Robotic pancreatic tumor enucleation by the double bipolar technique using the da Vinci SP system: An initial case report with a technical detail

Pancreatic tumor enucleation is a procedure that can preserve pancreatic function and is sometimes performed using a minimally invasive approach. Recently, a single‐port robotic platform called da Vinci SP has been developed. However, the technical details of pancreatic tumor enucleation using da Vinci SP have not been reported to date. We report a male patient in his 70s who underwent robotic SP pancreatic tumor enucleation for a pancreatic neuroendocrine tumor. The dissection between the tumor and pancreatic parenchyma was performed using the double bipolar technique. The operative time was 139 min, and the estimated blood loss was 4 mL. The patient had an uneventful recovery and was discharged on the sixth day after the surgery. Robotic SP pancreatic tumor enucleation appears to be a feasible procedure with lower invasiveness and better cosmesis.


| INTRODUCTION
Pancreatic tumor enucleation is a minimally invasive surgical procedure that can preserve pancreatic function. 1It is often indicated for low malignant tumors of the pancreas.In recent years, reports have emerged on the use of laparoscopic surgery aiming for reduced invasiveness and improved postoperative cosmesis. 2However, pancreatic tumor enucleation is considered a technically challenging procedure that requires delicate dissection between the pancreatic tumor and the pancreatic parenchyma.There is a significant risk of major postoperative complications, such as pancreatic fistula.
To overcome the limitations associated with the laparoscopic approach, robotic surgical systems have been utilized. 3,4Recently, a single-port robotic platform called da Vinci SP has been developed.By utilizing the advantages of da Vinci SP, not only does it can overcome issues such as restricted angles of forceps and hand tremors that are specific to laparoscopic surgery, but it can also improve cosmesis. 5Therefore, the da Vinci SP is expected to be a highly useful surgical support device for pancreatic tumor enucleation.In this report, we present the details of our technique and experience using da Vinci SP for the enucleation of pancreatic body tumors.A male patient in his 70s underwent a routine health examination, during which a pancreatic tumor was incidentally detected.The tumor, measuring 16 mm in diameter, was well-demarcated and hypervascular in the pancreatic body, as confirmed by a contrast-enhanced CT scan.No significant lymph node enlargement was observed in the surrounding area (Figure 1).Based on these findings, a pancreatic neuroendocrine tumor was suspected.No signs suggestive of hormone-producing tumors were observed.
To evaluate the relationship between the tumor and the main pancreatic duct, an endoscopic ultrasound (EUS) examination was performed.The imaging revealed a 5 mm distance between the tumor and the main pancreatic duct, suggesting the possibility of preserving the duct during enucleation.With the aim of facilitating duct preservation and minimizing postoperative complications, an endoscopic retrograde cholangiopancreatography (ERCP) was performed, and a pancreatic duct stent was placed preoperatively.The patient suffered post-ERCP pancreatitis after the stent placement, which was relieved conservatively.To enhance surgical precision and overcome the limitations of conventional minimally invasive techniques, we utilized the da Vinci SP robotic system for the enucleation procedure.

| SURGICAL PROCEDURE
The surgery was performed in the supine position with the head elevated at 10 and an intra-abdominal insufflation pressure of 10 mmHg.A 3 cm incision was made at the umbilicus.The SP Access Port Kit Large was attached, and docking with da Vinci SP was performed.A 12 mm trocar was inserted in the left abdomen as the assistant port.The SP Maryland Bipolar and SP Fenestrated Bipolar forceps were used as right and left graspers, respectively, and a double bipolar technique 6 was employed for dissection.The SP Round Toothed Retractor was used for the retractor arm.
After resection and windowing of the lesser omentum, the tumor in the pancreatic body was visualized.Intraoperative ultrasound examination confirmed the relationship between the tumor and the main pancreatic duct (Figure 2).By applying three-dimensional countertraction using the retraction grasper and left-hand grasper, a delicate dissection plane between the tumor and pancreatic parenchyma was identified.Dissection was carried out using bipolar electrocautery with the Maryland grasper (Figure 3).Suction was performed through the assistant port.The dissection was completed without significant bleeding or injury to the pancreatic parenchyma.The tumor was extracted through the umbilical port, and a drain was placed, which was led out through the assistant port site, concluding the surgery (Figure 4).The total operative time was 139 min, and the estimated blood loss was 4 mL (Video S1).

| POSTOPERATIVE COURSE
The operative time was 139 min.The estimated blood loss was 4 mL.The patient had an uneventful recovery.The patient resumed drinking water from the day after the surgery and restarted meals on the second day after the surgery.Due to the low drainage volume and

