|Year : 2019 | Volume
| Issue : 1 | Page : 61-64
Predicting preterm labour by means of uterine artery doppler velocimetry during peak uterine contraction in patients with normal cervical length
Mahsa Naemi1, Laleh Eslamian1, Nastaran Teimoory1, Maryam Moshfeghi2, Ali Tajik3
1 Department of Obstetrics and Gynecology, Tehran University of Medical Sciences, Tehran, Iran
2 Department of Endocrinology and Female Infertility, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
3 Department of Community and Preventive Medicine, Tehran University of Medical Sciences, Tehran, Iran
|Date of Web Publication||4-Jan-2019|
Department of Obstetrics and Gynecology, Tehran University of Medical Sciences, Tehran
Source of Support: None, Conflict of Interest: None
Background: This study was conducted to evaluate the uterine artery Doppler velocimetry (UADV) during peak uterine contraction in order to predict preterm labour in Iranian women with a normal cervical length. Materials and Methods: This cohort study was conducted at Shariati Hospital within an interval of 1 year between January 2016 and January 2017. One hundred women within gestational age <24 weeks and preterm uterus contraction were enrolled. UADV during peak uterine contraction was evaluated by a perinatologist. Their flow velocity waveforms were recorded (during three consecutive uterine contractions), and the mean for uterine artery doppler pulsatility index (PI) was documented. Results: One hundred cases with the mean age of 31 ± 4.8 years were enrolled in this study. From this selection, eight (8%) cases delivered during the first 48 h of admission and 13 (13%) during the first 7 days. The mean gestational age and the PI were significantly different between cases who delivered during the first 48 h and those who failed to do so. The correlation coefficient between PI and gestational age was r = 0.2, P = 0.02. For women who delivered within the first 7 days, the mean velocity and the PI were considered as significant variables for predicting preterm birth. At last, similar to the first group, for those women who delivered within the first 14 days, the PI was the only predicting factor for preterm birth. Conclusion: This study concludes that the mean PI of uterine artery during peak contractions can be considered as a strong predictor of delivery in preterm labour in women with normal cervical length.
Keywords: Preterm labour, pulsatile index, uterine artery Doppler
|How to cite this article:|
Naemi M, Eslamian L, Teimoory N, Moshfeghi M, Tajik A. Predicting preterm labour by means of uterine artery doppler velocimetry during peak uterine contraction in patients with normal cervical length. Adv Hum Biol 2019;9:61-4
|How to cite this URL:|
Naemi M, Eslamian L, Teimoory N, Moshfeghi M, Tajik A. Predicting preterm labour by means of uterine artery doppler velocimetry during peak uterine contraction in patients with normal cervical length. Adv Hum Biol [serial online] 2019 [cited 2019 Mar 26];9:61-4. Available from: http://www.aihbonline.com/text.asp?2019/9/1/61/249516
| Introduction|| |
One of the most common causes of hospitalisation during pregnancy is preterm labour. Nearly one-fifth of women hospitalised for preterm labour. The frequency of preterm births is about 12%–13% in the USA and 5%–9% in many other developed countries. One of the main causes of preterm delivery is preterm premature rupture of membranes, while pre-eclampsia and foetal growth restriction (FGR) can be identified as other common causes that could lead to such complications., Several studies have reported an effect of smoking on length of gestation., It is often that following the assessment for preterm labour, the patient is admitted to centres that offer therapies such as tocolysis and steroids to inhibit uterus contractions or alternatively referred to hospitals for further treatments.,,
Previous studies have demonstrated that the intensity of uterine contractions is associated with end-diastolic flow., Moreover, they have confirmed that the compression of uterine arteries during contractions will result in the disappearance or reduction of diastolic component., Therefore, measurement of uterine artery (UTA) Doppler during contractions may be considered as a predictor of preterm birth in women who are admitted for preterm labour., This study has been designed to evaluate the analysis of UTA Doppler measurement during peak uterine contractions in order to predict preterm labour in Iranian women.
| Materials and Methods|| |
This is a cohort study conducted in Shariati Hospital as a referral centre affiliated to Tehran University of Medical Sciences (Tehran, Iran) from December 2016 to August 2017. The exclusion criteria were multiple pregnancies, rupture of membranes, gestational age <24 weeks or more than 35 weeks, non-cephalic presentation, uterine anomalies, placenta previa, abnormal placentation, chronic heart disease, inflammatory or infectious disease, gestational hypertension, pre-eclampsia, FGR, congenital abnormalities, oligohydramnios, polyhydramnios, diagnosed cervical incompetence and chorioamnionitis.
