COMPUTED TOMOGRAPHIC SCANNING OF L3 4 IN SUSPECTED DISC PROLAPSE - ISIT NECESSARY/

Computed tomography (CT) scanning is an accepted first line investigat ion for suspected lumbar prolapsed intervertebral disc disease (PID). However, it does involve ionizing radiation and any possible reduction in the dose is desirable. A questionnaire was sent to a random select ion of 60 CT centres in the UK to confirm that a routine scan of the t hree lower lumbar levels is current practice in a majority of centres, regardless of symptomatic presentation. All orthopaedic CT referrals over 2 years for suspected lumbar disc disease in Sheffield were studi ed retrospectively. Of 486 cases, 99 (20%) were shown to have disc dis ease, of which 16 (3.3%) had disease at the L3/4 level. Of these 16 ca ses, 11 were suspected clinically. Analysis of the long-term outcome o f the five unsuspected cases showed that in none did the CT findings m ake any significant contribution to this outcome. These results have a ltered our practice. Two-level scanning is now performed routinely and three-level scanning is only performed when specified clinical or rad iological indications are present.