Diagnosis of fetal death in utero with amniotic fluid creatine kinase.

There is a need for a widely available and accurate method of diagnosing fetal death in utero. The accepted standard technique for making this diagnosis is real-time ultrasonography, but this procedure is not available at all hospitals. However, almost every hospital laboratory has the capability of measuring creatine kinase in body fluids. One hundred eight pregnant women underwent real-time ultrasonography and analysis of amniotic fluid for creatine kinase. Ninety-one women with conditions that required amniocentesis during the second and third trimesters had a life fetus by ultrasonographic examination and a low level of amniotic fluid creatine kinase (0 to 3 sigma units per milliliter). Seventeen women with a dead fetus by ultrasonographic examination had an abnormally high level of amniotic fluid creatine kinase (5 to 9,800 sigma units per milliliter). The only erroneous diagnosis in this series involved a set of twins, one of whom was shown by real-time ultrasonography to be alive and the other dead. Both sacs contained abnormally high, although different, levels of creatine kinase. Analysis of creatine kinase in amniotic fluid is a reliable technique for diagnosing fetal death.