Minimally Invasive Anatomic Resection of Liver Segment VIII Based on Portal Territory to Treat Hepatocellular Carcinoma

Summary

This study details laparoscopic S8 segmentectomy techniques, emphasizing the transition from partial to anatomical resection guided by portal pedicle navigation. Enhanced 3D anatomical comprehension, refined minimally invasive skills, and intraoperative ultrasound mastery improved procedural precision and safety, reducing complications while optimizing hepatic surgical outcomes through systematized anatomical resection protocols.

Abstract

Hepatectomy is the primary treatment for hepatocellular carcinoma (HCC) and is categorized into anatomical hepatectomy and non-anatomical hepatectomy based on the extent of resection. Anatomical hepatectomy utilizes the portal territory (PT) liver segment or subsegment as the basic anatomical unit, systematically resecting the tumor-bearing PT and completely removing the Glisson system that supplies and demarcates this area to enhance oncological efficacy. Non-anatomical hepatectomy follows the principle of radical oncological resection, emphasizing the removal of liver tissue more than 1 cm away from the tumor margin. With the popularization of precision surgery concepts, minimally invasive anatomical hepatectomy based on PTs has been widely applied. However, the minimally invasive resection of segment S8 of the liver is still considered one of the most challenging liver resections. We successfully performed an anatomical resection of portal territory segment S8 of the liver using intraoperative ultrasound, fluorescent laparoscopy, and Lannaec membrane dissection techniques, achieving good short-term clinical outcomes.

Introduction

Hepatocellular carcinoma, commonly known as liver cancer, is one of the most common malignant tumors in China. In 2022, there were 367,700 new cases of liver cancer in China, making it the fourth highest in terms of incidence; the number of deaths reached 316,500, making it the second leading cause of cancer-related deaths¹. Hepatectomy provides one of the best opportunities for long-term survival in patients with HCC². Liver resection can be classified into anatomic liver resection (AR) and non-anatomic liver resection (NAR) based on the extent of resection. AR involves the complete resection of anatomically independent liver segments or combined segments, along with the hepatic parenchyma within the tumor-bearing portal vein branches, to achieve better oncological outcomes and avoid complications from residual ischemic or congested areas. The advantage of AR is reflected in the thoroughness of tumor excision and the complete preservation of the inflow and outflow hepatic ducts of the remaining liver³. On the other hand, NAR, also known as irregular liver resection, refers to the resection of liver tissue more than 1 cm away from the tumor margin based on oncological radical resection principles. This surgical method does not strictly adhere to the anatomical segmentation of the liver but is tailored according to the location and size of the tumor, aiming to preserve as much normal liver tissue as possible while ensuring a safe margin for tumor excision.

With the advancement of precision surgery concepts and a deeper understanding of the liver's anatomy, the theory and practice of anatomical liver resection based on the portal territory (PT-AR) have gained recognition and initial promotion in recent years⁴. PT-AR involves preoperative three-dimensional reconstruction and basin analysis to identify the tumor-bearing portal territory (PT) and plan the surgery accordingly. Intraoperatively, liver segments or subsegments within the basin are used as basic anatomical units, with indocyanine green (ICG) fluorescence staining navigation being the primary method, supplemented by exposing representative intersegmental hepatic veins (IHVs). The liver is then dissected along physiological fissures to achieve complete resection of the tumor-bearing portal basin while ensuring the integrity and functional preservation of the future liver remnant (FLR). Superimposed intraoperative ultrasound-guided puncture for portal positive staining or retrograde staining after ligation of the target hepatic pedicle is a fundamental technical requirement for achieving PT-AR.

Laparoscopic liver resection is acknowledged for its minimally invasive approach and superior recovery outcomes when compared to traditional open surgery. However, the complexity of resecting different liver segments varies. The location of segment VIII of the liver deep within the upper abdomen, near the hepatic veins and inferior vena cava, along with the challenge of directly accessing the Glissonean pedicle of segment VIII, makes laparoscopic anatomical liver resection particularly challenging for this segment^5,6,7,8,9.

