-risk primigravid antenatal mothers were included in the study. Cervical length was measured transvaginally at 37 weeks.
Results and analysis: The average length of the cervix ranged from 1 to 5 cm. The cervical length was <3 cm in 48.3% of patients and >3 cm in 51.7% of patients. Among the 370 primigravid mothers, 248 were delivered by labor natural (67%), 97 by lower segment cesarean section (LSCS) (26.2%), and 25 by instrumental delivery (3.8%). Patients with a cervical length of <3 cm had a shorter duration of labor when compared to patients with a cervical length of >3 cm. The need for induction and the induction delivery interval was less in patients with shorter cervical length.
Conclusion: Ultrasonography (USG) is one of the key investigations in antenatal care. Transvaginal cervical length measurement is a useful tool to predict favorable outcomes in labor induction and the progress of labor. Hence routine measurement of transvaginal cervical length in all the antenatal mothers will help the treating obstetrician in planning the management of delivery.
How to cite this article: Dakshnamurthy P, Vasu K, Rajendran K. A Study of Transvaginal Cervical Length Measurement at Term in the Prediction of Labor Outcome. Int J Infertil Fetal Med 2023;14(3):129–132.
Source of support: Nil
Conflict of interest: None
Keywords: Cervical length measurement, Induction, Labor outcome, Mode of delivery, Onset of labor, Transvaginal ultrasound
INTRODUCTION
Ensuring the best antenatal care is the epitome of a normal healthy pregnancy with the delivery of a healthy child. History taking, regular antenatal checkups, clinical examination, and investigations are carried out at monthly intervals till 7 months then at 2 weekly intervals till 36 weeks, and weekly once till delivery. The goal of good antenatal care is to identify maternal and fetal complications at the earliest and treat them on time with the appropriate measures to prevent morbidity and mortality.
In the past decade, ultrasonography (USG) has played a key role in the accurate dating of pregnancy, screening of fetal anomalies, early detection of fetal growth restriction, and other complications.
The cervix undergoes a lot of changes during pregnancy both at micro and macro levels.1 Collagen rearrangement and realignment in the cervix play a key role in the effacement and dilatation of the cervix and the progress of labor.2 USG measurement of cervical length in preterm labor has made a significant impact in the management of preterm labor as well as a useful predictor of the onset of spontaneous labor. Cervical length measurement is also useful to assess the success of labor induction.3
The main objective of our study was to determine the predictive value of cervical length measurement using USG in low-risk primigravid mothers with regard to the onset of labor, need for induction, and outcome of labor.
MATERIALS AND METHODS
Our study was conducted in a tertiary care hospital for 1 year period from January to December 2022. The study was initiated after the approval of the ethical committee. Informed consent was obtained from the patient as well as one of the key family members.
The study population was recruited from the antenatal clinic of the tertiary care hospital. The inclusion criteria were all primigravid with 37 weeks of gestation, fetuses in cephalic presentation, and those without any medical and surgical complications. Patients with antepartum hemorrhage, multiple gestation, medical disorders, ruptured membranes, previous LSCS, cervical cerclage, and malpresentation were excluded from the study.
A detailed history taking, clinical and obstetric examination was done for all patients. First-trimester USG was done and used to calculate the gestational age. Repeat USG was done later at 37 weeks of gestation which measured the fetal biometric parameters and amniotic fluid index. Cervical length was also measured using transvaginal USG. To avoid the change in the position and shape of the cervix, the vaginal probe was placed 3 cm proximal to the cervix. The sagittal view of the cervical canal length was measured. Three measurements were taken in the absence of uterine contractions which included the distance between the internal and external os at their farthest points. The shortest measurement was taken as the final cervical length.
All the antenatal mothers were observed till delivery as per the protocol of the hospital. The patients who went in for spontaneous onset of labor were followed up and were delivered as per their progress. The mode of delivery was decided as per the maternal and fetal conditions during labor. Patients who did not deliver on the expected date of delivery were admitted to the antenatal ward and were monitored with fetal kick count and modified biophysical profile till 40 weeks plus 2 days. At 40 weeks plus 3 days favourability of the cervix was assessed using a modified bishops score (MBS) and induction of labor was done. Intracervical application of dinoprostone prostaglandins E 2 (PGE2) gel 0.5 mg or mechanical induction with Foley’s catheter were the methods used for the induction. In cases where Foley’s catheter was used for induction, MBS was reassessed after 24 hours and further induction with PGE2 gel application was considered. Pre and postgel-reactive cardiotocograph tracings were ensured in all individuals. After 6 hours of the first PGE2 gel application, further cervical assessment was done. Depending upon the MBS, a second dose of PGE2 gel was instilled.
