Radiographic and clinical predictors of bladder rupture in blunt trauma patients with pelvic fracture

RATIONALE AND OBJECTIVES: Bladder rupture is a potentially serious injury in blunt trauma patients. We determined whether location and displacement of pelvic fractures and the degree of hematuria can accurately predict bladder injury. MATERIALS AND METHODS: A retrospective database of 721 blunt trauma pelvic fractures that presented to a single large regional level 1 trauma center between January 1, 1997, and July 15, 2003, was expanded to include data on bladder injury and the initial urinalysis. Multiple logistic regression was performed to determine if an association exists between pelvic fracture pattern, degree of hematuria, and bladder injury. A potential clinical prediction rule was then derived using a point system for four independent, significant risk factors identified from the logistic regression results. RESULTS: There were 37 bladder ruptures (5.0%), all of which presented with hematuria >30 red blood cells per high-powered field (RBC/HPF). Pelvic injuries that were independently associated with bladder injury included diastasis of the pubic symphysis >1 cm, RR = 9.8 (95% CI 4.6-20.9), and fracture of the obturator ring with displacement >1 cm RR = 3.2 (95% CI 1.6-6.5). No patient with isolated acetabular fractures sustained bladder injury. A clinical prediction rule was derived, consisting of a single point for each of the significant pelvic injury sites in patients with hematuria >30 RBC/HPF. Patients with a prediction score of 0 had a 2.3% probability of bladder injury, whereas patients with scores of 1 and 2 had probabilities of bladder injury of 9.2% and 43.7%, respectively. CONCLUSIONS: Patients with isolated acetabular fractures and patients with <30 RBC/HPF did not sustain bladder injury. In addition to hematuria, specific pelvic injury patterns are associated with bladder rupture. If validated, a clinical prediction rule derived from this data has the potential to guide the care of the blunt trauma patient.