Unexplained renal colic: What is the utility of IV contrast?

MDCT of the Abdomen: Common Misdiagnoses at a Busy Academic Center

“…It can be a challenge to detect nonstone renal pathologic disorders on these limited studies. Pathologic disorders, including aneurysm, arteriovenous malformation, small renal cell carcinomas or transitional cell carcinomas, and pyelonephritis, may not be identifiable in the absence of IV contrast [8]. At our institution, even experienced radiologists have missed important renal pathologic disorders on these examinations (Fig.…”

Acute Urinary Tract Disorders

“…Miller and colleagues 4 performed a study to evaluate the utility of intravenous (IV) contrast in patients with flank pain and found that of the 708 patients who received IV contrast only 43 (6%) had actionable findings that required IV contrast, including 32 patients who had pyelonephritis, for which imaging is not initially indicated unless the patient has complicating factors. 5 Of the 8 patients, 6 with renal cell carcinoma had masses large enough to be distinguished without IV contrast.…”

“…5 Of the 8 patients, 6 with renal cell carcinoma had masses large enough to be distinguished without IV contrast. 4 Specific indications for IV contrast in patients who present with flank pain include unilateral renal stranding/enlargement with risk factors for renal infarct or vein thrombosis (ie, patients with dysrhythmia, thromboembolic disease history, or elevated levels of lactate dehydrogenase), perirenal fluid collection, renal mass/complicated cyst, or unexplained hematuria. 6 During the past decade, there has been an emphasis on reducing the radiation dose of CT scans performed for flank pain given the young age and frequency of imaging within the affected patient population.…”

“…In addition, patients can have a mild leukocytosis and fever for 1 to 2 days after a renal infarct, further complicating the diagnostic process. 68 In the setting of relevant risk factors (myocardial infarction, malignancy, aortic aneurysm, and cardiac valvular disease), CT imaging with contrast should be performed when there is an enlarged kidney with surrounding perinephric edema of unknown cause on an initial unenhanced CT. 4 The most common cause for renal infarction is thromboembolism from a cardiac source. Although nonspecific, markedly elevated serum lactate dehydrogenase levels, a serum marker for cell necrosis, is helpful in suggesting the diagnosis.…”

Loin pain and a normal CT KUB: what to do?

“…The addition of contrast to a plain CT may also identify several non‐urological causes of loin pain. In a retrospective study of 708 patients presenting with suspected renal colic, the addition of contrast CT identified significant findings in 67 (9.4%) patients that were not visible on plain imaging . Findings included splenic artery aneurysm, renal vein thrombosis, pulmonary embolus, appendiceal mucocoele, arterial bypass occlusion and gallbladder adenomyatosis.…”