Application of Modified Single-Incision Technique for Fluorescence-Guided Laparoscopic Cholecystectomy

Gallstones affect approximately 20% of the global population, representing a significant worldwide health burden¹. Cholecystectomy remains the gold-standard treatment for gallstones. Since laparoscopic cholecystectomy (LC) became the mainstream approach in the 1990s, minimally invasive techniques have continued to evolve, particularly over the past decade, driven by innovations in surgical instrumentation and imaging technology².

With the advancement of minimally invasive techniques, single-incision laparoscopic cholecystectomy (SILC) has emerged as a promising approach, offering superior postoperative pain control and cosmetic outcomes³. However, its widespread adoption remains hindered by the inherent chopstick effect. Unlike conventional laparoscopic surgery's inverted-triangle workspace, SILC requires all instruments and the camera to share a single port, leading to frequent instrument collisions and compromised visualization -- factors that collectively elevate procedural risks. Studies suggest this configuration may prolong operative time, increase the risk of biliary tract injury, and elevate the incidence of postoperative incisional hernias^4,5,6. Furthermore, the altered ergonomics and constrained working space necessitate a steeper learning curve for surgeons. Current SILC innovation is thus centered on a critical challenge: how to retain the minimally invasive benefits of a single-port approach while mitigating its spatial limitations.

Recently, near-infrared fluorescence imaging with indocyanine green (ICG-NIRF) has gained widespread adoption in hepatobiliary surgery^7,8,9. Clinical studies demonstrate that ICG-NIRF significantly improves surgical outcomes compared to conventional white-light imaging: it reduces postoperative adverse events from 12.8% to 6.4%, decreases mean operative time by 7.5 min, and substantially lowers conversion rates to open surgery in technically challenging cases -- particularly those involving acute inflammation, obesity, or Mirizzi syndrome¹⁰. These demonstrated benefits establish a solid foundation for combining ICG-NIRF with the single-incision technique to address its inherent technical limitations.

Inspired by these findings, our center developed an innovative modified SILC plus ICG-NIRF technique, building upon conventional SILC. This approach maintains a 2.5 cm umbilical incision as the primary working port while incorporating a subxiphoid micro-incision for electrocautery hook insertion. The modification requires no additional trocars and preserves stable CO₂ pneumoperitoneum.

By externalizing the energy device, this technique significantly reduces instrument crowding within the umbilical port. Surgeons regain the ergonomic benefits of traditional triangular instrument arrangement, facilitating more intuitive retraction, coagulation, and dissection. The familiar configuration enables a seamless transition from standard laparoscopic cholecystectomy to SILC, while preserving the minimally invasive and cosmetic advantages of single-port surgery (Figure 1A-B).

The integration of ICG-NIRF fluorescence imaging provides dual benefits: enhanced biliary tree visualization and improved surgical field exposure (Figure 1C-D). This combination proves particularly valuable in managing complex cases involving inflammation, obesity, or anatomical variations, where it substantially reduces the risk of iatrogenic injury. In our preliminary clinical application involving 31 patients, the technique demonstrated promising outcomes, including a mean operative time of 63.3 ± 17.9 min, minimal blood loss (6.2 ± 4.9 mL), and a short postoperative hospital stay (2.2 ± 1.0 days). No bile duct injury or conversion to open surgery occurred, with only one case of post-operative fever. These quantitative results strengthen the rationale for adopting this integrated approach.

This study aims to further evaluate the clinical efficacy of the modified operation and confirm the reproducibility and broad applicability of this modification.

Written informed consent has been obtained from the patient for performing this study. This research was performed in compliance with the guidelines of the human research ethics committee of the Fifth Affiliated Hospital of Sun Yat-sen University. All human biological materials and surgical waste were handled in accordance with institutional biomedical waste disposal protocols.

1. Patient selection and preoperative preparation

1. Patient inclusion and exclusion criteria: Include elective patients with benign gallbladder disease who have cosmetic concerns or desire reduced postoperative pain, with ASA class I-II. Exclude patients with acute severe cholecystitis, biliary duct stones, a history of upper abdominal surgery, suspected malignancy, severe comorbidities, or umbilical infection.
2. Preoperative preparation involved a standard workup. Perform clinical assessment, laboratory tests (complete blood count, liver/renal function, coagulation, etc.), non-contrast computed tomography (CT) of the upper abdomen, pre-anesthesia evaluation, prophylactic antibiotic administration, and preoperative fasting.

2. Fluorescence imaging

1. Dissolve 1 vial of ICG (25 mg) in 10 mL of normal saline. Subsequently, inject 1 mL of the solution into 100 mL of normal saline for dilution. Finally, administer an intravenous injection of 10 mL of the final diluted solution (0.25 mg ICG) to the patient 45 min before the surgery¹¹.
2. Set up the DPM-I fluorescence system, a dual-channel image-guided device, operating in white-light (380-665 nm) and near-infrared (810-1,200 nm) spectrums¹¹.
   NOTE: It is recommended to configure the fluorescence system at a medium initial sensitivity level and adjust the signal sensitivity in real time during surgery according to the visualization outcome.
3. Under white light mode, aim the laparoscope at a pure white sterile gauze and press the white balance button. Then, aim the laparoscope at a target with a clear texture (such as gauze) and adjust the focus.

