Assessment of dipstick sensitivity and specificity for screening of hypertensive pregnancies

Abstract

OBJECTIVE: Hypertensive disorders during pregnancy are a significant cause of maternal, fetal, and neonatal morbimortality; hence the need for an accurate and simple diagnostic method for situations of obstetrical emergencies. The dipstick is widely used as method for the detection of protein in urine. The objective of our study is to compare dipstick results obtained from urinary samples with the results of 24-h proteinuria tests, which is considered the gold standard for detection of urinary protein.
MATERIALS AND METHODS: We carried out a retrospective study with medical records of patients admitted to the Obstetrics Center of the Hospital de Clínicas in 1998 due to increase in blood pressure. Statistical analysis of data was carried out using the c2 test. This study was approved by the Ethics and Research Committee of the Hospital de Clínicas.
RESULTS: 175 medical records of patients who presented hypertensive disorder were retrospectively studied. Our population presented an age average of 28 years, 34% of mothers were primiparas and 54% presented a gestational age of less than 36 weeks. As to the final diagnosis, 21% showed mild preeclampsia, 20.4% severe preeclampsia, 9.2% preeclampsia over essential hypertension, 37% transient hypertension, and 10% chronic systemic hypertension. Comparison of dipstick test to 24-h proteinuria exam indicated dipstick sensitivity of 78%, specificity of 64%, positive predictive value of 59%, and negative predictive value of 81%.
CONCLUSIONS: Our results suggest that dipstick should not be used as the sole method for screening preeclampsia and that, in obstetrical emergencies, clinical presentation of the patient should be given priority over the dipstick. Other methods of screening of proteinuria should also be assessed with the objective of reducing falsenegative results.