Clinical application of maternal serum cytokine determination in premature rupture of membranes - interleukin-6, an early predictor of neonatal infection?

Background In cases of premature rupture of membranes (PROM), an early detection of fetal infection is necessary in order to weigh infectious complications against prematurity. As routine parameters (leukocytes, C-reactive protein (CRP), fever, and fetal tachycardia) lack satisfactory sensitivity and specificity, this study evaluates whether the determination of interleukin-6 (IL-6), interleukin-8 (IL-8) or soluble interleukin-2 receptor (IL-2R) in maternal serum could supplement or replace routine inflammation parameters. Methods. In this prospective study results of clinical and laboratory parameters were investigated with respect to neonatal infection in 71 patients with FROM. IL-6, IL-8 and IL-2R were determined by enzyme immunoassays. Results. Best specificity and sensitivity could be demonstrated for CRP and IL-6. Both elevation of CRP and IL-6 correlated significantly (p<0.01 and p <0.001, respectively) with the onset of neonatal infection. At a cutoff of 11 pg(ml, IL-6 reaches a sensitivity of 81% and a specificity of 76% CRP a specificity of 76% (cutoff 1.2 mg/dl) and a sensitivity of 56%. In 4/ 16 (25%) cases developing neonatal infection, IL-6 increased earlier than CRP. IL-8 and IL-2R results showed a less significant correlation with fetal outcome. Conclusions. Determination of IL-6 in maternal serum can significantly contribute to an earlier detection of fetal infection in patients with PROM.