**6. Ultrasound-guided techniques**

It has been demonstrated that making biopsies under IOUS guidance, laparoscopic or "classic," have a high diagnostic accuracy and are considered safe procedures with possible impact on surgical management [86, 87]. For example, liver metastases detected intra-operatively and confirmed by histopathological examination as having pancreatic origin could be a contraindication for pancreatic radical surgery [58].

In terms of non-excisional treatment of hepatic tumor formations, this can also be achieved by ablative techniques, such as ethanol injection [88], RFA (coagulation necrosis induced by high-frequency alternating currents-thermal energy) [89] and MWA (same as RFA, although MWA uses different parts of the electromagnetic spectrum) [90]. Although the elective treatment is by percutaneous approach, there are situations when both classical or laparoscopic method are indicated.

Laparoscopic approach is particularly preferred on patients who are on the waiting list for liver transplantation or for those who cannot benefit from liver resection due to comorbidities, liver cirrhosis, or hepatic dysfunction due to chemotherapy, especially when percutaneous procedures are not possible [91–93]. Indications are subcapsular lesions located in the immediate vicinity of important structures (diaphragm, stomach, and gallbladder) or difficult to approach (caudal lobe). [84, 94–96]. Moreover, these ablation techniques can be combined with hepatic resections or can be performed serially after surgical resections, improving the oncological outcome and prognosis [97–99]. In the majority of cases treated by these procedures, IOUS is used as a guidance tool and for evaluation the efficacy of the treatment and appearance of complications [94].

Multiple studies have demonstrated that IOUS-guided ablations are a safe and an effective treatment option that provides excellent local control of both primary and secondary hepatic tumor lesions [64, 94, 100–102]. Recent studies have also reported that intraoperative RFA has a local recurrence rate equivalent to that obtained from low-grade HCC surgery [11, 96] and colorectal hepatic metastases [64, 100].
