The effect of fetal fibronectin testing on admissions to a tertiary maternal-fetal medicine unit and cost savings

Using Fetal Fibronectin Test to Reduce Hospital Admissions with Diagnosis of Preterm Labor: An Economic Evaluation Study

Background: Preterm labor and delivery remain a major problem in obstetrics accounting for perinatal morbidity and mortality. The challenge is to identify those with true preterm labor to avoid unnecessary hospital admissions. The fetal fibronectin (FFN) test is a strong predictor of preterm birth and can help identify women with true preterm labor. However, its cost-effectiveness as a strategy for triaging women with threatened preterm labor is still debatable. Objective: To evaluate the effect of FFN test implementation on hospital resources by reducing the admission rate of threatened preterm labor in a tertiary hospital, Latifa Hospital, UAE. Methods: A retrospective cohort study of singleton pregnancies between 24 and 34 weeks of gestation who attended Latifa Hospital in the period of September 2015-December 2016, complaining of threatened preterm labor after the availability of an FFN test, and a historical cohort study for those who attended with threatened preterm labor before the availability of an FFN test. Data analysis was performed using a Kruskal-Wallis test, Kaplan-Meier, Fischer exact chi-square and cost analysis. The significance was set at p-value < 0.05. Results: In total, 840 women met the inclusion criteria and were enrolled. The relative risk of FFN for delivery at term was 4.35 times higher among the negative-tested compared to preterm delivery (p-value < 0.001). A total of 134 (15.9%) women were unnecessarily admitted (FFN tested negative, delivered at term) which yielded $107,000 in extra costs. After the introduction of an FFN test, a 7% reduction of threatened preterm labor admissions was recorded.

Fetal Fibronectin and Cervical Length as Predictors of Spontaneous Onset of Labour and Delivery in Term Pregnancies

(1) Objective: This study aimed to determine whether qualitative fetal fibronectin and transvaginal sonographic measurement of cervical length are effective in predicting delivery in term pregnancies within 5 days of the test. (2) Methods: We examined 268 women with singleton pregnancies presenting themselves at 37+0−40+4 weeks (median 38 weeks + 1 day) of gestation with irregular and painful uterine contractions, intact membranes and cervical dilatation less than 2 cm. All women were admitted to hospital up to 72 h after birth. On admission, a qualitative fetal fibronectin test was performed in cervicovaginal secretions and transvaginal sonographic measurement of cervical length was carried out. The primary outcome measure was delivery within 5 days of presentation. RESULTS: Among the women who delivered within 5 days after admission, 65.2% had positive fFN assessment, 43.5% had cervical length below 26 mm, 52.2% had the age > 32.5 years, 34.8% were nulliparous and 56.5% had gestational age ≥ 275 days. Logistic regression analysis demonstrated that significant contributors to the prediction of delivery within 5 days were fibronectin positivity, cervical length ≤ 26 mm, maternal age > 32.5 years and gestational age ≥ 275 days, with no significant contribution from parity. (3) Conclusions: Qualitative fetal fibronectin test and transvaginal cervical length measurement in term pregnancies are useful tests for predicting spontaneous onset of labour within 5 days. It helps women and healthcare providers to determine the optimum time for hospital admission.

Multifetal Gestations: Twin, Triplet, and Higher-Order Multifetal Pregnancies: ACOG Practice Bulletin, Number 231

The incidence of multifetal gestations in the United States has increased dramatically over the past several decades. For example, the rate of twin births increased 76% between 1980 and 2009, from 18.9 to 33.3 per 1,000 births (1). However, after more than three decades of increases, the twin birth rate declined 4% during 2014-2018 to 32.6 twins per 1,000 total births in 2018 (2). The rate of triplet and higher-order multifetal gestations increased more than 400% during the 1980s and 1990s, peaking at 193.5 per 100,000 births in 1998, followed by a modest decrease to 153.4 per 100,000 births by 2009 (3). The triplet and higher-order multiple birth rate was 93.0 per 100,000 births for 2018, an 8% decline from 2017 (101.6) and a 52% decline from the 1998 peak (193.5) (4). The long-term changes in the incidence of multifetal gestations has been attributed to two main factors: 1) a shift toward an older maternal age at conception, when multifetal gestations are more likely to occur naturally, and 2) an increased use of assisted reproductive technology (ART), which is more likely to result in a multifetal gestation (5). A number of perinatal complications are increased with multiple gestations, including fetal anomalies, preeclampsia, and gestational diabetes. One of the most consequential complications encountered with multifetal gestations is preterm birth and the resultant infant morbidity and mortality. Although multiple interventions have been evaluated in the hope of prolonging these gestations and improving outcomes, none has had a substantial effect. The purpose of this document is to review the issues and complications associated with twin, triplet, and higher-order multifetal gestations and present an evidence-based approach to management.

All the right moves: why in utero transfer is both important for the baby and difficult to achieve and new strategies for change

The best way to ensure that preterm infants benefit from relevant neonatal expertise as soon as they are born is to transfer the mother and baby to an appropriately specialised neonatal facility before birth (“ in utero”). This review explores the evidence surrounding the importance of being born in the right unit, the advantages of in utero transfers compared to ex utero transfers, and how to accurately assess which women are at most risk of delivering early and the challenges of in utero transfers.

Accurate identification of the women most at risk of preterm birth is key to prioritising who to transfer antenatally, but the administrative burden and pathway variation of in utero transfer in the UK are likely to compromise optimal clinical care. Women reported the impact that in utero transfers have on them, including the emotional and financial burdens of being transferred and the anxiety surrounding domestic and logistical concerns related to being away from home. The final section of the review explores new approaches to reforming the in utero transfer process, including learning from outside the UK and changing policy and guidelines. Examples of collaborative regional guidance include the recent Pan-London guidance on in utero transfers. Reforming the transfer process can also be aided through technology, such as utilising the CotFinder app.

In utero transfer is an unavoidable aspect of maternity and neonatal care, and the burden will increase if preterm birth rates continue to rise in association with increased rates of multiple pregnancy, advancing maternal age, assisted reproductive technologies, and obstetric interventions. As funding and capacity pressures on health services increase because of the COVID-19 pandemic, better prioritisation and sustained multi-disciplinary commitment are essential to maximise better outcomes for babies born too soon.

