Objective: To study the mothods in detecting  sentinel lymph node (SLN) and lymph node micrometastasis in patients with colorectal cancer and their clinical significance.
Methods: Sixty patients with colorectal cancer undergoing lymphatic mapping using methylene blue staining (group I) was analysed. The SLN was identified and removed, and the micro-metastases in sentinel lymph node were detected with HE and immunohistochemical staining technique. Other  sixty patients previously treated by direct radical lymphadenectomy were taken as comtrol group(gronp II).
Results: Fifty-four SLN were successfully identifed in group I,with a detection rate of 90.0%, which was higher than that of control group (24/60,40%)(P<0.05); in group I,  thirty-six positive SLN were dectected by HE staining, and six micro-metastases (33.3%) were found in eighteen negative SLN by use of Cytokeratin 20 immuno-histochemical staining.
Conclusions: The success rate achieved by combining methylene blue staining and cytokeratin 20 immunohistochemical staining in detecting SLN and lymph node microstasis is higher than that achieved by using either technique mentioned above alone.