THE VALUE OF UNENHANCED HELICAL COMPUTERIZED-TOMOGRAPHY IN THE MANAGEMENT OF ACUTE FLANK PAIN

Purpose: We developed an algorithm using unenhanced computerized tomog raphy (CT) for the management of acute flank pain and suspected ureter al obstruction. Materials and Methods: During a 25-month interval 417 patients with acute flank pain underwent unenhanced helical CT. The fi nal diagnosis was confirmed by additional imaging or clinical followup . For all patients who underwent additional imaging studies the offici al dictated radiology reports were used to determine whether the studi es were recommended based on CT findings. Cases requiring intervention were evaluated to determine whether additional imaging was performed before the procedure. Medical records were reviewed and/or patients we re interviewed to document the course of therapy and long-term outcome . Results: Unenhanced helical CT diagnosed ureteral stone disease with 95% sensitivity, 98% specificity and 97% accuracy. Of the 38 patients requiring intervention, including nephrostomy catheters in 18, lithot ripsy in 3 and ureteroscopic stone extraction in 7, additional imaging (excretory urography) was performed in only 1. Additional imaging stu dies generated by CT were done in 3 cases in which the dictated report s were indeterminate for ureteral stones, including negative excretory urography in 2 and retrograde urography in 1. In 1 patient in whom CT misdiagnosed a ureteral stone unnecessary retrograde urography reveal ed the calcification to be a gonadal vein phlebolith. Seven patients w ith false-negative examinations reported spontaneous stone passage wit h no complications. Conclusions: Unenhanced helical CT accurately dete rmines the presence or absence of ureterolithiasis in patients with ac ute flank pain. CT precisely identifies stone size and location. When ureterolithiasis is absent, other causes of acute flank pain can be id entified. In most cases additional imaging is not required.