Negative fetal fibronectin: who is still treating for threatened preterm labor and does it help?

OBJECTIVE: Fetal fibronectin (fFN) has a high negative predictive value for delivery in the next seven days in patients at risk for preterm birth. Providers sometimes disregard a negative result and manage the patient for threatened preterm labor. Our objective was to identify the rate at which patients with a negative fFN were managed for threatened preterm labor and if delivery outcomes were improved with such management. STUDY DESIGN: Retrospective chart review of 111 patients at a single institution evaluated in the obstetrical triage unit for symptoms of threatened preterm labor with negative fFN results over a 19-month period between November 2004 and June 2006. Charts were reviewed for baseline patient characteristics such as gestational age at presentation to triage and fFN testing, prior obstetrical history, cervical examination and contraction frequency. Gestational age at delivery was documented. Rates of admission to the hospital and treatments for threatened preterm labor in this cohort were reviewed. RESULTS: Thirty-seven of patients (33%) with a negative fFN result were managed for threatened preterm labor (admitted to the hospital, given tocolytics, steroids, or intravenous antibiotics) by their provider. Patients undergoing these interventions were more likely to have cervical dilatation, effacement and were contracting more frequently. Only one of the patients delivered within 7 or 14 days of fFN testing. There was no advantage seen to management of threatened preterm labor in the setting of a negative fFN in terms of pregnancy prolongation, even when analyzing the patients with meaningful clinical findings (dilated 2 cm, effaced >or=80%, or contracting >or=12 times/h). CONCLUSION: Patients with meaningful clinical findings suspicious for preterm labor are more likely to undergo interventions by their physicians in the face of a negative fFN. This management does not improve length of gestation.     

Examining the relationship between positive mid-gestational fetal fibronectin assays and histological evidence of acute placental inflammation

AIMS: Both acute placental inflammation and positive mid-gestational cervico-vaginal fetal fibronectin assays have been independently correlated with preterm delivery. We conducted this study to examine the relationship between positive mid-gestational fetal fibronectin (fFN) assays and histological evidence of acute placental inflammation at delivery among women presenting with symptomatic preterm labor. METHODS: This retrospective chart review included women who underwent cervico-vaginal fFN testing for preterm contractions between 24-34 weeks gestation and also had placental histological analysis after delivery. Women with a multiple gestation, cerclage, preterm premature rupture of membranes, intercourse or vaginal bleeding within 24 h before the assay were excluded. The primary outcome was histological evidence of acute placental inflammation defined as acute chorioamnionitis, acute deciduitis, funisitis, or microabscess formation. RESULTS: Of 82 women who met all study inclusion criteria, 45% were fFN positive. Women with positive assays were no more likely to have histological evidence of acute inflammation noted at birth than women with negative assays (45% vs. 26%, P=0.07). The assay had a sensitivity of 58.6%, specificity of 62.3%, positive predictive value of 46.0%, and negative predictive value of 73.3% for predicting acute inflammation at delivery. CONCLUSIONS: No association exists between positive fetal fibronectin assays and acute histologic placental inflammation at birth.     