This study demonstrates the portal venous regional anatomical resection of liver segment S8 for hepatocellular carcinoma. Our aim is to detail the technique and key steps of this surgery, including the laparoscopic ultrasound-guided puncture technique and liver pedicle dissection technique based on the Lannaec membrane. By sharing this protocol, we hope to provide evidence supporting the feasibility and safety of laparoscopic portal venous regional anatomical liver resection in the treatment of S8 hepatocellular carcinoma, ultimately improving patient treatment outcomes.

Protocol

The study involving laparoscopic anatomic liver resection for Segment 8 (LALR-S8) has adhered to standard ethical practices. It received approval from the Ethics Committee of the Shenzhen People's Hospital (LL-KY-2020462). Additionally, informed written consent was obtained from each patient, ensuring that the research complies with medical ethics norms and requirements.

1. Patient selection

1. Use the following inclusion criteria:
   1. Perform LALR-S8 on patients with benign or malignant liver tumors and ensure that they undergo standard cardiopulmonary evaluations, blood tests, and biochemical assessments; ensure that they have no contraindications for surgery or anesthesia.
   2. Perform preoperative imaging, including abdominal CT angiography, three-dimensional reconstruction of the liver and vasculature, and enhanced MRI, as well as calculations of residual and standard liver volumes.
2. Use the following exclusion criteria: patients with liver function classified as Pugh-Child Class C; those who cannot tolerate general anesthesia; patients with intrahepatic or extrahepatic metastases; those who have undergone open surgery; and patients who have received segmental resections or other combined surgical treatments.

2. Preoperative preparation, surgical position, and anesthesia

1. Preoperative preparation
   1. History and physical examination: Assess liver function, coagulation profile, ICG clearance test, and overall health status.
   2. Imaging: Obtain detailed preoperative imaging (e.g., enhanced abdominal CT, MRI, and three-dimensional reconstruction of the liver and vasculature) to delineate the anatomy of segment 8 of the liver and its vasculature (Figure 1)
   3. Fasting: Ensure the patient adheres to fasting instructions, typically starting from midnight the day before the surgery.
   4. Medications: Administer prophylactic antibiotics if necessary and review any medications that may impact bleeding or liver function.
   5. Informed consent and education: Explain the laparoscopic procedure, including its methods, risks, and benefits, and obtain informed consent.
2. Surgical position
   1. Supine position: Position the patient on the operating table in the supine position.
   2. Reverse Trendelenburg position: Slightly tilt the operating table to facilitate exposure and access to the liver.
      NOTE: This position helps to move the liver upwards and away from the upper abdomen.
   3. Stabilization: Secure the patient to the operating table to prevent movement during the procedure.
3. Anesthesia
   1. General anesthesia: Administer general anesthesia to ensure the patient remains unconscious and comfortable throughout the surgery.
   2. Induction and maintenance: Use intravenous induction agents (e.g., propofol) and muscle relaxants (e.g., succinylcholine) for intubation. Maintain anesthesia with inhaled agents (e.g., sevoflurane) and supplemental analgesics (e.g., fentanyl). Adjust the depth of anesthesia to ensure adequate anesthesia and patient safety.
   3. Monitoring: Continuously monitor heart rate, blood pressure, blood oxygen saturation, and end-tidal carbon dioxide levels.

