Validación del índice de impedancia venosa renal en la valoración de Uropatía obstructiva aguda. Hospital Vicente Corral Moscoso. 2017-2018

Abstract

Background. Acute obstructive uropathy represents a cause very frequent of abdominal pain in the emergency rooms of Ecuador. Given the clinical suspicion of acute obstructive uropathy, the first diagnostic tool is grayscale ultrasound, however, because it only detects anatomical changes, its sensitivity and specificity is poor. Doppler ultrasound by measuring the arterial resistance index have been used to get more functional information, nevertheless the conclusions have not been satisfactory; recent studies have been focused on the venous site of the vascular tree for the diagnosis of acute obstruction. Objective. To determine the validity of the renal venous impedance index by Doppler ultrasound for the assessment of acute obstructive uropathy. Material and methods. A diagnostic test validation study was made in 163 patients who attended the Radiology Department of Vicente Corral Moscoso Hospital in the city of Cuenca from January 2017 to January 2018. The sample was calculated on the basis of prevalence of renal colic in a study conducted in the city of Cuenca of 61.3%, expected sensitivity of 94%, expected specificity of 99%, accuracy of 5%, confidence level of 95%, and took into account of 15% of the losses that might occur. Patients were selected with clinical suspicious of renal colic. All individuals underwent intravenous venous Doppler ultrasound in both kidneys and Urography by computed Tomography (UroTC) as a gold test. Results: The sensitivity and specificity of the venous impedance index by Doppler ultrasound in the diagnosis of acute obstructive uropathy is high. The sensitivity and specificity was 81% and 93% respectively. The area under the ROC curve was 0.891 which determines that the diagnostic test was an excellent test for the diagnosis of acute obstructive uropathy. A cutoff value of 0.30 has a sensitivity of 90% and a specificity of 18%. Therefore, this technique could be used routinely in the diagnosis of hydronephrosis due to acute obstructive uropathy.