Accuracy of Residual Urine Measurement in Post-operative Gynecological Patients by Normal Saline Instillation versus Re-catheterization

Abstract

A total of 90 post-operative gynecological patients, who needed residual urine measurement were studied in the Department of Obstetrics and Gynecology, Faculty of Medicine Siriraj Hospital, Mahidol University between June 1, 1999 and April 30, 2000. Residual urine in each patient was measured by the normal saline instillation technique, followed by re-catheterization which is considered as the gold standard. The accuracy and agreement of the results of residual urine measurement by the two techniques were calculated. In comparison with re-catheterization, the accuracy of the normal saline instillation technique was 83.3%, sensitivity was 66.7%, specificity was 96.1%, positive predictive value was 92.8%, negative predictive value was 79%, false positive rate was 3.9%, and false negative rate was 33.3%. The Kappa coefficient was 0.65 (P < 0.001). No complications from either technique were found. Residual urine measurement in post-operative gynecologic patients by normal saline instillation yielded fair to good agreement with re-catheterization. Due to a high percentage of false negative rate, this new method may not be suitable for current clinical practice. Improvement in the technique and further studies are needed.