Abstract
Twiddler's syndrome, the migration of a catheter tip out of a vessel by intentional or unintentional self-manipulation, is presented in a case report of a young child with Langerhans' cell histiocytosis. Since this migration is a potentially serious complication of internal venous catheters, an overview compares and contrasts the differences between internal and external central venous catheters. The need to consider Twiddler's syndrome in an assessment of a patient with an internal venous catheter is emphasized.