Menoufia Medical Journal

ORIGINAL ARTICLE
Year
: 2017  |  Volume : 30  |  Issue : 2  |  Page : 338--342

Multiple ultrasonographic parameters and fetal fibronectin measurement for prediction of preterm labor at risk


Ahmed N Eissa, Osama A El Kilani, Ahmed M Amer 
 Department of Obstetrics and Gynecology, Faculty of Medicine, Menoufia University, Menoufia, Egypt

Correspondence Address:
Ahmed M Amer
Department of Obstetrics and Gynecology, Faculty of Medicine, Menoufia University, Menoufia
Egypt

Abstract

Objective The present study was conducted to evaluate cervical length measurement, placental score, and amniotic fluid volume by ultrasound, and the level of fetal fibronectin (FFN) between 24 and 34 weeks of gestation as predictors of preterm labor. Background Spontaneous preterm birth continues to be the major contributor to perinatal morbidity and mortality. Early detection of preterm labor is difficult because initial symptoms and signs are often mild and may occur in normal pregnancy. The traditional criteria for preterm labor (persistent contractions accompanied by progressive cervical dilatation and effacement) are most accurate. Other means have been thought to detect preterm labor early. These include ultrasound examination of the cervix to measure the cervical length, measurement of amniotic fluid index, and detection of FFN in the cervicovaginal sample. Patients and methods This study was carried out on 80 pregnant women attending the antenatal care clinic of Kafr El-Dwar General Hospital from July 2014 to April 2015. The patients were divided into two groups: group one (50 cases), which included patients who have no history of unexplained preterm labor, and group two (30 cases), which included patients who have a history of unexplained preterm labor. Patients were followed up for the occurrence of preterm labor pain. Full complete history was taken from all cases, and then general examination was done for them. FFN testing and transabdominal and transvaginal ultrasound examination between 24 and 34 weeks of gestation with assessment of cervical length, fetal viability, number, fetal biometry (biparietal diameter, femur length, abdominal circumference), placenta (score, site, and maturity), and amniotic fluid (amount and turbidity) were performed. Results The results of this study revealed that the risk of preterm delivery (PTD) is inversely correlated with cervical length. Routine transvaginal scan of the cervix performed between 24 and 34 weeks helped to identify patients at risk of PTD; women with oligohydramnios are found to be liable to develop preterm labor. Assay of FFN in cervicovaginal secretions has proven to be a valuable test in the prediction of spontaneous PTD. Conclusion The first step in the prevention of preterm labor is early identification of women at risk for preterm birth by the use of ultrasonography to detect cervical length and amniotic fluid volume and by the detection of FFN in cervicovaginal secretion.



How to cite this article:
Eissa AN, El Kilani OA, Amer AM. Multiple ultrasonographic parameters and fetal fibronectin measurement for prediction of preterm labor at risk.Menoufia Med J 2017;30:338-342


How to cite this URL:
Eissa AN, El Kilani OA, Amer AM. Multiple ultrasonographic parameters and fetal fibronectin measurement for prediction of preterm labor at risk. Menoufia Med J [serial online] 2017 [cited 2017 Dec 18 ];30:338-342
Available from: http://www.mmj.eg.net/text.asp?2017/30/2/338/215445


Full Text

 Introduction



Preterm delivery (PTD) is defined as the birth of an infant at less than 37 weeks of gestation. Given the significance of this clinical problem, a large amount of time and energy has been dedicated toward the prevention of preterm birth [1]. Preterm birth is the single largest cause of prenatal mortality and morbidity in infants without anomalies in developed nations. Prematurity remains a leading cause of neonatal morbidity and mortality in developed countries, accounting for 60–80% of deaths of these infants [2]. Digital examination of the cervix, with assessment of uterine contractions along with these high-risk factors, was used for prediction of preterm labor. Unfortunately, these methods are subjective, inaccurate, and thus neither sensitive nor specific [3].

