A novel method for collecting vaginal pool for fetal lung maturity studies

Vaginal fluid interleukin-6 concentrations as a point-of-care test is of value in women with preterm prelabor rupture of membranes

BACKGROUND

Preterm prelabor rupture of membranes is frequently complicated/accompanied by infection and inflammation in the amniotic cavity. A point-of-care determination of amniotic fluid interleukin-6 has been shown to be a potentially clinically useful approach to assess inflammatory status of the amniotic cavity. Amniocentesis in preterm prelabor rupture of membranes is not broadly used in clinical practice, and therefore, a shift toward a noninvasive amniotic fluid sampling method is needed.

OBJECTIVE

The first aim of this study was to evaluate the association between the point-of-care vaginal and amniotic fluid interleukin-6 concentrations in fresh unprocessed samples obtained simultaneously. The second goal was to determine the diagnostic indices and predictive value of the point-of-care assessment of vaginal fluid interleukin-6 concentration in the identification of microbial invasion of the amniotic cavity, intraamniotic inflammation, and microbial-associated intraamniotic inflammation in patients with preterm prelabor rupture of membranes.

STUDY DESIGN

A prospective cohort study was conducted in women with singleton gestation complicated by preterm prelabor rupture of membranes at between 24+0 and 36+6 weeks. A total of 153 women with singleton pregnancies were included in this study. Vaginal fluid was obtained from the posterior vaginal fornix by aspiration with a sterile urine sample tube with a suction tip. Amniotic fluid was obtained by transabdominal amniocentesis. Interleukin-6 concentrations were assessed with a lateral flow immunoassay in both fluids immediately after sampling. Microbial invasion of the amniotic cavity was determined based on a positive polymerase chain reaction analysis. Intraamniotic inflammation was defined as an amniotic fluid point-of-care interleukin-6 concentration ≥745 pg/mL.

RESULTS

Several results were obtained in this study. First, it was possible to perform the point-of-care assessment of interleukin-6 in vaginal fluid in 92% of the women (141 of 153), and only those women were included in the analyses. Second, the rate of microbial invasion of the amniotic cavity and intraamniotic inflammation was 26% (36 of 141) and 19% (27 of 141), respectively. Microbial-associated intraamniotic inflammation was identified in 12% of the women (17 of 141). Third, a strong positive correlation was found between the interleukin-6 concentrations in vaginal and amniotic fluids (Spearman rho 0.68; P < .0001). Fourth, the presence of microbial invasion of the amniotic cavity, intraamniotic inflammation, or microbial-associated intraamniotic inflammation was associated with higher vaginal fluid interleukin-6 concentrations in both crude and adjusted analyses. Fifth, a vaginal fluid interleukin-6 concentration of 2500 pg/mL was determined to be the best cutoff value for the identification of microbial invasion of the amniotic cavity (sensitivity of 53% [19 of 36], specificity of 89% [93 of 104], positive predictive value of 63% [19 of 30], negative predictive value of 85% [93 of 110], positive likelihood ratio of 5.0 [95% confidence interval, 2.5-9.5], and negative likelihood ratio of 0.5 [95% confidence interval, 0.4-0.8]); intraamniotic inflammation (sensitivity of 74% [20/27], specificity of 91% [104/114], positive predictive value of 67% [20 of 30], negative predictive value of 94% [104 of 111], positive likelihood ratio of 8.4 [95% confidence interval, 4.5-15.9], and negative likelihood ratio of 0.3 [95% confidence interval, 0.2-0.5]); and microbial-associated intraamniotic inflammation (sensitivity of 100% [17 of 17], specificity of 90% [111 of 124), positive predictive value of 57% [17 of 30], negative predictive value of 100% [111 of 111], positive likelihood ratio of 9.5 [95% confidence interval, 5.7-16.0], and negative likelihood ratio of 0).

CONCLUSION

The point-of-care assessment of interleukin-6 in vaginal fluid is an easy, rapid, noninvasive, and inexpensive method for the identification of intraamniotic inflammation and microbial-associated intraamniotic inflammation in preterm prelabor rupture of membranes pregnancies, showing good specificity and negative predictive value.

