Importance of specimen size in accurate needle liver biopsy evaluation of patients with chronic hepatitis C.

BACKGROUND & AIMS: In patients with chronic hepatitis C (CHC), percutaneous needle liver biopsy examination establishes the severity of necroinflammatory activity and fibrosis, thus guiding treatment decisions. Optimal biopsy specimen size remains controversial. We sought to determine how varying lengths of biopsy specimens influence the grading and staging of CHC.

METHODS

We used 100 liver biopsy specimens from patients with CHC. The slides were evaluated blindly using the METAVIR scoring system, after being covered with paper, so that only specific specimen lengths (5 mm, 10 mm, 15 mm, and > or =20 mm) were visible. In each case, the scores obtained with biopsies 5 mm, 10 mm, or 15 mm long were compared with the scores at 20 mm or greater by weighted kappa statistics (kappa of >.75 signified excellent agreement). A subset of specimens 20 mm or greater was selected for a blinded repeat scoring to assess intraobserver agreement. The kappa statistics for the designated features and lengths were compared using analysis of variance.

RESULTS

In assessing the stage of fibrosis, the weighted kappa statistics for agreement with the 20-mm or greater score at 5 mm, 10 mm, and 15 mm were .75, .85, and .92, respectively. In assessing the histologic activity score, the corresponding figures were .73, .81, and .77, respectively. Average kappa statistic comparisons showed that intraobserver agreement was significantly better than agreement between the 20-mm or greater scores and those at shorter lengths; the 5-mm kappa scores were significantly lower than the others; and there was no significant difference between the 10-mm and 15-mm kappa scores.

CONCLUSIONS

Liver biopsy specimens measuring at least 10 mm usually reflect the grade and stage of CHC reliably. Relatively little improvement in diagnostic accuracy is obtained with longer specimens.