胎儿纤维连接蛋白对先兆早产孕妇发生早产的预测价值

目的研究胎儿纤维连接蛋白（fetal fibronectin，fFN）对先兆早产孕妇发生早产的预测价值，及与宫颈长度联合应用时对早产的预测意义。方法联合国内三家医院对有先兆早产症状的孕妇进行阴道后穹窿分泌物中fFN的测定及宫颈的超声检测，追踪这些孕妇的妊娠结局。结果（1）共检测122例先兆早产孕妇，75例fFN阳性，阳性率为61.5％。（2）阳性孕妇中7d内、14d内、37周前分娩率分别为22．7％（17／75）、41．3％（31／75）、65．3％（49／75）；阴性孕妇则分别为0％（0／47）、0％（0／47）、12．8％（6／47）。对于7d内、14d内和37周内分娩的阴性预测值分别为100％、100％和87．2％。（3）50例孕妇同时进行了宫颈长度的测量。以宫颈长度≤26mm为异常。50例中fFN（＋）和宫颈长度同时异常者7d内、14d内、37周前分娩率分别为13．3％（2／15）、40．0％（6／15）、93．3％（14／15），均显著高于fFN（＋）而宫颈长度正常的孕妇。宫颈长度异常而fFN阴性者中无一例14d内分娩。二者同时异常预测先兆早产孕妇发生早产的敏感性为70％，特异性为97．2％，阳性预测值为93．3％，阴性预测值为85．4％。结论（1）在先兆早产孕妇中阴道后穹窿分泌物fFN阳性对先兆早产孕妇发生早产有一定的预测意义，阴性预测短期内不发生早产的价值较大。（2）fFN测定与宫颈长度联合应用可以提高37周前早产阳性预测结果，但对短期内发生早产的预测意义不大。     

Will cervicovaginal interleukin-6 combined with fetal fibronectin testing improve the prediction of preterm delivery?

OBJECTIVE: We sought to investigate if determination of cervicovaginal interleukin-6 (IL-6) levels would enhance the positive predictive value of fetal fibronectin (fFN) for preterm birth. METHODS: A prospective cohort study was undertaken of 135 women between 24 and 34 weeks gestation with symptoms of suspected preterm labor. Cervicovaginal secretions were collected for both IL-6 and fFN and measured by immunoassay and ELISA, respectively. Outcome variables included preterm delivery in less than 48 h, within 7 days, and prior to 37 weeks. Statistical analysis was performed with Fisher's exact test, regression for logarithmic transform levels, and multivariate logistic regression. ROC curves were created for IL-6 levels. RESULTS: IL-6 and fFN levels were both elevated in cervicovaginal secretions of women with symptoms of preterm labor. IL-6 values >100 pg/ml resulted in a odds ratio for delivery at <37 weeks of 1.57 (95%CI=0.89-2.75, P=.11), whereas fFN values >50 ng/ml resulted in a preterm delivery risk of 4.58 (95%CI=1.54-13.35, P=.003). Combining IL-6 and fFN results did not improve upon the predictive value of fFN alone for preterm birth [odds ratio 4.00 (95%CI=1.31-12.17, P=.015)]. CONCLUSION: Cervicovaginal IL-6 levels did not provide any additional, independent effect on the prediction of preterm birth beyond that of fFN testing alone.     

Fetal fibronectin for evaluation of preterm labor in the setting of cervical cerclage

Objective: To evaluate the efficacy of fetal fibronectin (fFN) testing in cervical cerclage patients presenting with acute signs or symptoms of preterm labor. Methods: A total of 71 fFN tests were performed in 48 women between 23 and 34 weeks’ gestation who presented at two institutions at risk for imminent delivery with cerclage in situ. Results: The sensitivity, specificity, positive predictive value, and negative predictive value for delivery within 2 weeks of fFN testing were 100, 77, 28 and 100%, respectively. For delivery before 34 weeks sensitivity, specificity, positive predictive value, and negative predictive value were 91, 78, 56 and 97%, respectively. The relative risk of delivery <34 weeks with positive fFN was 16.7 (P < 0.001). Conclusions: For patients with cervical cerclage, fFN testing is a valid diagnostic tool in the evaluation of preterm labor.     

