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Title: Feasibility and Safety of Pure Single-Port Robotic Surgery Using the "Integrated Functional Assistant Port" (iFAP) Technique: A Retrospective Cohort StudyAffiliations:
Authors: Young Hwii Ko,1 Jae Youn Jang,2 Yeong Uk Kim3
Title page
Running title: Integrated Functional Assistant Port (iFAP) for SP Surgery
1Department of Urology, Ewha Womans University Mokdong Hospital, Seoul, Korea
2Department of Urology, Daegu Fatima hospital, Daegu, Korea
3 Department of Urology, College of Medicine, Yeungnam University, Daegu, Korea
Corresponding author
Young Hwii Ko
1Department of Urology, Ewha Womans University Mokdong Hospital, Seoul, Korea
Tel: +82-10-7301-4570, Fax: +82.53-627-5535, E-mail: urokyh@naver.com
Word count of abstract
239
Word count of text
1966
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Acknowledgement
The authors thank Yewoon Ko (Department of Communication Design, Dankook University, Gyeonggi-do, Republic of Korea) for assistance with the illustration of Figure 1.
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Author Contribution
Conceptualization: YHKData curation: YHK, JYJFormal analysis: YUKFunding acquisition: YHKInvestigation: YUKMethodology: JYJProject administration: YHKResources: YHKSoftware: YHKSupervision: YHKValidation: JYJ, YUKVisualization: YHKWriting – original draft: YHKWriting – review & editing: YHK, JYJAuthor’s disclosure The authors have no conflict of interest in this article.
Data curation: YHK, JYJ
Formal analysis: YUK
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Funding
acquisition: YHK
Investigation: YUK
Methodology: JYJ
Project administration: YHK
Resources: YHK
Software: YHK
Supervision: YHK
Validation: JYJ, YUK
Visualization: YHK
Writing – original draft: YHK
Writing – review & editing: YHK, JYJ
Author’s disclosure
The authors have no conflict of interest in this article.
Funding
This study was supported by Korea Health Industry Development Institute (RS-2023-00262969)
Abstract
Minimally invasive urologic surgery continues to evolve with the adoption of the da Vinci SP® single-port system. However, the lack of effective bedside assistance in "pure" single-port surgery often necessitates an additional "plus-one" incision or relies on flexible instruments with limited functionality. We describe the "Integrated Functional Assistant Port" (iFAP) technique, which incorporates a rigid laparoscopic trocar within a single multi-channel access platform, and evaluate its feasibility and safety. This retrospective cohort study included 60 consecutive patients who underwent pure single-port robot-assisted surgery using the iFAP technique between September 2023 and January 2025. Procedures included partial nephrectomy (RAPN), adrenalectomy, and nephroureterectomy. The iFAP technique involved inserting a standard rigid trocar alongside the robotic cannula through a single umbilical or flank incision. All procedures were successfully completed without conversion. Mean docking and console times were 12.6 ± 6.6 min and 102.4 ± 51.9 min, respectively. The iFAP technique provided stable pneumoperitoneum and effective smoke evacuation. Perioperative complications occurred in 3.3% of patients (one incisional hernia, one ileus), both in the RAPN group. In RAPN subgroup analysis, moderate complexity tumors (RENAL score 7–9) showed longer warm ischemic times than low complexity tumors (26.2 vs. 23.4 min; p = 0.007) but equivalent complication rates. The iFAP technique is a safe and feasible modification that overcomes the functional limitations of pure single-port surgery. By enabling robust rigid assistance within a single incision, it preserves the cosmetic benefits of single-site surgery while maintaining high surgical performance.
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Introduction
The introduction of the da Vinci SP® single-port system (Intuitive Surgical, Sunnyvale, CA, USA) has marked a significant paradigm shift in minimally invasive urologic surgery. By delivering a flexible camera and multi-jointed instruments through a single cannula, this system enables multi-quadrant access and complex reconstruction through a single incision [1, 2]. These technological advancements have allowed surgeons to overcome the technical challenges of triangulation and visualization that limited earlier laparoendoscopic single-site (LESS) surgery.