Towards a better understanding of risk selection in maternal and newborn care: A systematic scoping review

Globally, millions of women and their children suffer due to preventable morbidity and mortality, associated with both underuse and overuse of maternal and newborn care. An effective system of risk selection that differentiates between what care should be provided and who should provide it is a global necessity to ensure women and children receive appropriate care, at the right place and the right time. Poor conceptualization of risk selection impedes evaluation and comparison of models of risk selection across various settings, which is necessary to improve maternal and newborn care. We conducted a scoping review to enhance the understanding of risk selection in maternal and newborn care. We included 210 papers, published over the past four decades, originating from 24 countries. Using inductive thematic analysis, we identified three main dimensions of risk selection: (1) risk selection as an organisational measure to optimally align women's and children's needs and resources, (2) risk selection as a practice to detect and assess risk and to make decisions about the delivery of care, and (3) risk selection as a tool to ensure safe care. We found that these three dimensions have three themes in common: risk selection (1) is viewed as both requiring and providing regulation, (2) has a provider centred focus and (3) aims to avoid underuse of care. Due to the methodological challenges of contextual diversity, the concept of risk selection needs clear indicators that capture the complexity of care to make cross-setting evaluation and comparison of risk selection possible. Moreover, a comprehensive understanding of risk selection needs to consider access disparity, women's needs, and unnecessary medicalization.

Comparison of Fetal Fibronectin and Phosphorylated Insulin-Like Growth Factor Binding Protein-1 Testing to Predict Preterm Delivery in Symptomatic Women: A 10-Year Retrospective Study

OBJECTIVE

To assess the diagnostic accuracy and cost-effectiveness of fetal fibronectin (fFN) and cervical phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) tests, individually and in combination, to predict preterm delivery within 48 hours, 7 days and 14 days in symptomatic women.

METHOD

We selected women in Victoria, British Columbia, who presented between January 2008 and December 2017 at <34 weeks gestation at intermediate risk for labour (intact membrane, cervical dilatation <3 cm, and >6 contractions per hour). We calculated sensitivity, specificity, and positive and negative predictive values (PPV, NPV) for independent and concurrent testing and conducted a cost-effectiveness analysis to ensure appropriate test utilization.

RESULTS

We identified 2911 cases. Both fFN and phIGFBP-1 tests showed high and comparable NPV in predicting risk of delivery within 48 hours, 7 days and 14 days (fFN: 99.3%, 98.5% and 97.3%; phIGFBP-1: 98.8%, 97.9% and 96.1%). In 1976 cases, samples for fFN and phIGFBP-1 tests were collected and analyzed concurrently. Concurrent analysis increased specificity (90.8%, 91.4%, and 91.8%) and PPV (11.8%, 19.8% and 24.2%). Independently, both tests had comparable sensitivity, while the fFN test had higher specificity. Concurrent testing offered the highest PPV. The net gain in PPV comes with a clinically insignificant net loss (<1%) in NPV when compared with either of the tests individually.

CONCLUSION

Clinical usefulness of PPV for either test is limited. Routine concurrent testing comes with additional costs, and fFN has additional collection requirements. Point-of-care phIGFBP-1 testing has proven to be cheaper, simpler, and equally effective. Ordering physicians should be provided with education on how to interpret test results and should have protocols to guide clinical decision making.

The review of results of foetal fibronectin at the Royal Cornwall Hospital Treliske

The manufacturer of a popular qualitative fFN assay, changed to using a quantitative assay following results from EQUIPPE study. The objective of our study was to compare our hospital data collated from our qualitative fFN assay with EQUIPPE's data, with a view to establish its validity in our hospital. We undertook a retrospective study over a 22-month period to review the data of 432 preterm pregnant women at less than 34 weeks of gestation, who presented to the labour ward with symptoms of threatened preterm labour warranting a fFN test. None of the patient with results between 11 and 199 ng/mL delivered within 7 days. However, there was a rise in percentage of delivery at higher levels. For example, 73% of patients with levels greater or equal to 500 ng/mL delivered within 7 days. Our results are comparable with those of the EQUIPPE study. This has led to changes that could potentially save our hospital money. Impact statement What is already known on this subject? The fFN test is a well validated test used to diagnose a preterm delivery. Most units are changing from the qualitative assays that just show positive or negative results to quantitative assays that give specific numeric values. Manufacturers give a numeric range for positive and negative results. What do the results of this study add? Although our study is local to our population, our findings show that potentially more money could be saved and fewer women separated from their families, if the negative level of the fFN test is increased (following a review of their local practice). What are the implications of these findings for clinical practice and/or further research? More units should review or audit their fFN results and choose what levels to use as a cut off for the test locally. More importantly, a multicentre research is needed to validate if the negative level needs increasing from 49 ng/mL.

Prediction of preterm delivery in symptomatic women using PAMG-1, fetal fibronectin and phIGFBP-1 tests: systematic review and meta-analysis

OBJECTIVE

To assess the accuracy of placental alpha microglobulin-1 (PAMG-1), fetal fibronectin (fFN) and phosphorylated insulin-like growth factor-binding protein-1 (phIGFBP-1) tests in predicting spontaneous preterm birth (sPTB) within 7 days of testing in women with symptoms of preterm labor, through a systematic review and meta-analysis of the literature. The test performance of each biomarker was also assessed according to pretest probability of sPTB ≤ 7 days.

METHODS

The Cochrane, MEDLINE, PubMed and ResearchGate bibliographic databases were searched from inception until October 2017. Cohort studies that reported on the predictive accuracy of PAMG-1, fFN and phIGFBP-1 for the prediction of sPTB within 7 days of testing in women with symptoms of preterm labor were included. Summary receiver-operating characteristics (ROC) curves and sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and positive (LR+) and negative (LR-) likelihood ratios were generated using indirect methods for the calculation of pooled effect sizes with a bivariate linear mixed model for the logit of sensitivity and specificity, with each diagnostic test as a covariate, as described by the Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy.

