Dilemma of elevated CA 19-9 in biliary pathology.

Carbohydrate antigen 19-9 (CA 19-9) is a tumor marker which has been extensively evaluated and widely utilized primarily in diagnosing and prognosticating pancreaticobiliary malignancies. Levels may be significantly influenced and elevated in cases of benign biliary conditions however, especially in obstructive jaundice, thereby posing difficulty in distinguishing between benign and malignant cholestasis. A myriad of studies have focused on elucidating proper use and interpretation of CA 19-9 in pancreatic cancer as well as in the setting of cholestasis. These studies have demonstrated that many factors influence CA 19-9 values and various methods for interpreting CA 19-9 in obstructive jaundice have been proposed. With improvements in diagnostic imaging, advancements in endoscopic modalities, and likelihood that management will not change based on the results of the test, clinicians should be cautious when ordering CA 19-9 and consider the reasons for measuring the tumor marker.