Blunt renal trauma in children with previously undiagnosed pre-existing renal lesions and guidelines for effective initial management of kidney injury.

Objectives: To record pre-existing renal lesions (PERL) found incidentally during evaluation for blunt renal trauma in children, determine their importance, suggest guidelines for the effective initial management of children with significant renal trauma and to evaluate the role of temporary percutaneous nephrostomy tube drainage (TPND) in these patients.

Patients And Methods: We reviewed 338 children who were hospitalized with blunt abdominal trauma between 1992 and 2000. Thirty-one patients had significant renal injury, 17 before 1997 (reviewed retrospectively) and the others reviewed and followed prospectively.

Results: Eleven of the 31 children had a PERL, which had been undiagnosed before the injury. The mean (range) follow-up was 52 (15-104) months. There were 22 boys and nine girls (mean age 9.1 years, range 2-13). The mean age was lower in patients with a PERL than in children with isolated renal injury. The most common cause of blunt renal injuries was a fall (45%) followed by motor vehicle accidents. Renal stones were present in five children, pelvi-ureteric junction obstruction in four, megaureter in one and a renal cyst in one. The mean injury severity scores were 12 in the children with a PERL and 14 in patients without. TPND was used in seven (22%) children; four were associated with a PERL. The mean grade of injury score for the kidney was higher in patients with a PERL and in children who underwent TPND than in patients who previously had a normal kidney and in children who did not undergo TPND. Early surgical intervention was required in three children; all were associated with a PERL. Of the 13 children who underwent surgery 11 had previous disease.

Conclusions: The frequency of PERL is high (36%) in children with blunt renal trauma. PERL can predispose minor trauma to cause kidney injury even with no evidence of hydronephrosis. When a minor trauma results in renal injury, it is important to seek a PERL. In selected patients, TPND may decrease the length of hospital stay and improve the outcome of the injured kidney, thereby decreasing the need for further surgery in those with isolated renal injury; however, it appears not to decrease the need for later operations in children with a PERL.