Robotic laparoendoscopic single-site ultrasound-guided renal artery balloon catheter occluded hybrid partial nephrectomy (LESS-HPN): a prospective pilot study
Robot assisted partial nephrectomy (RAPN) is recognized as an effective minimally invasive alternative to open surgery for the treatment of clinically localized renal tumors . Laparoendoscopic single-site surgery (LESS) seeks to enhance the minimal invasiveness of laparoscopic procedures . Robotic laparoendoscopic single-site partial nephrectomy (R-LESS PN) has demonstrated technical feasibility and safety, yielding superior cosmetic outcomes, reduced postoperative analgesic requirements, and faster recovery . However, the renal hilum dissection becomes more complicated due to the external collisions of the instruments and the restricted motion of the assistant due to the narrow space . Consequently, Kaouk et al. reported R-LESS PN with the omission of hilar clamping, primarily for selected exophytic tumors . Despite these advancements, R-LESS PN still requires refinements to address these challenges . Previously, we introduced a laparoscopic ultrasound (LUS) guided intervention technique to assist off-clamp partial nephrectomy, called Ultrasound-Guided Renal Artery Balloon Catheter Occluded Hybrid Partial Nephrectomy (UBo-HPN) . This technique involves temporarily occluding the renal arterial blood supply using a Fogarty balloon catheter. Preliminary results from our cohort study indicated that UBo-HPN is a safe approach that yields comparable surgical, oncological, and functional outcomes . In this study, we explored a novel surgical approach aimed at achieving intracorporeal minimally invasiveness: robotic laparoendoscopic single-site ultrasound-guided renal artery balloon catheter occluded hybrid partial nephrectomy (LESS-HPN) and reported its short-term outcomes in the first 10 cases.   Patients A total of 10 patients with T1 stage renal tumors, enrolled between March and July 2023, were prospectively included in this study. The inclusion criteria included the following: (i) patients with renal tumor and clinical stage were limited to T1NoMo, which was confirmed by image examination; (ii) patients aged 16–85 years. The exclusion criteria included the following: (i) patients with renal tumors near renal hilus or invading the renal sinus area that may require simultaneous occlusion of the renal vein during the resection of the tumor; (ii) patients whose tumor is supplied by multiple arteries and is difficult to block with one balloon; and (iii) patients with severe cardiovascular and cerebrovascular diseases, especially with large vascular lesions. Informed consent was obtained from all patients, and assessments were conducted by the same physician. A preoperative evaluation was jointly performed by one surgeon and one specialized sonographer, based primarily on preoperative ultrasound, contrast enhanced CT, and CTA (only for cases requiring branch artery occlusion). This study was registered in the Chinese Clinical Trial Registry and approved by the institutional ethics review board. This work has been reported in line with the STROCSS criteria . LESS-HPN technique All surgeries were performed using the da Vinci XI Surgical System (Intuitive Surgical, Sunnyvale, CA, USA). After administering general anesthesia, the patient assumed a 70-degree lateral position. Following the open Hasson technique, a 4.5–5.0 cm lateral rectus incision was made on the affected side, and a Freeport (Ningbo SensCure Biotechnology) was inserted. The Freeport was equipped with one 8-mm optic trocar and two 8-mm working trocars, which were positioned at 12 o’clock, 3 o’clock, and 9 o’clock directions, respectively. Additionally, two assistant trocars were placed within the Freeport. (Fig. ). Through the two assistant channels on the Freeport, the monitoring area of the LUS probe was able to cover a large area of abdominal organsand vessels (Fig. ). After locating the tumor with LUS, the perirenal fat was directly incised to expose the renal tumor border. Unlike conventional PN, the paracolic sulci, most of the perirenal fat, and renal hilum structures did not need to be dissected. Actually, prophylactic dissection of the renal artery was performed in the first few cases of UBo-HPN, but this proved unnecessary. Therefore, the renal artery was not dissected in any of the subsequent LESS-HPN cases. Ultrasound-guided femoral artery puncture was performed, and a vascular sheath was inserted. Under full LUS guidance, a catheter and a guidewire were advanced through the femoral vascular sheath into the main, branch, or accessory renal artery. A Fogarty balloon catheter was then placed at the target artery along the guidewire, inflated