RESULTS

Bivariate mixed model pooled sensitivity of PAMG-1, fFN and phIGFBP-1 for the prediction of sPTB ≤ 7 days was 76% (95% CI, 57-89%), 58% (95% CI, 47-68%) and 93% (95% CI, 88-96%), respectively; pooled specificity was 97% (95% CI, 95-98%), 84% (95% CI, 81-87%) and 76% (95% CI, 70-80%) respectively; pooled PPV was 76.3% (95% CI, 69-84%) (P < 0.05), 34.1% (95% CI, 29-39%) and 35.2% (95% CI, 31-40%), respectively; pooled NPV was 96.6% (95% CI, 94-99%), 93.3% (95% CI, 92-95%) and 98.7% (95% CI, 98-99%), respectively; pooled LR+ was 22.51 (95% CI, 15.09-33.60) (P < 0.05), 3.63 (95% CI, 2.93-4.50) and 3.80 (95% CI, 3.11-4.66), respectively; and pooled LR- was 0.24 (95% CI, 0.12-0.48) (P < 0.05), 0.50 (95% CI, 0.39-0.64) and 0.09 (95% CI, 0.05-0.16), respectively. The areas under the ROC curves for PAMG-1, fFN and phIGFBP-1 for sPTB ≤ 7 days were 0.961, 0.874 and 0.801, respectively.

CONCLUSIONS

In the prediction of sPTB within 7 days of testing in women with signs and symptoms of preterm labor, the PPV of PAMG-1 was significantly higher than that of phIGFBP-1 or fFN. Other diagnostic accuracy measures did not differ between the three biomarker tests. As prevalence affects the predictive performance of a diagnostic test, use of a highly specific assay for a lower-prevalence syndrome such as sPTB may optimize management. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

The fetal fibronectin test: 25 years after its development, what is the evidence regarding its clinical utility? A systematic review and meta-analysis

Background: The identification of women at risk for preterm birth should allow interventions which could improve neonatal outcome. Fetal fibronectin, a glycoprotein which acts normally as glue between decidua and amniotic membranes could be a good marker of impending labour when its concentration in cervicovaginal secretions between 22 and 36 weeks of gestation is ≥50 ng/mL. Many authors worldwide have tested this marker with many different methodologies and clinical settings, but conclusions about its clinical use are mixed. It is time for a comprehensive update through a systematic review and meta-analysis.Methods: We searched PubMed, Cochrane Library, and Embase, supplemented by manual search of bibliographies of known primary and review articles, international conference papers, and contact with experts from 1-1990 to 2-2018. We have selected all type of studies involving fetal fibronectin test accuracy for preterm delivery. Two authors independently extracted data about study characteristics and quality from identified publications. Contingency tables were constructed. Reference standards were preterm delivery before 37, 36, 35, 34, and 32 weeks, within 28, 21, 14, or 7 d and within 48 h. Data were pooled to produce summary likelihood ratios for positive and negative tests results.Results: One hundred and ninety-three primary studies were identified allowing analysis of 53 subgroups. In all settings, none of the summary likelihood ratios were >10 or <0.1, thus indicating moderate prediction, particularly in asymptomatic women and in multiple gestations.Conclusions: The fetal fibronectin test should not be used as a screening test for asymptomatic women. For high-risk asymptomatic women, and especially for women with multiple pregnancies, the performance of the fetal fibronectin test was also too low to be clinically relevant. Consensual use as a diagnostic tool for women with suspected preterm labor, the best use policy probably still depends on local contingencies, future cost-effectiveness analysis, and comparison with other more recent available biochemical markers.

Use of fetal fibronectin testing in women transferred for threatened preterm labour in remote far north Queensland

BACKGROUND

Threatened preterm labour is a common reason for medical transfer from remote communities; however, many transferred women do not deliver preterm. A tool for prediction of preterm birth such as fetal fibronectin may reduce transfers and related social and economic costs.

AIM

To review the use of fetal fibronectin testing in women transferred for threatened preterm labour from Cape York to Cairns Hospital between 2011 and 2015 and determine the role testing could play in reducing transfers and associated costs.

MATERIALS/METHODS

Records from the Royal Flying Doctor Service and Cairns Hospital were accessed. Women transferred solely for threatened preterm labour were included in the study. Fetal fibronectin testing, hospital admission, outpatient stays and birth outcome data were collated and analysed. Costs were assigned using the National Hospital Cost Data Collection, round 19.

RESULTS

Forty-seven women were included in the study; however, only 20 underwent fetal fibronectin testing. Transfer of 30 women who had either a negative test or were not tested but delivered at term resulted in 41 inpatient nights and 443 excess outpatient nights, costing an estimated AU$57 408. Aeromedical transfers were estimated to cost a further $151 500.

CONCLUSION

Adherence to clinical guidelines and greater availability and use of fetal fibronectin testing in Cape York have the potential to reduce aeromedical transfers for threatened preterm labour. Substantial inpatient and excess outpatient stays could be avoided with associated reduction in health system and social costs. Strategies to improve adherence to guidelines and increase access to testing are required.

Predicting preterm birth: Cervical length and fetal fibronectin

Spontaneous preterm birth remains the leading cause of neonatal morbidity and mortality worldwide, and accounts for a significant global health burden. Several obstetric strategies to screen for spontaneous preterm delivery, such as cervical length and fetal fibronectin measurement, have emerged. However, the effectiveness of these strategies relies on their ability to accurately predict those pregnancies at increased risk for spontaneous preterm birth (SPTB). Transvaginal cervical shortening is predictive of preterm birth and when coupled with appropriate preterm birth prevention strategies, has been associated with reductions in SPTB in asymptomatic women with a singleton gestation. The use of qualitative fetal fibronectin may be useful in conjunction with cervical length assessment in women with acute preterm labor symptoms, but data supporting its clinical utility remain limited. As both cervical length and qualitative fetal fibronectin have limited capacity to predict preterm birth, further studies are needed to investigate other potential screening modalities.

Implementation of foetal fibronectin testing: Admissions, maternal interventions and costs at 1 year

Foetal fibronectin testing (fFN) has a high negative predictive value for preterm delivery, but it has a cost implication. This two-stage prospective study evaluated the real patient costs and clinical impact of introducing the fFN test in women presenting acutely with threatened preterm labour in a tertiary UK obstetric hospital. Introduction of the fFN test for women with threatened preterm labour reduced antenatal admissions and in utero transfers, and reduced steroid treatment and tocolysis, even at 1 year after implementation. The total number of bed days for women with threatened preterm labour who did not deliver during admission fell from 132 (mean 8.8 days) to 25 days (mean 3.6 days). The mean cost of admission per woman before introduction of the fFN test was £1032 (95% CI £880 to £1184); after it was £339 (95% CI £261 to £417). In this small single centre study, the introduction of the test produced a cost saving of £693 per woman (95% CI, £464 to £922) which over 12 months potentially saves £74844 (95% CI £50,112 to £99,576). Further studies are needed to formally evaluate the cost-effectiveness of the fFN test and its impact on clinical decision-making in large populations.

