Objectives: During the preoperative evaluation of potential kidney donors, the increased sensitivity of spiral computed tomography (CT) could detect more asymptomatic small (less than 4 mm) renal calculi. However, whether these stones will be of consequence later has yet to be determined. We evaluated the rate of spontaneous passage, development of symptoms, and change in the size of asymptomatic renal calculi in donor kidneys transplanted without removal of the calculi. Methods: Five donor kidneys from living donors were transplanted with small (less than 4 mm), asymptomatic renal calculi incidentally detected on CT (eight stones). No donors had any metabolic derangements or history of previous lithiasis. Each kidney was laparoscopically removed and transplanted with the calculi in situ. The recipients were followed up with serial creatinine measurements, history taking, and CT scans. Results: None of the recipients had had any symptoms consistent with the progression of disease, including hydronephrosis, renal failure, or the elevation of serum creatinine at a mean follow-up of 711 ± 334 days. The follow-up CT scans showed spontaneous passage of the stones in 3 patients. In the remaining 2 patients, two of the stones remained stable, and one had increased in size from 1 to 2 mm. Those with the stones remaining had had a significantly shorter length of follow-up (204 ± 72 versus 711 ± 200 days, P <0.05). Conclusions: In our series of 5 patients with small asymptomatic renal calculi, none of the patients have had complications, and only three of the eight stones were still in situ at the latest follow-up visit. Transplantation of small (less than 4 mm), asymptomatic stones in situ can be safely performed with adequate follow-up and monitoring for the development of obstructing transplant stones.
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