**5.5 Ante-situ, in-situ and ex-situ procedures: Extreme liver surgery**

Liver transplantation has brought with it advances in techniques that can be applied to nontransplant hepatic surgery. The lessons learned from reducing adult-sized livers for implantation in children, living related donor liver transplantation and split liver transplantation can all be applied in the nontransplant setting. Tumours that were considered unresectable with standard techniques can now be considered for resection using in-situ, ante-situ and ex vivo or bench liver surgery. In the last technique, the liver is completely removed from the patient and perfused with preservation solution. A bloodless transection of hepatic parenchyma can then be performed allowing complex reconstruction of hepatic veins or portal structures after which the liver is reimplanted in the patient. The ex vivo technique was first performed by Pichlmayr and colleagues in 1988 and has been applied sparingly in selected patients since then (Hemming et al. 2000).

The common basis for in-situ, ante-situ and ex-situ resection is the total vascular exclusion (TVE) of the liver, and the perfusion of the organ by preservation hypothermic solution. The principles are the same for the three techniques, which differ only in the extent to which liver is mobilized from its vascular connections, hylum and caval vein. Generally, a veno-venous bypass is used to avoid venous congestion during prolonged caval and portal crossclamping and a hypothermic preservation solution is instilled through the portal vein (Fortner et al. 1978). In a study population about liver resection under TVE, Azoulay et al. concluded that standard TVE of any duration with hypothermic perfusion of the liver, in this issue in-situ procedure, was associated with a better tolerance to ischemia. Furthermore, compared with TVE ≥ 60 minutes, it was associated with better post-operative liver and renal functions and lower morbidity (Azoulay et al. 2005). The main indications of the three techniques are tumours that involve vascular structures of the hylum, venous confluence or inferior vena cava (IVC), or are in close proximity to them. The technique can be used for benign, primary or metastatic tumours. The decision about what technique to use depends on the tumour location and its relationship with the three hepatic veins and caval vein. It is important to notice that the ex-situ technique is losing support due to its high morbidity and mortality. The location of the lesion or lesions in or near the suprahepatic IVC represents a true challenge due to the impossibility of using conventional resection techniques. Furthermore, optimal perioperative anaesthetic management is crucial in this setting, and the anaesthesia team should be familiar with the hepatic transplant procedure.

The involvement of the inferior vena cava does not necessarily preclude resection (Figure 5). Liver resection with reconstruction of the IVC can be performed in selected cases. The resected IVC may then be replaced with an autogenous vein graft or a prosthetic material. The mortality rate of resection IVC is 4.5-25% and morbidity up to 40% (Azoulay et al. 2005). The increased risk associated with the procedure appears to be balanced by the possible benefits, particularly when the lack of alternative approaches is considered (Hemming et al. 2004).

In conclusion, liver resections, due to the adoption of several advanced techniques, such as vascular exclusion, veno-venous bypass, hypothermic perfusion of the liver (in-situ, antesitu or ex-situ), have become more common and, when IVC is involved, resection of the vein is no longer considered a contraindication.

Fig. 5. Huge liver metastasis in a 64 year old patient with colon cancer. First surgery was an extended right hepatectomy plus Sg 1 segmentectomy, after PVE of right and Sg 4 portal veins. A left hemicolectomy was performed 7 weeks later.
