['Computed tomography (CT) is the most common staging investigation in colorectal cancer (CRC). Up to 25% of patients are found to have previously undetected hepatic lesions when intraoperative ultrasound (IOUS) of the liver is used during CRC resection. We aimed to assess the ability of IOUS to detect additional liver lesions/metastases at primary colorectal resection, and to evaluate whether contrast-enhanced IOUS (CE-IOUS) improves the detection and characterization of hepatic lesions.', 'We performed a single-centre, prospective pilot study. At CRC resection, patients underwent IOUS of the liver. Contrast-enhanced IOUS of the liver was undertaken using i.v. sulphur hexafluoride micro-bubbles (SonoVue, 4.8 ml). Findings of CT, non-enhanced IOUS and CE-IOUS were compared. Changes in staging or management were noted. Additional lesions were corroborated with iron oxide magnetic resonance imaging (MRI).', 'Among 21 patients, IOUS demonstrated additional lesions in seven (33%). Contrast altered the diagnosis of non-enhanced IOUS in four (20%) and changed the management strategy in three (14%) patients. Thus, IOUS in combination with the contrast agent altered the intraoperative or postoperative management plan in four patients.'] Does contrast-enhanced intraoperative ultrasound improve detection of liver metastases during surgery for primary colorectal cancer?