Resistive index in renal colic: the effect of nonsteroidal anti-inflammatory drugs

Objective To investigate the effect of nonsteroidal antiinflammatory drugs (NSAIDs) on the Endings of Doppler ultrasonography (DU) in patients with ac ute unilateral renal obstruction. Patients and methods The study included 60 patients (120 kidneys) with unil ateral loin pain suspected to be of renal origin. All patients were evaluat ed using renal ultrasonography (US) and intravenous urography (IVU) during the attack of loin pain and before giving any medication. Then the patients were given 75 mg diclofenac sodium and DU studies were repeated at 6 and 1 2 h. In 10 patients with acute renal colic, DU was possible 12-24 h after t he relief of ureteric obstruction. The mean resistive index (RI) and Delta RI at baseline were compared with the mean values 6 and 12 h after giving d iclofenac. The RI and Delta RI were considered positive at values greater t han or equal to 0.70 and greater than or equal to 0.06, respectively. The s ensitivity, specificity and overall accuracy of RI and Delta RI values befo re and after giving diclofenac were calculated using IVU as the reference s tandard. Results IVU showed that both kidneys were normal in 20 patients that 40 had unilateral obstruction. Al baseline, the mean (SD) RI was 0.72 (0.06) in t he 40 obstructed kidneys, significantly higher than the RI of 0.60 (0.06) f or the 60 normal kidneys (P<0.001). Six hours after giving diclofenac, the mean RI of normal kidneys remained stable and that of the obstructed kidney s decreased significantly to 0.67 (0.06) (P<0.001) and was almost stable at 12 h. Nevertheless, the mean RI of the obstructed kidneys remained signifi cantly higher than that of the normal kidneys at 6 and 12 h after diclofena c. The mean Delta RI decreased significantly from 0.11 (0.04) at baseline t o 0.06 (0.04:) at 6 h after diclofenac (P<0.001) and remained almost stable at 12 h. In the 10 patients undergoing DU after the relief of obstruction, the mean RI returned to normal. At baseline, RI was sensitive in 70% and s pecific in 98%, while Delta RI was sensitive in 88% and specific in all cas es. Six hours after diclofenac, the specificity of RI and Delta RI remained stable while the sensitivity decreased significantly to 50% and 68%, respe ctively. Conclusion NSAIDs significantly decrease the RI of acutely obstructed kidne ys, causing a significant reduction in the sensitivity of DU values identif ying acute renal obstruction. To evaluate acute loin pain, DU should be car ried out while the patient is in pain and before giving NSAIDs.