The impact of contemporary bladder management techniques on struvite calculi associated with spinal cord injury.

OBJECTIVE: To evaluate the incidence, risk factors and complications of upper tract struvite calculi, often associated with spinal cord injury (SCI), as such patients have a high incidence of urinary infection complicating their neurogenic voiding dysfunction, by reviewing a large population of patients with SCI in whom modern techniques of bladder management were used. PATIENTS AND METHODS: Between 1982 and 1996, 1669 patients with SCI were admitted to our institution; 1359 of these patients sustained their injuries during the study period. During this time, their bladder management was based on urodynamic and imaging criteria, using techniques such as early intermittent catheterization, sphincterotomy and bladder augmentation where possible to create a catheter-free, low-pressure reservoir. All instances of upper tract struvite calculi in this population were documented. Risk factors for stone development, presentation and complications, management and recurrence rates were assessed. RESULTS: Over the 15 years, 58 patients (3.5% of the SCI population) were treated for a total of 144 episodes of struvite calculi. The incidence of stones in those injured since 1982 was 1. 5%; 67% of these patients had complete spinal cord lesions, 54% had lesions of the cervical cord and 53% developed their first stone >10 years after injury. Only 22% presented within 2 years of injury. The group of patients developing stones had a significantly higher incidence of indwelling catheters (49%), bladder stones (52%) and vesico-ureteric reflux (28%) than those who were stone-free. The development of recurrent urinary tract infections was the most common mode of presentation. The stone-free rate after treatment was 87%. Normal renal function was preserved in 72% of patients. CONCLUSIONS: In a large population of patients with SCI managed using contemporary bladder techniques the incidence of upper tract calculi was 3.5%; 30% of these stones were complete or partial staghorns. Those patients with complete cord lesions, permanent indwelling catheters and vesico-ureteric reflux were at the highest risk. Stone clearance was 87% and recurrent stones occurred in 69% of patients. Struvite renal calculi continue to be a significant problem in the spinal cord injury population.