A randomised controlled trial of metronidazole for the prevention of preterm birth in women positive for cervicovaginal fetal fibronectin: the PREMET Study

OBJECTIVE: To determine whether metronidazole reduces early preterm labour in asymptomatic women with positive vaginal fetal fibronectin (fFN) in the second trimester of pregnancy. DESIGN: Randomised placebo-controlled trial. SETTING: Fourteen UK hospitals (three teaching). POPULATION: Pregnancies with at least one previous risk factor, including mid-trimester loss or preterm delivery, uterine abnormality, cervical surgery or cerclage. METHODS: Nine hundred pregnancies were screened for fFN at 24 and 27 weeks of gestation. Positive cases were randomised to a week's course of oral metronidazole or placebo. MAIN OUTCOME MEASURES: Primary outcome was delivery before 30 weeks of gestation. Secondary outcomes included delivery before 37 weeks. RESULTS: The Trial Steering Committee (TSC) recommended the study be stopped early; 21% of women receiving metronidazole (11/53) delivered before 30 weeks compared with 11% (5/46) taking placebo [risk ratio 1.9, 95% confidence interval (CI) 0.72-5.09, P = 0.18]. There were significantly more preterm deliveries (before 37 weeks) in women treated with metronidazole 33/53 (62%) versus placebo 18/46 (39%), risk ratio 1.6, 95% CI 1.05-2.4. fFN was a good predictor of early preterm birth in these asymptomatic women; positive and negative predictive values (24 weeks of gestation) for delivery by 30 weeks were 26% and 99%, respectively (positive and negative likelihood ratios 15, 0.35). CONCLUSION: Metronidazole does not reduce early preterm birth in high risk pregnant women selected by history and a positive vaginal fFN test. Preterm delivery may be increased by metronidazole therapy.     

Will cervicovaginal interleukin-6 combined with fetal fibronectin testing improve the prediction of preterm delivery?

Objective: We sought to investigate if determination of cervicovaginal interleukin-6 (IL-6) levels would enhance the positive predictive value of fetal fibronectin (fFN) for preterm birth.

Methods: A prospective cohort study was undertaken of 135 women between 24 and 34 weeks gestation with symptoms of suspected preterm labor. Cervicovaginal secretions were collected for both IL-6 and fFN and measured by immunoassay and ELISA, respectively. Outcome variables included preterm delivery in less than 48 h, within 7 days, and prior to 37 weeks. Statistical analysis was performed with Fisher's exact test, regression for logarithmic transform levels, and multivariate logistic regression. ROC curves were created for IL-6 levels.

Results: IL-6 and fFN levels were both elevated in cervicovaginal secretions of women with symptoms of preterm labor. IL-6 values > 100 pg/ml resulted in a odds ratio for delivery at < 37 weeks of 1.57 (95%CI = 0.89–2.75, P =. 11), whereas fFN values > 50 ng/ml resulted in a preterm delivery risk of 4.58 (95%CI = 154–13.35, P =. 003). Combining IL-6 and fFN results did not improve upon the predictive value of fFN alone for preterm birth [odds ratio 4.00 (95%CI = 1.31–12.17, P =. 015)].

Conclusion: Cervicovaginal IL-6 levels did not provide any additional, independent effect on the prediction of preterm birth beyond that of fFN testing alone.     

The clinical significance of a positive Amnisure test in women with preterm labor and intact membranes

Objective: This study was conducted to examine the frequency and clinical significance of a positive Amnisure test in patients with preterm labor and intact membranes by sterile speculum exam. Study design: A retrospective cohort study was performed including 90 patients with preterm labor and intact membranes who underwent Amnisure tests prior to amniocentesis (< 72?h); most patients (n?=?64) also underwent fetal fibronectin (fFN) tests. Amniotic fluid (AF) was cultured for aerobic/anaerobic bacteria and genital mycoplasmas and assayed for matrix metalloproteinase-8. Results: (1) the prevalence of a positive Amnisure test was 19% (17/90); (2) patients with a positive Amnisure test had significantly higher rates of adverse pregnancy and neonatal outcomes (e.g., impending preterm delivery, intra-amniotic infection/inflammation, and neonatal morbidity) than those with a negative Amnisure test; (3) a positive test was associated with significantly increased risk of intra-amniotic infection and/or inflammation, delivery within 7, 14, or 28 days and spontaneous preterm birth (< 35 weeks) among patients with a negative fFN test. Conclusions: A positive Amnisure test in patients with preterm labor and intact membranes is a risk factor for adverse pregnancy outcome, particularly in patients with a negative fFN test. A positive Amnisure test in patients without symptoms or signs of ROM should not be taken as an indicator that membranes have ruptured.     

