Extravasation of the contrast in the unused urinary bladder

Ruptured bladder or extravasation from the bladder is almost always associated with trauma. Spontaneous extravasation is extremely rare with only a few reported cases. All those reported extravasations occurred in the patients diagnosed with end stage renal disease (ESRD) and were self limiting conditions. During the one-year period of 2001, voiding cystourethrography (VCUG) of 115 patients were performed in our institution with various indications. The authors found 3 cases with extravasation of contrast from the bladder during VCUG. All extravasations were occurred in ESRD patients and the VCUG was performed as part of the routine investigation prior to renal transplantation. The presented cases shared a similar observation of 1) no traumatic catheterization, 2) only minimal and self limiting extravasation and 3) no immediate or delayed symptom associated with extravasation. The cause and mechanism of leakage remain uncertain. Hypertonicity and mucosal changes within the unused bladder were purposed as probably the two main causes of extravasation.