The predictive value of physical examinations for ascites.

To determine the predictive value of physical signs for ascites, we compared the results of physical examination with those of abdominal sonography in 90 men in hospital with liver disease. The positive predictive values of shifting dullness and prominent fluid waves were low (51% and 73%). We divided the patients into two groups: those with prolonged prothrombin times (72% prevalence of ascites by sonogram), and those with normal prothrombin times (15% prevalence). In patients with prolonged prothrombin times, a prominent fluid wave had a very high positive predictive value for ascites (96%). Many patients with prolonged prothrombin times had ascites despite negative physical signs. In contrast, in those with normal prothrombin times, both shifting dullness and prominent fluid waves were usually falsely positive. Patients with normal prothrombin times and no shifting dullness rarely (2%) had ascites. The predictive value of physical signs for ascites depends on the prevalence of ascites in groups of patients that are examined. The prothrombin time is a useful index for identifying inpatients with a high or low prevalence of ascites and the predictive value of physical signs is enhanced by interpreting them in combination with a patient's prothrombin time.