Despite these advantages, the "pure" single-port approach presents distinct challenges in clinical practice. The absence of a rigid assistant port often limits the bedside assistant's ability to provide effective suction, smoke evacuation, and dynamic tissue traction, which are critical for complex oncologic procedures [3]. To mitigate these limitations, many surgeons have adopted a "plus-one" approach, placing an additional assistant trocar separate from the primary incision [4, 5]. However, this modification inevitably creates an additional scar, compromising the cosmetic benefits that define single-site surgery. Although flexible assistant instruments compatible with the SP system exist, they often lack the rigidity and tensile strength required for robust tissue manipulation [6].
To address this unmet need, we standardized a modified access technique termed the "Integrated Functional Assistant Port" (iFAP). This approach integrates a standard rigid laparoscopic trocar alongside the robotic cannula within a unified multi-channel access platform, thereby restoring the functional capabilities of standard laparoscopy without the need for an additional skin incision. The objective of this study is to describe the technical details of the iFAP technique and to evaluate its feasibility and perioperative outcomes in 60 consecutive cases involving various urologic procedures.
Materials and Methods
Study design and participants
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This retrospective observational study was conducted at a single tertiary referral center after obtaining approval from the Institutional Review Board (IRB No. YUMC-2024-05-001-002). A
The requirement for informed consent was waived due to the retrospective nature of the study. We identified all consecutive patients who underwent robot-assisted urologic surgery using the da Vinci SP® system between September 2023 and January 2025. The inclusion criteria were patients undergoing urologic robotic surgery (including partial or radical nephrectomy, adrenalectomy, and nephroureterectomy) utilizing the iFAP technique via a single skin incision. Patients who required conversion to standard multi-port robotic or open surgery, or those who required an additional skin incision ("plus-one" port) outside the primary single-site platform, were excluded from the analysis.Surgical technique: the iFAP approach
All surgical procedures were performed by a single experienced surgeon (Y.H.K.) using the da Vinci SP® system. The patient positioning (modified flank or supine) and surgical approach (transperitoneal or retroperitoneal) were determined based on the target organ and lesion characteristics. The core principle of the iFAP technique is the integration of a functional rigid assistant port within the single incision. A single 3–4 cm skin incision depend on the size of the removed specimen (therefore up to 6cm for nephroureterectomy) was made at the abdominal wall including umbilicus for transperitoneal access or at the flank/pararectal area for retroperitoneal access. A commercial multi-channel access platform (e.g., Uniport, DalimSurgNET, Seoul, Korea) was utilized. The SP robotic cannula was inserted through the central channel of the platform. Crucially, a standard 5-mm or 12-mm rigid laparoscopic trocar was inserted through an adjacent channel within the same port system, running parallel to the robotic cannula (Fig. 1). This configuration allowed the bedside assistant to utilize standard rigid laparoscopic instruments, such as a suction-irrigator or laparoscopic grasper, providing dynamic traction and effective smoke evacuation directly at the surgical field working in synergy with the robotic arms.
Fig. 1
Setup of the Integrated Functional Assistant Port (iFAP) technique. (A) Schematic illustration demonstrating the co-axial configuration. The da Vinci SP® cannula is placed centrally, while a standard rigid laparoscopic trocar is inserted through an adjacent channel within the same multi-channel access platform. This allows a rigid assistant instrument to enter parallel to the robotic arms. (B) Intraoperative external view. The assistant utilizes a rigid suction-irrigator through the integrated assistant port, working in synergy with the SP system without an additional skin incision.
Data collection and outcomes
Data were extracted from a prospectively maintained institutional database. Baseline demographic variables included age, gender, body mass index (BMI), American Society of Anesthesiologists (ASA) physical status score, and history of prior abdominal surgery. Perioperative parameters included operative times, estimated blood loss (EBL), and length of hospital stay. Docking time was defined as the time interval from the initial skin incision to the moment the surgeon sat at the console. For patients undergoing robot-assisted partial nephrectomy (RAPN), tumor complexity was assessed using the RENAL nephrometry score, and warm ischemic time (WIT) was recorded.