Before the study, all participants were asked to fill out an informed consent form. The procedure began with a sonography done by an expert perinatologist using a Doppler ultrasound machine (Philips Affiniti 70). The criterion considered at the admission was mainly the occurrence of uterine contractions. However, the cervical dilation and ripening were also evaluated through a digital examination to exclude false labour. This was followed by transabdominal ultrasonography to measure the patient's UTA Doppler pulsatility index (PI) and velocimetry. When the patients experienced three consecutive uterine contractions, the flow velocity waveforms and peak PI were recorded and their means were calculated. All patients were observed during the following intervals: 48 h, 7 days and 14 days, by practitioners who were blinded to the study. They recorded the following data for all case studies: age, parity, gravidity, abortion, previous preterm labour, family history and gestational age.
Data were analysed using SPSS software version 20 (SPSS Inc., Chicago, IL, USA). Independent-samples t-test was used to compare the results for variables. The indices used for this study were the mean, standard deviation and correlation coefficient. Following the analysis of logistic regression, a receiver operating characteristic curve was used to determine the optimal cut-off values that considered P < 0.05 as significant.
| Results|| |
One hundred case studies with the mean age of 31 ± 4.8 years were selected during the study period. Eight (8%) of them had previous preterm labour; moreover six (6%) had a family history of preterm labour. The basic characteristics of these patients are summarised in [Table 1].
Eight (8%) of the cases within our sample were delivered within the first 48 h of admission, 13 (13%) within the first 7 days and 11 (11%) within the first 14 days. The study demonstrates that the mean gestational age and PI were significantly different in cases who delivered within the first 48 h; the study also demonstrates that the mean PI and velocity were significantly different between those cases in our sample who delivered within the first 7 days and those who failed to do so. Following these calculations, it was further suggested that the cases who delivered within the first 14 days were significantly different in their PI measurements than those who failed to do so [Table 2].
|Table 2: Comparison of factors between cases who delivered within the first 48 h, 7 days and 14 days and those who did not|
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The correlation coefficient between PI and gestational age in this study was r = 0.2 and P = 0.02. In addition, the UTA PI was the only predictor (odds ratio [OR] = 0.08, P = 0.01) for a successful delivery within the first 48 h. For those cases who delivered within the first 7 days, UTA PI and velocity were the predictors for preterm birth, and for those cases who delivered within the first 14 days, UTA PI was the only predictor for preterm birth [Table 3].
|Table 3: Logistic regression while considering the delivery during 48 h, first 7 days and first 14 days as dependent and the pulsatile index, velocity and gestational age as independent variables|
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The PI cut-off points that lead to predictions of preterm delivery are as follows: for deliveries within the first 48 h, the cut-off point is measured as 0.98 with sensitivity and specificity of 75% and 70%. For deliveries within the first 7 days, the cut-off point is measured as 1 with sensitivity and specificity of 84% and 76%. For deliveries within the first 14 days, the cut-off point is measured as 0.95 with sensitivity and specificity of 63% and 69%.
| Discussion|| |
The result of this study demonstrates that the mean PI was significantly higher in case studies who delivered preterm, while velocity was not a strong indicator for difference observed in cases who delivered preterm and those who failed to do so.
The findings of this study were in agreement with Olgan and Celiloglu who evaluated 172 women with gestational age between 24 and 32 weeks. In their study, they considered velocity and UTA PI during maximum contractions as predictors of preterm labour. They concluded that the mean UTA PI in women who delivered within the first 7 days was significantly higher than those who delivered later. Therefore, they confirmed that the PI can be considered as a predictor of preterm delivery. Similar to the results of our study, they reported a weak correlation between PI and the gestational age. In addition, in our study, the mean PI was the only predictor of preterm delivery during the first 48 h, the first 7 days and the first 14 days. The OR for the PI during the first 48 h was less than the OR for the 7 or the 14 days in women with preterm labour. Therefore, it can be concluded that the UTA PI is a strong indicator to predict preterm delivery in women with preterm contraction.
These findings slightly disagree with the conclusions made by Olgan and Celiloglu who considered the best cut-off point for PI during the first 48 h, the first 7 days and the first 14 days as 1.93, 1.32 and 1.26 as opposed to our findings of 0.98, 1 and 0.95 for similar intervals.
This study confirms that the uniform rectangular array Doppler Index is a valuable method in predicting preterm delivery. This method is made more convenient considering the non-invasive and accessible nature of its application. Currently, this method is applied to predict pre-eclampsia, FGR, placental abruption and stillbirth., However, in this study, it has been demonstrated that this method can also be a predictive factor for evaluating preterm birth in high-risk women.
Despite these findings, this study was faced with a limitation regarding sample size. Considering this research was conducted in a tertiary hospital, our samples were limited. To further confirm the findings of this research, a more complete sample size is required.
| Conclusion|| |
This study concludes that the mean PI of uterine artery during peak contractions can be considered as a strong predictor of delivery in preterm labour in women with normal cervical length.
We gratefully acknowledge the kind support of the participants for their precious collaboration in this study as well as staffs of referred hospitals.
Financial support and sponsorship
This study was financially supported by Tehran University of Medical Sciences.
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]