Subclinical intrauterine infection is an important cause of preterm labor, specifically where tocolysis has failed. Fifty patients in preterm labor with singleton pregnancies were studied prospectively to determine whether the presence or absence of C-reactive protein, a nonspecific marker for infection, would correlate with success or failure of tocolysis. Of the 50 patients, tocolysis failed in 11 of 15 women with a positive C-reactive protein determination. Tocolysis succeeded in 33 of 35 cases where C-reactive protein was negative (P less than .0005). Urinary tract infection occurred in 40% of the study patients, but was not a confounding factor in the interpretation of C-reactive protein.
Handwerker, S. M., Tejani, N. A., Verma, U. L., & Archbald, F. (1984). Correlation of maternal serum C-reactive protein with outcome of tocolysis. Obstetrics and gynecology, 63(2), 220-224.
Handwerker SM, Tejani NA, Verma UL, Archbald F. Correlation of maternal serum C-reactive protein with outcome of tocolysis. Obstet Gynecol. 1984;63(2):220-224.
Handwerker, S. M., et al. "Correlation of maternal serum C-reactive protein with outcome of tocolysis." Obstetrics and gynecology, vol. 63, no. 2, 1984, pp. 220-224.
Tocolytics were administered in 66 consecutive women in uncomplicated preterm labour with intact fetal membranes (53 singleton and 13 twin pregnancies). C-reactive protein (CRP), a marker of infection, was determined daily and used retrospectively to investigate the role of subclinical infection in preterm labour and to predict the efficacy of tocolysis and the development of a clinical perinatal infection. CRP was also determined in 66 women in uncomplicated labour at term (53 singleton and 13 twin pregnancies). The placenta was examined for histological evidence of infection in all patients who were delivered before 36 weeks (n = 21) and in all women in the control group (n = 66). Elevated CRP levels were more often found in patients who were refractory to tocolysis, suggesting an underlying infectious morbidity. Placental infection was found in 62% of the preterm delivery group and in 12% of the control group. There was an association between elevated CRP levels and histological evidence of placental infection. However, confounding factors such as urinary tract infections limit the usefulness of the CRP test. Because CRP cannot predict clinical perinatal infection accurately, its clinical relevance is very limited.
In this study we evaluated different markers of infection and their relationship to preterm delivery. Forty-four consecutive women with singleton pregnancies in uncomplicated preterm labor were investigated. C-reactive protein (CRP) in peripheral maternal blood, amniotic fluid cytokines, amniotic fluid leukocyte count, and amniotic fluid culture were performed in all patients. Thirty-six patients responded to standard tocolytic therapy and delivered after 34 weeks' gestation. In eight patients treatment failed and they delivered before 34 weeks' gestation. Two of these eight patients had a positive amniotic fluid culture for Ureaplasma urealyticum. The positive culture was accompanied by an elevated neutrophil count in the amniotic fluid. Elevated amniotic fluid levels of tumor necrosis factor (TNF) (more than 23 pg/mL), interleukin-6 (IL-6) (more than 2292 pg/mL) and interleukin-8 (more than 164 pg/mL) correlated with early preterm delivery. CRP levels in serum had a low sensitivity (38%) but a high specificity (94%) in predicting preterm delivery. This study indicates that preterm labor can be initiated by infection. Markers of infection obtained by amniocentesis have a better sensitivity and positive predictive value than noninvasive markers. Elevated IL-6 (more than 2292 pg/mL) seems to be the best predictor for preterm delivery, with a sensitivity of 75% and a specificity of 97%.
The purpose of this study was to determine the relationship between C-reactive protein (CRP) levels and intraamniotic infection in 48 women presenting with preterm labor and intact membranes. Blood samples for CRP tests were obtained immediately before the performance of transabdominal amniocentesis. The prevalence of amniotic fluid cultures positive for organisms was 14.6%. In 16 women (33.3%) positive CRP levels were obtained. There were no significant differences in the prematurity rate or the prevalence of microbial invasion of the amniotic cavity between women with positive CRP levels and women with negative levels. The sensitivity, specificity, and positive and negative predictive values for the detection of amniotic infection were 71.5%, 73.2%, 31.3% and 93.8%, respectively. Based on these results, we suggest that in women with preterm labor and negative CRP levels, routine amniocentesis may not be essential to the initial workup.
C-reactive protein has been used to identify patients at high risk for infectious morbidity with preterm labor or preterm rupture of membranes. In this article we report on 104 patients with preterm labor symptoms (n = 45) or preterm rupture of the membranes (n = 59) and serial evaluations of C-reactive protein measured by latex agglutination and laser nephelometry. The simple, inexpensive latex method appears comparable to the laser method in predicting infectious morbidity and can be used clinically. Elevated C-reactive protein values before delivery predict infectious morbidity in only 8% to 29% of patients, and up to 18% of patients with serious infections may be misdiagnosed as having normal C-reactive protein values before delivery.