3. Modified single-port trocar advancement

1. Position the patient in a supine position. After administering general anesthesia, identify the surgical sites for the modified SILC procedure: the umbilicus, for the primary 2.5 cm single-incision port, and the subxiphoid area, for the anticipated 3 mm micro-incision.
2. Shave and thoroughly sterilize the entire abdominal field from the xiphoid process to the pubic symphysis to accommodate both access points. Complete all necessary aseptic procedures, including wearing a surgical hood and sterile gloves. Finally, create a sterile field using sterile drapes centered on the umbilicus and encompassing the subxiphoid area.
3. Make a 2.5 cm supraumbilical incision through the skin and fascia using a pointed-tip blade. Then, place the single-incision laparoscopic device and establish pneumoperitoneum at 11-13 mmHg (Figure 2A).
4. Make a stab incision 2 cm inferior to the xiphoid process using a scalpel, then insert the electrocautery hook (Figure 2B). No additional trocar is required. Insert the electrocautery hook under continuous coagulation to prevent bleeding.

4. Gallbladder suspension

1. Fix a suture to the gallbladder's fundus-body junction using a Hem-o-lok clip. Insert a single-use suture passer at the body surface projection of the gallbladder (Figure 2C).
2. Grasp the suture, then elevate and fix the gallbladder to the abdominal wall (Figure 2D).

5. Exposure of Calot's triangle

1. Dissect Calot's triangle using an electrocautery hook to achieve the Critical View of Safety (CVS)¹². The dissection is considered complete when the following criteria are met: (1) the hepatocystic triangle is cleared of fat and fibrous tissue, (2) the lower one-third of the gallbladder is separated from the liver bed, and (3) only two structures -- the cystic duct and the cystic artery -- are seen entering the gallbladder.
2. Switch to fluorescence mode and proceed with the dissection of Calot's triangle under fluorescent guidance (Figure 2E). If obscured anatomy, active bleeding, or suspected biliary injury occurs, convert to multiport laparoscopy or open surgery immediately.
3. Isolate the cystic artery, then ligate its proximal end with a Hem-o-lok clip. Subsequently, divide the artery completely into a single action using the electrocautery hook between the clip and the gallbladder.

6. Removal of the gallbladder

1. Dissect the gallbladder from its fossa (Figure 2F). Isolate the cystic duct. Apply two Hem-o-lok clips proximally (close to the common bile duct) and one clip distally (close to the gallbladder). Then, sharply divide the cystic duct completely into a single cut with scissors between the proximal and distal clips.
2. Place the gallbladder into a specimen retrieval bag and extract it from the abdominal cavity. Place a drainage tube through the umbilical incision in cases of severe local inflammation, suspected bleeding, or bile leakage.

7. Post-operative procedures

1. Suture the umbilical incision subcutaneously, followed by a cosmetic intradermal closure with 4-0 polyglactin. The subxiphoid incision for electrocautery hook insertion requires only one or two intradermal stitches.
2. Submit the gallbladder specimen for pathological biopsy. Recheck inflammatory markers and liver function tests on postoperative day 2.
3. Remove the drainage tube when the drainage is clear and less than 20 mL per day. This completes the fluorescence-guided modified SILC procedure.

Between August and December 2024, a total of 31 cases of fluorescence-guided modified single-port LC were recorded in our center, with demographic data presented in Table 1. Among these, 28 cases were successfully completed, while 3 cases were converted to conventional multi-port LC (2 due to inadequate exposure of the Calot's triangle and 1 due to severe inflammatory adhesions discovered during the procedure), resulting in a success rate of 90% (28/31). Peri-operative patient outcomes are summarized in Table 2. The mean operative time was 63.3 ± 17.9 min, with an estimated blood loss of 6.2 ± 4.9 mL and a post-operative hospital stay of 2.2 ± 1.0 days. One case of post-operative fever was observed. There were no conversions to open surgery or occurrences of bile duct injury.

These outcomes effectively establish the practical benefits of our modified technique. The procedure was not only feasible with a high success rate but also efficient and safe, as evidenced by the short operative times, minimal blood loss, and absence of major complications. This supports our premise that the integration of a subxiphoid micro-incision and fluorescence guidance can overcome the technical challenges of traditional SILC, making single-port cholecystectomy safer and more accessible.

