Intraoperative ultrasound: a review on its role in liver surgery for primitive and metastatic tumors.

Intra-operative ultrasound is an invaluable tool in hepatic surgery, either for restaging either as a guidance during resection of liver neoplasms. Nowadays, intraoperative ultrasound is still considered the most accurate diagnostic technique for detecting focal liver lesions in both hepatocellular carcinoma and colorectal liver metastases, which represent the most frequent indication for liver resection. Moreover, the use of ultrasound guidance is mandatory for planning the surgical strategy, deciding the exact resection plane and during the parenchymal transection, in order to respect the surrounding vessels and biliary structures. Every surgical procedure performed on the liver is strictly dependent from the knowledge of the liver anatomy and from the ultrasounds; definitely in liver surgery the ultrasounds represent the link between the surgical anatomy and the surgical intervention. To maximize the benefit, intraoperative ultrasound should be carried out by the surgeon himself in the perspective of surgical guidance. Here is presented an updated and extensive review of the role of ultrasounds in liver surgery, describing and analyzing the possible applications of this invaluable tool from the surgeon's point of view. Technical aspects, principles of intraoperative re-staging and ultrasound-guided liver resection, application and possible advantages of laparoscopic ultrasound and new perspective in intraoperative study of the liver are discussed.