Management of Hemodynamically Stable Gunshot Wound with Bullet in Psoas Muscle
Proceed immediately to CT abdomen and pelvis with IV contrast to characterize the full extent of injury, identify any occult vascular or hollow viscus injuries along the bullet trajectory, and determine whether operative, angiographic, or non-operative management is appropriate. 1
Rationale for CT with IV Contrast as Next Step
The American College of Radiology recommends CT chest, abdomen, and pelvis with IV contrast as the standard imaging for hemodynamically stable patients with ballistic trauma of uncertain trajectory, providing up to 99% negative predictive value for triaging and enabling precise identification of organ injuries, vascular injuries, and the complete missile trajectory 1, 2
Single-acquisition whole-torso imaging is preferred over segmental imaging so that the complete bullet tract can be followed through all tissue planes, as the projectile path may traverse multiple compartments beyond the visible entry wound 1, 2
Contrast enhancement is critical because it accurately characterizes solid organ injuries (liver, spleen, kidney), detects active arterial extravasation (which appears as 85-370 HU compared to 40-70 HU for clotted blood), identifies pseudoaneurysms requiring angioembolization, and reveals hollow viscus injuries that mandate surgical exploration 3, 4
Why the Psoas Location Demands Comprehensive Imaging
A bullet lodged in the psoas muscle indicates a retroperitoneal trajectory that may have injured the kidney, ureter, major retroperitoneal vessels (aorta, IVC, iliac vessels), lumbar plexus, or traversed the peritoneal cavity to injure intra-abdominal organs before coming to rest in the psoas 5, 6
The blast effect from gunshot wounds extends approximately 2 cm from the bullet path, meaning structures adjacent to the psoas (including the colon, small bowel, kidney, and major vessels) may be injured even without direct contact 2
CT with delayed excretory phase may be required for follow-up if ureteral or bladder injury is suspected based on the trajectory, as these injuries are frequently associated with retroperitoneal gunshot wounds 2
Clinical Algorithm Based on CT Findings
If CT shows active arterial extravasation:
- Proceed to angiography with embolization rather than immediate surgery, as this is the most effective method for controlling ongoing arterial bleeding in hemodynamically stable patients 1, 7
If CT shows solid organ injury without active bleeding:
- Non-operative management with serial clinical examinations and repeat imaging as needed 3
If CT shows hollow viscus injury, peritoneal violation with free air, or signs of peritonitis:
- Immediate surgical exploration is required 3
If CT shows venous bleeding only:
- Supportive care with transfusion and serial monitoring may be appropriate 1
If CT is entirely negative:
- Admission for serial clinical examinations is still recommended, as CT misses bowel injury in 20% of cases initially, particularly injuries that develop over 12-24 hours 2
Critical Caveats and Pitfalls
If the patient becomes hemodynamically unstable at any point (systolic BP <90 mmHg, heart rate >110 bpm), immediately abort imaging and proceed directly to the operating room 3, 2
"Mild tenderness" does not exclude significant injury in penetrating trauma, as the peritoneal irritation from hollow viscus perforation may take hours to develop, and retroperitoneal injuries often present with minimal initial abdominal findings 5, 6
Place radiopaque markers at all entry and exit wounds before CT to aid in trajectory analysis and ensure no additional wounds are missed 1, 2
Multiphasic imaging (arterial and venous phases) provides additional information about the source of active bleeding and helps differentiate arterial from venous hemorrhage, which has direct treatment implications 1
Do not perform noncontrast CT alone, as it is inadequate for evaluating vascular injuries and significantly limits the ability to characterize solid organ damage 2