Urolithiasis in the exstrophy-epispadias complex

Purpose: We sought to determine the incidence of urolithiasis in patients with the exstrophy-epispadias complex, associated risk factors and guidelines for the proper clinical management of this problem. Materials and Methods: We retrospectively reviewed the chart and x-rays of 530 patients with the exstrophy-epispadias complex treated at our institution. Results: Stones formed in 77 of the 530 patients (15%), including 16% of those with classic exstrophy, 25% of those with cloacal exstrophy and 3% of those with epispadias. White and male individuals were most commonly affected. Most calculi formed in the bladder, whether native or augmented by enterocystoplasty. Standard techniques were successful for stone removal. Most calculi consisted of calcium apatite, calcium oxalate monohydrate or magnesium ammonium phosphate, usually in combination with at least I other element. The risk of stone formation was associated with augmentation cystoplasty (p <0.001) and a bladder neck procedure to increase outlet resistance (p <0.001). Other risk factors included urinary tract infection, foreign bodies, vesicoureteral reflux and urinary stasis but not acidosis or immobilization. Stones recurred in 30 patients (39%), including equal numbers of those treated with open and closed techniques, and recurrence was associated with urinary tract infection or struvite composition (p <0.05). Serum calcium abnormalities were not present in any patient, including those with metabolic acidosis or prolonged immobilization. Urinary chemistry studies were incomplete or unavailable. Conclusions: These data suggest that urolithiasis in the exstrophy-epispadias complex is related to risk factors associated with surgical reconstruction of this condition. The role of metabolic abnormalities that may predispose to urolithiasis is unknown but under investigation. Standard treatment is effective but stone recurrence remains a significant problem. Urine chemistry data may provide information to help minimize stone development in this patient population.