genitourinary disorders
Urinary Calculi
Diagnosis of Urinary Calculi
Clinical differential diagnosis Urinalysis Imaging Determination of calculus composition The symptoms and signs may suggest other diagnoses, such as (eg, due to Appendicitis , Acute Cholecystitis : Intestinal Obstruction : Overview of Pancreatitis : With most of these disorders, urinary symptoms are uncommon and other symptoms may suggest which organ system is actually involved (eg, vaginal discharge or bleeding in pelvic disorders among females). Dissecting aortic aneurysm must be considered, particularly in older patients, because, if a renal artery is affected, it can cause hematuria, pain that radiates along a ureteral distribution, or both. Other considerations in the general evaluation of acute abdominal pain are discussed elsewhere (see Evaluation ). Because giving high volumes of fluid does not speed stone passage, normal volumes of IV or oral hydration should be used. Patients suspected of having a calculus causing colic require urinalysis and usually an imaging study. If a calculus is confirmed, evaluation of the underlying disorder, including calculus composition testing, is required. Macroscopic or microscopic hematuria is common, but urine may be normal despite having multiple calculi. Pyuria with or without bacteria may be present. Pyuria suggests infection, particularly if combined with suggestive clinical findings, such as foul-smelling urine or a fever. A calculus and various crystalline substances may be present in the sediment. If so, further testing via 24-hour urine collections is usually necessary to identify the cause because the composition of the calculus and crystals cannot be determined conclusively by microscopy. The only exception is when typical hexagonal crystals of cystine are found in a concentrated, acidified specimen, confirming cystinuria. Noncontrast helical CT is the most common initial imaging study. This study can detect the location of a calculus as well as the degree of obstruction. Moreover, helical CT may also reveal other causes of the pain (eg, Overview of Aortic Aneurysms ). For patients who have recurrent calculi, cumulative radiation exposure from multiple CT scans is a concern. However, the routine use of low-dose renal CT can meaningfully reduce cumulative radiation dose with little loss of sensitivity ( Although most urinary calculi are demonstrable on plain x-ray, neither their presence nor their absence obviates the need for more definitive imaging, so this study can be avoided except in some patients with suspected recurrent calculi. Both renal Ultrasonography and The calculus is obtained by straining the urine (or, if necessary, during operative removal) and sent to the laboratory for stone analysis. Some calculi are brought in by patients. Urine specimens that show microscopic crystals are sent for crystallography. In patients with a single calcium calculus and no additional risk factors for calculi, evaluation to exclude Hyperparathyroidism is sufficient. Evaluation entails urinalysis and determination of plasma calcium concentration on 2 separate occasions. Predisposing factors, such as recurrent calculi, a diet high in animal protein, or use of vitamin C or D supplements, should be sought. Patients with a strong family history of calculi, conditions that might predispose to calculi formation (eg, Sarcoidosis , bone metastases, 1.Zilberman DE, Tsivian M, Lipkin ME, et al: Low dose computerized tomography for detection of urolithiasis—its effectiveness in the setting of the urology clinic.J Urol185(3):910-914, 2011. doi: 10.1016/j.juro.2010.10.052 2.Pearle MS, Goldfarb DS, Assimos DG, et al: Medical management of kidney stones—AUA guideline. doi: 10.1016/j.juro.2014.05.006J Urology92(2):316-24, 2014. doi: 10.1016/j.juro.2014.05.006 