Excerpt from Renal Calculi

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Background

Acute passage of a kidney stone from the renal pelvis through the ureter gives rise to pain at times so excruciating that it has been likened to the discomfort of childbirth. The often sudden, extremely painful episode of renal colic prompts more than 450,000 visits to EDs annually and places emergency physicians on the front line of management of acute nephrolithiasis. ED management is focused on excluding other serious diagnoses and providing adequate pain relief.

Pathophysiology

Most calculi arise in the kidney when urine becomes supersaturated with a salt that is capable of forming solid crystals. Symptoms arise as these calculi become impacted within the ureter as they pass toward the urinary bladder.

Frequency

United States

The lifetime prevalence of nephrolithiasis is approximately 12% for men and 7% for women in the United States. Recurrence rates after the first stone episode are 14%, 35%, and 52% at 1, 5, and 10 years, respectively. An increased incidence has been noted in the southeastern United States, prompting the term "stone belt" for this region of the country.

International

Incidence is lower in nonindustrialized countries.

Mortality/Morbidity

• Approximately 80-85% of stones pass spontaneously.
• Approximately 20% of patients require hospital admission because of unrelenting pain, inability to retain enteral fluids, proximal urinary tract infection (UTI), or inability to pass the stone.
• A ureteral stone associated with obstruction and upper UTI is a true urologic emergency. Complications include perinephric abscess, urosepsis, and death. Immediate involvement of the urologist is essential.

Race

• White males are affected 3-4 times more often than African American males.
• African Americans have a higher incidence of infected ureteral calculi than whites.

Sex

• The male-to-female ratio is approximately 3:1.
• Female patients have a higher incidence of infected hydronephrosis.

Age

Peak onset of symptomatic nephrolithiasis is in the third and fourth decades of life.

• Beware of the patient older than 60 years with an apparent first kidney stone. Consider the possibility of symptomatic abdominal aortic aneurysm (AAA) in the older patient, and rule out this possibility before pursuing the diagnosis of nephrolithiasis. Use bedside ultrasonography if the patient's condition is potentially unstable. CT scan is a reasonable alternative in the patient in stable condition.
• Nephrolithiasis in children is rare; approximately 5-10 children aged 10 months to 16 years are seen annually for the condition at a typical US pediatric referral center.

Please click here to view the full topic text: Renal Calculi