Cytokines in noninvasively obtained amniotic fluid as predictors of fetal inflammatory response syndrome

BACKGROUND

In patients with preterm premature rupture of membranes, intrauterine inflammation and/or infection is frequently present, can lead to fetal inflammatory response syndrome, and is associated with adverse neonatal outcome. Clinical decision making requires balancing the potential benefits of pregnancy prolongation against the risk of intrauterine infection. Diagnostic tests in maternal serum are of moderate prediction value and amniocentesis is an invasive procedure. Therefore, markers obtained noninvasively would be helpful in patients with expectant management.

OBJECTIVES

To determine the predictive values of amniotic fluid interleukin-6 and tumor necrosis factor-α in vaginal secretions for fetal inflammatory response syndrome and/or histologic funisitis and for adverse neonatal outcome in patients with preterm premature rupture of membranes.

STUDY DESIGN

In this prospective multicenter case-control study, vaginal secretions were sampled daily with a noninvasive method from 99 women with preterm premature rupture of membranes and expectant management. Amniotic fluid interleukin-6 and tumor necrosis factor-α were measured by 2 different immunoassays (an automated chemiluminescent enzyme immunoassay and a lateral flow immunoassay). After delivery, patients were divided into a control or a fetal inflammatory response syndrome group according to neonatal interleukin-6 in cord plasma and/or the presence of funisitis. Univariate and multivariate regression analyses were performed and prediction models were developed by calculating receiver operating characteristic curves.

RESULTS

Gestational age at delivery was lower and latency period was longer in the fetal inflammatory response syndrome group compared to the control group. The strongest risk factor for composite adverse neonatal outcome was fetal inflammatory response syndrome (odds ratio, 2.48; confidence interval, 1.40-4.38). The median concentrations of amniotic fluid interleukin-6 and tumor necrosis factor-α in vaginal secretions were significantly higher in the fetal inflammatory response group compared to the control group in both immunoassays (P < .001). The area under the curve of the clinical reference model (including common clinical parameters) was 0.66. Adding interleukin-6 and tumor necrosis factor-α into the model improved the area under the curve to 0.92 (in both assays, interleukin-6 IMMULITE and QuickLine); 0.87 (tumor necrosis factor-α IMMULITE) and 0.94 (tumor necrosis factor-α QuickLine), respectively.

CONCLUSION

The strongest risk factor for worse neonatal outcome (composite neonatal outcome) was fetal inflammatory response syndrome. Amniotic fluid interleukin-6 and tumor necrosis factor-α seem to be good predictors for fetal inflammatory response syndrome and for histologic funisitis and may improve the clinical management of patients with preterm premature rupture of membranes. The noninvasive technique of sampling amniotic fluid from vaginal secretions facilitates daily measurements and bedside assessment of cytokines and is in this respect preferable to invasive amniocentesis.

A transcervical amniotic fluid collector: a new medical device for the assessment of amniotic fluid in patients with ruptured membranes

AIM

To describe a new device for the transcervical collection of amniotic fluid (AF) in patients with ruptured membranes, and to compare the concentration of proteins in fluid retrieved by transabdominal amniocentesis and the transcervical AF collector.

STUDY DESIGN

Paired AF samples were collected in patients with preterm prelabor rupture of membranes (PROM) (n=11) by transabdominal amniocentesis and with the transcervical AF collector (Yoon's AF Collector™). Three proteins known to have high concentrations in AF [α-fetoprotein (AFP), β-human chorionic gonadotrophin (β-hCG), and prolactin] were measured.

RESULTS

(1) There was a significant correlation between the concentrations of analytes in AF obtained by transabdominal amniocentesis and by the transcervical AF collector (r=0.94, P<0.001 for AFP; r=0.96, P<0.001 for β-hCG; r=0.72, P<0.05 for prolactin); (2) Bland-Altman plots showed no evidence of heteroscedasticity between transabdominal or transcervical AF concentrations of these markers.

CONCLUSIONS

There was a strong correlation between the concentrations of proteins in AF collected by amniocentesis or with the transcervical device.