Detection of colorectal liver metastases using intraoperative ultrasonography. Intraoperative ultrasonography of the liver has been carried out in 99 patients undergoing surgery for colorectal cancer. Palpation of the liver, preoperative abdominal ultrasonography and computed tomography scanning were also performed in all patients. Metastases were identified in 26 of the 99 patients (26 per cent). Intraoperative ultrasonography diagnosed more metastases than palpation, abdominal ultrasonography or CT scanning, identifying metastases in 24 of the 26 patients, including six patients in whom the metastases were not detected by any other technique. Identification and localization of impalpable liver metastases is therefore possible using intraoperative ultrasonography. 