Diamine oxidase in the diagnosis of ruptured fetal membranes

Diamine oxidase activity is present in amniotic fluid but absent from vaginal secretions, providing a method for diagnosing rupture of membranes. Vaginal secretions were absorbed onto sterile paper strips, eluted, and assayed for diamine oxidase activity. Interfering substances included maternal serum, iodine antiseptics, and large amounts of meconium. Two of 109 prenatal clinic (negative control) specimens displayed measurable diamine oxidase activity; one of 144 postamniotomy (positive control) specimens had no diamine oxidase activity. Of 75 test specimens obtained by speculum examination and 488 test specimens obtained without the aid of a speculum, 18 and 62, respectively, displayed a diamine oxidase test result different from results of conventional tests (nitrazine paper, ferning, fetal cell stains). These discrepancies are discussed in view of the utility of the diamine oxidase test as an adjunct to conventional methods for diagnosing rupture of membranes. The diamine oxidase test appears to be objective, sensitive, quantitative, and capable of detecting amniotic fluid leaks more than 25 hours after rupture of membranes. It can be performed in 1 hour and requires a scintillation counter.