Hematuria: Is it useful in predicting renal or ureteral stones in patient presenting to emergency department with flank pain?
As I have spent several weeks at the emergency room, I have noticed many patients who came in with kidney stones, and one of the main imaging modalities that were used was a non-contrast CT scan. I wanted to look closer to see if any updates were available in new imaging modalities or other lab tests that could be done to find out if someone has a kidney stone without subjecting them to radiation. I found a study that aimed to assess the effectiveness of hematuria/microhematuria as a diagnostic test for renal and ureteral stones in emergency room patients with acute flank pain, comparing it with the gold standard, non-contrast CT scans.
A retrospective cohort review included 604 patients treated for flank pain and suspected urolithiasis from 2006 to 2011 in the emergency room setting. All patients underwent non-contrast CT scans and urinalysis. The sensitivity, specificity, and predictive values of hematuria for diagnosing renal and ureteral stones were calculated. 388 patients (64%) had stones, while 216 patients (36%) did not. Calculating for sensitivity and specificity, patients with hematuria showed 77% sensitivity, 33% specificity, 67% positive predictive value, and 45% negative predictive value for diagnosing stones. There were no significant differences in hematuria incidence based on the number, size, or location of stones, though ureteral stones had higher hematuria incidence compared to renal stones.
While microhematuria is more sensitive to ureteral stones, its absence does not rule out urolithiasis. Therefore, non-contrast CT scans remain the gold standard for diagnosis of nephrolithiasis. CT scans provide a more accurate and detailed diagnosis, crucial for effective patient management. Future prospective studies with larger samples are needed to further evaluate hematuria’s diagnostic accuracy for ureteral stones. At the moment, CT scans should be prioritized for definitive diagnosis in patients with suspected urolithiasis.