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The primary outcome was the incidence of perioperative complications, which were categorized and graded according to the Clavien-Dindo classification system. Secondary outcomes included successful completion of the procedure without additional ports and length of hospital stay. To ensure accurate assessment of postoperative complications, including delayed wound events such as incisional hernia, all patients were followed up for a minimum of 6 months.Statistical analysis
Continuous variables are presented as mean ± standard deviation (SD), and categorical variables are expressed as frequencies and percentages. Subgroup comparisons were performed using Student’s t-test for continuous variables and Fisher’s exact test for categorical variables. A p-value < 0.05 was considered statistically significant.
Results
Baseline characteristics
A total of 60 consecutive patients were included in the final analysis. The mean age of the cohort was 59.7 ± 14.0 years, and the study population consisted of 36 males (60.0%) and 24 females (40.0%). The majority of patients were classified as ASA score II (63.3%). The distribution of surgical procedures included RAPN (n = 26, 43.3%), adrenalectomy (n = 13, 21.7%), nephroureterectomy (n = 11, 18.3%), radical nephrectomy (n = 5, 8.3%), and others (n = 5, 8.3%). The transperitoneal approach was utilized in 40 cases (66.7%), while the retroperitoneal approach was employed in 20 cases (33.3%).
Perioperative outcomes
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All procedures were successfully completed using the iFAP technique without conversion to open or standard multi-port surgery. The mean docking time was 12.6 ± 6.6 minutes, demonstrating consistent efficiency across different procedure types. The mean console time varied significantly depending on the surgical complexity, ranging from 55.4 ± 19.3 minutes for adrenalectomy to 168.0 ± 57.8 minutes for nephroureterectomy (Table 1). The assistant was able to perform effective suction, irrigation, and clip application using rigid instruments without significant collision with the robotic arms. The overall mean initial incision length was 4.3 ± 1.3 cm, and the mean final incision length was 4.7 ± 1.7 cm (Fig. 2).Fig. 2
Surgical wound and specimen retrieval in a retroperitoneal robot-assisted partial nephrectomy case. (A) The single incision site with the wound protector in place during the procedure. (B) Measurement of the final skin incision length (approximately 4 cm) following specimen extraction, highlighting the minimal surgical footprint. (C) The excised renal tumor specimen (approsimately 3cm) retrieved intact through the single incision.
Perioperative complications occurred in 2 patients (3.3%), both within the RAPN group. Specific complications included one case of incisional hernia requiring surgical repair and one case of postoperative ileus managed conservatively. No Clavien-Dindo grade III or higher complications were observed in the adrenalectomy, nephroureterectomy, or radical nephrectomy groups. The mean length of hospital stay was 7.7 ± 4.1 days.
Subgroup analysis: RAPN complexity
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In the subgroup analysis of the RAPN cohort (n = 26), patients were stratified by tumor complexity into low (RENAL score 4–6; n = 13) and moderate (RENAL score 7–9; n = 13) groups. The mean warm ischemic time was significantly longer in the moderate complexity group (26.2 ± 2.0 min) compared to the low complexity group (23.4 ± 2.8 min; p = 0.007). However, the complication rates were identical between the two groups (7.7% vs. 7.7%, Table 2).Discussion
The primary challenge in adopting the da Vinci SP system has been the lack of robust bedside assistance. Since the introduction of the SP platform, several high-volume centers have reported their initial experiences, highlighting both the potential and the pitfalls of this technology. Kaouk et al. [1, 2], in their pioneering work, demonstrated the feasibility of pure SP surgery but acknowledged the technical difficulties associated with inadequate traction and suction due to the absence of a rigid assistant port. Similarly, Lenfant et al. [7] reported on pure SP partial nephrectomy, noting that while feasible, the procedure often required the surgeon to perform self-assistance using the fourth arm, which can increase console time and mental workload.
To overcome these functional deficits, many surgeons have adopted a "plus-one" approach, placing an additional assistant trocar separate from the primary incision. Agarwal et al. [4] and Ng et al. [5] described using a 12-mm accessory port placed laterally to facilitate suturing and suction during SP radical prostatectomy. While this modification significantly enhances safety and efficiency, it inevitably creates an additional scar, thereby compromising the fundamental cosmetic advantage of single-site surgery. Furthermore, Heo et al. [8] reported that patients undergoing pure SP surgery reported higher cosmetic satisfaction scores compared to those with additional ports, underscoring the value of maintaining a single-incision approach.