It was desirable to have more objective methods that could accurately and rapidly identify patients at risk of preterm labor. A number of methods have been proposed – such as the evaluation of the presence of cervicovaginal fetal fibronectin (FFN) [4]. The recommendations for cervical length measurement as a screening test are based on the fact that ultrasonographic assessment is a widely accepted and well-standardized method, which requires only a relatively short training period. Another advantage is its high negative predictive value, which was found in all studies including low-risk and high-risk women. This provides the opportunity to avoid unnecessary intervention and reduce time of hospitalization [5].

Aim

The aim of this study is to predict the occurrence of preterm labor by the use of ultrasonography to detect cervical length and amniotic fluid volume and by the detection of FFN in cervicovaginal secretion.

 Patients and Methods



This prospective cohort study was carried out on 80 pregnant women attending the antenatal care clinic of Kafr El-Dwar General Hospital from July 2014 to April 2015. All cases signed a well-informed written consent to declare their agreement. The patients were divided into two groups: group I (50 cases) included patients with no history of preterm labor, which was divided into two subgroups (group IA: those who delivered a full-term fetus, and group IB: those who delivered a preterm fetus); and group II (30 cases) included patients with a history of preterm labor, which was divided into two subgroups (group IIA: those who delivered a full-term fetus, and group IIB: those who delivered a preterm fetus). Next, all patients were followed up for occurrence of preterm labor pain.

Full complete history was taken from all cases including medical and surgical conditions to define high-risk factors and exclusion criteria. Rupture of amniotic membranes, labor pains, and vaginal bleeding were considered as exclusion criteria. Next, full examination was done.

FFN testing was done for all cases, which is a two-step procedure; the first step is obtaining a cervicovaginal sample by a sterile swab during a standard speculum examination, before undergoing vaginal examination (the patient will not be able to have sex or use lubricants for 24 h before the test, because both can cause a false positive FFN result). The second step is processing the sample to detect the presence or absence of at least 50 ng/ml of FFN.

Transabdominal and transvaginal ultrasound examinations were done for all cases between 24 and 34 weeks of gestation for assessment of cervical length, fetal viability, fetal biometry (biparietal diameter, femur length, abdominal circumference), estimation of gestational age, placenta (score, site, and maturity), and amniotic fluid (amount and turbidity).

Patients in group I were followed up monthly, whereas those in group II were followed up weekly in the outpatient antenatal clinic until delivery. In each visit, the previous examinations were done for all cases.

 Results



With regard to the demographic characteristics, there was no significant difference between the two groups regarding age, gravidity, parity, and gestational age at first sampling [Table 1].{Table 1}

As regards placental score, there was no statistically significant difference either between groups or subgroups [Table 2].{Table 2}

With regard to amniotic fluid volume, there was a highly significant statistical difference between groups IA and IB and a significant statistical difference between groups IIA and IIB. The amniotic fluid volume was lower in groups IB and IIB than in groups IA and IIA (highly significant) [Table 3].{Table 3}

With regard to cervical length, there was a highly significant statistical difference between groups IA and IB and between groups IIA and IIB. The cervical length was lower (≤25 mm) in groups IB and IIB than in groups IA and IIA, respectively (highly significant) [Table 4].{Table 4}

With regard to FFN, there was a significant statistical difference between groups IA and IB and a highly significant difference between groups IIA and IIB. FFN was higher in groups IB and IIB than in group IA and IIA, respectively (highly significant). In group I, six (12%) cases developed preterm labor during follow-up, whereas five (16.7%) cases developed preterm labor during follow-up in group II with a highly significant difference (P = 0.000) [Table 5].{Table 5}

 Discussion



Spontaneous preterm birth continues to be the major contributor to perinatal morbidity and mortality [6]. The present study included 80 pregnant women at 24–34 weeks of gestation during routine antenatal visits. These 80 ladies were examined using transvaginal and transabdominal ultrasound for cervical length, amniotic fluid index (AFI), placental score, and assessment of pregnancy status. In addition, measurement of FFN was done. The aim was early prediction of PTD.

Patients were regularly followed up in the outpatient antenatal clinic until delivery, and data for pregnancy outcome and gestational age at delivery were obtained from the hospital filing system or by contacting the patients.