Fetal fibronectin as a predictor of spontaneous preterm labour in asymptomatic women with a cervical cerclage

Objective  To assess the accuracy of fetal fibronectin (fFN) testing for prediction of preterm labour in asymptomatic high-risk women with a cervical cerclage.
Design  Retrospective observational study.
Setting  United Kingdom.
Population  Nine hundred and ten asymptomatic women at high-risk of Preterm birth referred to specialist antenatal clinics and undergoing fFN testing between November 1997 and December 2007.
Methods  Women had fFN tests taken between 23⁺⁰ and 27⁺⁶ weeks' gestation, on one or more occasions.
Main outcome measures  Sensitivity, specificity, positive predictive values and negative predictive values of fFN testing for predicting delivery <30 and <37 weeks were compared in those with and without cerclage.
Results  For delivery <30 weeks' gestation, the specificity of fFN testing was significantly lower in women with cervical cerclage (77% vs 90%; P  ≤ 0.00001). The sensitivity of the test was similar between the groups (78.6 (no-cerclage) vs 60% (cerclage); P  > 0.4). The negative predictive value of the fFN test for delivery <30 weeks was high in both groups (>98%).
Conclusions  Asymptomatic high-risk women with cerclage in situ are more likely to have a false positive fFN test. The negative predictive value is similar.     

Fetal fibronectin as a predictor of preterm delivery in patients with preterm contractions and cervical changes

OBJECTIVE: The purpose of the study was to assess the clinical value of fetal fibronectin assay in the group of women presenting with preterm contractions and cervical changes. STUDY DESIGN: We prospectively evaluated 82 patients between 23-34 weeks of gestation presenting with signs and symptoms of preterm labor, intact membranes and cervical dilatation < 3 cm. In all cases cervico-vaginal samples were collected and assayed for the presence of fetal fibronectin. The primary outcome was delivery < or = 28 days from examination. RESULTS: The rate of preterm delivery (< 37 weeks) was 25.6% (21/82) and 17.1% (14/82) of the patients delivered < or = 28 days from the examination. The mean Bishop score was significantly higher in patients delivered < 28 days (5.9 +/- 1.2 vs 4.7 +/- 1.4; p = 0.004). Positive result of fFN (> 0.05 mg/ml) was found in 71.4% of patients that were delivered < or = 28 days and in 7.4% delivered > 28 days (p < 0.001). For predicting delivery < or = 28 days the positive fFN testing had sensitivity of 71.4%, specificity of 92.7%, PPV of 66.7% and NPV of 94%. The cutoff value for Bishop's score > or = 5 had sensitivity of 85.7% and specificity of 48.5%. Performing fFN testing only in patients with Bishop score > or = 5 resulted in the sensitivity of 71.4%, specificity of 95.6%, PPV of 76.9% and NPV of 94.2%. CONCLUSIONS: Fetal fibronectin is a very good predictor of imminent preterm delivery. It needs further research whether performing of the fFN assay can be limited only to the patients with the estimated Bishop's score > or = 5.     

