# Transperitoneal and retroperitoneal robot-assisted urology in infants ≤ 10kg: a FRUCT multi-centre study

Fabrizio Vatta, Alice Faure, Quentin Ballouhey, Nathalie Botto, Thomas

Loubersac, Alexis Arnaud, Olivier Abbo, Kiarash Taghavi, Julien Rod,
Thomas Blanc

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Fabrizio Vatta, Alice Faure, Quentin Ballouhey, Nathalie Botto, Thomas Loubersac, et al.. Transperitoneal and retroperitoneal robot-assisted urology in infants ≤ 10kg: a FRUCT multi-centre study. Journal of Pediatric Urology, 2025, 10.1016/j.jpurol.2025.09.014. hal-05353533

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Original Research

# Transperitoneal and retroperitoneal robot-assisted urology in infants ≤ 10 kg: A FRUCT multi-centre study

Fabrizio Vatta <sup>a,b</sup>, Alice Faure <sup>c</sup>, Quentin Ballouhey <sup>d</sup>, Nathalie Botto <sup>a</sup>, Thomas Loubersac <sup>e</sup>, Alexis Arnaud <sup>f</sup>, Olivier Abbo <sup>g</sup>, Kiarash Taghavi <sup>h,i</sup>, Julien Rod <sup>j</sup>, Thomas Blanc <sup>a,b,*</sup>

## Summary

## Objective

Robot-assisted surgery is now established in pedia-
tric urology; however, data on indications and mor-
bidity in children weighing less than 10 kg remain
limited. This study evaluates the feasibility and
outcomes of robotic surgery in infants.

## Study design

A retrospective analysis of prospectively collected multicentric data was performed over nine years (2015–2024) including infants weighing less than 10 kg who underwent robot-assisted urological surgery. Demographic data, perioperative characteristics, and complications were collected from seven university hospitals.

## Results

83 infants were included, with a median age at
surgery of 12 months (IQR: 8–16) and a median
weight of 9 kg (IQR: 8–10). The main procedures
were pyeloplasty (n = 37, 44 %), nephrectomy
(upper pole or total, n = 20, 24 %), and adrenalec-
tomy (n = 14, 17 %). Twenty-one procedures (25 %)

were performed using a retroperitoneal approach.
There were three conversions to open surgery: two
during Wilms tumor surgery and one during bilateral
adrenalectomy. The median hospital stay was 2 days
(IQR: 1–3).

Regarding 30-day morbidity, 10 infants (12 %) experienced complications (Grade II Clavien-Dindo), including febrile UTI (5 cases), stent displacement following pyeloplasty (3 cases), and transient urinary retention after bilateral ureteral reimplantation (2 cases). Additional complications observed beyond 30 days included two urinary tract infections (Grade II), one recurrence of hydrocolpos requiring reoperation (Grade IIIb), and one recurrence of ureteropelvic junction obstruction requiring reoperation (Grade IIIb). Median follow-up was 25 months (IQR: 11–66).

## Conclusion

This study demonstrates that robot-assisted uro-
logical surgery is feasible and safe in infants as
young as three months of age. The reduced work-
space does not appear to limit this surgical
approach, whether via transperitoneal or retro-
peritoneal approach.

* Correspondence to: Thomas Blanc, Service de chirurgie viscérale, urologie et transplantation pédiatrique, Hôpital Necker-Enfants malades, APHP, 149 Rue de Sèvres, 75015, Paris, France.
thomas.blanc@aphp.fr
(T. Blanc)

## Keywords

Robotic surgery; Urology;
Oncology; Pediatrics; Transper-
itoneal; Retroperitoneal

Received 28 April 2025
Revised 7 September 2025
Accepted 12 September 2025
Available online xxx

<footnote><sup>a</sup>Service de Chirurgie Viscérale, Urologie et Transplantation Pédiatrique, Hôpital Necker-Enfants Malades, APHP, Paris, France</footnote>

<footnote><sup>b</sup>Université Paris Cité, Paris, France</footnote>

<footnote><sup>c</sup>Service de Chirurgie Viscérale et Urologie Pédiatrique, Hôpitaux Universitaires de Marseille TIMONE, APHM, Marseille, France</footnote>