Practice Bulletin No. 159: Management of Preterm Labor

Preterm birth is the leading cause of neonatal mortality and the most common reason for antenatal hospitalization . In the United States, approximately 12% of all live births occur before term, and preterm labor preceded approximately 50% of these preterm births . Although the causes of preterm labor are not well understood, the burden of preterm births is clear-preterm births account for approximately 70% of neonatal deaths and 36% of infant deaths as well as 25-50% of cases of long-term neurologic impairment in children . A 2006 report from the Institute of Medicine estimated the annual cost of preterm birth in the United States to be $26.2 billion or more than $51,000 per premature infant . However, identifying women who will give birth preterm is an inexact process. The purpose of this document is to present the various methods proposed to manage preterm labor and to review the evidence for the roles of these methods in clinical practice. Identification and management of risk factors for preterm labor are not addressed in this document.

An elevated amniotic fluid prostaglandin F2α concentration is associated with intra-amniotic inflammation/infection, and clinical and histologic chorioamnionitis, as well as impending preterm delivery in patients with preterm labor and intact membranes

OBJECTIVE

To determine whether an elevated amniotic fluid concentration of prostaglandin F2α (PGF2α) is associated with intra-amniotic inflammation/infection and adverse pregnancy outcomes in patients with preterm labor and intact membranes.

MATERIALS AND METHODS

The retrospective cohort study included 132 patients who had singleton pregnancies with preterm labor (< 35 weeks of gestation) and intact membranes. Amniotic fluid was cultured for aerobic and anaerobic bacteria as well as for genital mycoplasmas. Intra-amniotic inflammation was defined by an elevated amniotic fluid matrix metalloproteinase-8 (MMP-8) concentration (>23 ng/mL). PGF2α was measured with a sensitive and specific immunoassay. The amniotic fluid PGF2α concentration was considered elevated when it was above the 95th percentile among pregnant women at 15-36 weeks of gestation who were not in labor (≥170 pg/mL).

RESULTS

(1) The prevalence of an elevated amniotic fluid PGF2α concentration was 40.2% (53/132) in patients with preterm labor and intact membranes; (2) patients with an elevated amniotic fluid PGF2α concentration had a significantly higher rate of positive amniotic fluid culture [19% (10/53) versus 5% (4/79); p = 0.019], intra-amniotic inflammation/infection [49% (26/53) versus 20% (16/79); p = 0.001], spontaneous preterm delivery, clinical and histologic chorioamnionitis, and funisitis, as well as a higher median amniotic fluid MMP-8 concentration and amniotic fluid white blood cell count and a shorter amniocentesis-to-delivery interval than those without an elevated concentration of amniotic fluid PGF2α (p < 0.05 for each); and (3) an elevated amniotic fluid PGF2α concentration was associated with a shorter amniocentesis-to-delivery interval after adjustment for the presence of intra-amniotic inflammation/infection [hazard ratio 2.1, 95% confidence interval (CI) 1.4-3.1; p = 0.001].

CONCLUSION

The concentration of PGF2α was elevated in the amniotic fluid of 40.2% of patients with preterm labor and intact membranes and is an independent risk factor for intra-amniotic inflammation/infection, impending preterm delivery, chorioamnionitis, and funisitis.

Prescribing patterns of antenatal corticosteroids in women with threatened preterm labor

OBJECTIVE

To assess the impact of cervical length (CL) measurement and fetal fibronectin testing (fFN) on the clinicians' decision to prescribe antenatal corticosteroids (ACS) to women with symptoms of preterm labor.

STUDY DESIGN

This is a secondary analysis of a prospective cohort study including women with symptoms of preterm labor and intact membranes between 24 and 34 weeks' gestation. We compared the proportion prescribed and completed ACS courses, preterm delivery within seven days and median intervals from ACS to delivery in four groups: group 1 CL<10 mm, group 2 CL 10-30 mm and positive fFN, group 3 CL 10-30 mm and negative fFN, group 4 CL>30 mm.

RESULTS

ACS were prescribed to 63/65 (97%) women in group 1, 176/192 (91%) in group 2, 111/172 women (65%) in group 3 and 55/242 (23%) in group 4. In group 1, 42 (65%) women delivered within seven days, compared to 34 (18%) in group 2, 6 (3%) in group 3 and 3 (1%) in group 4. Median intervals between ACS and delivery were 6 days (IQR 3-61 days), 44 days (IQR 17-69 days), 53 days (IQR 37-77 days) and 66 days (IQR 43-78 days) in group 1, 2, 3 and 4 respectively.

CONCLUSION

ACS were prescribed frequently to women with a CL of 10-30 mm and a negative fFN test or a CL>30 mm. There is room for improvement in the prescription of ACS in these low risk women.

Fetal fibronectin as a biomarker of preterm labor: a review of the literature and advances in its clinical use

Spontaneous preterm birth (sPTB) is a challenge in obstetrics today, and is the leading cause of neonatal morbidity and mortality. The ability to predict preterm birth had, until recently, been poor. The biomarker fetal fibronectin (fFN), found at the maternal–fetal interface, when present in high concentrations in cervicovaginal fluid, has been shown to increase the risk of sPTB in symptomatic and asymptomatic women. Recently, further research has been performed into the applicability of such a test to clinical practice, and its effects on management decisions and patient outcomes. Owing to its high negative predictive value, a negative fFN result has been shown to reduce unnecessary interventions, change patient management and reduce healthcare costs, by allowing early reassurance and return to normal care pathways, while care can be concentrated on those at risk. The development of a bedside quantitative fFN test has shown promise to further improve the positive predictive abilities of fFN, as have combined predictive models with cervical length and fFN.

The short-term prediction of preterm birth: a systematic review and diagnostic metaanalysis

OBJECTIVE

To assess the diagnostic accuracy of fetal fibronectin (fFN), fetal breathing movements (FBM), and cervical length (CL) for the short-term prediction of preterm birth in symptomatic patients.

STUDY DESIGN

Diagnostic metaanalysis using bivariate methods.