Vaginal fetal fibronectin as a predictor of spontaneous preterm delivery in triplet gestations

Objective: To assess the diagnostic accuracy of vaginal fetal fibronectin (fFN) sampling for predicting preterm birth in asymptomatic women carrying triplet gestations. Methods: An historical cohort of patients carrying triplet gestations between 1998 and 2010 was identified from a single practice by chart review. All patients were screened with fFN testing at 2–3 week intervals from 22 weeks to 32 weeks of gestation. Outcomes evaluated were spontaneous preterm birth prior to 28, 30, and 32 weeks’ gestation and delivery within 2 and 3 weeks of testing. Results: There were 56 pregnancies that met criteria for inclusion. For delivery prior to 30 weeks’ gestation, the test had a sensitivity of 75%, a specificity of 85.4%, a positive predictive value of 46.2%, a negative predictive value of 95.3%, positive likelihood ratio of 5.13, and a negative likelihood ratio of 0.29 (p < 0.0001). For delivery within 3 weeks of a single fFN assessment, the test had a sensitivity of 53.3%, a specificity of 95.8%, a positive predictive value of 53.3%, a negative predictive value of 95.8%, positive likelihood ratio of 12.7 and negative likelihood ratio of 0.48 (p < 0.0001). Conclusion: Fetal fibronectin testing provides moderate to high prediction of spontaneous preterm birth in triplet gestations.     

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.     

The significance of a positive fetal fibronectin in the setting of a normal cervical length in twin pregnancies

To estimate the risk of preterm birth in asymptomatic women with twin pregnancies with a normal cervical length (CL) and a positive fetal fibronectin (fFN), we reviewed a retrospective cohort of twin pregnancies delivered in our practice from 2005 to 2010. Patients were screened from 22 to 32 weeks with CL and fFN at 2- to 4-week intervals. We examined 244 patients with twin pregnancies and a normal CL (>25 mm) between 22 and 32 weeks and compared outcomes based on the fFN result. Fourteen (5.7%) patients had a positive fFN and 230 (94.3%) patients had a negative fFN. Positive fFN was associated with an increased the risk of spontaneous preterm birth < 37 weeks (85.7% versus 38.3%, p = 0.001), < 35 weeks (50% versus 11.8%, p < 0.001), < 34 weeks (35.7% versus 6.9%, p < 0.001), and < 32 weeks (21.4% versus 2.2%, p < 0.001). On adjusted analysis, a positive fFN was independently associated with preterm birth < 32 weeks (odds ratio 6.8, 95% confidence interval 1.42, 32.2) and gestational age at delivery (p = 0.001). In the setting of a normal CL, a positive fFN is significantly associated with preterm birth in asymptomatic twin pregnancies. Contingency model screening of fFN in asymptomatic twin pregnancies solely based on CL evaluation may fail to identify a cohort of at-risk patients.     

Pregnancy outcome in women with preterm labor symptoms without cervical change

OBJECTIVE: This study was undertaken to determine pregnancy outcome in women who have preterm labor symptoms without cervical change according to fetal fibronectin status. STUDY DESIGN: Patients who were examined at the obstetric emergency department with symptoms of preterm labor but without cervical change underwent fetal fibronectin collection. Pregnancy outcome and fetal fibronectin results were analyzed after delivery. RESULTS: Of the 235 patients sampled, 20% (n = 48) had positive fetal fibronectin results. The mean +/- SD gestational age at delivery was lower in women with positive fetal fibronectin results (34.2 +/- 4.1 vs 37.7 +/- 2.3 weeks; P <.001); these women were more likely to deliver preterm as a result of preterm labor than women with other obstetric indications (46% vs 19%; P <.001). Infants born to these women demonstrated lower birth weight (2317 +/- 895 g vs 2877 +/- 557 g; P =.003), were more likely to be admitted to the neonatal intensive care unit (42% vs 14%; P <.001), and were more likely to die in the neonatal period (11% vs 0%; P <.001). CONCLUSION: Patients with symptoms of preterm labor but without cervical change who have negative fetal fibronectin results are less likely to deliver preterm. Therefore in women with symptoms but without cervical change fetal fibronectin should be considered for risk assessment.     

Fetal fibronectin as a predictor of preterm birth.

