Robotic Thymectomy Using the Single-Port Robotic System via the Subxiphoid Approach

Abstract

Technological advances have led to significant progress in minimally invasive surgery in the field of general thoracic surgery. Thymectomy, which has traditionally been performed via an open approach through a median sternotomy, is now entering a new era because of the advantages offered by robot-assisted thoracic surgery. Robotic thymectomy using the single-port robotic system via the subxiphoid approach has recently been introduced. This innovative technique offers several potential benefits, including reduced postoperative pain, faster recovery, and improved cosmetic outcomes. However, it can be technically challenging during the early phase, especially for less experienced robotic surgeons. In this study, we present our surgical technique in detail, providing tips and highlighting potential pitfalls to aid in overcoming these technical challenges.

Introduction

Robotic thymectomy is now widely accepted as an alternative to median sternotomy and video-assisted thoracoscopic surgery (VATS) thymectomy for the treatment of thymic epithelial tumors and myasthenia gravis. This approach offers several advantages, including enhanced visualization and superior instrument maneuverability, which facilitate more precise and delicate dissection during thymectomy [1]. Recent studies have demonstrated that robotic thymectomy delivers superior perioperative outcomes while maintaining long-term oncological results comparable to those of open thymectomy [2,3]. Conventional robotic thymectomy, initially performed with a multiport technique using either a subxiphoid or transthoracic approach, has evolved to become increasingly minimally invasive through advances in technology and surgical methods [4].

Robotic thymectomy using the da Vinci single-port (SP) robotic system (Intuitive Surgical Inc.) via the subxiphoid approach represents a significant innovation. The da Vinci SP system is specifically designed for SP surgery. South Korea was the first country to approve its use in general thoracic surgery, facilitating its adoption across various surgical procedures, including thymectomy [5-8]. This approach may yield improved cosmetic results, reduced postoperative pain, and faster recovery. Although long-term outcomes remain to be established, we previously reported superior short-term outcomes [9]. In this review, we present this technique as used at Korea University Guro Hospital from the learner’s perspective.

Patient selection

Based on our institutional experience, the indications and contraindications for robotic thymectomy using the SP robotic system mirror those of conventional minimally invasive thymectomy [9-11]. Tumor invasion into the pericardium, lung, innominate vein, or phrenic nerve is not a contraindication, and such tumors can be safely resected with the SP system. However, invasion of the great vessels, excluding the innominate vein, is considered a contraindication. A history of radiotherapy and a tumor exceeding 8 cm are regarded as relative contraindications.

Obesity is not a contraindication for the subxiphoid approach; however, gaining experience with lean patients can facilitate the initial learning phase. Additionally, certain anatomical variations, such as an elongated or posteriorly curved xiphoid process or pectus excavatum, may pose challenges when using this approach.

Surgical procedure: step by step

Supplementary Video 1 provides a detailed, step-by-step overview of the procedural workflow for robotic thymectomy using the SP robotic system via a subxiphoid approach.

Step 1: Patient positioning and port mapping

The patient is placed in the supine position with lumbar extension and hips flexed and abducted (frog-leg position) to minimize collisions or pressure from the SP robotic system (Fig. 1A). One-lung ventilation is not routinely applied, except when the tumor invades adjacent structures. A vertical subxiphoid incision is preferred to facilitate emergency conversion to median sternotomy if necessary. A 2.5–3 cm incision is made 1–2 cm caudal to the xiphoid process without resection (Fig. 1B). An additional port is not routinely created. However, if stapler insertion proves difficult or intermittent suction is required, an auxiliary 12-mm port may be created in the sixth or seventh intercostal space along the midclavicular line, depending on the location of the lesion.

Fig. 1.

Patient positioning and port mapping. (A) The patient in the supine position with lumbar extension. (B) Incision for the subxiphoid approach. The 2.5–3 cm incision is made 1–2 cm caudal to the xiphoid process. Additional port sites, when necessary, are indicated by an “X.”

Step 2: Creation of the subxiphoid tunnel and floating dock technique

The tissues surrounding the incision are carefully dissected to create adequate space for the wound retractor. The subcutaneous fat is meticulously separated from the linea alba to avoid inadvertent peritoneal injury. Extensive blunt dissection is then performed in the preperitoneal space and along the sternal attachment of the diaphragm. Subsequently, the SP access port (Intuitive Surgical Inc.) is inserted through the incision, and carbon dioxide (CO₂) is insufflated to 6–10 mm Hg.