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Recently, attempts have been made to introduce assistant instruments through the same incision to avoid extra scarring. A recent Italian multicenter study by Gallo et al. [9] described a "sidecar" technique where an 8-mm AirSeal® trocar is inserted through the same skin incision but via a separate fascial puncture next to the SP access port. This method closely mirrors our iFAP technique in concept; however, our approach utilizes a commercial multi-channel platform (e.g., Uniport) that houses both the robotic cannula and the assistant trocar within a single gel-cap system. This "all-in-one" integration simplifies the docking process and minimizes the risk of air leakage or fascial bridge trauma that might occur with separate fascial punctures in close proximity.Our findings compare favorably with these existing reports. The iFAP technique enabled the use of standard rigid laparoscopic instruments—such as a rigid suction-irrigator or laparoscopic grasper—providing dynamic traction and effective smoke evacuation that flexible suction devices often fail to deliver [6]. In our cohort, the conversion rate to standard multi-port or open surgery was 0%, and the "plus-one" conversion rate was also 0%, confirming that the iFAP setup provides sufficient assistance even for complex procedures like retroperitoneal nephroureterectomy or moderate-complexity RAPN.
Our comparative analysis of RAPN cases stratified by RENAL nephrometry score provides compelling evidence for the efficacy of iFAP. Although the moderate complexity group (RENAL 7–9) exhibited significantly longer warm ischemic times (26.2 min vs. 23.4 min; p = 0.007), this did not translate into increased perioperative morbidity (complication rate 7.7% vs. 7.7%). This suggests that the rigid assistance provided by iFAP allows for precise tumor excision and renorrhaphy even in challenging anatomical scenarios, matching the safety profile of multi-port series reported in recent meta-analyses [10]. Additionally, the versatility of our technique is evidenced by its successful application in retroperitoneal approaches [11], facilitating triangulation even in confined spaces without the collision issues described in earlier single-site literature [12].
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Several limitations of this study warrant careful consideration. First, the retrospective design involving a single surgeon may introduce selection bias. Second, the cohort size is relatively small, which limits the statistical power to detect rare complications. Third, regulatory restrictions on remote suction systems (e.g., ROSI) in our region necessitated the development of this manual assistance technique, potentially limiting its relevance in regions where such automated systems are standard. Crucially, the results should be interpreted within the context of the institutional learning curve. While our center introduced the da Vinci SP system in September 2021, the pure SP iFAP technique was formally adopted in September 2023. Consequently, the data presented herein reflect the initial learning period of this specific technique. During this phase, we observed a trend toward reduced operative times and the successful expansion of indications to more complex pathologies, driven by the stabilization of surgical steps and the increasing proficiency of a dedicated SP bedside assistant. The rapid adaptability of the surgical team suggests that the learning curve for iFAP is manageable for experienced robotic teams. Furthermore, despite being an initial report, we enforced a strict 1-year follow-up protocol for all patients to rigorously monitor for short- to mid-term complications, such as incisional hernias or readmissions. The low incidence of delayed complications in this follow-up period supports the durability and safety of the single-fascial incision closure used in the iFAP technique.In conclusion, this study demonstrates that the iFAP technique is a feasible modification for maintaining a single-incision approach while integrating the functional benefits of rigid laparoscopic assistance. The data indicate that this method effectively addresses the limitations of inadequate traction and suction often encountered in pure single-port surgery, without compromising perioperative safety or cosmetic outcomes. Further prospective studies with larger cohorts are required to validate these findings and to compare long-term outcomes with standard multi-port approaches.
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Figure and table legends
Table 1. Baseline characteristics and perioperative outcomes stratified by surgical procedure (N = 60). Data presented as mean ± SD or n (%). †Others includes Ureterolithotomy (n = 1) and Distal Ureterectomy (n = 1).
Table 2. Comparative outcomes of RAPN stratified by tumor complexity (n = 26). *Statistically significant (p < 0.05).