Blunt renal trauma in the pediatric population: indications for radiographic evaluation.

OBJECTIVES: The purpose of this study was to define more clearly the clinical indications for radiographic evaluation of blunt renal injury in the pediatric population.
METHODS: Children evaluated for blunt abdominal trauma at the Children's Hospital of Los Angeles and Los Angeles County/University of Southern California Medical Center undergo routine physical examination, laboratory analysis, and computed tomography (CT) scan of the abdomen and pelvis regardless of urinalysis results. We retrospectively evaluated the abdominal and pelvic CT scans of 412 children sustaining blunt abdominal trauma between June 1985 and June 1990. A total of 48 children, ages 6 months to 14 years (mean 5.6 years), with CT-documented renal injuries secondary to blunt trauma were identified. The radiographic findings were correlated with clinical presentation in this group of patients.
RESULTS: Of the 48 children sustaining renal injuries (12% of the group), 23 (48%) had renal contusions and 25 children (52%) sustained more serious (significant) renal injuries. Of the children with significant renal injuries, 17 (68%) had minor renal lacerations and 8 (32%) had major renal lacerations. No child sustained a renal pedicle injury. All 25 children sustaining significant renal injuries presented with hematuria: 17 (68%) had microscopic (more than 3 red blood cells per high-power field) and 8 (32%) had gross hematuria. In the 23 children with renal contusions, 4 (17%) had no hematuria, 13 (57%) had microscopic hematuria, and 6 (26%) presented with gross hematuria. Hypotension occurred in 2 of the 25 children with significant renal injuries and in 2 of 23 children with renal contusions. Fifteen of the 25 patients (60%) with significant renal injuries had associated organ injuries, and 17 of the 23 children (74%) with renal contusions had associated organ injuries.
CONCLUSIONS: In adults, gross hematuria and microscopic hematuria with hypertension following blunt trauma have been correlated with significant renal injuries requiring radiographic investigation. We conclude that these clinical criteria proposed to guide the radiographic evaluation of the adult population with blunt trauma do not apply to children. In our study, the degree of hematuria did not correlate with the degree of renal injury, and significant renal injury did occur with microhematuria in the absence of hypotension. We suggest that any child with a history of blunt abdominal trauma and any evidence of hematuria should undergo abdominal and pelvic CT scanning for the proper diagnosis and staging of renal and other associated intra-abdominal injuries.