As per the hospital protocol, if there was no improvement in the modified bishop’s score even after two doses of PGE2 gel application, it was considered a failed induction and the patient was taken up for emergency LSCS. In cases who had unsatisfactory progress of labor, augmentation wa s done using amniotomy and oxytocin infusion as required. Cervical length measurement, need for induction, induction delivery interval, mode of delivery, and LSCS rate with indications were assessed and recorded. The statistical data was analyzed using the Statistical Package for the Social Sciences software 23.0 version, Chi-Square test was used to find the significance of data and a probability value of <0.05 was considered and taken as significant.
RESULTS
In our study 11.4% of the patients were in the age-group of 18–20 years, 34.1% were between 21 and 25 years, 41.6% were between 26 and 30 years, 11.6% were between 31 and 35 years and 1.4% were above 35 years of age.
With regard to the body mass index (BMI) distribution, 2.7% of the patients had a BMI of <18.5, 41.6% had BMI between 18.5 and 24.9, 34.1% had a BMI of 25–29.9, and 21.6% had a BMI of >30. The cervical length was between 1 and 2 cm in 15.1% of patients, 2–3 cm in 54.1%, 3–4 cm in 16.2%, and 4–5 cm in 14.6% of patients (Fig. 1).
Fig. 1: Transvaginal cervical length distribution
Among the 370 patients, 68.6% went in for spontaneous onset of labor and 31.4% were postdated (Fig. 2). In the postdated pregnancies 37% were induced with Foley’s catheter and one dose of PGE2 gel, 14.7% with one dose of PGE2 gel, 48.3% with Foley’s and two doses of PGE2 gel (Fig. 3). Duration of induction delivery interval was <6 hours in 14.7%, <18 hours in 41.4%, and <24 hours in 44% of the patients (Fig. 4). Around 67% of the patients had labor natural, 26.2% underwent LSCS, 3.8% had outlet forceps delivery and 3% had vacuum delivery (Fig. 5). The indication for LSCS was fetal distress in 22.4%, failed induction (FI) in 23.5%, and failure to progress (FTP) in 51% (Fig. 6).
Fig. 2: Labor induction distribution
Fig. 3: Mode of induction of delivery distribution
Fig. 4: Duration of induction of delivery distribution
Fig. 5: Mode of delivery distribution
Fig. 6: Indication for LSCS distribution
The association of transvaginal sonogram (TVS) with the need for induction by the Chi-square test was χ2 = 145.286, p = 0. 0005 < 0.01 which showed a statistically significant association between TVS and the need for induction (Table 1). The association between TVS with the mode of delivery in patients who went in for spontaneous onset of labor by Chi-square test was χ2 = 50.362, with a p-value of =0.0005 < 0.01 which shows a statistically significant association between TVS and mode of delivery in patients who went in for spontaneous onset of labor (Table 2). The association between TVS with mode of delivery after induction by Chi-square test was χ2 = 21.383 with a p-value of 0.002 < 0.01 which shows a statistically significant association between TVS and mode of delivery after induction (Table 3).