RESULTS

Pooled sensitivities for fFN, FBM, and CL for delivery within 48 hours of testing were 0.62 (95% confidence interval [CI], 0.43-0.78), 0.75 (95% CI, 0.57-0.87) and 0.77 (95% CI, 0.54-0.90), respectively. Pooled specificities for fFN, FBM, and CL for delivery within 48 hours were 0.81 (95% CI, 0.74-0.86), 0.93 (95% CI, 0.75-0.98) and 0.88 (95% CI, 0.84-0.91). Pooled sensitivities for fFN, FBM, and CL for delivery within 7 days were 0.75 (95% CI, 0.69-0.80), 0.67 (95% CI, 0.43-0.84), and 0.74 (95% CI, 0.58-0.85). Pooled specificities for fFN, FBM, and CL for delivery within 7 days were 0.79 (95% CI, 0.76-0.83), 0.98 (95% CI, 0.83-1.00) and 0.89 (95% CI, 0.85-0.92). Based on a pretest probability of 10% for delivery within 48 hours, posttest probabilities (positive and negative) were 27% and 5% for fFN, 54% and 3% for fFN, and 42% and 3% for CL. For a pretest probability of 20% for delivery within 7 days, posttest probabilities (positive and negative) were 48% and 7% for fFN, 89% and 8% for FBM, and 63% and 7% for CL.

CONCLUSION

In symptomatic patients, for fFN, absence of FBM, and CL have diagnostic use as predictors of delivery within 48 hours and within 7 days of testing. Absence of FBM appears to be the best test for predicting preterm birth.

[Pronostic risk assessment of delivery, in patients admitted for threatened preterm birth, in a tertiary care maternity center]

OBJECTIVES

To assess preterm birth rate, in patients admitted for threatened preterm birth (TPB) in a tertiary care maternity center and evaluate our diagnostic and therapeutic tools.

MATERIALS AND METHODS

A retrospective cohort study, in a tertiary care maternity center (Marseille, France), reviewed all admissions for TPB from January 1 to December 31, 2009.

RESULTS

We recorded 224 admissions for TPB (181 single pregnancies and 43 twin pregnancies), 43.8% of TPB admissions were from materno-fetal transfer. Preterm birth rate was 44.9% (n=89), 39% (n=66) for single pregnancy and 76.6% (n=23) for twins. The 15 mm threshold for transvaginal sonography cervical length (CL) was the most relevant to predict the risk of preterm delivery, 77.3% (85/110) of patients with CL>15 mm having full term delivery.

CONCLUSION

For single pregnancy, most of the patients with cervical length>15 mm have full term delivery. It seems important to us to develop the use of more efficient predictive markers of risk-premature labor in order to improve the diagnosis and management of TPB.

Evaluation of the impact of fetal fibronectin test implementation on hospital admissions for preterm labour in Ontario: a multiple baseline time-series design

OBJECTIVE

To determine the impact of a health system-wide fetal fibronectin (fFN) testing programme on the rates of hospital admission for preterm labour (PTL).

DESIGN

Multiple baseline time-series design.

SETTING

Canadian province of Ontario.

POPULATION

A retrospective population-based cohort of antepartum and delivered obstetrical admissions in all Ontario hospitals between 1 April 2002 and 31 March 2010.

METHODS

International Classification of Diseases codes in a health system-wide hospital administrative database were used to identify the study population and define the outcome measure. An aggregate time series of monthly rates of hospital admissions for PTL was analysed using segmented regression models after aligning the fFN test implementation date for each institution.

MAIN OUTCOME MEASURE

Rate of obstetrical hospital admission for PTL.

RESULTS

Estimated rates of hospital admission for PTL following fFN implementation were lower than predicted had pre-implementation trends prevailed. The reduction in the rate was modest, but statistically significant, when estimated at 12 months following fFN implementation (-0.96 hospital admissions for PTL per 100 preterm births; 95% confidence interval [CI], -1.02 to -0.90, P = 0.04). The statistically significant reduction was sustained at 24 and 36 months following implementation.

CONCLUSIONS

Using a robust quasi-experimental study design to overcome confounding as a result of underlying secular trends or concurrent interventions, we found evidence of a small but statistically significant reduction in the health system-level rate of hospital admissions for PTL following implementation of fFN testing in a large Canadian province.

Fetal fibronectin: what does it mean?

LIKE MANY STAFF NURSES AND neonatal nurse practitioners (NNPs), I work at two different hospitals as part of my full-time job and at a third hospital in a PRN position. Working at several different institutions affords the opportunity for multiple and varied learning experiences. One of the hospitals is a busy center for high-risk labor and delivery. As part of the NNP duties there, I attend board report three times per day. This entails a detailed discussion of all women in labor and delivery, primarily focusing on the high-risk patients. Fetal fibronectin (fFN) is a common topic of discussion during board report. I thought that fFN helped the perinatologist determine whether or not the woman was in labor and in imminent danger of delivery, but that was all I knew. Like other authors of articles in this column, I used my knowledge deficit as the impetus to research this topic. Therefore, this column briefly discusses the burden of preterm delivery and the methods used to identify women at risk for preterm birth. It focuses specifically on fFN: what it is, how it is measured, what the test means, and the predictive value of the test.

Cost-effective standardization of preterm labor evaluation

OBJECTIVE

The purpose of this study was to determine the effect of a standardized evidence-based protocol for preterm labor evaluation on resource use and obstetrics outcomes.

STUDY DESIGN

We conducted a retrospective 12-month observational study of patients with symptoms of preterm labor at the Mayo Clinic. All patients underwent triage evaluation per a standardized protocol with a combination of cervical length measurement with contingent fetal fibronectin assay.

RESULTS

Of 201 patients who underwent evaluation, 3 women delivered within 7 days, and only 1 woman delivered after a negative evaluation. Mean gestational age at evaluation was 29 weeks 1 day, and delivery was at 38 weeks 3 days of gestation, with an average interval of 57.4 days until delivery. The rate of hospital admission was reduced by 56%, compared with the previous year; an estimated annual cost saving was $39,900.

CONCLUSION

Implementation of a standardized protocol for evaluation of preterm labor reduces the rate of unnecessary hospital admissions for observation with consequent significant reduction in expenses.

Prediction of preterm birth in symptomatic women using decision tree modeling for biomarkers

OBJECTIVE

The objective of the study was to use recursive partitioning (RP) to identify gestational age-specific and threshold values for infectious and endocrine biomarkers of imminent delivery.

STUDY DESIGN

RP was developed using a previously collected data set and then applied to a prospectively collected cohort of women in threatened preterm labor. Predictors of preterm birth were considered, including white blood cell count (WBC), corticotrophin-releasing hormone (CRH), cortisol, and maternal age.