In the da Vinci SP system, proper robotic arm articulation requires at least 10 cm of clearance from the cannula tip. Consequently, instrument movement may be constrained in areas near the incision site. To overcome this limitation, the floating dock technique suspends the cannula tip above the incision, thereby optimizing articulation and maneuverability (Fig. 2). Additionally, the cannula in the SP access port is shorter than a conventional metal cannula, permitting surgical maneuvers closer to the incision.

Fig. 2.

Floating dock technique using the multichannel SP access port (Intuitive Surgical Inc.). The red dotted line indicates the position of the cannula tip.

Step 3: Initial setup of the SP robotic system

The da Vinci SP patient cart is positioned on the patient’s right side. At the beginning of the procedure, the robotic endoscope is placed in the 6 o’clock position using the below mode, and because of the limited working space during the mediastinal pleura opening, only 2 robotic arms are preferably used. During the initial phase, the configuration of the robotic arms and their corresponding instruments is as follows (Fig. 3): (1) Lower middle hole: SP robotic endoscope; (2) Arm 1: Maryland bipolar forceps; (3) Arm 2: Unoccupied or Cadiere forceps; and (4) Arm 3: Monopolar cautery instrument.

Fig. 3.

(A, B) Setup of the single-port robotic surgical system during the early phase of the procedure. The lower middle port is used for the single-port robotic endoscope; arm 1 is equipped with Maryland bipolar forceps and arm 3 with a monopolar cautery instrument.

Step 4: Bilateral pleura opening and retrosternal dissection

The surgical procedure is similar to that of robotic thymectomy using the Xi system via the subxiphoid approach. After the connective tissue is dissected beneath the xiphoid process, the bilateral mediastinal pleura is opened to the level of the innominate vein. Once opened, the tissue depresses downward, thereby improving the surgical view. However, caution is required, as a sudden drop in blood pressure may occur. The thymus and adjacent tissues are then maximally dissected in a caudal‐to‐cranial direction to progressively expand the retrosternal working space.

Step 5: Dissection of the inferior pole

During the later phase, the robotic scope is repositioned to the upper middle position using the above mode. The arm configuration is then adjusted as follows (Fig. 4): (1) Upper middle hole: SP robotic endoscope; (2) Arm 1: Maryland bipolar forceps; (3) Arm 2: Cadiere forceps; and (4) Arm 3: Monopolar cautery instrument.

Fig. 4.

(A, B) Setup of the single-port robotic surgical system during the late phase of the procedure. The upper middle port is used for the single-port robotic endoscope; arm 1 is equipped with Maryland bipolar forceps, arm 2 with Cadiere forceps, and arm 3 with a monopolar cautery instrument.

After the bilateral cardiophrenic angles are identified, the bilateral inferior poles of the thymus are fully dissected. The inferior pole is separated from the pericardium from right to left, initially targeting the pericardial fat that envelops the thymic gland. While dissecting the right pericardial fat, a tunnel is fashioned by separating its base from the pericardium (Fig. 5A). Following completion of the right-sided dissection, an analogous tunneling maneuver is applied to the base of the left pericardial fat. The dissection then continues upward from the inferior pole (Fig. 5B). The procedure is performed in the sequence indicated by the arrows in Fig. 5. This technique enables safe identification of the phrenic nerves and facilitates smoother dissection of the thymic inferior poles.

Fig. 5.

Surgical sequence, as indicated by the arrows. (A) Tunneling of the right lower pole. (B) Tunneling of the left lower pole.

Step 6: Identification of the phrenic nerve

The phrenic nerve is first identified as a key landmark, guiding the lateral margin of dissection (Fig. 6). Using robotic arm 2, the thymus and its surrounding tissue are retracted medially toward the medial aspect of the nerve as dissection proceeds. The use of monopolar electrocautery should be minimized when working adjacent to the phrenic nerve. If the tumor is close to or invades the nerve, monopolar curved scissors may be preferable to cautery. Dissection of the thymus and adjacent tissues then continues cranially along the pericardium until the innominate vein is recognized as the second landmark.

Fig. 6.

Surgical view through the subxiphoid approach using the single-port robotic system, showing both phrenic nerves. (A) Right phrenic nerve. (B) Left phrenic nerve.