3. Surgical techniques

1. Following intravenous-inhalation anesthesia, position the patient in a 30° left lateral decubitus position with head elevation and legs separated. Use a five-port approach for liver resection, with an insufflation pressure maintained at 11-13 mmHg, central venous pressure at 3-5 cmH₂O, and the Pringle maneuver applied for 10-15 min of occlusion followed by a 5 min release.
2. Make a vertical incision 2 cm below the right edge of the umbilicus, and open the abdominal wall layers sequentially to access the abdomen. Insert a 12 mm trocar to establish pneumoperitoneum, then introduce the laparoscope into the abdominal cavity.
3. Place five trocars as follows: one 12 mm trocar in the suprumbilical region for observation; one 5 mm trocar at the right anterior axillary line; one 12 mm trocar below the right medial clavicle; one 5 mm trocar horizontally 2 cm below the xiphoid process; and one 12 mm trocar 2 cm above the umbilicus (Figure 2).
   NOTE: Common surgical instruments used in liver resection include intraoperative laparoscopic ultrasound, Harmonic scalpel, and bipolar coagulation devices.
4. Use intraoperative laparoscopic ultrasound (LUS) to guide the puncture, with ICG for positive staining of the anatomical resection of liver segment S8:
   1. Dissection of surrounding ligaments and identification of P8: Dissect the surrounding ligaments of the right liver lobe and use the LUS probe to identify the portal vein branch for segment 8 (P8), adjusting the puncture position and needle angle as necessary.
   2. Ultrasound probe insertion and positive staining with ICG: Insert the BK laparoscopic ultrasound probe through the 12 mm trocar port. Puncture the P8 with a 21 G percutaneous transhepatic cholangiography (PTC) needle guided by the LUS. Inject 5-10 mL of 1.25% ICG through the needle to stain segment VIII, ensuring no retrograde flow into adjacent segments (Figure 3)
5. Negative staining of the anatomical resection of liver segment S8 via the hilar approach:
   1. Dissection of the S8 hepatic pedicle: Expose the right anterior liver hilum based on the Lannaec membrane between the gate VI and gate V¹⁰. Then, dissect along the ventral side of the right anterior hepatic pedicle and towards the cephalad side on the left to expose the S8 hepatic pedicle; mobilize and lift this pedicle.
   2. Hemostasis and negative staining: After hilum dissection, apply a vascular clamp for hemostasis of the S8 hepatic pedicle (Figure 4) and confirm the ischemic line of segment S8 to include the tumor. Inject 5-10 mL of 1.25% ICG through the peripheral vein. Look for segment VIII that will be delineated by the fluorescence after 5 min (Figure 5).
6. Liver resection guided by fluorescent interface: Monitor fluorescence to confirm that the stained area covers the tumor. Make incisions along the interface between fluorescent and non-fluorescent areas using an ultrasonic scalpel or CUSA, while preserving intersegmental hepatic veins (Figure 6).
   NOTE: Both the tumor and the PT hepatic segment or subsegment can be resected completely in this way.
7. Hemostasis and inspection: Achieve hemostasis by electrocautery or suturing after lesion resection. Inspect the resection site to confirm there is no residual bleeding or bile leakage. On the cross-section, observe the intersegmental veins and the P8 segment end (Figure 7).

Results

Between January 2022 and December 2023, a total of 17 patients underwent hepatectomy of segment S8. Of these, seven cases involved non-anatomical resections, six cases were anatomical resections via the hepatic parenchymal approach, and four cases were portal territory anatomical resections. There were no significant differences in preoperative Child-Pugh scores, tumor size, and liver reserve function among the groups. The surgical time for the PT anatomical resection group was longer than that for the non-anatomical res...

Discussion

The resection of segment S8 of the liver, particularly anatomical resection, remains a significant challenge¹¹. The theoretical basis of portal pedicle-based anatomic hepatectomy has yet to gain widespread acceptance within the hepatic surgical community. Consequently, hepatobiliary surgeons continue to pursue robust clinical evidence to objectively evaluate the therapeutic value of anatomic liver resection. Recent advancements in hepatic anatomical re-conceptualization, particularly regarding Lae...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Bipolar electric coagulation forceps	Mindray	Seal 7	For blood vessel coagulation and division
Fluorescence Endoscopic camera system	Mindray	R1	An endoscopic camera system with 4K fluorescence imaging
Intraoperative Ultrasonic imaging system	ALOKA	UST-5418	With the four-directional flexible linear array ultrasonic laparoscopic transducer, the intraoperative ultrasound support ultrasonic elastography, contrast ultrasound, and magnetic navigation guided puncture
Intraoperative Ultrasonic imaging system	Mindray	LAP13-4Cs	Four-directional flexible linear array ultrasonic laparoscopic transducer which supports support ultrasonic elastography and contrast ultrasound
SPSS 20.0			statistical analysis software
Ultrasonic scalpel	Johnson & Johnson	ETHICON GEN11	For blood vessel coagulation and division