Citric acid (solution R) irrigation in the treatment of refractory infection (struvite) stone disease: is it useful?

Objective: Citric acid, in varying concentrations, has been used in the dissolution treatment of struvite renal calculi. Solution R (Uro-trainer), which contains 6% citric acid, is a solution licensed for use in the management of struvite stone disease in the UK. We report our experience.
Methods: 23 kidneys in 22 patients (10 male and 12 female patients, mean age 45, range 15-60 years) underwent solution R irrigation following debulking of the stone with percutaneous nephrolithotomy (n = 20), ureteroscopy and shock wave lithotripsy (n = 2) combined with open procedures (n = 4) between 1994 and 1998. The original stone configuration consisted of 14 staghorn, 4 partial staghorn and 5 large burden stones. Irrigation was performed through a nephrostomy tube (n = 20) or in a retrograde fashion (n = 3) using a closed infusion pump system (40 ml/h). The response to treatment was checked using a nephrostogram and/or plain X-ray.
Results: In 6 (26%) kidneys, after an average duration of 2 (1-5) days, irrigation had to be abandoned due to loin pain, leak or sepsis. The average duration of irrigation was 6.4 (1-20) days. At the end of irrigation, a total of 4 (17.4%) kidneys had complete radiographic clearance, while the stone was reduced to calyceal dust in 3 (13%). Partial response was seen in 11 (47.8%) and no response in 5 (21.8%) kidneys. Following additional alternative intervention(s) in 6 (26%) kidneys (4 with partial and 2 with no response) further clearance was achieved in 3 (13%) and calyceal dust status in 3 (13%). The response was better if the stone was reduced to less than 10mm prior to irrigation. At the mean follow-up of 2.44 (1-4) years, of 13 kidneys with stone clearance or calyceal dust, 9 suffered recurrence or re-growth, 5 of which required further interventions. Only 4 (17.4%) of 23 kidneys remained stone free.
Conclusions: In patients with complex stone disease, adjuvant solution R irrigation can reduce the stone burden. There is a considerable potential for side effects necessitating close monitoring for sepsis and electrolyte abnormalities. However, the overall success rate for solution R is limited.