<footnote><sup>d</sup>Service de Chirurgie Pédiatrique Viscérale, CHU de Limoges, Limoges, France</footnote>

<footnote><sup>e</sup>Service de Chirurgie Infantile, CHU de Nantes, Nantes, France</footnote>

<footnote><sup>f</sup>Service de Chirurgie Viscérale Pédiatrique, CHU de Rennes, Rennes, France</footnote>

<footnote><sup>g</sup>Service de Pédiatrie - Chirurgie Viscérale, CHU de Toulouse, Toulouse, France</footnote>

<footnote><sup>h</sup>Department of Paediatric Urology, Monash Children's Hospital, Melbourne, Australia</footnote>

<footnote><sup>i</sup>Department of Paediatrics, Monash University, Melbourne, Australia</footnote>

<footnote><sup>j</sup>Service de Chirurgie Viscérale et Urologie Pédiatrique, CHU de Caen - Normandie, Caen, France</footnote>
## Introduction

Robot-assisted surgery (RAS) has transformed the field of paediatric surgery, offering enhanced precision, improved visualisation, and better ergonomics compared to traditional laparoscopic techniques. This advancement has translated to shorter post-operative hospital stays, reduced analgesic requirements, and equivalent (if not improved) efficacy [1–3]. Specific advantages of robotic surgery include the ability to perform intricate manoeuvres in small spaces with enhanced visualization, which is particularly advantageous in infants [4]. Despite the increasing utilisation of RAS in paediatric urology over the past decade [5], a notable gap remains in its application to infants weighing less than 10 kg. A recent national study conducted in France [6] examined the evolution of robotic surgery between 2007 and 2020 across 11 centres, with only 6.6% of the 1401 children weighing less than 10 kg.

While successful outcomes of robot-assisted surgery in very young children have been reported in general surgical contexts, specific studies focusing on pediatric urological procedures in infants are sparse [7]. This is particularly relevant as nearly two-thirds of pyeloplasties in paediatric urology concern infants less than 24 months of age [8].

In addition to the weight limit, whatever the surgical access is, robot-assisted procedures in small infants remain challenging. In particular, the feasibility and outcomes of retroperitoneoscopy require further evaluation due to concerns regarding limited working space. In fact, the use retroperitoneoscopy has already been described in infants [9, 10]. However, no data has been published on the robotic application.

This multicentre study aims to address these gaps in knowledge by evaluating the feasibility and outcomes of RAS in children weighing less than 10 kg undergoing urological procedures, either via a trans peritoneal or a retro peritoneal approach. This large dataset seeks to provide insights into the safety and potential limitations of RAS in this infant's population.

## Materials and methods

This multicentre prospective study reviewed data collected over nine years (2015–2024) across seven tertiary care centres in France (French Robotic Urology Children Team - FRUCT), specializing in paediatric urology. The study included all children weighing less than 10 kg who underwent robot-assisted urological surgery using the da Vinci system (Intuitive Surgical) during the specified period. This study received approval from the appropriate Institutional Review Boards (NCT03274050) and an independent ethics committee, Comités de Protection des Personnes Ile de France VII.

Data extraction was performed using a standardized protocol to gather comprehensive demographic information, including age, sex, and preoperative diagnoses. Intraoperative details collected included type of procedure, surgical approach (e.g., transperitoneal or retroperitoneal), operative time, and any intraoperative complications or conversions to open surgery. The same retroperitoneal approach was used among the different centres that performed this technique, as described by Blanc et al., in 2019

[11]. The indications for surgery were standardised across all centres. Regarding pyeloplasty, the diagnosis of ureteropelvic junction obstruction was confirmed by renal ultrasound and either technetium-99m MAG-3 renal scan or uro-magnetic resonance imaging with functional evaluation. Surgery was indicated in the presence of symptoms (e.g., ipsilateral flank pain or recurrent febrile urinary tract infections) and/or when imaging showed either a differential renal function <40% or a decline in function >5% between two consecutive renal scans [12].

As for oncological cases, individual cases were discussed and management decisions made by the multidisciplinary tumour board in concert with SIOP guidelines. Children were also followed during the post-operative course by a multidisciplinary team.

