Renal Medicine and Genitourinary Trauma in the Athlete

Definition (Classifications)

Table 19.1 summarizes the classification of kidney trauma injuries according to severity. This classification correlates with the need for surgical intervention.

Epidemiology

Of all the GU organs, the external genitalia (penis, scrotum, and vulva) are most likely to be injured. Of the internal GU organs, the kidneys are the most likely to be injured after a patient experiences abdominal trauma.

Overall, the most common sport causing abdominal injury is cycling. Football, rugby, gymnastics, horseback riding, wrestling, martial arts, and hockey are a few of the sports that include activities capable of causing significant abdominal and consequent GU organ injury; the use of exercise equipment can do so as well.

The overall incidence of renal injury as a result of trauma ranges from 1.4% to 3.25%. Sports-related trauma to the kidney is uncommon and is reported to constitute only 15% to 20% of all traumatic renal injuries. Most cases of renal trauma are the result of blunt trauma specifically relating to motor vehicle accidents and falls. Kidney injuries are particularly common when a person is subjected to rapid deceleration forces. One analysis shows that of the 23,666 sports-related injuries among high school–age varsity athletes, only 18 kidney injuries were reported, none of which was serious. In an analysis of more than 653,000 trauma cases from the National Trauma Data Bank, 16,585 were identified as trauma from bicycle injuries. Only 2% of the patients in these cases experienced a GU tract injury, with the kidneys being the organ most likely affected (in 75% of cases), followed by the bladder and urethra (in 15% of cases) and the penis and scrotum (in 10% of cases). Sixty percent of the patients with GU injuries had evidence of concomitant fractures of the spine or pelvis, suggesting that isolated GU trauma is uncommon. Compared with renal injuries, testicular injuries in sports occur at a much lower rate. A review of a trauma registry of all cases of renal and testes injuries (1.4% of all injuries) showed that 92% involved the kidneys and 8% the testes. It is estimated that more than half of injuries to the testes occur during sporting events.

Pathobiology/Pathophysiology

The kidneys are located in the retroperitoneal space and are surrounded by visceral fat and the Gerota fascia. The kidneys lie on either side of the spinal column in front of the psoas muscle and medial to the quadratus lumborum muscle. The hepatic flexure of the colon on the right and the spleen and the splenic flexure on the left cover the kidneys anteriorly. Because the kidneys are protected by surrounding structures, traumatic kidney injuries during sporting activities occur mainly in association with major forces and are usually associated with injury to other organs.

Injuries to the renal parenchyma constitute the vast majority of cases. Preexisting renal abnormalities such as hydronephrosis, renal cysts, or an abnormal renal anatomic position increase the likelihood of renal injury during trauma and are reported in 4% to 19% of adults and 12% to 35% of children. ^5,10-–12 These subjects have more severe symptoms and are more likely to require surgical intervention. Vascular injuries of the kidneys occur during deceleration forces and result from damage to the renal pedicle. These cases may present with thrombosis or rupture of the vasculature.

Bladder injuries also occur as a consequence of blunt force trauma to the abdomen. The bladder's anatomic location deep in the anterior bony pelvis makes it less frequently injured by trauma. However, the weakest part of the bladder is the dome, which is mobile and susceptible to injury when the bladder is full.

The testes are particularly vulnerable to trauma because of their external location and lack of anatomic protection when blunt trauma forces the scrotum against the pelvic bone. Testicular rupture, scrotal wall hematoma, or intrascrotal hematocele are possible.

Diagnosis

Obtaining a thorough history is imperative. The initial evaluation of patients should include attention to vital signs recorded on the field and upon arrival at the hospital. The lowest recorded systolic blood pressure may indicate the need for radiologic assessment of subjects for a kidney injury. Careful examination of the abdomen, chest, and back is critical. Patients with evidence of abdominal or flank tenderness or hematoma, rib fractures, and penetrating injuries to the low thorax or flank may have sustained an injury to the kidney and require further assessment. Pelvic fractures in trauma may alert the physician to the potential of bladder injury. Increasing abdominal girth with “ascites” without hemodynamic instability and without a drop in hemoglobin levels should be cause for suspicion, as the diagnosis can be delayed. Persons with a testicular injury usually present with swelling, tenderness, and ecchymosis. Rupture of the testis is associated with immediate severe pain.