ارزش تشخيصي لاكتات دهيدروژناز و كراتينين مايع مهبلي در تشخيص پارگي زودرس پرده هاي جنيني

Diagnostic value ofLDH and creatinin in vaginal fluid for detection of premature rupture of membranes

Background and purpose: Premature rupture of membrane (PROM) is a common and challenging issue in obstetrics. Early diagnosis of PROM and the consequent infection has a pivotal role in proper management of patients. The detection of PROM is easier in a case with visible vaginal fluid, but is difficult when trivial amount of vaginal fluid presents. In this study, we aimed to assess the diagnostic value of LDH and creatinine in vaginal fluid for detecting PROM. Materials and methods: Pregnant women were recruited in the third trimester (28-42 weeks) when attending prenatal care unit at Kowsar Educational hospital, Ghazvin, Iran during 2008. Under sterile condition, vaginal fluid was collected using speculum. Fern test was performed and adequate vaginal fluid was aspirated from posterior fornix to measure LDH and creatinine. Results: 223 pregnant women with mean age of 25.4±5.5 (16-43) years were recruited into this study. The mean of gestational age was 37.6±3.2 weeks. Visible vaginal fluid was detected in 72 (32.3%) while Fern test was positive in 56 (25.1%). Visible vaginal fluid detected by a specialist is considered as a gold standard test. Using ROC curve analysis from SPSS, we have found that a cutoff point of >180 U/L for vaginal fluid LDH level is a reasonabl diagnostic value for PROM at sensitivity of 85%, specificity of 80%, PPV of 66.3%, NPV of 91.6% and an accuracy of 81%. The same analysis on vaginal creatinine using a cutoff point of >0.9 mg/dl showed diagnostic value with sensitivity of 72%, specificity of 35%, PPV of 34.7%, NPV of 72.6% and accuracy of 47%. Conclusion: Vaginal fluid LDH at a cutoff point of >180 U/L is clinically a useful diagnostic test for detection of PROM. Key words: Fetal membranes, PROM, LDH, creatinin