4. DISCUSSION
Urolithiasis is one of the common diseases of the urinary system, manifesting with severe pain that causes patients to frequently refer to ED.8 Although most ureteral stones pass spontaneously without intervention, the main challenge for emergency physicians is to identify patients at high risk for complications, such as obstructive uropathy. In our study, we found that patients with urolithiasis and without microscopic hematuria in UA had clinically more significant ureteral stones. In addition, emergency patients without microscopic hematuria had a higher risk of moderate to severe hydronephrosis than those with microscopic hematuria.
The investigation of microscopic hematuria in UA is a good screening test in patients with suspected renal colic, but its sensitivity varies between 69% and 84%.9 Kim et al.10found the sensitivity, specificity, positive predictive ​​and negative predictive values ​​of microscopic hematuria as 89.4%, 41.1%, 88.9% and 42.1%, respectively in the diagnosis of urolithiasis. They showed that 10.6% of the patients diagnosed with urolithiasis did not have hematuria. Luchs et al. reported that the incidence of a negative UA test was 16% in patients with renal colic caused by stones that were definitively diagnosed based on non-contrast abdominopelvic CT.9 Similarly, Gulacti et al. determined that hematuria was not observed in 12% of patients diagnosed with urolithiasis.11 In our study, we found renal colic due to ureteral stone without hematuria in 17.9% of the cases. Our data show that the absence of hematuria in UA does not rule out the diagnosis of urolithiasis.
Inci et al.12 reported no relationship between stone volume and microscopic hematuria. They found that the frequency of microscopic hematuria was 42% if the stone volume was 1-10 mm3, and 83% if 75-100 mm3. Mefford et al.6 determined that the presence or absence of microscopic hematuria was not related to the size of the stone and that patients without microscopic hematuria had a higher rate of moderate to severe hydronephrosis (42%) compared to those with microscopic hematuria. In addition, that study revealed that the incidence of moderate to severe hydronephrosis was 49% for ureteral stones of 5 mm or greater, while it was 14% for those smaller than 5 mm. In the current study, the incidence of moderate and severe hydronephrosis was higher in the patient group without microscopic hematuria than the patient group with microscopic hematuria. Unlike other studies, we found that pyuria and hematuria had an independent relationship.
CT has a very high diagnostic value for kidney stone disease (94-100% sensitivity and 92-99% specificity). It also provides important data in the planning of treatment by determining stone size and localization, and degree of hydronephrosis.13,14 In a study involving 1,824 patients with urolithiasis, Chang et al.15 reported that the severity of hydronephrosis before treatment was associated with the failure of shock wave lithotripsy. Cho et al.16 reported that patients suffering from urolithiasis without microscopic hematuria used medication more often and were hospitalized more frequently than those with microscopic hematuria. In our study, we detected a correlation between the degree of hydronephrosis and the absence of microscopic hematuria. Therefore, we suggest that rapid diagnosis and treatment are required by promptly performing non-contrast CT in the patient group without microscopic hematuria.