Teenager with catheter that infuses but does not draw back

Line study of a fibrin sheath on a central venous catheter
Scout from a line study (above) shows the tip of the catheter to be abnormally positioned in the right subclavian vein rather than in the superior vena cava. Injection of the catheter (below) shows a dilation in the diameter of the distal catheter, suggesting the contrast is inside a sheath encasing the distal catheter.

The diagnosis was fibrin sheath of the catheter tip.