RESULTS

At 22-27 weeks' gestation, WBC of greater than 12,000/mL was the most accurate predictor of delivery within 48 hours; at 28-31 weeks' gestation, CRH of greater than 684 pg/mL was the most accurate predictor; and at 32-26 weeks' gestation, CRH and maternal age were the most important variables.

CONCLUSIONS

These results indicate that maternal WBC greater than 12,000/mL prior to 28 weeks' gestation and CRH beyond 28 weeks are the most accurate biomarkers in predicting preterm birth within 48 hours. RP assists in establishing clinically relevant and gestational age-specific threshold levels for these variables.

The present and future of tocolysis

This chapter discusses the tocolytic agents currently in use for the treatment of preterm labour and considers them in light of the evidence base. These agents are the beta2 sympathomimetic agonists, magnesium sulphate (MgSO(4)), indomethacin, nifedipine and atosiban. The available evidence for these agents shows that the beta2 agents are effective but have significant maternal side effects and no effect on perinatal outcome. MgSO(4) and glyceryl trinitrate are clearly ineffective. Nifedipine is effective with a low maternal side effect profile and is associated with improved perinatal outcomes. Meta-analyses of the several randomized controlled trials of atosiban show that it is no more effective than other tocolytic therapies. Possible directions for the future will be discussed.

Performance of cervicovaginal fetal fibronectin in a community hospital setting

OBJECTIVE

To assess the accuracy of vaginal fetal fibronectin (FFN) as a screening test for preterm delivery in a community hospital.

STUDY DESIGN

A prospective cohort of patients at high risk for preterm delivery at a community hospital underwent testing with FFN over a 15 month-period (March 2004-May 2005). Indications for testing were preterm labor, multiple pregnancies, cervical shortening, and cerclage. Pregnancy characteristics were retrieved on all women with positive FFN results and controls in a 1:2 ratio. Outcome variables included interval to delivery; length of hospital stay; and rates of preterm delivery <37 weeks. In the presence of serial FFN testing, only the initial result was used for calculation of diagnostic indices. Statistical analysis utilized t-test, Fisher's exact test and logistic regression analysis to control for gestational age at testing, with P < 0.05 or odds ratio (OR) with 95% confidence interval (CI) not inclusive of the unity considered significant.

RESULTS

Two hundred and fifty seven FFN tests were performed in 230 women, of which 33 (14.3%) had positive FFN results. Duration of hospital stay was significantly shorter for patients with negative than positive results (8 h vs. 2.1 days, P = 0.011). Women with positive FFN were more likely to deliver within 14 days (OR = 6.5, 95% CI 1.4; 30.7), within 21 days (OR = 4.8; 95% CI 1.4; 16.6), before 34 weeks (OR = 5.0, 95% CI 1.7; 14.8) and before 37 weeks (OR = 3.1; 95% CI 1.3; 7.1) than women with negative results.

CONCLUSION

A negative FFN result provides enough reassurance to allow shorter hospital stay. In a real-world setting (a community hospital with a population heterogeneous for risk factors for preterm delivery, and in a non-protocol setting) the performance of FFN testing closely mirrors that obtained in academic institutions, where the test was studied in more uniform populations under strict protocols. The performance of vaginal fibronectin in patients with heterogeneous risk factors for preterm delivery closely mirrors that obtained in studies conducted in populations with homogeneous risk factors.

The impact of fetal fibronectin testing for women with symptoms of preterm labour in routine clinical practice within a New Zealand population

AIMS

To perform a comparative analysis of antenatal management received according to the results of cervico-vaginal fetal fibronectin (fFN) testing, and to review preterm delivery rates and fFN predictive values within a New Zealand population of women presenting with threatened preterm labour.

METHODS

Case note review of all fFN tests performed at Middlemore Hospital, South Auckland from August 2003 to March 2005 (n = 199). Data collected included risk factors for preterm delivery, signs and symptoms at presentation, antenatal management received after fFN test and outcome and delivery details. Positive and negative fFN results were compared.

RESULTS

Women with a positive fFN were more likely to receive antenatal corticosteroids (96.4 vs 4.7% RR 8.74 (95% CI 5.40-14.17)) and tocolysis (71.4 vs 2.4% RR 8.10 (95% CI 4.49-14.59)) and to be admitted antenatally (96.4 vs 54.4% RR 1.77 (95% CI 1.50-2.10)) with a higher mean cost of treatment (967.47 NZ dollars vs 335.27 NZ dollars P < 0.05). Rates of delivery < 34 weeks were higher in those with a positive fFN (41.9 vs 0.7% RR 62.06 (95% CI 8.43-457.14)).

CONCLUSION

Women with a positive fFN result received different treatment to those with a negative fFN. Use of fFN test in routine clinical practice allows management and resources to be targeted more appropriately and may limit unnecessary interventions.

Sonographic measurement of cervical length and fetal fibronectin testing in threatened preterm labor

OBJECTIVE

In women presenting with threatened preterm labor, both fetal fibronectin and sonographic measurement of cervical length have been shown to distinguish between true and false labor. The aim of this study was to determine whether the combination of both tests provides a better prediction than the individual tests alone.

METHODS

We examined 195 women with singleton pregnancies presenting at 24-36 (median 31) weeks of gestation with regular and painful uterine contractions, intact membranes and cervical dilatation of less than 3 cm. On admission to the hospital fetal fibronectin positivity in cervicovaginal secretions was determined and transvaginal sonographic measurement of cervical length was carried out. The results were not made available to the attending obstetrician. The primary outcome measure was delivery within 7 days of presentation.

RESULTS

Delivery within 7 days occurred in 51.4% (18 of 35) of those with cervical length below 15 mm and 0.6% (1 of 160) of those with cervical length of 15 mm or more, in 21.2% (18 of 85) of the fibronectin positive group and in 0.9% (1 of 110) of the fibronectin negative group. There was a significant association between cervical length and the incidence of fibronectin positivity (r = -0.921, P = 0.003). Logistic regression analysis demonstrated that the only significant contributor to the prediction of delivery within 7 days was cervical length, with no significant contribution from fibronectin positivity, ethnic origin, maternal age, gestational age, body mass index, parity, previous history of preterm delivery, cigarette smoking, or use of tocolytics.

CONCLUSIONS

In women with threatened preterm labor assessment of fetal fibronectin in cervicovaginal secretions does not improve the prediction of delivery within 7 days provided by the sonographic measurement of cervical length.

