| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Letters |
1
Serv. de Bioquím. Clín., Hosp. de Navarra, C/Iruñlarrea 3, Pamplona 31008, Spain,
2
Serv. de Ginecol. y Obstet., Hosp. Virgen del Camino, Pamplona, Spain
a Author for correspondence.
To the Editor:
Microbial invasion of the amniotic cavity has been demonstrated in 16.1% of women with preterm labor and intact membranes (1). This situation is frequently difficult to diagnose because its clinical manifestations occur late in pregnancy and because biochemical and microbiological studies are required for accurate diagnosis (2). Saito et al. (3) implicated cytokines in the pathophysiology of preterm labor, and high concentrations of interleukin-6 (IL-6) have been detected in amniotic fluid of women with amniotic infection (4). Moreover, we thought that a proteinase, e.g., elastase, located in the polymorphonuclear neutrophils (PMN) might be involved in infection-associated preterm labor. We therefore undertook a study of IL-6, elastase-PMN (which has not been studied before), leukocytes, and glucose concentrations in amniotic fluid in women in preterm labor.
After having consented, 35 women (ages 14 to 39 years) between weeks 26 and 34 of gestation and with a clinical pattern of preterm labor underwent amniocentesis to detect infection-associated preterm delivery. Antibiotic use before amniocentesis was not excluded in this study.
Amniotic fluid was poured into a sterile flask, and an aliquot was plated on routine aerobic and anaerobic media. We checked for the presence of leukocytes with a microscope, using a Neubauer chamber. After centrifugation of the amniotic fluid, we measured the glucose concentration (hexokinase method) with a CX-7 Synchron Analyzer (Beckman Instruments, Brea, CA). Some aliquots of amniotic fluid were prepared and stored at -70 °C until analyzed for elastase and IL-6. IL-6 content was determined with an ELISA (ref. 1534475; Boehringer Mannheim, Mannheim, Germany), for which the manufacturer's stated detection limit is 10 ng/L and within- and between-run CVs are 8% and 15%, respectively. Elastase-PMN was determined by immunoassay (ref. 11332; Merck, Darmstadt, Germany) adapted to an RA-1000 Analyzer (Bayer Diagnostics, Madrid, Spain); in our hands, the detection limit of this assay is 12.3 µg/L, and within- and between-run CVs are 7.2% and 8.3%, respectively. For each technique, we used the accompanying quality-control material. Comparisons between subjects were calculated with Mann–Whitney U-test, and possible correlations between biochemical variables were assessed with Spearman's test.
Table 1
displays the test results. Median amniotic fluid concentrations
of glucose, leukocytes, elastase, and IL-6 were significantly different
between women with positive and negative culture results and also
between patients who developed preterm labor and those with term
delivery. The significant correlations were: elastase vs IL-6,
r = 0.512 (P = 0.05); elastase vs
leukocytes, r = 0.392 (P = 0.05);
elastase vs glucose, r = -0.468 (P =
0.05); and leukocytes vs IL-6, r = 0.468
(P = 0.05). The remaining correlation coefficients were
not significant.
|
Preterm delivery occurred in 42.8% of the population studied. Escherichia coli, Klebsiella pneumoniae, and Candida nonalbicans species were isolated in 11.5% of the population. This prevalence of a positive fluid culture is very similar to the results of Romero et al. (4).
Gauthier et al. (5) found an association between low glucose concentration in amniotic fluid and intramniotic infection. In an infectious process, one would expect to find a low concentration of glucose, a high number of leukocytes, and a high concentration of elastase. In our study, the highest correlation coefficient obtained was between elastase and IL-6 in amniotic fluid.
In summary, we found (a) a high elastase concentration correlating with the other biochemical variables and (b) a median glucose concentration significantly lower and mean values for elastase, leukocytes, and IL-6 significantly higher in women with preterm labor than in those with term labor. We conclude, therefore, that elastase may be a useful new marker of amniotic infection and of the possibility of preterm labor delivery.
References
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