with saline to occlude the blood supply. After confirming complete occlusion of the tumor’s arterial blood supply using color Doppler flow imaging (CDFI) or contrast-enhanced laparoscopic ultrasound (CE-LUS), the tumor was routinely excised and the wound was sutured in the conventional manner. The balloon catheter was deflated and withdrawn, and the renal wound was inspected for bleeding. The specimen was extracted through the incision. and a drain tube was placed at its lowest point (Supplementary Fig. ). Hemostasis at the femoral artery puncture site was achieved using an arterial closure device. Technical success was defined as the simultaneous achievement of: (i) complete occlusion of arterial blood flow confirmed by CDFI, or CE-LUS, with direct visualization during the following tumor resection and suturing, and (ii) absence of conversion to conventional multiport robot assisted or laparoscopic partial nephrectomy. All patients received follow-up every three to six months. Study variables Baseline information was recorded for all patients. The complexity of tumors was determined with the R.E.N.A.L. score . Intraoperative variables including operation time, warm ischemia time (WIT), estimated blood loss (EBL), blood transfusion, and incision length was recorded. The number of additional access and any kind of conversion were recorded.Intraoperative or postoperative complications were grade according to Clavien-Dindo classification . Patients received follow-up every three to six months in the first two years and then annually. Statistical analysis Categorical variables were expressed as frequencies and percentages. Continuous variables that conformed to a normal distribution were expressed as mean ± standard deviation (SD). Those that did not fit the normal distribution were expressed as median and interquartile range (IQR). Comparisons between the two groups (anterior vs. posterior location) were conducted using Student t-tests, and comparisons of dichotomous variables were conducted using Fisher’s exact probability method. Two-sided P value < 0.05 was considered for statistical significance.   A total of 10 patients with T1 stage renal tumors, enrolled between March and July 2023, were prospectively included in this study. The inclusion criteria included the following: (i) patients with renal tumor and clinical stage were limited to T1NoMo, which was confirmed by image examination; (ii) patients aged 16–85 years. The exclusion criteria included the following: (i) patients with renal tumors near renal hilus or invading the renal sinus area that may require simultaneous occlusion of the renal vein during the resection of the tumor; (ii) patients whose tumor is supplied by multiple arteries and is difficult to block with one balloon; and (iii) patients with severe cardiovascular and cerebrovascular diseases, especially with large vascular lesions. Informed consent was obtained from all patients, and assessments were conducted by the same physician. A preoperative evaluation was jointly performed by one surgeon and one specialized sonographer, based primarily on preoperative ultrasound, contrast enhanced CT, and CTA (only for cases requiring branch artery occlusion). This study was registered in the Chinese Clinical Trial Registry and approved by the institutional ethics review board. This work has been reported in line with the STROCSS criteria .   All surgeries were performed using the da Vinci XI Surgical System (Intuitive Surgical, Sunnyvale, CA, USA). After administering general anesthesia, the patient assumed a 70-degree lateral position. Following the open Hasson technique, a 4.5–5.0 cm lateral rectus incision was made on the affected side, and a Freeport (Ningbo SensCure Biotechnology) was inserted. The Freeport was equipped with one 8-mm optic trocar and two 8-mm working trocars, which were positioned at 12 o’clock, 3 o’clock, and 9 o’clock directions, respectively. Additionally, two assistant trocars were placed within the Freeport. (Fig. ). Through the two assistant channels on the Freeport, the monitoring area of the LUS probe was able to cover a large area of abdominal organsand vessels (Fig. ). After locating the tumor with LUS, the perirenal fat was directly incised to expose the renal tumor border. Unlike conventional PN, the paracolic sulci, most of the perirenal fat, and renal hilum structures did not need to be dissected. Actually, prophylactic dissection of the renal artery was performed in the first few cases of UBo-HPN, but this proved unnecessary. Therefore, the renal artery was not dissected in any of the subsequent LESS-HPN cases. Ultrasound-guided femoral artery puncture was performed, and a vascular sheath was