Patterns of colorectal liver metastases according to Couinaud's segments.

Purpose: It is commonly believed that the right lobe of the liver is the most frequent site of colorectal liver metastases. However, direct evidence for this is lacking in the literature. This study was designed to document and evaluate the pattern of liver metastases according to liver segments.
Methods: A retrospective medical records review of 270 patients with hepatic metastases from colorectal adenocarcinoma was performed to determine the pattern of metastases according to Couinaud's segments. There was operative confirmation of liver metastases in 202 patients (75 percent). A total of 1,166 segments were involved with liver metastases and were used in this analysis. Segment I was excluded from calculations because of its dual blood supply. When groups contained different numbers of Couinaud's segments an appropriate correction was made in the statistical comparison.
Results: There were 736 (63 percent) right lobe segments (V, VI, VII, VIII) and 430 (37 percent) left lobe segments (II, III, IV) involved with metastases (P < 0.001). Of 430 left lobe segments, 298 (69 percent) involved the left lateral segment (II, III) and 132 (31 percent) involved the medial segment (IV) of the left lobe (P = 0.25). When evaluating patients with 4 or less segments involved, there were 258 right lobe segments (75 percent) and 88 left lobe segments (25 percent) involved with metastases (P < 0.0001). Of 88 left lobe segments with 4 or less segments involved, there were 68 segments (77 percent) involving the left lateral segment and 20 segments (23 percent) involving the medial segment of the left lobe (P = 0.035). All of these relationships were statistically independent of the primary tumor site.
Conclusions: We have documented an overall predominance of right hepatic lobe metastases independent of site of the primary colorectal carcinoma. However, when metastases occurred in the left lobe, the left lateral segment (II, III) was more commonly affected than the medial segment (IV), but this difference was statistically significant only when there were four or less segments involved with liver metastases.