Penetrating trauma to the flank or buttocks may result in a number of serious retroperitoneal, intraperitoneal, or vascular injuries, many of which require operative repair. Further complicating the evaluation, the signs and symptoms may be subtle or delayed in retroperitoneal, diaphragmatic, bowel, or rectal injuries. The decision to pursue an operative versus conservative course is informed by the emergency evaluation and imaging.
ANATOMY AND PATHOPHYSIOLOGY
The flank is defined as the region between the anterior and posterior axillary lines, bordered superiorly by the sixth ribs and inferiorly by the iliac crests, containing retroperitoneal organs, soft tissue, ribs, and spine.1 Although a penetrating wound to the flank can produce intraperitoneal injury with the associated findings of peritonitis or hemoperitoneum, it is possible that a penetrating flank injury could injure only the retroperitoneal organs or musculoskeletal tissue, which can be difficult to ascertain from exam alone. The thoracic cavity, spine, intra-abdominal, and retroperitoneal organs are all at risk for injury from a penetrating flank wound depending on the depth, trajectory, velocity, and construct of the projectile. Bullet or missile wounds, especially high-velocity wounds, may cause damage from direct trauma, kinetic energy, or cavitation.2 Stab injuries are low velocity and cause injury through direct tissue damage.3
Perform a primary survey using the Advanced Trauma Life Support protocol. Obtain information about the mechanism of injury, how much time has passed since the event, and the nature of the weapon. For gunshot wounds, attempt to ascertain the type of gun, number of wounds, and patient distance from the weapon. Examining the location of wounds may assist in estimating the bullet path and structures at risk for injury; however, trajectory estimates can be unreliable as bullets can fragment or ricochet.4,5 For stab wounds, attempt to determine the size and trajectory of the weapon as well as the depth of penetration. Examine for abdominal tenderness and peritoneal signs that may indicate intraperitoneal injury along with signs of injury to the GI or GU tracts, such as gross blood on rectal exam, at the urethral meatus, or in the urine. Spinal tenderness or neurologic deficits mandate further evaluation of the spine (Figure 264-1). Wounds near the costal margin or superior flank should raise concern for possible thoracic or diaphragmatic injury.
Bone windows of abdominopelvic CT after a gunshot wound to the flank. Comminuted fracture of L3 with retained bullet fragments and hematoma in spinal canal are visible (arrows). The patient was paraplegic and also had a perinephric hematoma. [Photo contributed by Truman Medical Center-Hospital Hill, Kansas City, MO.]
Patients with penetrating flank trauma who do not require emergent laparotomy need further evaluation ...