Induction | Total | ||||
---|---|---|---|---|---|
No | Yes | ||||
TVS | 1–2 | Count | 50 | 6 | 56 |
% | 19.6% | 5.2% | 15.1% | ||
2–3 | Count | 175 | 25 | 200 | |
% | 68.6% | 21.7% | 54.1% | ||
3–4 | Count | 20 | 40 | 60 | |
% | 7.9% | 34.8% | 16.2% | ||
4–5 | Count | 10 | 44 | 54 | |
% | 3.9% | 38.3% | 14.6% | ||
Total | Count | 255 | 115 | 370 | |
% | 100.0% | 100.0% | 100.0% |
Mode | Total | |||||
---|---|---|---|---|---|---|
Labor natural | LSCS | Instrumental | ||||
TVS | 1–2 | Count | 46 | 2 | 2 | 50 |
% | 22.5% | 4.9% | 20.0% | 19.6% | ||
2–3 | Count | 147 | 24 | 4 | 175 | |
% | 72.1% | 58.5% | 40.0% | 68.6% | ||
3–4 | Count | 9 | 8 | 3 | 20 | |
% | 4.4% | 19.5% | 30.0% | 7.9% | ||
>4 | Count | 2 | 7 | 1 | 10 | |
% | 1.0% | 17.1% | 10.0% | 3.9% | ||
Total | Count | 204 | 41 | 10 | 255 | |
% | 100.0% | 100.0% | 100.0% | 100.0% |
Mode | Total | |||||
---|---|---|---|---|---|---|
Labor natural | LSCS | Instrumental | ||||
TVS | 1–2 | Count | 5 | 0 | 1 | 6 |
% | 11.4% | 0.0% | 6.7% | 5.2% | ||
2–3 | Count | 16 | 7 | 2 | 25 | |
% | 36.4% | 12.5% | 13.3% | 2186% | ||
3–4 | Count | 11 | 23 | 6 | 40 | |
% | 25% | 41.1% | 40.0% | 34.8% | ||
>4 | Count | 12 | 26 | 6 | 44 | |
% | 27.3% | 46.4% | 40.0% | 38.2% | ||
Total | Count | 44 | 56 | 15 | 115 | |
% | 100.0% | 100.0% | 100.0% | 100.0% |
DISCUSSION
In our study, 370 low-risk primigravid mothers were recruited. The age-group of the patients was between 18 and 40 years with the mean age being 26 years. Obstetric USG was done at 37 weeks of gestation along with the transvaginal measurement of cervical length. In all the patients the cervical length ranged between 1 and 5 cm. Around 51.7% of the patients had a cervical length >3 cm and in 48.3% the cervical length was <3 cm. The patients were observed till term and noted whether they entered spontaneous labor or went postdated. Postdated pregnancy was the only indication for induction of labor. The mode of delivery in patients who went in for spontaneous onset of labor and who were induced was observed and tabulated.
In our study, 248 patients (67%) were delivered by labor natural, 97 patients (26.2%) by LSCS, and 25 patients (3.8%) by instrumental delivery. It was observed that patients with cervical length <3 cm had a shorter duration of labor when compared to patients with a cervical length of >3 cm. The above finding of our study concurred with the work of Tan et al., which reported that transvaginal measurement of cervical length had a superior sensitivity in predicting the onset of labor.4 In a study done by Kanwar et al. concluded that the cervical length measurement by TVS provides a better prediction of normal vaginal delivery.5 Many studies revealed that the average median cervical length was 2.5 cm and also concluded that cervical length measurement by USG can be used in predicting the successful onset of labor.6-8 In our study, 255 patients entered spontaneous labor of which 147 patients with a cervical length of 2–3 cm delivered normally which concurred with the study of Pandis et al.8 A study done by Rozenberg et al. differed from our study concluding that Bishop score was better than measuring cervical length.9
A study done by Jaisaby et al. concluded that patients with longer cervical length had a delay in the onset of labor.10 The findings concur with our study where 44 patients with a cervical length of 4–5 cm needed induction while only 25 patients with a cervical length of 2–3 cm required induction.11 The longer the cervical length the longer the induction delivery interval. The need for a second dose of PGE2 was greater in patients who had a cervical length of >4 cm.
Hoogeveen et al. study compared Bishop score and cervical length measurement and found that cervical length measurement was a better predictor of failed induction which concurred with our study.12 In nulliparous women measurement of cervical length is a better predictor of successful labor induction.13 Cervical length measurement by USG is a better predictor of cervical ripening and vaginal delivery at 41 weeks of gestation.14
Both in patients who entered spontaneous labor (70%) and in patients who were induced (59%), the LSCS rates were high in patients with a cervical length of >4 cm. In patients with a cervical length of <3 cm had relatively lower LSCS rates. It was 28% in patients who entered spontaneous labor and 13.7% in patients who were induced to LSCS. Cervical length measurement is an independent predictor of the mode of delivery.15
CONCLUSION
The USG plays an important and key role in the routine antenatal care. Transvaginal measurement of cervical length has become an integral part of obstetric USG.
Many studies have proven a better association between cervical length with the onset and duration of labor which concurred with our study. Cervical length can also be used as a predicting tool for favorable outcomes after labor induction and progress.
Hence routine measurement of transvaginal cervical length in all the antenatal mothers will help the treating obstetrician in planning the management of delivery.
ORCID
Padmalatha Dakshnamurthy https://orcid.org/org/0009-0009-2027-6972
Kannan Rajendran https://orcid.org/0000-0003-3536-6515
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