Figure 1: Representative intra-operative and post-operative views. (A) Wound appearance after conventional four-port LC. (B) Wound appearance after modified SILC: an umbilical incision combined with a small subxiphoid incision. (C) View of Calot's triangle under white-light imaging, where bile ducts are hidden under adipose tissue. (D) Fluorescence imaging of Calot's triangle, enabling visualization of bile ducts before dissection. Please click here to view a larger version of this figure.

Figure 2: Fluorescence-guided modified SILC procedure. (A) Make a 2.5 cm supraumbilical incision and place the single-incision laparoscopic device. (B) Insert the electrocautery hook with continuous coagulation 2 cm inferior to the xiphoid process. (C) Insert a single-use suture passer at the body surface projection of the gallbladder. (D) Suspend the gallbladder. (E) Dissect Calot's triangle following fluorescence navigation. (F) Remove the gallbladder from its fossa. Please click here to view a larger version of this figure.

Table 1: Demographic data of the patients.

Table 2: Peri-operative outcomes of the patients.

LC is the traditional gold-standard surgical approach for benign gallbladder diseases¹³. With the ongoing advancement of minimally invasive surgical techniques, SILC has emerged, aiming to further reduce postoperative pain and improve cosmetic outcomes for patients^3,14. However, single-incision laparoscopic techniques present several challenges, including the chopstick effect -- caused by the parallel arrangement of instruments through the umbilical port -- which complicates surgical manipulation, instrument collision due to the confined incision space, and difficulty in achieving the CVS^15,16,17. SILC demands higher surgical expertise and has a steeper learning curve compared to conventional multi-port LC. Several previous studies have shown that SILC is associated with longer operative time^18,19,20, as well as increased risks of bile duct injury and incisional hernia^5,6.

To preserve the minimally invasive advantages of SILC while minimizing inadvertent injuries and shortening the learning curve, our center has progressively developed a fluorescence-guided modified single-incision laparoscopic cholecystectomy technique. Between August and December 2024, a total of 31 cases of fluorescence-guided modified SILC were recorded in our center, with a success rate of 90% (28/31), which is comparable to rates reported in previous studies (92%~94%)^19,21. There were no conversions to open surgery or occurrences of bile duct injury.

The key advantages of this technique are as follows: Subxiphoid placement of the electrocautery hook conforms to most surgeons' operating habits, effectively overcoming the chopstick effect associated with SILC. This modification demonstrates the potential to reduce operative time and may contribute to minimizing iatrogenic injuries to blood vessels and biliary structures. Preservation of single-incision benefits: Surgical trauma remains comparable to that of conventional SILC. Although requiring an additional small incision (in addition to the umbilical port), this heals rapidly without compromising the minimally invasive nature. This approach contributes to reduced postoperative pain and superior cosmetic results. ICG fluorescence navigation provides real-time biliary visualization, further enhancing procedural safety by ensuring clear anatomical identification. To secure the CVS, visualization of Calot's triangle is the most important step in laparoscopic cholecystectomy²². ICG fluorescence navigation represents an emerging intraoperative visualization technique^8,23. Through extensive preliminary experimentation, the ICG administration protocol was optimized as follows: intravenous injection of 0.25 mg ICG administered 45 minutes preoperatively¹¹. Under these parameters, the technique enables timely and clear visualization of extrahepatic bile ducts while minimizing hepatic background fluorescence interference. This optimized approach facilitates more effective achievement of the CVS^24,25, decreases operative time and conversion rates^25,26, helps prevent vascular and biliary injuries^8,27, along with a reduction in post-operative hospital stay^9,28.

While the modified single-port LC technique offers clear minimally invasive advantages, ensuring efficient gallbladder removal and minimizing iatrogenic injury remain the foremost priorities. Careful patient selection is crucial, the pre-operative identification of risk factors, such as high BMI^29,30, gangrenous cholecystitis³¹, Mirizzi syndrome³², or a history of upper abdominal surgery³³ -- serves as an indicator of heightened surgical complexity, demanding either an experienced senior surgeon or due consideration of a multi-port approach initially.

Intra-operatively, the following findings represent common indications for conversion to additional trocar placement: Inability to achieve a CVS due to severe inflammation or fibrotic adhesions in Calot's triangle; Uncontrolled bleeding from the cystic artery or liver bed; suspected or confirmed bile duct injury. In such situations, timely conversion -- by adding one or more strategically placed trocars -- should be considered a prudent and standard surgical strategy rather than a failure, ensuring both patient safety and the successful completion of the procedure.

In conclusion, the fluorescence-guided modified SILC represents a feasible and effective surgical approach. It successfully preserves the cosmetic and minimally invasive benefits of single-port surgery while overcoming the technical challenges and high risk of iatrogenic injury inherent to conventional SILC. The clear visual guidance provided by ICG fluorescence helps standardize the critical steps of dissection, which may shorten the learning curve for surgeons adopting this technique. To further validate these advantages, our center plans to initiate a subsequent study with a larger sample size to directly compare this novel technique against traditional SILC, which we believe will firmly establish its significant potential for broader clinical application.