Step 7: Dissection of the superior pole

Superior pole dissection is the most challenging and delicate phase of thymectomy. As with the inferior pole, creating a tunnel at the base of the superior pole facilitates a safer, more convenient surgical approach (Fig. 5B). A clear surgical view is crucial, and the greatest advantage of robotic thymectomy over VATS is its superior visualization during this step (Fig. 7). Proper positioning of the robotic endoscope is essential, and gentle caudal traction is applied via robotic arm 2. Dissection typically begins on the right superior pole, followed by the left. Care should be taken to preserve the integrity of the thymic capsule as dissection continues down to the thyrothymic ligament.

Fig. 7.

Dissection of the superior pole. (A) Intraoperative view during superior pole dissection. (B) Operative field after specimen removal.

The final step, dissection of the thymic vessels from the innominate vein, is associated with greater safety and feasibility. Meticulous exposure of the vessels is essential to avoid injury. Because the da Vinci SP system currently lacks a dedicated energy device, most thymic vessels are secured with robotic Hem-o-lok clips. When vessels are divided without clips or an energy device, bleeding rarely occurs once CO₂ insufflation is stopped. Therefore, robotic Hem-o-lok clips are preferred. The inferior thyroid vein is preserved whenever possible and is not routinely divided.

Step 8: Specimen removal and chest drainage insertion

After dissection is completed, robotic arm 3 is removed to provide adequate space for insertion of the retrieval bag. The thymic specimen is placed in the bag and extracted from the body without requiring an additional incision (Fig. 8A). The subxiphoid route facilitates easier specimen removal compared with the transthoracic approach. Two Jackson-Pratt drains (Evacuator Barovac, 100 mL; Sewoon Medical Co.) are then introduced into each pleural cavity via the working port, again avoiding further incisions. Finally, the wound is closed in a layer-by-layer fashion (Fig. 8B).

Fig. 8.

Findings following completion of the procedure. (A) Extracted specimen. (B) Surgical wound (2.5 cm) with 2 Barovac drains in place.

Surgical tips and pitfalls

For thymectomy, positioning the Cadiere forceps in arm 2 to provide traction and stabilization while simultaneously using arms 1 and 3 for dissection increases surgical efficiency and minimizes the risk of instrument collision. This configuration is especially advantageous during the initial learning phase of the SP robotic system.

We do not routinely employ a sternal elevation retractor or remove the xiphoid process. Instead, CO₂ gas insufflation is used to depress the pericardium and adjacent tissues, thus creating sufficient surgical space. This improves the surgical field and helps prevent inadvertent injury. However, in patients with pectus excavatum, CO₂ insufflation alone may be insufficient to expand the retrosternal area; in these cases, the use of a sternal elevator may be helpful. Although blood loss during thymectomy is usually minimal, CO₂ insufflation can cause hemodynamic instability due to vessel compression.

The left phrenic nerve runs across the pericardium and may be obscured by the heart’s position. To optimize visualization of this nerve, the endoscopic camera should be set to “Cobra” mode, positioned above the surgical field, and then tilted diagonally downward toward the 1–2 o’clock orientation. If the nerve remains obscured, gentle cardiac compression can be applied. If its position remains unclear, an intravenous injection of 12.5 mg of indocyanine green can be administered to identify the pericardiophrenic vessels, which run parallel to the phrenic nerve [12].

Literature review

Although the SP robotic system has gained popularity, clinical evidence validating its use remains limited. To identify the most recent data on robotic thymectomy using the SP robotic system via a subxiphoid approach, a literature review was conducted by systematically searching the MEDLINE and Embase databases. Ultimately, five studies were selected for inclusion in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Table 1 summarizes SP robotic system via a subxiphoid approach. All studies demonstrated the technique’s feasibility and safety, with a 0% conversion rate to open thymectomy. Moreover, SP robotic thymectomy was associated with a lower conversion rate to multiport surgery, a shorter chest tube duration, and a reduced postoperative hospital stay compared with SP VATS thymectomy. The primary limitation is the lack of long-term oncological outcomes, as the SP system was only recently approved for use in general thoracic surgery. Additional large-scale randomized controlled trials are warranted to establish the clinical efficacy of this method.

Table 1.