Post-operative course was evaluated by analysing length of hospital stay (defined as the number of days from surgery to discharge), and complications within and beyond 30 days post-surgery, classified according to Clavien-Dindo system [13].

Statistical analysis utilized methods appropriate for summarizing demographic characteristics, procedural details, and post-operative complications. Data were expressed as medians with interquartile ranges (IQR) in brackets for continuous variables, and as counts and percentages for categorical variables.

## Results

A total of 83 children (46 boys) underwent 84 robot-assisted urological procedures. All data are summarized in Table 1. The median age at the time of surgery was 12 months (8–16), and the median weight was 9 kg (8–10). The youngest patient was a 3-month-old weighing 4.2 kg.

All procedures were performed using Da Vinci X or Xi system, and all surgeries have been carried out using 8 mm instruments. Surgeries were performed by 10 senior surgeons, 5 of them performing oncology cases, and one fellow. Residents and fellows were assisting the senior surgeon either at the console or as bed assistant.

The most common procedure was robot-assisted laparoscopic pyeloplasty, performed in 37 children (45%). Of these, 15 cases (40%) utilised a retroperitoneal approach. We did not find statistical differences in terms of peri- or post-operative complications comparing these two approaches. Among the transperitoneal cases (n = 22), four were redo pyeloplasties. None of these reoperations had a primary procedure utilising a robotic approach.

Other indications were adrenalectomy for neuroblastoma (n = 14), upper pole nephrectomy (n = 7), ureteric reimplantation (n = 6), total nephrectomy (n = 6), nephrectomy for Wilms tumours (n = 5), ureteroureterostomy (n = 4), synchronous bilateral adrenalectomy (n = 2), and isolated cases of urogenital sinus surgery, ureterectomy post-nephrectomy, and bladder diverticulum excision. Indications for early pelvic surgery were based on the symptomatic evolution of these infants: significant increasing hydrocolpos volume (urogenital sinus) and recurrent urinary tract infections (bladder diverticulum).