Preterm delivery remains the leading cause of perinatal mortality and occurs in approximately 7-9% of pregnancies. The main problem for the obstetrician is the inability to detect women at risk from this complication. The presence of fetal fibronectin (fFN) in cervicovaginal secretions has been proposed as a specific predictor of preterm delivery. Immunohistochemical studies suggest that fFN is present in the extracellular matrix of the decidua basalis next to the intervillus space. It has been studied intensively in symptomatic patients and has a positive predictive value of 43-79%. It has also a negative predictive value of 99.7% for birth within 7 days and 93% for delivery before 37 weeks. Similarly, in high-risk asymptomatic women, it has been proved a useful screening tool for the prediction of preterm delivery, yielding a sensitivity of 43-92%, a specificity of 52-93%, a positive predictive value of 43-85% and a negative predictive value of 86-99%. In low-risk asymptomatic women, fFN has a sensitivity of 63-73%, a specificity of 80-98%, a positive predictive value of 13-36% and a negative predictive value of 95-97%. In women presenting with preterm contractions, a negative test may make one withhold potentially dangerous tocolytic therapy. In asymptomatic women this test can identify patients who have a very high risk for early delivery. Women identified as being high-risk can be offered steroid injections in order to improve lung maturity in preterm babies. Additionally, they can be counselled about the signs and symptoms of preterm labour, so that they can seek medical advice before labour is actually established. However, extensive research is still needed, as no clear benefit in preventing preterm birth using this test, has been shown so far.     

Interleukin-8 and glucose in amniotic fluid, fetal fibronectin in vaginal secretions and preterm labor index based on clinical variables are optimal predictive markers for preterm delivery in patients with intact membranes

AIM: Various predictive markers for preterm delivery have been proposed in previous studies. We investigated which marker is most reliable. METHODS: In 126 patients with preterm labor before 32 weeks of gestation and intact membranes, who had regular uterine contractions with cervical changes effaced > or =50%, we evaluated seven markers: interleukin (IL)-8, glucose, and granulocyte count in amniotic fluid (AF); fetal fibronectin (fFN) in vaginal secretions; IL-8 in cervical mucus; cervical length; and preterm labor index (PLI) based on clinical variables. The relationships of these variables to the occurrence of preterm delivery before 34 weeks were examined by logistic regression analysis. RESULTS: Values for AF IL-8, AF granulocyte count, fFN in vaginal secretions, and PLI were significantly higher, while the value for AF glucose was significantly lower, in patients delivering before 34 weeks than those in patients delivering at or following 34 weeks (P < 0.0001 for all). The most sensitive marker for predicting delivery before 34 weeks was AF IL-8 (sensitivity, 67.8%). The most specific markers were AF IL-8 (specificity, 95.5%) and PLI (specificity, 95.5%). By the logistic regression analysis, AF IL-8, AF glucose, fFN in vaginal secretions and PLI showed independent relationships with delivery before 34 weeks (P = 0.0009, P = 0.0032, P = 0.0131 and P = 0.0038, respectively). CONCLUSIONS: In preterm labor with intact membranes, AF IL-8, AF glucose, fFN in vaginal secretions and PLI were highly predictive markers for detecting preterm delivery before 34 weeks.     

Cervilenz assessment of cervical length compared to fetal fibronectin in the prediction of preterm delivery in women with threatened preterm labor

Objective.?To determine whether cervical length (CL) measured by the Cervilenz? measuring device is an effective screening tool for the prediction of preterm delivery (PTD) compared to fetal fibronectin (fFN).

Methods.?We evaluated fFN and CL among women who enrolled into a randomized control trial (RCT) comparing management algorithms for threatened preterm labor between 24 and 34 weeks' gestation. In all subjects, fFN was collected, with CL determined in blinded fashion. The sensitivity, specificity, and positive and negative predictive values (NPV) for fFN or Cervilenz in prediction of PTD within 7 days or prior to 37 weeks were determined.

