We evaluated the ability of a testing panty liner (TPL) embedded with a pH/ammonia indicator polymer to differentiate amniotic fluid leakage from urine. A multicenter, open-label study in which 339 pregnant women (age 18 to 45 years, minimum 16 weeks' gestation, presenting with unexplained vaginal wetness) were enrolled. The TPL was worn and the results read by the subject and a health care provider (HCP) who was blinded to the subject's reading. Results were compared with the standard clinical diagnosis, as determined by direct visualization of vaginal pooling, crystallization (ferning), and nitrazine tests, performed by a second blinded HCP. Subject experience with the test was assessed with a brief questionnaire. The TPL accurately detected 154 of the 161 subjects found to have amniotic fluid leakage by the standard diagnosis; thus, the sensitivity of the TPL was 95.65%. The specificity was 84.46% (% true negative readings), as the TPL demonstrated a negative result for 125 of the 148 subjects whose clinical diagnosis was negative for amniotic fluid leakage. The overall agreement between the TPL readings of the clinician and that of the subject was 97.40%. The TPL is a reliable test to determine the presence of amniotic fluid leakage.