No procedure faced difficulty for robotic setup and port placement.
<table><caption>Table 1 Summary of study data by procedure (total 83 patients, 84 procedures).</caption><thead><tr><th>Procedure</th><th>Cases (n)</th><th>Retroperitoneal approach</th><th>Median age in months (IQR)</th><th>Median weight in Kg (IQR)</th><th>Sex (M:F)</th><th>Median operative time (min)</th><th>Median hospital stay (days)</th><th>Conversion to open surgery</th><th>30-day morbidity</th><th>Complications beyond 30 days</th><th>Median follow up in years (IQR)</th></tr></thead><tbody><tr><td>Pyeloplasty</td><td>37</td><td>15</td><td>10 (7–14)</td><td>9 (8.2–9.8)</td><td>25:12</td><td>205 (180–266)</td><td>2 (1–3)</td><td>0</td><td>4 febrile urinary tract infections (Grade II), 3 stent displacements (Grade II)</td><td>1 recurrence of ureteropelvic junction obstruction (Grade IIIb), 1 febrile urinary tract infection (Grade II)</td><td>1.9 (0.8–3.9)</td></tr><tr><td>Adrenalectomy for neuroblastoma</td><td>14</td><td>4</td><td>13.7 (12.6–17.2)</td><td>9.3 (9–10)</td><td>8:6</td><td>95 (62–135)</td><td>2 (1–33)</td><td>0</td><td>—</td><td>—</td><td>1.9 (1.2–4.1)</td></tr><tr><td>Upper pole nephrectomy</td><td>7</td><td>0</td><td>14 (10–17)</td><td>8.3 (7.8–9.5)</td><td>1:6</td><td>200 (195–224)</td><td>2 (1–3)</td><td>0</td><td>—</td><td>1 febrile urinary tract infection (Grade II)</td><td>5.6 (3–9.8)</td></tr><tr><td>Ureteric reimplantation</td><td>6</td><td>0</td><td>14 (13–20)</td><td>9.5 (9–10)</td><td>4:2</td><td>132 (118–165)</td><td>3 (2–4)</td><td>0</td><td>2 transient urinary retentions (Grade II); 1 febrile urinary tract infection (Grade II)</td><td>—</td><td>8.2 (7.5–9.3)</td></tr><tr><td>Total nephrectomy<sup>c</sup></td><td>6</td><td>2</td><td>12 (8–17)</td><td>9 (7.2–9)</td><td>4:2</td><td>167 (93–240)</td><td>1.5 (1–4)</td><td>0</td><td>—</td><td>—</td><td>2 (0.6–3.5)</td></tr><tr><td>Nephrectomy for wilms tumors<sup>c</sup></td><td>5</td><td>1</td><td>11.5 (7.5–20)</td><td>8.8 (7.4–9.6)</td><td>2:3</td><td>193 (127–213)</td><td>4 (2–6)</td><td>2<sup>a</sup></td><td>—</td><td>—</td><td>5.3 (4.8–6.1)</td></tr><tr><td>Ureteroureterostomy</td><td>4</td><td>0</td><td>11 (10–13)</td><td>9.6 (8.9–9.9)</td><td>2:2</td><td>195 (130, 260)</td><td>2 (1–5)</td><td>0</td><td>—</td><td>—</td><td>5.6 (3.9–6.6)</td></tr><tr><td>Synchronous bilateral adrenalectomy</td><td>2</td><td>0</td><td>4.9 (3–6.8)</td><td>4.6 (4.2–5)</td><td>0:2</td><td>320 (280–360)</td><td>17 (13–21)</td><td>1<sup>b</sup></td><td>—</td><td>—</td><td>4.8 (3.7–5.9)</td></tr><tr><td>Urogenital sinus procedure</td><td>1</td><td>0</td><td>6.8</td><td>8</td><td>0:1</td><td>302</td><td>4</td><td>0</td><td>—</td><td>1 recurrence of hydrocolpos (Grade IIIb)</td><td>4.6</td></tr><tr><td>Ureterectomy post-nephrectomy</td><td>1</td><td>0</td><td>13</td><td>9</td><td>0:1</td><td>162</td><td>7</td><td>0</td><td>—</td><td>—</td><td>1</td></tr><tr><td>Bladder diverticulum excision</td><td>1</td><td>0</td><td>20</td><td>9.4</td><td>1:0</td><td>245</td><td>1</td><td>0</td><td>—</td><td>—</td><td>3.3</td></tr></tbody></table>

<footnote><sup>a</sup> One conversion was due to poor respiratory tolerance following a diaphragmatic injury, and by a difficult dissection in the second one.</footnote>

<footnote><sup>b</sup> Conversion motivated by the restricted workspace, significant adhesions of the adrenal gland to the vena cava, and bleeding from the liver capsule.</footnote>

<footnote><sup>c</sup> A six-month-old boy with Denys-Drash syndrome in terminal renal failure underwent a bilateral nephrectomy with a retroperitoneal approach. On the left side the nephrectomy was for a Wilms tumor.</footnote>
There were three conversions to open surgery (3%). One case involved a girl with Wilms tumour infiltrating the liver, requiring a diaphragmatic resection for a suspected extension. The diaphragmatic opening was poorly tolerated during the robotic procedure, necessitating conversion. The second case of conversion during Wilms tumor surgery was due to a difficult dissection. Another conversion occurred in a 3-month-old girl undergoing synchronous bilateral adrenalectomy for ACTH-independent Cushing's syndrome. This was due to significant adhesions between the right adrenal gland and inferior vena cava. No bleeding or intra-operative complications occurred. None of the conversions related to limited workspace or collisions between robotic instruments. Furthermore, no robot-related injuries occurred. The median hospital stay was 2 days (1-3), and the median follow-up was 25 months (11-66). Within 30 days post-surgery, 10 children (12%) experienced complications classified as Clavien-Dindo grade II. These included febrile urinary tract infections (5 cases, 6%), stent displacement after pyeloplasty (3 cases, 4%), and transient urinary retention after bilateral ureteral reimplantation (2 cases, 2%). Beyond 30 days, complications included two urinary tract infections (Grade II), one recurrence of hydrocolpos requiring reoperation (Grade IIIb), and one recurrence of ureteropelvic junction obstruction requiring reoperation (Grade IIIb).

