Stone clearance from the lower pole following shock wave lithotripsy is poor, especially for stones greater than 10 mm. in diameter. Calculi greater than 10 mm. in diameter are better managed initially with percutaneous removal due to its high degree of efficacy and acceptably low morbidity.

The new england journal of medicine n engl j med 350;7 www.nejm.org february 12, 2004 684 This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the author's clinical recommendations.A 39-year-old man reports an eight-hour history of colicky pain in the right lower quadrant radiating to the tip of his penis. He had previously had a kidney stone, which passed spontaneously. Physical examination shows that he is in distress, is afebrile, and has tenderness of the right costovertebral angle and lower quadrant. Urinalysis shows microhematuria. Helical computed tomography (CT) of the abdomen and pelvis shows a 6-mm calculus of the right distal ureter and mild hydroureteronephrosis. How should this patient be treated?Up to 12 percent of the population will have a urinary stone during their lifetime, and recurrence rates approach 50 percent. 1 In the United States, white men have the highest incidence of stones, followed in order by white women, black women, and black men. 2,3 Fifty-five percent of those with recurrent stones have a family history of urolithiasis, 4 and having such a history increases the risk of stones by a factor of three. 5The classic presentation of a renal stone is acute, colicky flank pain radiating to the groin. As the stone descends in the ureter, the pain may localize in the abdominal area overlying the stone and radiate to the gonad. Peritoneal signs are absent. As the stone approaches the ureterovesical junction (Fig. 1), lower-quadrant pain radiating to the tip of the urethra, urinary urgency and frequency, and dysuria are characteristic, mimicking the symptoms of bacterial cystitis. Physical examination typically shows a patient who is often writhing in distress, trying to find a comfortable position. Tenderness of the costovertebral angle or lower quadrant may be present. Gross or microscopic hematuria occurs in approximately 90 percent of patients; however, the absence of hematuria does not preclude the presence of stones. 6 Owing to the shared splanchnic innervation of the renal capsule and intestines, hydronephrosis and distention of the renal capsule may produce nausea and vomiting. Thus, acute renal colic may mimic acute abdominal or pelvic conditions. diagnosisThe best imaging study to confirm the diagnosis of a urinary stone in a patient with acute flank pain is unenhanced, helical CT of the abdomen and pelvis (Fig. 1). 7 In a prospective trial of 106 adults with acute flank pain, all patients underwent both unenhanced helical CT and intravenous urography (the previous gold standard), 8 and the results of each were interpreted separately and in a blinded fashion by a radiologist. Seventy-five patients received a diagnosis of ureteral stones. The sensitivity of CT was 96 percent, as compared with 87 percent for urography, and the respective specificities were 100 percent and 94 percent (P<0.001 for both compar...

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MethodologyThe following guidelines were based on MEDLINE and PUBMED searches of English language literature, in addition to consensus conference proceedings. Levels of evidence and grades of recommendation were assigned for each investigation and treatment, as per the modified Oxford Centre for Evidence-Based Medicine grading system. Where the literature was inconsistent or scarce, a consensus expert opinion was generated to provide treatment guidelines.

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