'Sinking pellet' sign of bladder perforation

Preoperative diagnosis of urinary bladder perforation due to penetrating missile injury may be difficult to establish. Although retrograde cystography usually demonstrates extravasation, it may be normal on occasion. In shotgun blast wounds, metallic pellets are usually distributed randomly throughout the abdominal cavity, but clumping of pellets in the pelvis on the plain film of the abdomen suggests that they may be lying in a hollow viscus such as the bladder. The authors present 2 cases with this finding.