Knotting of urethral catheter within bladder: an unusual complication in cystourethrography.

Complications in voiding cystourethrography are infrequent and may include infection, catheter-induced trauma, bladder rupture, and allergic reaction to contrast. We report a case in which the catheter formed a knot within the bladder lumen. To our knowledge, this is the first complication of this type to be reported. We believe this particular complication can be avoided by inserting a catheter within the bladder lumen short enough to prevent looping and possible knot formation.