Spur cell anemia associated with extrahepatic biliary tract obstruction.

Two patients with extrahepatic biliary obstruction developed spur cell hemolytic anemia. Hemolysis and erythrocyte morphology reverted to normal when the obstruction was relieved. During the hemolytic phase, one patient's plasma converted normal erythrocytes to spur cells and normal plasma converted the patient's spur cells to normal morphology. The spur cells were discovered only when the patients' blood was examined under phase microscopy. We suggest that spur cells may occur in association with biliary obstruction more frequently than previously suspected and that their presence may be uncovered using phase microscopy.