Infection and labor: the detection of endotoxin in amniotic fluid.

Intra-amniotic infections are frequently caused by gram-negative organisms. Lipopolysaccharide, or endotoxin, is a component of the cell wall of these bacteria. The Limulus amebocyte lysate assay is the most sensitive test clinically available for the detection of endotoxin in biologic samples. The diagnostic value of the Limulus amebocyte lysate assay test for the detection of intra-amniotic infection has been examined and compared with that of the Gram stain. The Gram stain had a 60.8% sensitivity and 9.6% false positive rate. The Limulus amebocyte lysate assay had a 69% sensitivity and a 4.8% false positive rate. When both tests were used in combination, the sensitivity improved to 95.6%, whereas the false positive rate was 14.3%. The Limulus amebocyte lysate assay test is a rapid, sensitive, inexpensive, and simple test for the detection of gram-negative intra-amniotic infections.