The disadvantages of standard percutaneous nephrolithotomy (PCNL) as compared with ureteroscopy or extracorporeal shock-wave lithotripsy include increased blood loss, greater pain, and longer hospital stay. A 13-Fr "mini-perc" technique using a ureteroscopy sheath for PCNL was developed in an attempt to address these drawbacks. Nine "mini-percs" have been performed in patients aged 40-73 years with stone burdens of < or = 2 cm2. On average, patients had 1.4 stones with a cross-sectional area of 1.5 cm2. The mean total procedure time, estimated blood loss, and hematocrit decrease were 176 min, 83 ml, and 6.6%, respectively. On average, patients used 14 mg of parenteral morphine and stayed 1.7 days in the hospital. There was no procedure-related complication or transfusion. Eight of nine kidneys (89%) were stone-free on early follow-up at a mean of 3.8 weeks. As compared with standard PCNL, the "mini-perc" technique has similar early success rates in selected patients and may offer advantages with respect to hemorrhage, postoperative pain, and shortened hospital stays.

No abstract

Kidney stones have been associated with use of the ketogenic diet in children with refractory seizure disorders. We performed a case-control study examining risk factors for the development of stones on the ketogenic diet, and prospectively followed children initiating the ketogenic diet to evaluate the incidence of urolithiasis. Clinical characteristics of 18 children presenting with stones (8 uric acid stones, 6 mixed calcium/uric acid stones, 1 calcium oxalate/phosphate stone, 3 stones not evaluated) were compared with characteristics of non-stone-forming children initiating the ketogenic diet at Johns Hopkins since July 1996. Since July 1996, 112 children initiating the ketogenic diet have been followed for development of stones. Follow-up times on the diet range from 2 months to 2.5 years. Of 112 children, 6 have developed stones (3 uric acid, 3 mixed calcium/uric acid stones) (0.8 children developing stones/ 100 patient-months at risk). Comparisons of children presenting with stones on the ketogenic diet with characteristics of the entire cohort initiating the ketogenic diet suggest younger age at diet initiation and hypercalciuria are risk factors for the development of stones. Prospective evaluation of children initiating the ketogenic diet revealed that almost 40% of patients had elevated fasting urine calcium: creatinine ratios at baseline; this increased to 75% after 6 months on the diet. Median urine pH was 5.5 at diet initiation, and remained at 6.0 thereafter. In a subset of patients tested, urinary citrate excretion fell from a mean of 252 mg/24 h pre diet initiation to 52 mg/24 h while on the diet. Uric acid excretion remained normal. Patients maintained on the ketogenic diet often have evidence of hypercalciuria, acid urine, and low urinary citrate excretion. In conjunction with low fluid intake, these patients are at high risk for both uric acid and calcium stone formation.

The significant failure rate for proximal testes suggests that efforts to improve orchiopexy should continue.