Rule of 15: A New Diagnostic Tool to Differentiate Benign and Malignant Portal Vein Thrombus

Key words: New diagnostic tool, Rule of 15, Portal vein thrombosis. Background: Portal vein thrombosis(PVT) can develop in patient’s with cirrhosis. It can be benign or malignant. Differentiation of these are important because outcome is different for both. Aims: Find out variables that can differentiate between benign and malignant PVT. Methods: Cross-sectional study. Patients with cirrhosis with PVT were taken up for the study. Results: There were 31 benign and 73 malignant PVT. Among the variables analyzed Age , Bilirubin , INR , Eosinophil count , Portal vein diameter and AFP were statistically significant between Benign and Malignant Thrombus. Cut off of Portal Vein diameter of > 15 mm with AFP level of > 15 was suggestive of Malignant portal vein thrombus with sensitivity of 76.7% and Specificity of 97% and accuracy of 83 %. Conclusions• Contrast enhanced CT(CECT) abdomen has sensitivity of 86% sensitivity and 100 % specificity in detecting malignant PVT from benign, But due to impaired renal function which is common among cirrhotics CECT cannot be used in all patients with cirrhosis for PVT characterization. In this situation rule of 15 aids in diagnosis of nature of thrombus• This rule of 15 is a simple diagnostic tool to differentiate benign from malignant thrombus especially in the setting of malignant thrombus without focal lesion and in cirrhotics with renal impairment with a comparable sensitivity and specificity to CECT and it needs to be validated by further studies so that this score can be applied for characterization of portal vein thrombosis in all cirrhotics irrespective of renal impairment.