The use of standard imaging techniques and their diagnostic value in the workup of renal colic in the setting of intractable flank pain

Objectives. This study reviews the rate at which diagnostic imaging techniques are used in patients with intractable flank pain attributed to renal colic who are admitted to the hospital through the emergency room and determines the diagnostic values of plain film of the abdomen (kidney, ureter, bladder [KUB]) and of ultrasonography (US) of the urinary tract, using intravenous urography (IVU) as the gold standard for establishing the presence of a calculus. Methods. We reviewed the medical records of 288 patients who were admitted to our medical center over a period of 5 consecutive years for intractable flank pain, the admission and working diagnosis in all cases being that of renal colic, and we retrieved all data pertaining to their diagnostic evaluation. Results. A total of 265 patients (92%) were subjected to KUB, 158 (55%) to IVU, and 135 (45%) to US of the renal-urinary tract. Two diagnostic imaging techniques were used in the same patient in the following combinations: KUB and IVU in 146 patients (51%), KUB and US in 110 (38%), and IVU and US in 60 (21%). Three imaging techniques (IVU, KUB, and US) were utilized in 54 patients (19%). The sensitivity and specificity of KUB alone were 95% and 65%, respectively, and the positive and negative predictive values were 82% and 88%. The sensitivity of US alone was 93%, its specificity 83%, the positive predictive value 93%, and the negative predictive value 83%. The sensitivity of combined KUB and US (requiring both tests to be positive for diagnosing the presence of a calculus) was 89%, the specificity 100%, the positive predictive value 100%, and the negative predictive value 81%. Conclusions. Our data indicate that combining US with KUB provides the best diagnostic algorithm that approaches the yield of IVU in excluding the presence of a calculus in the renal-urinary tract in patients who present with intractable flank pain.