Intraoperative ultrasound (IOUS) is essential in the management of metastatic colorectal liver lesions.

Metastatic tumors to the liver account for the majority of hepatic neoplasms. Improvement in resection has been shown to be beneficial and has remained the treatment of choice, carrying a 5-year survival rate of approximately 20 to 30 per cent. In evaluating candidates for surgery, intraoperative assessment for resectability is a key factor and dictates surgical approach, as well as patient prognosis. Historically, imaging techniques such as CT scan, magnetic resonance imaging, and CT arterial portography (CTAP) have been used in preoperative evaluation. However, the sensitivities of these diagnostic tools have been found to be less than optimal. Intraoperative ultrasound (IOUS) has emerged as an important tool in accurately staging metastatic liver disease with a sensitivity of 98 per cent. From 1994 to 1996, 23 patients have undergone IOUS for evaluation of suspected liver neoplasms in an ongoing prospective study. All patients had colorectal carcinoma. All patients received preoperative CT scan, and 11 patients with positive CT scans had CTAP. Fifteen patients were found to have colorectal metastasis to the liver. Surgical management in 7 of the 15 patients was modified because of the use of IOUS. Two patients were found to have unresectable disease thus abandoning hepatic resection, two were found to have additional lesions undetected by preoperative evaluation and were resected, and in two patients margins of resection were changed. One patient was found to have benign hepatic cysts, and no resection was performed. The use of IOUS modified the management of 44 per cent of our patients with liver metastases. IOUS should be routinely used in patients undergoing liver resection for metastatic liver disease.