We report a case of penetration of the inferior vena cava (IVC) by all four primary struts of a Celect caval filter in a 17-year-old girl with Klippel-Trénaunay syndrome. The girl presented with acute lower abdominal and right leg pain 17 days after filter insertion. An abdominal radiograph demonstrated that the filter had moved caudally and that the primary struts had splayed considerably since insertion. Contrast-enhanced CT confirmed that all four primary struts had penetrated the IVC wall. There was a small amount of retroperitoneal hemorrhage. The surrounding vessels and viscera were intact. The filter was subsequently retrieved without complication.