Exudative v/s transudative ascites: differentiation based on fluid echogenicity on high resolution sonography.

ABSTRACT

Real time sonography was performed in 52 patients with ascites to evaluate the accuracy of sonography in differentiating an exudative from a transudative collection. The echogenicity of ascites was graded I, II and III using the echogenicity of normal abdominal viscera as comparative standard reference points. Grade I collections (31 patients) were either absolutely anechoic, or showed few internal echoes secondary to particulate matter. Grade II collections (7 patients) were hypoechoic as compared to the liver and spleen. Grade III collections (14 patients) had an echogenicity similar to or greater than that of the liver and spleen. The results of diagnostic aspiration in all patients were then compared to the sonographic grade of the ascitic fluid. All transudates (28 patients) had a Grade I echogenicity. Only 3 patients with an exudative ascites had a Grade I echogenicity. The remaining 21 patients with an exudative collection had an echogenicity equal to or greater than Grade II. Using these results, an ascitic fluid echogenicity of Grade I had a 92.32% sensitivity, 100% specificity, a positive predictive value of 1 and a negative predictive value of 0.875 in diagnosing transudates. An ascitic fluid echogenicity of Grade II or more had a sensitivity of 87.5%, specificity of 100%, a positive predictive value of 1 and a negative predictive value of 0.903 in diagnosing transudates.