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 uppe r tract struvite calculi, often associated with spinal cord injury (SCT), a s such patients have a high incidence of urinary infection complicating the ir neurogenic voiding dysfunction, by reviewing a large population of patie nts with SCI in whom modem techniques of bladder management were used. Patients and methods Between 1982 and 1996, 1669 patients with SCI were adm itted to our institution; 1359 of these patients sustained their injuries d uring the study period. During this time, their bladder management was base d on urodynamic and imaging criteria, using techniques such as early interm ittent catheterization, sphincterotomy and bladder augmentation where possi ble to create a catheter-free, low-pressure reservoir. All instances of upp er tract struvite calculi in this population were documented. Risk factors for stone development, presentation and complications, management and recur rence rates were assessed. Results Over the 15 years, 58 patients (3.5% of the SCI population) were tr eated for a total of 144 episodes of struvite calculi. The incidence of sto nes in those injured since 1982 was 1.5%; 67% of these patients had complet e spinal card lesions, 54% had lesions of the cervical cord and 53% develop ed their first stone > 10 years after injury. Only 22% presented within 2 y ears of injury. The group of patients developing stones had a significantly higher incidence of indwelling catheters (49%), bladder stones (52%) and v esicoureteric reflux (28%) than those who were stone-free. The development of recurrent urinary tract infections was the most common mode of presentat ion. The st-one-free rate after treatment was 87%. Normal renal function wa s preserved in 72% of patients. Conclusions In a large population of patients with SCI managed using contem porary bladder techniques the incidence of upper tract calculi was 3.5%; 30 % of these stones were complete or partial staghorns. Those patients with c omplete cord lesions, permanent indwelling catheters and vesico-ureteric re flux were at the highest risk. Stone clearance was 87% and recurrent stones occurred in 69% of patients. Struvite renal calculi continue to be a signi ficant problem in the spinal cord injury population.