inserted. Under full LUS guidance, a catheter and a guidewire were advanced through the femoral vascular sheath into the main, branch, or accessory renal artery. A Fogarty balloon catheter was then placed at the target artery along the guidewire, inflated with saline to occlude the blood supply. After confirming complete occlusion of the tumor’s arterial blood supply using color Doppler flow imaging (CDFI) or contrast-enhanced laparoscopic ultrasound (CE-LUS), the tumor was routinely excised and the wound was sutured in the conventional manner. The balloon catheter was deflated and withdrawn, and the renal wound was inspected for bleeding. The specimen was extracted through the incision. and a drain tube was placed at its lowest point (Supplementary Fig. ). Hemostasis at the femoral artery puncture site was achieved using an arterial closure device. Technical success was defined as the simultaneous achievement of: (i) complete occlusion of arterial blood flow confirmed by CDFI, or CE-LUS, with direct visualization during the following tumor resection and suturing, and (ii) absence of conversion to conventional multiport robot assisted or laparoscopic partial nephrectomy. All patients received follow-up every three to six months.   Baseline information was recorded for all patients. The complexity of tumors was determined with the R.E.N.A.L. score . Intraoperative variables including operation time, warm ischemia time (WIT), estimated blood loss (EBL), blood transfusion, and incision length was recorded. The number of additional access and any kind of conversion were recorded.Intraoperative or postoperative complications were grade according to Clavien-Dindo classification . Patients received follow-up every three to six months in the first two years and then annually.   Categorical variables were expressed as frequencies and percentages. Continuous variables that conformed to a normal distribution were expressed as mean ± standard deviation (SD). Those that did not fit the normal distribution were expressed as median and interquartile range (IQR). Comparisons between the two groups (anterior vs. posterior location) were conducted using Student t-tests, and comparisons of dichotomous variables were conducted using Fisher’s exact probability method. Two-sided P value < 0.05 was considered for statistical significance.   From March to July 2023, a total of 10 patients were included in the study, as outlined in Table . Among them, five patients (50%) had an anteriorly located tumor, while the remaining five patients (50%) had a posteriorly located tumor. Four patients (40%) had a history of one or more prior abdominal surgeries. The mean tumor diameter was 2.9 ± 1.1 cm, predominantly located on the left side in 80% of cases. Tumors were mostly T1a stage (80%), with 70% having a R.E.N.A.L. score less than 7. No statistically significant differences were observed in the baseline data between different tumor location (anterior and posterior) groups. LESS-HPN was successfully completed in all 10 cases, as indicated in Table . The mean operative time was 103.3 ± 11.1 min, including 21.0 ± 2.7 min of WIT. The mean 48-hour post-operative serum creatinine increase (δSerum creatinine) was 1.6 ± 12.0 µmol/L, accompanied by an estimated glomerular filtration rate (eGFR) decreased of 3.1 ± 8.1 ml/min/1.73 m 2 . Hemoglobin decreased by 1.8 ± 6.9 g/L postoperatively. The mean EBL was 42.0 ± 22.5 ml, with no intraoperative blood transfusion required in any case. The median incision diameter, measured upon suturing completion, was 4.6 (IQR 4.5,4.7) cm. There was no case of adding additional access. And no conversion to renal artery clamping, to radical nephrectomy, to open surgery, or to standard robot laparoscopy occurred. The operative time for posterior tumors was significantly shorter ( p = 0.041). Other surgical outcomes were found to be independent of tumor location (anterior/posterior). Among the 10 patients, renal artery occlusion was accomplished in six cases (60%) and branch artery occlusion was accomplished in two (20%). For patients with accessory renal arteries, one patient (10%) underwent accessory renal artery occlusion without main renal artery occlusion. Another had main renal artery occlusion without accessory artery occlusion (Supplementary Table ). The median follow-up time was 10.5 mo. Postoperative pathology confirmed no positive surgical margin, and no recurrence was observed during follow-up. Four patients (40%) were diagnosed with clear cell renal cell carcinoma. Angiomyolipoma was diagnosed in 2 cases (20%). Papillary renal cell carcinoma, chromophobe renal cell carcinoma, oncocytoma and multilocular cystic renal neoplasm was diagnosed in 1 case (10%) respectively (Supplementary Table ).   