In both children, redo robotic surgery was performed; however, these second procedures were not included in the present series, as the 2 children weighed more than 10 kg at the time of the redo procedure.

No recurrence occurred in all oncological cases at last follow up.

Over the study period, the frequency of surgical interventions in this age group has steadily increased (Fig. 1).

## Discussion

This study demonstrates the safety and feasibility of performing robot-assisted surgery in infants weighing less than 10 kg across a wide range of urological procedures. Consistent with recent studies, pyeloplasty emerged as the primary indication for robotic urological surgery in this study [14].

The European Association of Urology and the European Society for Pediatric Urology guidelines state that, in experienced hands, the success rates of minimally invasive pyeloplasty (90-95%) are comparable to those of the open approach [15]. However, for infants weighing less than 10 kg and/or younger than one year, evidence supporting robot-assisted pyeloplasty is considered to be limited due to technical difficulties, limited working space, and a lack of robust, long-term data [16].

Nevertheless, recent studies have demonstrated the feasibility and safety of this technique in small infants particularly with a transperitoneal approach. The largest published series to date is from Rague et al. reported 79 pyeloplasties via a transperitoneal approach in children weighing less than 10 kg, showing that robot-assisted pyeloplasties are both safe and effective. Lower weight among children in their cohort was not predictive of complications or worse intraoperative, perioperative, or postoperative

outcomes. They concluded that weight alone should not be used as an exclusion criterion for RAS surgery, provided the surgeon has experience in infant robotic surgery [7].

Additionally, findings from a multi-centre study emphasize that robot-assisted laparoscopic pyeloplasty matches laparoscopic techniques in terms of success while offering significantly reduced operative times and enhanced ergonomic benefits for surgeons, making it a preferred approach for children under 15 kg [17]. The feasibility of RAS in transperitoneal pyeloplasty is also further confirmed by a North American multi-centre study reporting a cohort of 60 children with an average weight of 8.1 kg [18].

Despite these recent publications, there remains a documented trend favouring other surgical approaches in infants. A national North American study by Varda et al. analysed trends in the utilization of open, laparoscopic, and robot-assisted pyeloplasty from 2003 to 2015. Of approximately 12,000 pyeloplasties performed, the study observed increasing use of robot-assisted surgery across all age groups except for children under one year of age (where the open approach remained predominant). Nonetheless, the study noted that open pyeloplasty in this age group decreased from 100% in 2003, to 83% in 2015 [19]. This indicates that while robot-assisted pyeloplasty remained a niche technique for infants weighing less than 10 kg, its adoption was already gradually growing up to 2015. This positive trend is supported by a selection of further and more recent studies, that focused mainly (but not only on pyeloplasty), as shown in Table 2 [7,18,20-24]. An increase in robot-assisted techniques in infants weighing less than 10 kg was observed in this study, demonstrating a clear and consistent rise in the utilization of robot-assisted pyeloplasty over the past decade.

In our experience, careful port placement and laparoscopic identification of surgical landmarks prior to robot docking are crucial minimising problems. Many studies report a minimum required distance between ports of approximately 5-6 cm. In small infants, achieving this distance is often impossible, making meticulous port positioning essential to reducing instrument collisions and risks to the patient [Fig. 2]. It is particularly important to plan trocar placement with a comprehensive understanding of the exact movements required for each robotic arm during

