A stone formed in the urinary tract, but usually found in the renal pelvis and/or kidney calyces. These vary in composition but may contain urates, calcium, oxalate, calcium carbonate, phosphates, and cystine.
See: calculus, renal; lithotriptor

SYMPTOMS
Predisposing factors include dehydration, infection, obstruction, and metabolic factors. In the U.S., urinary stones develop in 2% to 10% of people, more often in southeastern states than in other parts of the country. Males have a 3 times higher rate than females, especially between ages 30 and 40. Struvite calculi, which account for about 15% of all stones, are found primarily in females, usually related to urinary tract infections. Pain related to obstruction is the primary symptom. Classic renal colic travels from the costovertebral angle to the suprapubic region and external genitalia. Its intensity fluctuates, but is excruciating at its peak. Nausea and vomiting usually accompany the most severe pain. Diagnosis is based on the clinical picture plus CT scan or MRI, excretory urography, KUB X-rays, and stone analysis.

PATIENT CARE
The patient is encouraged to verbalize anxieties and concerns regarding severe pain. Pain relief measures are instituted as prescribed; they include analgesics, antispasmodics, and warm, moist heat. All urine is strained for stones, and any calculus is sent for laboratory analysis. Vigorous hydration with oral or intravenous fluids assist in passage of small stones (90% are smaller than 5 mm in diameter). If a lithotriptor is to be used to shatter the calculus for removal by suction or natural passage, the duration of the procedure and follow-up care are explained. Procedures for surgical removal depend on the location of the calculus, and include cystoscopy with ureteral manipulation, or a flank or lower abdominal laparoscopic or open approach. All diagnostic studies are explained and the patient is encouraged to verbalize fears and concerns. Urine is observed for hematuria, and specimens are tested for specific gravity and pH. Vital signs are monitored; if temperature is elevated, antipyretic measures are instituted as ordered, and antibiotics specific to cultured organisms are prescribed. Fluids are forced (PO/IV) to enhance dilution of urine, and intake and output are monitored. Fruit juices, specifically cranberry juice or cranberry tablets, help to acidify urine. The health care professional stays alert for complications such as infection, stasis, and retention. A catheter is inserted as ordered. Dietary management is based on the composition of the stone. If phosphate stones are present, patients should increase their intake of acid-ash foods such as cereals, eggs, meat, and cranberry and grape juices. Persons prone to uric acid stones should consume an alkaline-ash diet of green vegetables and fruits and avoid foods high in purine. To minimize urinary tract infections, esp. for female patients, the patient is taught proper perineal hygiene, and the need for increased fluid intake is emphasized.

Postsurgery, the patient usually has an indwelling catheter or a nephrostomy tube in place. Bloody drainage is expected, and this tube should never be irrigated without a specific physician order. If the kidney was removed, the patient should be reassured that the body can adapt well to one kidney. Pulmonary hygiene using an inspirometer is stressed in the presence of flank or abdominal incisions. Dressings are assessed for drainage, and changed per protocol, and signs of hemorrhage or infection reported promptly.