Results.?Fifty-two subjects were evaluated. CL?<30?mm correlated with PTD?<7 days (r?=?0.31, p?=?0.04) and fFN positivity (r?=?0.43, p?=?0.006). CL?<30?mm and fFN had excellent NPV for PTD?<7 days (97.1 vs. 97.3%), and the area under the receiver operator characteristic curves were similar for prediction of PTD?<7 days (76.6 vs. 75.2%, p?=?0.71) or?<37 weeks (56.7 vs. 55.2%, p?=?0.71).

Conclusions.?Measurement of CL with Cervilenz appears to be equivalent to fFN in screening symptomatic women for PTD within 7 days or prior to 37 weeks. Given cost and turnaround time with fFN testing, Cervilenz represents a promising new tool for real time, clinically useful results in the management of women with threatened preterm labor.     

Contingent Use of Fetal Fibronectin Testing and Cervical Length Measurement in Women With Preterm Labour

ObjectiveTo evaluate the contingent use of fetal fibronectin (fFN) testing and cervical length (CL) measurement to predict preterm delivery, and to validate the use of phosphorylated IGFBP-1 as a predictor of preterm delivery.MethodsWe recruited 71 women with a clinical diagnosis of preterm labour between 24 and 34 weeks, and tested for the presence of fFN and IGFBP-1 in the cervicovaginal secretions of all women immediately before CL measurement.ResultsAmong the 66 women with complete outcome, four were excluded from the final analysis as two had assessment for fFN but no CL measurement, and another two had CL measured but no screening for fFN. Among 62 women with complete results, the mean gestational age at recruitment was 29.4 ± 2.5 weeks. Six women (9.6%) delivered within two weeks of assessment, and 14 (22.5%) delivered before 34 weeks. A positive fFN test resulted in a sensitivity of 83%, a specificity of 84%, a positive predictive value of 36%, and a negative predictive value of 98% for delivery within two weeks; for CL < 25 mm, these figures were 50%, 52%, 10%, and 91%, respectively, and for a positive IGFBP-1, they were 17%, 93%, 20%, and 91%, respectively. A policy of contingent use of fFN (in which the test was assumed to be positive if CL ≤ 15 mm, and fFN was only measured if the CL was between 16 and 30 mm) gave sensitivity, specificity, positive and negative predictive values of 80%, 61%, 17%, and 97%, respectively for delivery within two weeks. Using this contingent use protocol, only one third of women needed fFN screening after CL measurement.ConclusionIn this study, IGFBP-1 screening did not predict preterm delivery and fFN screening provided the best predictive capacity. A policy of contingent use of testing for fFN after CL measurement, or contingent use of CL measurement after fFN screening (depending on available resources) is a promising approach to limit use of resources.     

Effect of digital cervical examination on the expression of fetal fibronectin.

OBJECTIVE: To determine whether oncofetal fibronectin (fFN) assays from symptomatic women are influenced by digital examination of the cervix. STUDY DESIGN: Cervicovaginal fFN specimens were obtained from women at 22-34 weeks' gestational age with symptoms of preterm labor immediately prior to a digital examination of the cervix and two hours after. Fetal fibronectin was assayed by a specific enzyme-linked immunoassay. Results were reported as positive (> or = 50 ng/mL) or negative (< 50 ng/mL). Paired initial and repeat fFN results were compared for statistical difference, and the clinical outcomes were used to assess the accuracy of the initial and repeat results. RESULTS: Fifty symptomatic women at an average gestational age of 29.3 +/- 2.0 weeks were enrolled. Eighty-six percent of the repeat fFN results remained unchanged after a digital examination, (P = .26, beta = .2). The predictive value of a negative fFN obtained after a digital examination was 97% for the absence of spontaneous preterm delivery in < 8 or < 15 days. Two of 16 initially positive results became negative after an examination, and one patient delivered two days later. Five of 34 initially negative fFN results became positive after an examination, and 5/5 delivered more than seven days later. CONCLUSION: Digital examination of the cervix has an effect on fFN results. The routine use of fFN after a digital examination is not recommended.