Endotoxins in culture medium for human in vitro fertilization

Endotoxins were detected in a few batches of culture medium during the authors' human in vitro fertilization program. Two distinct levels of endotoxins were assayed: greater than 1 ng/ml and less than 1 ng/ml. The source of endotoxin was traced to culture media obtained from a reputable manufacturing company. The incidence of fertilization per patient was not significantly affected by the presence of endotoxins, but fertilization assessed on the overall number of oocytes was significantly reduced (53%) when endotoxin levels were greater than 1 ng/ml compared with an assay negative for endotoxins (66%) (P = 0.047). The percentage of oocytes cleaving after the observation of two pronuclei was not significantly different, but the degree of fragments observed in the conceptus was significantly more severe if the endotoxin level reached 1 ng/ml. In this investigation, the incidence of pregnancy was 8% when the endotoxin level was greater than 1 ng/ml, 30% if less than 1 ng/ml, and 32% if no endotoxins were detected. This study suggests that, although endotoxins may be present in the culture medium at a deleterious level of at least 1 ng/ml, fertilization and cleavage will be obtained, but there will be a significant increase in the incidence of conceptuses with cytoplasmic fragments; this may result in a reduction in the incidence of pregnancy.