Surgeries/year

<figure><img src="image_3.png" /><figcaption>**Fig. 1** Number of robotic procedures performed per years in infants. *2024 is an incomplete year of 9 months only.</figcaption></figure>
<table><caption>**Table 2** Summary of a selection of paediatric urology literature reporting robotic procedures in infants less than 10 kg.</caption><thead><tr><th>Procedure</th><th>Country (Year)</th><th>Cases (n)</th><th>Age</th><th>Weight</th><th>Conversion to open surgery</th><th>Robotic complications</th><th>Complications</th></tr></thead><tbody><tr><td>Pyeloplasty, ureteroureterostomy [7]</td><td>Chicago, USA (2021)</td><td>101</td><td>Median 7 months</td><td>Median 8 kg</td><td>0</td><td>0</td><td>12 complications (9/12 in &gt;50th percentile weight groups)</td></tr><tr><td>Pyeloplasty, ureteroureterostomy, heminephrectomy, nephrectomy [20]</td><td>Colombus, USA (2021)</td><td>12</td><td>Median 5 months</td><td>Median 7 kg</td><td>0</td><td>0</td><td>4 febrile UTIs (33 %)</td></tr><tr><td>Pyeloplasty [21]</td><td>Chicago, USA (2021)</td><td>44</td><td>Median 4 months</td><td>Median 7 kg</td><td>0</td><td>0</td><td>7 complications (1 ileus, 4 UTIs, 2 port-site hernias)</td></tr><tr><td>Pyeloplasty [18]</td><td>Multi-centre, USA (2015)</td><td>62</td><td>Average 7 months</td><td>Median 8 kg</td><td>0</td><td>0</td><td>7 complications (2 port-site hernias, 1 urinary leak, 1 UTI, 1 retained stent, 1 post-op calculus, 1 ileus)</td></tr><tr><td>Pyeloplasty, ureteroureterostomy [22]</td><td>Cincinnati, USA (2014)</td><td>10</td><td>Median 8 months</td><td>Median 8 kg</td><td>0</td><td>0</td><td>3 complications (1 urinary leak, 1 ileus, 1 UTI)</td></tr><tr><td>Pyeloplasty [23]</td><td>Beijing, China (2019)</td><td>31</td><td>Average 4 months</td><td>Average 7 kg</td><td>0</td><td>0</td><td>7 complications (2 urinary leaks, 3 UTIs)</td></tr><tr><td>Pyeloplasty [24]</td><td>Houston, USA (2017)</td><td>20</td><td>Average 5 months</td><td>NA</td><td>0</td><td>0</td><td>1 re-do procedure required at 8 months post-operatively</td></tr></tbody></table>

the procedure. This includes alternating the instruments between arms based on the specific movements needed at each stage of the surgery [25,26].

Additionally, trocar insertion depth must be adjusted with specific precautions. The fulcrum of the trocar or "Remote Center" (marked by a thick black band on the metal trocar), typically positioned within the abdominal wall of adults, must be moved externally in infants to increase working space. This adjustment partially determines the manoeuvrability of the instruments. Careful abdominal wall suspension, achieved by applying slight traction on each trocar, helps to optimise working space and instrument movements. Moreover, use of the robotic Hasson-cone for the optic trocar, in our experience, prevents the camera from slipping out of the patient, ensuring stable and constant traction on the robotic camera port.

In terms of instruments, we preferred 8 mm articulated tools. Although 5 mm instruments were available for robotic surgery, 8 mm instruments proved more effective in confined working spaces, allowing for more complex movements [27].

The cut-off size limit for children eligible for robotic surgery remains debated. There is no consensus regarding the safety criteria for infants undergoing robotic procedures [27]. Finkelstein et al. suggested a minimum distance of 13 cm between the anterior iliac spines, and 15 cm between the pubic symphysis and xyphoid as a cut-off for case selection. Our experience suggests these measurements can be reduced to 11 cm and 14 cm, respectively [28].

Our findings also support the feasibility of robot-assisted retroperitoneal surgery as an alternative to the transperitoneal approach in selected paediatric cases. The transperitoneal approach remains the most common approach for robot-assisted laparoscopy in both adults and children [29,30]. One of the main advantages of the transperitoneal technique is that it provides a more familiar approach with a larger working space. However, the retroperitoneal approach offers direct access to the urinary tract, enabling conservative treatment in cases of anastomotic leakage. This prevents urine encountering the peritoneal cavity and related organs [31].

A study by Badawy et al. found that the retroperitoneal approach to pyeloplasty led to shorter operative times, reduced hospital stays, quicker bowel recovery, and earlier resumption of oral feeding compared to the transperitoneal approach [32].

Retroperitoneal surgery in infants was performed in only three out of the seven centres that participated in this study, where senior surgeons had significant experience in laparoscopic and robot-assisted retroperitoneoscopy. This highlights the technical expertise required for this approach.