The Evaluation of the Fetal Fibronectin Test for Prediction of Preterm Delivery in Symptomatic Patients

OBJECTIVE

This study was conducted to evaluate the usefulness of testing for fetal fibronectin (fFN) to rule out the diagnosis of preterm labour in symptomatic patients in a Canadian setting.

METHODS

This was a prospective, blinded clinical evaluation of fFN testing in women presenting with threatened preterm labour at between 24 and 34 weeks' gestation at two Canadian tertiary care centres.

RESULTS

Of the 149 women tested, 32 had a positive fFN test. In the total patient population, 10.1% delivered within seven days of testing, and 18.2% delivered prior to 34 weeks. A negative fFN result was associated with a 97.4% likelihood of delivering more than seven days after testing and with a 91.4% chance of delivering after 34 weeks.

CONCLUSION

The fFN test appears to provide useful information in the risk assessment of Canadian women presenting with symptoms compatible with preterm labour. A negative test has a high predictive value for delivering more than seven days after presentation.

Assessment of the impact of introducing fetal fibronectin assay in the management of preterm labour at Middlemore Hospital, New Zealand

Elevated levels of fetal fibronectin (fFN) in cervicovaginal secretions beyond 20-22 weeks of gestation are used as a predictor of preterm birth in patients with corroborative symptoms and signs.

AIM

To assess the impact of introducing the fFN assay on the diagnosis, length of hospital stay and cost of managing patients presenting with symptoms of premature labour in our hospital.

METHODS

The first 30 fFN-tested patients (fFN group) were prospectively recruited and followed up until delivery. Hospital stay and management costs (costs of individual tests and treatment administered) and neonatal outcomes were compared with 30 matching historical controls.

RESULTS

Overall management costs of the fFN-group were comparable with controls (NZ dollar 918 versus NZ dollar 943 per patient, p = 0.44). The fFN-group had a trend towards reduced length of hospital stay (p = 0.082), less tocolysis (p = 0.002) and use of steroids (p < 0.001). The cost of managing an fFN-positive patient was more than an fFN-negative patient, but not statistically significant (NZ dollar 1117 versus NZ dollar 846, respectively, p = 0.11).

CONCLUSION

Despite a trend towards reduced hospital stay and less use of obstetric intervention, total expenditure in patient management has not reduced with the availability of the fFN assay in our hospital. This may only reflect the slow introduction of a new policy that with time may be implemented to full effect.

Cervicovaginal fibronectin improves the prediction of preterm delivery based on sonographic cervical length in patients with preterm uterine contractions and intact membranes

OBJECTIVE

The purpose of this study was to examine the diagnostic performance of ultrasonographic measurement of the cervical length and vaginal fetal fibronectin determination in the prediction of preterm delivery in patients with preterm uterine contractions and intact membranes.

STUDY DESIGN

Ultrasound examination of the cervical length and fetal fibronectin determination in vaginal secretions were performed in 215 patients admitted with preterm uterine contractions (22-35 weeks) and cervical dilatation of </=3 cm. Outcome variables were the occurrence of preterm delivery within 48 hours, 7 days, and 14 days of admission, delivery </=32 and </=35 weeks, as well as the admission-to-delivery interval. Statistical analysis included chi-square test, receiver-operator characteristic (ROC) curve analysis, logistic regression, and survival analysis.

RESULTS

The overall prevalence of preterm delivery </=35 weeks was 20% (43/215). The prevalence of spontaneous preterm delivery within 48 hours, 7 days, and 14 days of admission, and delivery </=32 and </=35 weeks were 7.9% (17/215), 13.0% (28/215), 15.8% (34/215), 8.9% (9/101), and 15.8% (34/215), respectively. ROC curve analysis and contingency tables showed a significant relationship between the occurrence of preterm delivery and both cervical length and fetal fibronectin results ( P < .01 for each). Both tests performed comparably in the prediction of spontaneous preterm delivery. However, when fetal fibronectin results were added to those of cervical length (<30 mm), a significant improvement in the prediction of preterm delivery was achieved.

CONCLUSION

Fetal fibronectin adds prognostic information to that provided by sonographic measurement of the cervical length in patients with preterm uterine contractions and intact membranes.

The Randomized Nitric Oxide Tocolysis Trial (RNOTT) for the treatment of preterm labor

OBJECTIVE

This study was undertaken to assess the effectiveness of glyceryl trinitrate (GTN) patches in comparison with beta2 sympathomimetics (beta2) for the treatment of preterm labor.

STUDY DESIGN

A multicenter, multinational, randomized controlled trial was conducted in tertiary referral teaching hospitals. Women in threatened preterm labor with positive fetal fibronectin or ruptured membranes between 24 and 35 weeks' gestation were recruited and randomly assigned to either beta2 or GTN with rescue beta2 tocolysis if moderate-to-strong contractions persisted at 2 hours. Obstetric and neonatal outcomes were assessed.

RESULTS

Two hundred thirty-eight women were recruited and randomly assigned, 117 to beta2 and 121 to GTN. On a strict intention-to-treat basis, there was no significant difference in the time to delivery using Kaplan-Meier curves (P = .451). At 2 hours, 27% of women receiving beta2 had moderate or stronger contractions compared with 53% in the GTN group (P < .001). This led to 35% of women in the GTN group receiving rescue treatment. If delivery or requirement for beta2 rescue are regarded as treatment failure, then a significant difference was observed between the 2 arms (P = .0032). There were no significant differences in neonatal outcomes.

CONCLUSION

GTN is a less efficacious tocolytic compared with ss2 sympathomimetics.

Does fetal fibronectin use in the diagnosis of preterm labor affect physician behavior and health care costs? A randomized trial

OBJECTIVE

The purpose of this study was to determine whether a knowledge of fetal fibronectin results affects patient treatment and health care costs.

STUDY DESIGN

Women between 24 and 34 weeks of gestation with a singleton pregnancy and preterm uterine contractions were eligible for enrollment. Once informed consent was given, a fetal fibronectin specimen was obtained, and women were assigned randomly into 2 groups. In 1 group, results of the fetal fibronectin test were available; in the other group, results were not available. The use of inpatient and outpatient health care resources subsequent to enrollment was ascertained through the use of medical records, hospital billing data, and patient interviews. This study was powered to allow the detection in the fetal fibronectin group of a 20% reduction in total health care-related costs.

