Laboratory Studies
The usual surgical profile includes the following:
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Complete blood cell (CBC) count
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Blood type
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Activated partial thromboplastin time and prothrombin time
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Electrolytes
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Blood urea nitrogen
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Creatinine
In addition, perform a urinalysis (with culture and sensitivity).
Imaging Studies
Confirmation is usually based on radiologic findings from the following studies:
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A radiograph of the kidneys, ureters, and bladder (KUB): Ninety percent of stones are radiopaque.
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A CT scan provides information to quantify stone mass. This also shows uric acid stones, which are radiolucent. It also assists in outlining renal pelvic anatomy anthe presence location of the stone within the collecting system. It also helps with identification of vascular anatomy. It is critical prior to performing a pyelolithotomy.
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An intravenous pyelogram (IVP) provides information on collecting system anatomy, demonstrating filling defects where stone burden is located. This also shows uric acid stones. See the image below.
Intravenous pyelogram demonstrating ureteropelvic junction obstruction with dilatation of the collecting system and lack of excretion of contrast.
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Cystoscopy and a retrograde pyelogram offer similar information as IVP and are performed when patients have renal failure, usually with a creatinine level of more than 1.8 g/24 h. See the image below.
Retrograde pyelogram demonstrating ureteropelvic junction obstruction secondary to annular stricture.
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Renal scintigraphy should be considered in patients with a large stone burden and long-standing obstruction. The kidney function in this clinical scenario can be extremely poor, and, if confirmed on functional study, a nephrectomy may be more appropriate.
Perform a renal scan to confirm function of the kidney in question if renal atrophy is noted.
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Intravenous pyelogram demonstrating ureteropelvic junction obstruction with dilatation of the collecting system and lack of excretion of contrast.
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Retrograde pyelogram demonstrating ureteropelvic junction obstruction secondary to annular stricture.