The routine application of retroperitoneoscopy has expanded its use to other conditions, such as adrenalec-tomies for neuroblastoma. Neuroblastoma was the most common tumour in our cohort, with 10 cases performed via transperitoneal approach and four via a retroperitoneal approach. Minimally invasive surgery is increasingly uti-lized for the resection of neurogenic tumours in children. A recent meta-analysis by APSA indicated that small neuro-genic tumours without image-defined risk factors (IDRFs)
<figure><img src="image_4.png" /><figcaption>**Fig. 2** Trocar placement for transperitoneal approach (1a – Adrenalectomy) and retroperitoneal approach (1b – Pyeloplasty).</figcaption></figure>

are suitable candidates for minimally invasive resection, provided that oncologic principles are closely followed [33].

As for other uro-oncological procedures, total nephrectomy for Wilms' tumor was the second most common indication, with four cases performed via transperitoneal approach. The use of minimally invasive surgery for Wilms' tumours remains widely debated. Concerns about tumour rupture and spillage, which leads to upstaging, intensified chemotherapy, and radiotherapy, have long hindered the adoption of this approach [34,35]. For this reason, we would recommend that more complex robotic surgery should be undertaken in a graduated fashion in accordance with surgeons and team expertise and in the context of multidisciplinary team. Nonetheless, numerous studies have confirmed the feasibility of this procedure in selected cases adhering to oncologic guidelines [36,37]. As for robotic surgery, a recent meta-analysis published in 2025 confirmed the feasibility and promising results of this technology in children, although the age range reported was between 1.2 and 14 years [38]. In our study and practice, robot-assisted surgery for renal tumours is contraindicated when the following criteria are present: tumour crossing the midline OR tumour infiltrating extrarenal structures, especially liver or diaphragm infiltration OR tumour with encasement of renal vessels (e.g. sarcomas, carcinomas) OR Estimated tumour volume/Estimated patient blood volume >2% [37]. Finally, two patients with McCune-Albright syndrome in this series underwent bilateral adrenalectomy.

As with other published series, the conversion rate for oncological procedures remained higher, reflecting concerns regarding tumour upstaging, haptic feedback and robotic performance. This aligns with previously published case series [39,40].

Further prospective studies with larger cohorts and standardized follow-up protocols are needed to validate these findings and provide more robust data on the long-term benefits and potential risks of robot-assisted surgery in this infant population.

This study nonetheless has several limitations. Firstly, the limited number of some interventions may restrict the strength of conclusions that can be drawn. The results must be interpreted in light of the absence of a control group. Furthermore, the heterogeneity in surgical volume and experience among different centres could influence the results and their interpretation.

## Conclusion

This multi-centre study confirms the feasibility and safety of robot-assisted surgery in infants weighing less than 10 kg. Both transperitoneal and retroperitoneal approaches were effectively utilized for a range of urological procedures, including pyeloplasties, partial or total nephrectomies, and adrenalectomies. These procedures demonstrated low complication rates. Notably, the study underscores that even oncological procedure can be successfully performed robotically in infants.
Further studies involved larger cohorts and longer follow-up periods are essential to validate these findings and optimize protocols for this unique group of patients.

## Permission to reproduce material from other sources

We have not used materials from other sources.

## Patient consent statement

Informed consent was obtained from all individual participants included in the study.

## Author contributions

TB and JR conceived the idea of the article.

FV, AF, QB, NB, TL, AA, OA, JR and TB developed the study and performed data collection.

Patients were operated upon by FV, AF, QB, NB, TL, AA, OA, JR and TB.

AF, QB, NB, TL, AA, OA, JR and KT verified the statistical analysis and the results.

All authors discussed the results and contributed to development of the discussion and thus the final manuscript.

TB and KT revised the manuscript prior to publication.

## Data statement

The data that support the findings of this study are not openly available and are available from the corresponding author upon reasonable request.

## Ethical compliance

This study received approval from the appropriate Institutional Review Boards (NCT03274050) and an independent ethics committee, the Comités de Protection des Personnes Ile de France VII.

## Clinical trial registration

It is a prospective study registered at the Good Clinical Practice Network (NCT03274050).

## Funding statement

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

## Conflicts of interest

TB is an official proctor for Intuitive Surgical. None of the other authors have any disclosures.

## References

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