Nephrolithiasis Differential Diagnoses

Updated: Dec 03, 2016
  • Author: Chirag Dave, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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DDx

Diagnostic Considerations

Moore and colleagues derived and validated an objective clinical prediction rule for uncomplicated ureteral stones that uses five patient factors—sex, timing, origin (ie, race), nausea, and erythrocytes (STONE)—to create a score between 0 and 13 (the STONE score). Patients with a high STONE score are very likely to have a kidney stone and very unlikely to have an important disorder other than a kidney stone as a cause of their symptoms, and thus may be able to avoid a computed tomography (CT) scan or be evaluated with a reduced-dose scan. [13]

The following factors were most predictive of ureteral stones:

  • Male sex
  • Short duration of pain
  • Non-black race
  • Presence of nausea or vomiting
  • Microscopic hematuria

In the validation cohort, probability by STONE score and percentage of patients found to have ureteral stones were as follows [13] :

  • Low probability (STONE score 0-5): 9.2% of patients
  • Moderate probability (score 6-9): 51.3% of patients
  • High probability (score 10-13): 88.6% of patients

CT scans revealed acutely important alternative causes of symptoms on CT scan in 2.9% and 3.7% of the derivation and validation cohorts overall. In the high score group, however, only 0.3% of the derivation cohort and 1.6% of the validation cohort had acutely important alternative findings. [13]

The diagnosis of stone is often made on the basis of clinical symptoms alone, although confirmatory tests are usually performed. At this point, the goals and opinions of physicians in different specialties diverge.

From the point of view of the emergency department (ED) physician, making the diagnosis of a renal or ureteral stone and excluding appendicitis or abdominal aortic aneurysm (AAA) is sufficient. A urologist, who must ultimately make the decision about possible surgery, may require additional information. Before such a decision can be made, a urologist must know about the size, orientation, radiolucency, composition, and location of the stone and must know about overall kidney function, the presence of any infection, and other clinical information.

Beware of the patient older than 60 years with an apparent first kidney stone. Consider the possibility of symptomatic 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 stable patient.

Failure to diagnose or delay in diagnosing symptomatic AAA may lead to medicolegal liability. The pain of a leaking AAA often is misdiagnosed initially as renal colic. In one series of 134 patients with symptomatic AAA presenting to the ED, the following statistics were reported [14] :

  • Eighteen percent had an initial misdiagnosis of nephrolithiasis.
  • All were older than 60 years and none had a prior history of renal calculi.
  • Eighty percent had a pulsatile mass noted by at least one examiner.
  • Forty-three percent had microhematuria on urinalysis.
  • Delay of diagnosis of AAA in the ED was associated with higher mortality and morbidity rates than in the group who received the correct diagnosis promptly.

Failure to diagnose and promptly treat a urinary tract infection (UTI) proximal to a ureteral stone is also a potential source of medicolegal liability. Urgent urologic intervention must be sought in these patients.

Other conditions to consider include the following:

  • Pyonephrosis
  • Renal artery embolus

Differential Diagnoses