Minimally invasive surgery, with its focus on reducing invasiveness, prioritizes better cosmetic outcomes and advantages in postoperative analgesia . R-LESS further reduces complication risks compared to conventional LESS . Despite the da Vinci single-port (SP) system offering improved integration with LESS surgery, its limited availability in most medical centers is largely due to cost considerations. UBo-HPN aims to maximize minimally invasive intracorporeal techniques. This technique eliminates the need for dissection of the renal hilum, paracolic sulci, or kidney mobilization. The intra-abdominal approach involves a small peritoneal incision and fenestration of the renal tumor surface. Instead of traditional renal artery clamping, a Fogarty balloon catheter, guided by LUS, temporarily occludes arterial blood flow. Our unpublished clinical data of70 cases has confirmed its safety and a high technical success rate. To further advance intracorporeal and cutaneous minimally invasive goals, we developed the LESS-HPN technique. Initial results from 10 cases indicated that LESS-HPN was a safe procedure, with no complications or recurrence. The average EBL for LESS-HPN was 42 ml, significantly lower than the previously reported multi-port RAPN or R-LESS PN . The most promising feature of LESS-HPN was the synergy between R-LESS and UBo-HPN, which together result in favorable surgical outcomes. The mean operative time of 103 min was much shorter than the durations exceeding 300 min reported for both LESS-PN or multi-port RAPN . Additionally, the WIT for both the anterior and posterior groups was notably reduced to 21.8 and 20.2 min, respectively, which not only surpassed the reported LESS-PN duration of 26.5 min but also approached the WIT of multi-port PN at 20.2 min . Furthermore, our cohort exhibited a significantly lower postoperative decline in eGFR . Previous studies have reported high conversion rates for LESS, ranging from 7.9 to 14.2%, and the need for additional ports in 19–61.6% of LESS-PN procedures . Notably, 37% of cases were converted due to difficult dissection, and 25% due to bleeding . In contrast, our research suggested that LESS-HPN offered a viable solution to these challenges, as none of our cases required additional access or conversion to conventional surgery. Simplifying the intracorporeal procedure has significantly reduced the complexity of dissection, particularly in the renal hilar structures, thus minimizing the risk of vascular damage and bleeding. In essence, LESS-HPN renders LESS procedures less technically demanding and more minimally invasive . Another notable advantage of LESS-HPN was its ability to achieve highly selective branch renal artery occlusion in cases where the tumor was supplied by specific branches, as confirmed by CTA. Despite the variability in the renal vascular anatomy and tumor-specific blood supply, CTA imaging combined with LUS guidance allowed ultrasonographers to clearly identify the branches of the target artery supplying the tumor . This selective intravascular occlusion, as opposed to segmental renal artery clamping, mitigated the risk of dissecting higher-order tumor feeding arteries and associated vascular damage . Following selective branch artery occlusion, the partial ischemia of the kidney can be promptly confirmed by CDFI or CE-LUS . Our preliminary findings demonstrated that LESS-HPN is particularly effective for non-complex renal tumors, making it a preferable option for patients with a history of prior abdominal surgery and significant intra-abdominal adhesions . In such cases, LESS-HPN minimized intracorporeal manipulation, offering more pronounced minimally invasive advantages. Limitation LESS-HPN shows greater effectiveness for certain patients, including those with lower BMI . However, the classic flaws of LESS such as instrument collisions still presents. Additionally, there is necessarily a learning curve for LESS-HPN. Lastly, this study was limited by its small sample size.   LESS-HPN shows greater effectiveness for certain patients, including those with lower BMI . However, the classic flaws of LESS such as instrument collisions still presents. Additionally, there is necessarily a learning curve for LESS-HPN. Lastly, this study was limited by its small sample size.   Our first exploration with LESS-HPN indicated that it is a safe and feasible alternative to the treatment of renal tumors. LESS-HPN, a combination of R-LESS with UBo-HPN, achieve both cutaneous and intracorporeal minimally invasiveness. Controlled studies with larger size were expected in the future.   Below is the link to the electronic supplementary material. Supplementary Material 1   