Preoperative ultrasonography screening for liver metastases of patients with colorectal cancer.

: The clinical value of preoperative ultrasonography in screening for synchronous liver metastases was prospectively evaluated in 338 patients with colorectal cancer. Synchronous liver metastases were observed at laparotomy in 11.5% (39/338) of the patients. The liver metastases had been found by preoperative ultrasonography in 30 patients and missed in nine. The overall accuracy rate, sensitivity and specificity, and the positive and negative predictive values of this modality were 0.970, 0.769, 0.997, 0.968 and 0.971, respectively. In detecting liver metastases, the results were superior to those of biochemical blood tests and measurements of carcinoembryonic antigen serum levels. The accuracy of the ultrasonography was also superior to that of these other tests combined. The results indicate ultrasonography to be an indispensable preoperative examination for patients with colorectal cancer.