RESULTS

The 2 groups were similar with respect to maternal age, parity, race, cervical examination at admission, and estimated gestational age at enrollment and at delivery. Women who did not have fetal fibronectin results available were no different than those women who did with respect to initial length of labor and delivery observation (median, 4 hours vs 3 hours), hospital admission (28% vs 26%), tocolysis (18% vs 16%), cessation of work (27% vs 26%), or total health care-related costs (log mean +/- SD, 7.6 +/- 1.2 vs 7.5 +/- 1.1).

CONCLUSION

In this study population, the use of fetal fibronectin did not affect physician behavior or health care costs related to preterm contractions.

Prospective randomized controlled trial of fetal fibronectin on preterm labor management in a tertiary care center

OBJECTIVE

The purpose of this study was to investigate the effect of the rapid fetal fibronectin on the length of hospital stay and the use of preterm labor interventions in a tertiary care center.

STUDY DESIGN

Women who were seen in the Labor and Delivery Unit with symptoms of preterm labor were assigned randomly to receive fetal fibronectin (n=46 women) or to preterm labor management without fetal fibronectin (n=51 women). Physicians were not blinded to the result; groups were compared.

RESULTS

There was no difference between groups in demographic or obstetric characteristics, the hours spent in labor and delivery, the number of women who were admitted to the antepartum service, the length of stay, or medical interventions. When the results for women with a negative fetal fibronectin test were compared to women with a positive fetal fibronectin test, a significant difference was found in admissions to the antepartum service (P=.032) and the length of stay (P=.008).

CONCLUSIONS

A negative fetal fibronectin test was associated with fewer admissions to the antepartum ward and a shorter length of stay.

Biochemical predictors of preterm labor: fetal fibronectin and salivary estriol

Preterm birth is a major complication of pregnancy and remains a leading cause of neonatal morbidity and mortality worldwide. Improvements in the authors' understanding of the pathophysiology of preterm labor have led to the development of novel diagnostic tools of use to identify women at greatest risk for preterm birth. Currently two FDA-approved biochemical tests are available in the United States: (1) fetal fibronectin and (2) salivary estriol. The presence of a positive fetal fibronectin test in the midtrimester of pregnancy is strongly associated with early spontaneous preterm birth. In contrast, a positive salivary estriol test is associated with late preterm birth, thus limiting its clinical use. Both tests have low test sensitivity and are currently used clinically for their negative predictive values. That is, women who screen negative are at very low risk for preterm birth and, thus, no interventions are indicated to prevent preterm birth. Women with a positive test are at increased risk and would be candidates for intervention. One of the main limitations of fetal fibronectin and salivary estriol, and an array of other proposed markers, is the fact that while these markers may aid in identification of women at increased risk for preterm birth, the authors currently have no clearly effective obstetric interventions for preterm-birth prevention in these high-risk women. Use of tocolytics, antimicrobials, or progesterone therapy currently has limited or unproven benefit in the management of women deemed at increased risk using these markers. Thus, until effective targeted obstetric interventions are available, the use of biochemical markers to identify women at increase risk for preterm birth remains largely research tools.

Fetal fibronectin: the impact of a rapid test on the treatment of women with preterm labor symptoms

OBJECTIVE

The purpose of this study was to determine whether knowledge of the results of a rapid fetal fibronectin test affects treatment decisions during the evaluation and treatment of possible preterm labor. Previous observational studies have suggested that a negative test might help to avoid unnecessary intervention.

STUDY DESIGN

This was a randomized study of women who were between 24 weeks and 34 weeks 6 days of gestation with symptoms of preterm labor and who were seen in three community hospitals. A rapid fetal fibronectin test was performed on all subjects. Patients were assigned randomly to a group whose results were known to physician or to a group whose results were not known. Treatment decisions were at the discretion of the physician.

RESULTS

One hundred eight samples were collected between September 2000 and December 2001. There were 10 positive fetal fibronectin tests. The overall prevalence of delivery within 2 weeks for the study population was 2.8%. For women who had negative fetal fibronectin test results, the hospital stay was not significantly shorter when the result was known (6.8 hours) than when it was not known (8.1 hours, P =.35). However, when the physician knew the fetal fibronectin status of women with a negative test result who were observed for >6 hours, the hospital stay was shortened 40%, to 22.7 hours from 37.8 hours (P =.04).

CONCLUSION

Fetal fibronectin testing may be able to supplement clinical judgment in the evaluation of the condition of patients with symptoms of preterm labor. The greatest benefit of fetal fibronectin testing might be for the patient whom the physician judges to be at high risk for imminent delivery. In such patients, the knowledge of a negative fetal fibronectin may shorten the hospital stay.

Accuracy of cervicovaginal fetal fibronectin test in predicting risk of spontaneous preterm birth: systematic review

OBJECTIVE

To determine the accuracy with which a cervicovaginal fetal fibronectin test predicts spontaneous preterm birth in women with or without symptoms of preterm labour.

DESIGN

Systematic quantitative review of studies of test accuracy.

DATA SOURCES

Medline, Embase, PASCAL, Biosis, Cochrane Library, Medion, National Research Register, SCISEARCH, conference papers, manual searching of bibliographies of known primary and review articles, and contact with experts and manufacturer.

STUDY SELECTION

Two reviewers independently selected and extracted data on study characteristics, quality, and accuracy.

DATA EXTRACTION

Accuracy data were used to form 2x2 contingency tables with spontaneous preterm birth before 34 and 37 weeks' gestation and birth within 7-10 days of testing (for symptomatic pregnant women) as reference standards. Data were pooled to produce summary receiver operating characteristic curves and summary likelihood ratios for positive and negative test results.

DATA SYNTHESIS

64 primary articles were identified, consisting of 28 studies in asymptomatic women and 40 in symptomatic women, with a total of 26 876 women. Among asymptomatic women the best summary likelihood ratio for positive results was 4.01 (95% confidence interval 2.93 to 5.49) for predicting birth before 34 weeks' gestation, with corresponding summary likelihood ratio for negative results of 0.78 (0.72 to 0.84). Among symptomatic women the best summary likelihood ratio for positive results was 5.42 (4.36 to 6.74) for predicting birth within 7-10 days of testing, with corresponding ratio for negative results of 0.25 (0.20 to 0.31).

CONCLUSION

Cervicovaginal fetal fibronectin test is most accurate in predicting spontaneous preterm birth within 7-10 days of testing among women with symptoms of threatened preterm birth before advanced cervical dilatation.