Liver resection: information & specialists for liver resections

Definition: Liver resection

Liver resection is a surgical procedure in which part of the liver is removed or separated. Possible reasons for this removal or separation are benign, malignant or accidental diseases.

There are different surgical options for liver resection. Depending on the extent of the liver disease

• a small piece of the liver (atypical liver resection),
• part of the liver (segmental resection) or
• half of the liver (hemipepatectomy)

surgically removed.

Anatomy of the liver

The liver is visually characterized by

• a strong ligamentous structure (the falciform hepatic ligament and the base of the teres hepatic ligament) and
• an indentation on the side facing the organs (the sagittal fissure)

into a larger right and a smaller left lobe of the liver.

However, this does not correspond to the functional structure of the liver. The functional structure is based on the branching of the hepatic veins (portal branching) into individual, independent subunits. These are called liver segments. The hepatic veins supply the liver with blood.

According to Couinaud (French anatomist and surgeon), there are eight liver segments. These are numbered clockwise and begin on the underside of the liver with the so-called lobus caudatus ("tailed" liver segment) as segment I.

Figure 1: Surgical specimens after removal of several liver segments due to liver metastases from colon cancer

The special thing about the liver is its high regenerative capacity. Even if it is damaged to more than fifty percent of its total mass, it can regenerate almost completely. This damage is often caused by poisoning or alcohol.

Even after surgical removal (resection) of up to 75 percent of the total mass of the liver, the liver can "grow back" completely. However, this depends on the liver function.

Figure 2: Sliced liver tissue with a central liver metastasis

The liver accounts for a total of 20 to 30 percent of the cardiac output of the human body. Cardiac output is a measure of the heart's pumping function. It is calculated using the heart rate and the stroke volume of the heart per minute.

The blood is pumped via

• arterial (10 to 20 percent of the blood supply) and
• portal venous (inflow from the large hepatic vein - portal vein)

vessels (80 to 90 percent of the blood supply) in a three-dimensional network to the liver.

Hepatic veins drain the blood from the liver. Other vessels draining blood from the liver are the bile ducts. The duct systems have a higher content of collagen and elastin. These are components of the wall of the individual structures. As a result, they differ significantly in their structure and resistance from the organ tissue (parenchyma) of the liver. The bile ducts are the most resistant structures.

Resection procedure for liver resection

These properties can be utilized in liver resection. Cutting procedures (dissection procedures) that utilize this different tissue composition are referred to as selective.

These include above all

• the so-called blunt dissection,
• the so-called ultrasonic aspirator (CUSA®) and
• the so-called water jet dissector (Water-Jet).

Non-selective surgical procedures are to be distinguished from these. These do not differentiate between liver parenchyma and duct structures.

Examples are

• mechanical instruments such as the scalpel, scissors and, to a limited extent, the stapler and
• thermal instruments such as the so-called high-frequency coagulator, the laser or the UltraCision® scissors, which work both thermally and mechanically.

Appearance and anatomy of the liver © Henrie | AdobeStock

Results of a liver resection

Decisive parameters for the postoperative outcome and survival of the patient are

• the amount of intraoperative blood loss and
• the amount of transfusion required. This refers to the amount of blood products required per operation - primarily concentrates of red blood cells and blood plasma.

In modern liver surgery, surgical methods should therefore be used that

• are gentle on the liver tissue and
• and minimize bleeding.

Thanks to continuous improvements in surgical techniques , the mortality rate for liver resections is currently 2 to 4 percent. The most important prognostic factors for survival after liver resection are listed in Table 1.

Table 1: Prognostically significant factors for survival after liver resection

Procedure for liver resection

Selected selective surgical options for liver resection are discussed below. The technique used to dissect the liver tissue is highly dependent on the surgeon's habits and training.

Figure 3: Surgical site (liver) after removal of several liver segments

Liver resection with blunt dissection

The finger fragmentation technique was first described in 1958. This involves crushing the parenchyma of the liver between the fingers. This allows larger vessels to be isolated and then ligated.

This technique is very archaic and unsuitable for modern, blood-saving, parenchyma-sparing, segment-oriented liver surgery. This original form of dissection is still mentioned in a few textbooks, but is no longer used in everyday clinical practice.

Blunt dissection with a clamp is a further development of this method. The liver tissue is crushed between clamps. At the same time, more resistant blood vessels and bile ducts are mechanically isolated from the parenchyma. The clamp technique is still used, but the blood loss and operation time are unsatisfactory. In principle, however, all variants of liver resection are possible using the clamp dissection technique.

