Can one predict when ultrasound will be useful with percutaneous liver biopsy?

OBJECTIVE: We previously showed that ultrasound altered position of biopsy in 15% of cases by demonstrating intervening structures. This study was des igned to test whether one could predict in which cases ultrasound would be useful. METHODS: A standard percussion technique was used. The site chosen was mark ed. Criteria were established to indicate whether a move might be predicted to be likely. If 10 or more points were assigned, then it was predicted th at ultrasound would change position. A difficult percussion was assigned 10 points; obesity, 5 points; and chest deformity, 5 points. The ultrasound w as then applied to the marked spot in every case. If an intervening structu re was present within 6 cm, the biopsy site was moved. Otherwise, the biops y was taken from the marked site. RESULTS: One hundred seventeen consecutive liver biopsies were included bet ween January 1999 and January 2000. The criteria predicted the desirability of nine moves. No moves were made, however, in these cases. In 17 cases (1 4.5%), moves were made because of intervening structures. None of the cases were predicted. A move was made in 1 of 23 obese patients. There was no st atistical difference in moves made between obese and nonobese patients. CONCLUSIONS: Using criteria of difficult percussion, obesity, and unusual c hest shape, we could not predict when ultrasound would be useful. This is i n contrast to the belief that ultrasound can be applied to selected liver b iopsies considered in advance to be more difficult, as in the obese patient s, and instead suggests that to avoid intervening structures, one should ap ply ultrasound to all cases.