| DISCUSSION
3][4] By comparing it to conventional laparotomy, minimally invasive approaches significantly reduce abdominal wall damage and improve cosmesis.However, in laparoscopic surgery, the axis of surgical manipulation is limited by the ports.To achieve appropriate dissection, it is necessary to align the surgical field with the axis of operation by manipulating the tumor and pancreas.However, the pancreas itself is often a fixed organ, making it difficult to maneuver as desired.Overcoming the range of motion restrictions of multi-articulated robotic forceps is considered a significant advantage in pancreatic enucleation, leading to an increasing number of reports on robotassisted surgeries.
Even within the realm of laparoscopic surgery, reduced port surgery, which reduces the number of port incisions, and the ultimate form of single-port surgery have been reported as effective in further reducing abdominal wall damage. 7However, reducing the number of ports in laparoscopic surgery leads to stricter limitations on movement, increasing the technical difficulty.][10][11][12][13] There has been a case series report on its usefulness in pancreatic surgery, including pancreatic enucleation, but the detailed techniques of dissection have not been elucidated. 10We have previously performed various robotassisted surgeries using a double bipolar technique, which utilizes the electric arc discharge that occurs between the tips of bipolar forceps, and reported its usefulness. 6In this case, as well, delicate dissection between the tumor and pancreatic parenchyma using the double bipolar technique was feasible.The pancreas is a highly vascular organ, and in laparoscopic enucleation, energy devices with strong hemostatic capability are often used.The da Vinci SP is a relatively new surgical platform, and a significant drawback of the da Vinci SP system is the absence of available energy devices, such as ultrasonic coagulation devices or vascular sealing devices.The double bipolar technique is applicable to the da Vinci SP system as well, enabling the safe progression of surgery through delicate dissection and cutting maneuvers, thereby avoiding significant bleeding.In the double bipolar technique, it is possible to proceed with the dissection while using the same forceps for detachment and grasping.This approach reduces the need for frequent forceps exchanges and minimizes the required number of forceps, resulting in time and cost savings.The robotic camera provides a magnified view, allowing visualization of the tissue plane that needs to be dissected between the pancreatic parenchyma and the tumor (arrowheads).Tissue dissection is performed by utilizing arc discharges occurring within the gap of the Maryland bipolar forceps.
The preoperative evaluation of the tumor biology is especially important when we consider to choose minimally invasive surgery like pancreatic tumor enucleation.In this case, the preoperative biopsy was not performed.Recently, the usefulness of biopsy by the EUS fine needle aspiration (EUS-FNA) for pancreatic neuroendocrine tumors has been reported. 14Although the accuracy of grading diagnosis for small tumors is still controversial, 15 important information about tumor biology can be obtained by EUS-FNA.Considering the final pathological diagnosis of a Grade 2 tumor, pancreatic tumor enucleation might be considered a more conservative procedure than the standard recommended surgery.If findings suggestive of a high grade on the preoperative biopsy had been observed, there was a possibility that pancreatic tumor enucleation might not have been chosen for this patient.There is a possibility that at least a search for metastasis through lymph node sampling should have been conducted, and we acknowledge this as a point for reflection.
In conclusion, we demonstrated the successful use of the da Vinci SP robotic system for pancreatic tumor enucleation.Robot-assisted enucleation using da Vinci SP holds promise as a valuable surgical approach for selected cases of pancreatic tumors.At the moment, the robotic pancreatic tumor enucleation is not covered by the health insurance system in Japan, so this operation was performed at the patient's expense.Further studies are warranted to validate its benefits and establish its role in clinical practice.

CONFLICT OF INTEREST STATEMENT
Payment or activities from a third party for any aspect of the submitted work.Ichiro Uyama has received consulting fees and payment for the lectures from Intuitive Surgical.Ichiro Uyama is a member of the advisory board of Intuitive Surgical.Yuichiro Uchida and Takeshi Takahara have received payment for the lectures from Intuitive Surgical.Relevant financial activities outside the submitted work.Ichiro Uyama has received a consulting fee and payment for the lectures from Medtronic.Ichiro Uyama is a member of the advisory board of Medtronic.To minimize bias, they were excluded from all editorial decision-making related to the acceptance of this article for publication.Other authors declare no conflict of interest.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available on request from the corresponding author.The data are not publicly available due to privacy or ethical restrictions.

ETHICS STATEMENT
The institutional review board approved the study protocol (approval number: HM19-064).Written informed consent about this study was obtained from the patient.

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I G U R E 1 Contrast-enhanced CT imaging of tumor.A welldemarcated and hypervascular tumor in the pancreatic body surface was identified (arrowheads).

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I G U R E 2 Intraoperative ultrasonographic image of the tumor.Well-demarcated tumors (arrowheads) and the main pancreatic duct with an inside stent (arrow) were identified.low amylase levels, the drain was removed on the third day, and the patient was discharged on the sixth day after the surgery.No complications were observed.Pathological examination confirmed the complete resection of the tumor with the diagnosis of a pancreatic neuroendocrine tumor Grade 2 (Ki-67 labeling index 8.9%, mitotic count 16/50 high power field, hormonal status negative).

F I G U R E 4
Wound after procedure.The umbilical wound was 3 cm in length.The intra-abdominal drain was led out through the assistant port site.F I G U R E 3 Robotic dissection using double bipolar technique.The retraction arm holds the gauze (arrow) and pushes the pancreatic parenchyma toward the lower left corner of the screen.Meanwhile, the left-hand fenestrated bipolar forceps apply appropriate countertraction by pushing the tumor to the right side.
Ichiro Uyama was funded by Medicaloid in relation to the Collaborative Laboratory for Research and Development in Advanced Surgical Treatment, Fujita Health University.Koichi Suda was funded by Sysmex, Co. in relation to the Collaborative Laboratory for Research and Development in Advanced Surgical Intelligence, Fujita Health University.Koichi Suda is an Editorial Board member of ASES Journal and a co-author of this article.