A modification of this clamp technique is the blunt shear dissection. The parenchyma of the liver is carefully pushed apart with closed scissors, thereby isolating the duct structures.

The smaller duct structures are then closed with metal clips. The surgeon ligates (stitches around or cuts off) the larger vessels with a surgical thread and a needle.

Blunt scissor dissection is a frequently used method that can be performed quickly and inexpensively. In many centers, this type of dissection is used in

• non-nodular (cirrhotic) and
• and non-enzymatically altered (cholestatic) livers

cholestatic) livers is still the standard procedure.

Liver resection with ultrasonic aspirator (CUSA®)

The principle of the ultrasonic aspirator is based on the conversion of electrical energy into mechanical energy using ultrasound. CUSA® stands for Cavitron Ultrasonic Surgical Aspirator. It uses ultrasound to cut through the liver tissue and then aspirates the resulting suspension. The suspension is a mixture of fluid and liver tissue. The energy generated by the ultrasound causes the liver tissue to be severed.

Due to the different tissue composition, it is possible to selectively cut through the various structures of the liver tissue. Tissue with a high water content (parenchyma) is cut through more quickly than tissue with a higher tissue content (vessels, bile ducts).

The device is cooled by rinsing with saline, the severed tissue is dissolved and then aspirated. The aspirated fluid can then be used for a histological examination alongside the separated tissue.

Another advantage of the simultaneous suction function is the reduced risk of intraoperative tumor cell seeding during tumor removal.

In studies, liver resections with the ultrasonic aspirator have shown a significant reduction in

• intraoperative blood loss,
• the need for transfusion,
• the operation time,
• vulnerability and mortality as well as
• length of hospital stay

can be shown. However, the use of this procedure requires a relatively long intraoperative period during which the liver is not supplied with blood (so-called Pringle time).

Liver resection with water jet

The water-jet dissector uses a high-pressure water jet to cut through the liver tissue. The high-pressure liquid jet works with a pressure of 20 to 50 bar and a nozzle diameter of 0.1 to 0.2 mm.

This allows the liver parenchyma to be "rinsed" from the blood vessels and bile ducts according to their tissue composition (hardness gradient).

Figure 4: Dissection of the liver tissue with the water jet dissector - metal clips can be seen in the area of the resection surface (dissection surface) to prevent secondary bleeding and bile leakage

Liver resection (dissection) with the water jet can also be performed usingthe"keyhole technique" (laparoscopic). Studies show that using the Water-Jet

• the intraoperative blood loss,
• the liver resection time and
• ischemia time (time during which the liver is not supplied with blood)

can be decisively (significantly) reduced.

The additional application of high-frequency current or laser energy can significantly increase the speed of liver resection. Larger vessels can thus be preserved and smaller ones (diameter up to 1 mm) can be prevented with electricity.

Due to the advantages mentioned above, liver resection with the water jet is the standard procedure at our center for both open and laparoscopic liver resections.

Conclusion on liver resection

The surgical techniques for surgical resection of liver tissue have been continuously improved. The procedure is therefore a safe and standardized operation, especially in appropriate centers.

Currently, open surgery is the method of choice, especially for extensive oncological liver resections (in accordance with tumor standards). However, the development of suitable instruments for efficient and safe liver surgery has led to significant progress in laparoscopic liver surgery.

Current literature shows low postoperative complication rates for both laparoscopic and open liver resections.

Laparoscopic liver resection has a shorter hospital stay (hospitalization) and a lower complication rate. The method should therefore be used in patients with the right conditions, namely

• benign liver lesions and
• smaller carcinomas located in the peripheral area

should be prioritized.

Extensive liver resections are currently still more frequently performed using the open technique. However, a higher mortality rate and a longer hospital stay are to be expected for these procedures.

There is a lack of meaningful, larger studies in the literature on the oncological value of extended liver resections using laparoscopic and open techniques. These studies should also compare mortality, vulnerability and length of hospital stay. Smaller studies have already shown that the removal of half of the liver can also be safely performed laparoscopically.

Currently, the performance of extensive laparoscopic and laparoscopic-assisted liver resections is still being critically discussed. In the case of laparoscopic liver resections, there are disadvantages in the exact three-dimensional orientation of the surgeon, particularly in the case of extensive, central findings, for example when dissecting the large vessels.

Bleeding complications are the most common reason for conversion to open liver resection. Other disadvantages of laparoscopic procedures are

• the often longer time required
• the higher costs and
• greater dependence on the surgeon.

Nevertheless, laparoscopic liver resections by experienced surgeons will increasingly become the gold standard in liver surgery in the future.