Serum Bilirubin and Carbohydrate Antigen 19-9 Levels as Predictors of Malignancy in Obstructive Jaundice - A Retrospective Analysis

摘要

Background: Obstructive jaundice due to malignant pathology is often associated with high bilirubin levels. This may not always be true as malignant pathologies can still present with low bilirubin levels in the early stages or benign pathologies can present with high levels if there is associated cholangitis. Also, Carbohydrate Antigen (CA19-9) has been an unreliable predictor of malignancy. Aim and Objectives: Our study examined the combined accuracy of bilirubin levels and CA19-9, in order to predict malignancy as a cause of obstructive jaundice. Material and Methods: Bilirubin levels in a total of 900 patients with obstructive jaundice were analyzed over a period of 5 years in a retrospective study. CA 19-9 levels were also analyzed in those patients suspected to have malignancy on clinical evaluation or imaging (649 patients). The values of bilirubin in isolation and with CA19-9 in combination were used for co relation, along with imaging and histopathology. Results: Bilirubin levels in isolation, as a predictor of pathology in patients with obstructive jaundice were highly significant (Area under Curve =0.805; P 0.01). Bilirubin level 7 mg% provided the optimum combined sensitivity and specificity for malignancy (71.9% and 84.9%, respectively). The application of a bilirubin level 19 mg% achieved specificity of 99.1% for malignancy. The sensitivity and specificity of CA 19-9 in isolation was 70.9% and 78.3% respectively at a cut-off value of 37U/ml. In combination, the sensitivity and the specificity were 87.9% and 91.3% respectively. Conclusion: Serum bilirubin and CA 19- 9 levels are routinely done as a part of the patients workup for obstructive jaundice. When evaluated in combination the positive predictive value increases significantly to diagnose malignancy especially in cases where it is obscure. It acts as a valuable guide to the surgeon along with other modalities.