Mimics of Renal Colic: Alternative Diagnoses at Unenhanced Helical CT

Abstract

During the past decade, unenhanced computed tomography (CT) has become the standard of reference in the detection of urinary calculi owing to its high sensitivity (>95%) and specificity (>98%) in this setting. Numerous diseases may manifest as acute flank pain and mimic urolithiasis. Up to one-third of unenhanced CT examinations performed because of flank pain may reveal unsuspected findings unrelated to stone disease, many of which can help explain the patient's condition. Alternative diagnoses are most commonly related to gynecologic conditions (especially adnexal masses) and nonstone genitourinary disease (eg, pyelonephritis, renal neoplasm), closely followed by gastrointestinal disease (especially appendicitis and diverticulitis). Hepatobiliary, vascular, and musculoskeletal conditions may also be encountered. Vascular causes of acute flank pain must always be considered, since these constitute life-threatening emergencies that may require the intravenous administration of contrast material for diagnosis. Radiologists must be familiar with the typical findings of urinary stone disease at unenhanced CT, as well as the spectrum of alternative diagnoses that may be detected with this modality, to accurately diagnose the source of flank pain.

Emergency department imaging protocol for suspected acute renal colic: re-evaluating our service

“…The results of our study are in accordance with the 2006 study, with an overall positive rate of 47.5%, female positive rate of 26.8% and male positive rate of 61.6%. The rate of alternative diagnosis is also essentially unchanged (10% in our study vs 12% in 2006) and consistent, but at the lower end of the range, with a quoted range of 9-29% for patients presenting with flank pain [13].…”

Freqüência dos sinais de pielonefrite aguda em pacientes submetidos a tomografia computadorizada

“…One of the reasons for this disagreement may be related to the "window" utilized in the examination. It is important to note that this is a non-specific finding also observed in cases of previous inflammatory process sequela in vascular disease, trauma (6) or urinary tract obstruction (22) . All of the other (renal, perirenal and extrarenal) findings showed a statistically significant interobserver agreement (p = 0.005) ranging between moderate and almost perfect, despite the different levels of experience of the observers and the subjectivity in the evaluation of some findings.…”

MDCT technique and imaging findings of urinary stone disease: an expanded review

“…Some of the alternative diagnoses are congenital renal anomalies, infections (appendicitis, diverticulitis, pancreatitis, mesenteric lymphadenitis, cholecystitis, colitis, pyelonephritis), aortic aneurysm and dissection, ovarian cysts and neoplasms (renal, uterine and adnexal masses) (Figs. 18, 19) (11,50,51).…”

“…Indications for contrast-enhanced CT evaluation (based on unenhanced CT findings) are: i) presence of unilateral perinephric stranding without hydroureteronephrosis with or without renal enlargement (acute renal infarction, renal vein thrombosis, acute pyelonephritis); ii) significant hypo-/ hyperdense perirenal collection (urinoma, hematoma) with or without the b a presence of hydroureteronephrosis; iii) presence of a mass or complicated cyst with/without calculus; iv) negative unenhanced CT findings in a patient with unexplained hematuria (52). Common clinical conditions requiring contrastenhanced CT after unenhanced CT scan in a patient presenting with flank pain and hematuria are infections, neoplasms, renal cyst complications, vascular lesions, urinoma and acute perirenal hematoma, of which imaging findings are already defined elsewhere (51)(52)(53)(54)(55).…”