Ultrasonography compared with intravenous urography in investigation of urinary tract infection in adults.

OBJECTIVE To compare ultrasonography with intravenous urography for investigating adults with proved urinary tract infection. DESIGN Prospective study of patients presenting consecutively for radiological investigation of urinary tract infection between October 1988 and December 1989. Both investigations were performed concurrently and performed independently on routine lists by different duty radiologists, each of whom knew the details on the request form but not the findings of the other investigation. SETTING Radiology department of a teaching hospital. PATIENTS 158 Consecutive adults (89 women, 69 men; mean age 49.7 (range 18-83)) referred from general practitioners and hospital outpatient clinics with a history of proved urinary tract infection. INTERVENTIONS Urography and ultrasonography performed concurrently. When both examinations gave normal findings no clinical or radiological follow up was sought. All abnormal findings detected with either investigation were confirmed by subsequent imaging studies or by operative procedures. MAIN OUTCOME MEASURE Accuracy of detection of abnormalities of urinary system by ultrasonography compared with urography. RESULTS 113 Patients (72%) had normal urographic and ultrasonic findings. Overall, ultrasonography concurred with the findings of urography in 149 (94%) patients, and when a single abdominal radiograph was included in the procedure, in 152 (96%). Ultrasonography missed only one important diagnosis, that of mild papillary necrosis in normal sized kidneys in a diabetic patient. It detected one early bladder tumour not visible on urography and was able to clarify the nature of renal masses (simple cysts) evident on three urograms. CONCLUSION Ultrasonography provides a safe and accurate method of imaging the urinary tract in adults with infection. Combined with a plain abdominal radiograph, it should replace urography as the initial imaging investigation in these patients. Major savings would result from adopting this policy, and the risks to patients from ionising radiation and intravenous contrast media would be appreciably reduced.