The study showed that, of the 80 pregnancies, six (12%) cases developed preterm labor during follow-up in group I. Five (16.7%) cases developed preterm labor during follow-up in group II.

As regards gestational age of the patients, our results showed that there was no statistically significant difference between groups I and II. This is in agreement with [7],[8].

As regards the placental score, our results showed that there was no statistically significant difference between groups I and II (P = 0.088).

On the other hand, Chen et al. [9] have reported that the placental score has a role in prediction of preterm labor, as preterm placental calcification is associated with a higher incidence of adverse pregnancy outcome and may serve as an indicator of adverse maternal and fetal outcomes when noted on ultrasonography. Conversely, women with late preterm placental calcification are not at a greater risk for adverse pregnancy outcome [9].

As regards the amniotic fluid volume, our results showed that there is a highly significant statistical difference between groups IA and IB and a significant difference between groups IIA and IIB.

Women with oligohydraminos are more likely to be associated with preterm labor, but not all women with oligohydraminos are associated with preterm labor.

This is in accordance with the study by Petrozella et al. [10], who stated that pregnancies with decreased AFI between 24 and 34 weeks, including borderline AFI and oligohydramnios, were significantly more likely to be associated with preterm birth.

With regard to the cervical length, the results of the present study show that there was a highly significant statistical difference between groups IA and IB and between groups IIA and IIB. The cervical length was lower (≤25 mm) in groups IB and IIB than in groups IA and IIA, respectively.

This is in accordance with Hebbar and Koirala [11], who stated that performing ultrasonography (transvaginal scan) routinely at 24–28 weeks can predict PTD. The risk of spontaneous PTD increased steeply as cervical length decreased. At a cut-off value of more than 2.5 cm, the cervical length measurements had a sensitivity and specificity of 77 and 95%, respectively. These data suggested that the duration of pregnancy is directly related to length of the cervix; the shorter the cervix, the greater the chance of PTD.

Berghella et al. [3] have followed up high-risk women with serial ultrasound starting in the first trimester and noted that cervical length less than 25 mm rarely occurred before 14 weeks of gestation even in high-risk women who delivered preterm. They noted that the average gestational age at which a short cervix is detected is 18.7 ± 2.9 week of gestation.

On the other side, Tsoi et al. [12] have shown that delivery within 7 days occurred in 51.4% of those with cervical length below 15 mm and 0.6% of those with cervical length of 15 mm or more, in 21.2% of the fibronectin positive group and in 0.9% of the fibronectin negative group.

In the last few years, a growing number of studies have demonstrated that implementation of FFN testing has resulted in significantly reduced preterm labor admissions, maternal transfers, length of stay, and use of tocolytic agents [13].

With regard to FFN, the present study shows that there was a highly significantly difference between groups I and II (P = 0.000), with high FFN in groups IB and IIB than in groups IA and IIA, respectively.

This is in accordance with the studies by Katie et al. [6] and Tekesin et al. [14], who stated that negative results of FFN correlate with more weeks of pregnancy and more newborn weight at birth, as well as with less morbidity and mortality.

In addition, Tekesin et al. [14] have stated that principal usefulness of FFN assay lies in the high negative predictive value in patients with preterm labor.

The same results were stated by Sieng et al. [15], who showed that FFN can be used as a marker for PTD. In most of the studies, FFN cut-off value was 50 ng/ml, and the results were reported as either positive (≥50 ng/ml) or negative (<50 ng/ml).

Audibert et al. [16] reported that the examination of cervical secretions for FFN allows the prediction of PTD, a result that is consistent with the current study.

 Conclusion



Ultrasonographic assessment of cervical length and amniotic fluid volume has a promising role in the prediction of preterm labor. Considering the magnitude of preterm labor, cost of management of preterm babies, and morbidity–mortality associated with it, the use of ultrasonographic assessment of cervical length and AFI at 24–34 weeks as routine screening method is effective and can be offered to all pregnant women.

In addition, FFN in cervical secretions can be used as a predictor of PTD.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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