Background

Renal colic secondary to ureteral obstruction from a retained ballistic fragment is a rare sequela of abdominal gunshot wounds known as “buckshot colic.”¹ Ureteral injuries are overwhelmingly penetrating and comprise 1% to 2.5% of urological trauma overall. The ureter is injured in 2% to 5% of abdominal gunshot wounds.² Several case reports discuss endoscopic management strategies for retained bullet fragments, but none to our knowledge describe the use of a holmium:YAG laser to dust bullet fragments via a retrograde approach. The addition of retrograde endoscopy to the treatment armamentarium for buckshot colic is important as this approach offers a safer alternative to percutaneous or open intervention on a potentially treacherous abdomen following ballistic injury.

Case Presentation

A 33-year-old otherwise healthy male presented to the emergency department after sustaining an accidental, self-inflicted gunshot wound to the abdomen while hunting. He was taken emergently to the operating room (OR) for an exploratory laparotomy and repair of multiple bowel injuries. On postoperative day 2, a computerized tomography (CT) urogram was done showing a retained bullet fragment adjacent to the left ureter with associated left ureteral extravasation of urine. The patient was taken back for double-J stent placement, abdominal washout and colostomy creation. His course was further complicated by an enlarging urinoma requiring retroperitoneal drain placement and a left percutaneous nephrostomy tube. He was discharged on hospital day 25, voiding volitionally, but with a left ureteral stent, percutaneous nephrostomy tube and retroperitoneal drain still in place. Both external drains were removed in clinic 1 month later and a subsequent CT urogram showed no extravasation of contrast from the left ureter with the stent still in place.

The patient then underwent a stent exchange and colostomy takedown with complex abdominal wall reconstruction 4 months later. A 2 cm left proximal ureteral stricture with a bullet fragment in close proximity to the ureter was noted during this stent exchange.

Given the patient’s reconstructed abdominal wall and his desire to return to work as soon as possible, endoscopic management of this ureteral stricture was performed. He was taken to the OR for laser incision of the stricture 8 months after the initial injury. On ureteroscopic inspection, a urinary calculus appeared to be embedded in the ureteral wall at the level of the stricture. This was dusted with a 200-micron holmium:YAG laser via flexible ureteroscopy, at which time the stone was found to be overlying the bullet fragment. The bullet was dusted to half its original size using standard laser settings for urinary calculi and basket extraction was attempted. This was unsuccessful due to impaction of the remaining fragment and a stent was placed. The reduction in size of the bullet can be seen in the prelithotripsy and postlithotripsy images (figs. 1 and 2).

Figure 1. Prelithotripsy retrograde pyelogram showing entire bullet fragment abutting ureter.

Figure 2. Retrograde pyelogram following holmium laser dusting showing reduction in size of bullet fragment.

One month later, percutaneous antegrade ureteroscopy was performed using a holmium:YAG laser and the remaining bullet was fragmented and completely removed (fig. 3). The stricture subsequently recurred, but the patient opted for 2 additional temporizing endoscopic interventions before consenting to a successful open retroperitoneal ureteral reconstruction with a buccal onlay graft 18 months after his initial presentation.

Figure 3. Endoscopic view of retained bullet fragment being lasered.

Discussion

Delayed presentation of ureteral obstruction from a retained ballistic fragment is a rare complication of abdominal gunshot wounds. The first case was described in 1947, and both military and civilian cases have been reported as late as 40 years after the penetrating injury.³ Bullet fragments are thought to be lodged in the collecting system at either the time of the original injury or in a delayed fashion via erosion. Given the ureteral injury on presentation, it is likely that our patient falls into the former category. Presentation of delayed ureteral obstruction is often consistent with renal colic from obstructing kidney stones, including flank pain and hematuria. Depending on the time from the ballistic injury, retained bullet fragments may not be in the initial differential diagnosis. Noncontrasted CT combined with diagnostic ureteroscopy is the ideal modality for diagnosis as neither ultrasound nor plain film radiography sufficiently detail ureteral anatomy, and CT alone can be limited by the scatter artifact from retained metal.

Previous management strategies have included spontaneous passage, open surgical extraction and antegrade endoscopic removal. Most bullets are composed of lead and lead alloys and the reluctance to laser bullet fragments was likely due to the perceived risk of further iatrogenic ureteral trauma.⁴ Bedke et al reported that steel could be successfully fragmented by a holmium laser at settings safe for use in humans, while copper could not.⁵ Given that lead is a soft metal compared to iron, the major component of steel, it is not surprising that Ziegelmann et al first reported the safe use of a holmium laser to fragment a bullet via a percutaneous approach.¹

Our report of holmium laser dusting and then subsequent fragmentation of a retained bullet is the first to include a retrograde approach. While our patient still required both retrograde and antegrade procedures, this was due to patient and injury-specific considerations. Given the safety and feasibility of retrograde dusting of a bullet fragment that we have demonstrated, we believe a pure retrograde approach would be a reasonable treatment strategy in cases when the bullet fragments are wholly within the ureteral lumen. Furthermore, as both percutaneous endoscopy and open surgery carry greater potential morbidity and mortality, especially in a population with potentially altered anatomy due to the index trauma, retrograde endoscopy should be the preferred initial approach.

Conclusion

Ballistic injury of the kidney or ureter can lead to retained bullet fragments in the collecting system via either direct penetration or erosion. These bullet fragments can cause obstructive uropathy requiring intervention. Holmium:YAG laser energy can effectively dust lead bullet fragments using settings standard for urinary calculi via a retrograde approach. In this population with altered anatomy and intraabdominal scarring from the index trauma, percutaneous antegrade ureteroscopy and open surgery can be reserved until after a trial of retrograde endoscopic management due to the increased morbidity and cost of those approaches.