Summary of recent studies reporting robotic thymectomy using the single-port robotic system via the subxiphoid approach

Author (year)	No. of cases	Study design	Total operative time (min)	Hospital stay (day)	Conversion to open thymectomy
Park et al. [5] (2022)	17	Retrospective, multicenter, double-arm	120 (58–250)	3 (2–7)	0
Lee et al. [6] (2024)	41	Retrospective, single-center, single-arm	152.9±61.7	2.9±1.0a)	0
Lee et al. [9] (2024)	85	Retrospective, multicenter, double-arm	154.46±74.06	2.87±1.26a)	0
Kim et al. [7] (2024)	14	Retrospective, single-center, single-arm	135 (113–155)	3 (2–3)	0
Marshall et al. [8] (2024)	13	Prospective, multicenter, single-arm	173.0 (145.0–238.0)	2.0 (1.0–2.0)	0

Values are presented as number, median (interquartile range), or mean±standard deviation.

^a)Postoperative hospitalization.

Discussion

Conventional open thymectomy via median sternotomy has long been the standard approach due to the excellent surgical view it provides. However, advances in technology and surgical techniques have enabled minimally invasive thymectomy to emerge as a viable alternative [13]. Current guidelines have not yet endorsed minimally invasive thymectomy as the standard of care; however, as more clinical evidence supporting this approach becomes available, recommendations are expected to evolve accordingly.

The most innovative development in recent years is robotic thymectomy using the SP system via the subxiphoid approach. This technique offers a good surgical view, particularly by incorporating the bilateral phrenic nerves, making it a promising alternative to conventional methods [9]. It also provides excellent visualization of the area beneath the left innominate vein, facilitating the complete removal of ectopic thymic tissue. Moreover, in patients with myasthenia gravis, this approach enables extended thymectomy by permitting total resection of the lower inferior pole and surrounding fat tissue.

Traction with a single robotic arm, while using two robotic arms for dissection in a confined space, appears to be a rational and efficient technique that eliminates the need for additional assistance. Consequently, thymectomy may serve as an ideal introductory procedure for surgeons adopting the SP robotic system. This system’s current lack of a dedicated energy device and robotic stapler represents a limitation; however, these technical constraints are expected to be addressed with future advancements [14]. Moreover, by requiring only a single 2.5–3 cm abdominal incision, this approach minimizes intercostal nerve damage, resulting in reduced postoperative pain, faster recovery, and superior cosmetic outcomes from this minimally invasive technique.

The subxiphoid approach remains infrequently adopted by thoracic surgeons, and maneuvering 3 robotic arms alongside a single flexible robotic endoscope without collision can be particularly challenging, especially during the early learning phase. Nonetheless, all novel surgical techniques pose initial difficulties, and implementing appropriate changes is essential for improving surgical outcomes and quality of care. Although concerns may arise regarding the potentially steep learning curve associated with this technique, no studies to date have formally evaluated this aspect. Thus, a comparative analysis of the learning curves for subxiphoid SP robotic thymectomy versus conventional VATS and robotic-assisted thoracoscopic surgery (RATS) is warranted.

The studies summarized in Table 1 consistently demonstrate the feasibility and favorable short-term outcomes of robotic thymectomy using the SP robotic system via the subxiphoid approach. However, our literature review identified several associated limitations. First, most studies were retrospective with small sample sizes, and none included long-term oncologic outcomes. Second, heterogeneity in patient selection criteria, institutional experience, and surgical technique limits the generalizability of these findings. For instance, although our multi-institutional analysis revealed superior perioperative outcomes compared with SP VATS thymectomy, this may reflect selection bias toward patients with less complex pathology or more accessible anatomy. Finally, the absence of randomized controlled trials makes it difficult to definitively establish this technique’s equivalence or superiority relative to conventional multiport RATS or open surgery. Therefore, while current evidence supports the technical feasibility of this approach, further high-quality prospective studies are necessary to confirm its oncologic adequacy and long-term efficacy.

Conclusion

Robotic thymectomy using the SP robotic system via a subxiphoid approach is technically feasible and straightforward to perform. In the future, it may serve as an alternative to both conventional open and traditional minimally invasive thymectomy. By reviewing the existing literature alongside this report, beginners can master this new technique in a stepwise manner.

Supplementary materials

Supplementary materials can be found via https://doi.org/10.5090/jcs.25.041. Supplementary Video 1. Robotic thymectomy using the single-port robotic system via the subxiphoid approach.

Funding Statement

Funding This research was supported by a grant from the Korea-US Collaborative Research Fund (KUCRF), funded by the Ministry of Science and ICT and the Ministry of Health & Welfare, Republic of Korea (No., RS-2024-00466887); the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (No., RS-2024-00436472) and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No., RS-2025-00518091).