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Preparing for the worst: Management and predictive factors of open conversion during minimally invasive renal tumor surgery (UroCCR-135 study)

  • Nicolas Branger,
  • Nicolas Doumerc,
  • Thibaut Waeckel,
  • Pierre Bigot,
  • Louis Surlemont,
  • Sophie Knipper,
  • Géraldine Pignot,
  • François Audenet,
  • Frank Bruyère,
  • Alexis Fontenil,
  • Bastien Parier,
  • Cécile Champy,
  • Morgan Rouprêt,
  • Jean-Jacques Patard,
  • François Henon,
  • Gaëlle Fiard,
  • Julien Guillotreau,
  • Jean-Baptiste Beauval,
  • Constance Michel,
  • Simon Bernardeau,
  • Fayek Taha,
  • Richard Mallet,
  • Frederic Panthier,
  • Laurent Guy,
  • Louis Vignot,
  • Zine-Eddine Khene,
  • Jean-Christophe Bernhard

Publication: European Urology Open Science, May 2024

Background and objective

Data regarding open conversion (OC) during minimally invasive surgery (MIS) for renal tumors are reported from big databases, without precise description of the reason and management of OC. The objective of this study was to describe the rate, reasons, and perioperative outcomes of OC in a cohort of patients who underwent MIS for renal tumor initially. The secondary objective was to find the factors associated with OC.


Between 2008 and 2022, of the 8566 patients included in the UroCCR project prospective database (NCT03293563), who underwent laparoscopic or robot-assisted minimally invasive partial (MIPN) or radical (MIRN) nephrectomy, 163 experienced OC. Each center was contacted to enlighten the context of OC: “emergency OC” implied an immediate life-threatening situation not reasonably manageable with MIS, otherwise “elective OC”. To evaluate the predictive factors of OC, a 2:1 paired cohort on the UroCCR database was used.

Key findings and limitations

The incidence rate of OC was 1.9% for all cases of MIS, 2.9% for MIRN, and 1.4% for MIPN. OC procedures were mostly elective (82.2%). The main reason for OC was a failure to progress due to anatomical difficulties (42.9%). Five patients (3.1%) died within 90 d after surgery. Increased body mass index (BMI; odds ratio [OR]: 1.05, 95% confidence interval [CI]: 1.01–1.09, p = 0.009) and cT stage (OR: 2.22, 95% CI: 1.24–4.25, p = 0.008) were independent predictive factors of OC.

Conclusions and clinical implications

In MIS for renal tumors, OC was a rare event (1.9%), caused by various situations, leading to impaired perioperative outcomes. Emergency OC occurred once every 300 procedures. Increased BMI and cT stage were independent predictive factors of OC.

Commentary by Dr. Riccardo Bertolo

This was a retrospective study conducted in the framework of the UroCCR project (French network of research on kidney cancer, NCT03293563), a French multi-institutional prospectively maintained database of patients treated for kidney tumours. The study investigated open conversion during minimally-invasive surgery for renal tumours, aiming to elucidate its incidence, reasons, and perioperative outcomes. Between 2008 and 2022, 163 out of 8566 patients in the UroCCR database experienced open conversion during laparoscopic or robot-assisted partial or radical nephrectomy, with an overall incidence of 1.9%. Most conversions (>80%) were elective, with anatomical difficulties being the primary reason (>40% of the cases). Emergency conversions occurred approximately once every 300 procedures. Increased BMI and advanced tumour stage were independent predictive factors. Although open conversion was rare, the authors reported compromised perioperative outcomes in such instances.


This effort specifically explored a relatively rare adverse event that may occur during minimally-invasive surgery for renal cancer. The authors emphasised that while a minimally-invasive approach has become the standard in the treatment of localised renal tumours due to its favourable perioperative outcomes, open conversion remains a rare but significant complication. They add that while open conversion rates are decreasing over time, they still pose challenges for surgeons, particularly in emergency situations. The multi-institutional large database of the UroCCR network allowed the authors to describe the characteristics of patients who experienced open conversion meticulously. The authors also explored the reasons behind such conversion, the associated perioperative outcomes, and predictive factors for open conversion, shedding light on potential areas for improvement in the surgical planning and execution.


One notable aspect of the paper was its focus on distinguishing between elective and emergency conversion, providing insights into the different contexts in which such an intraoperative adverse event occurs. The authors stressed the importance of preoperative planning, including careful interpretation of imaging and patient counselling, to ideally mitigate the risk of conversion. They also highlighted the technical and non-technical skills required to manage the accident effectively, emphasising the role of communication, teamwork, and decision-making in navigating such challenging situations.


Well, open conversion rates are relatively low during minimally-invasive surgical treatment of renal tumours, with emergency open conversions being even more anecdotal. Factors such as higher BMI and advanced tumour stage are identified as predictive of open conversion, underscoring the importance of patient selection and risk assessment in surgical decision-making.


While the study provided valuable insights into the occurrence and management of open conversion in minimally-invasive surgery for renal tumours, the authors acknowledged certain limitations, such as the retrospective nature of their analysis and the potential biases in data collection. Notwithstanding such limitations, this research contributes to widening our understanding of this complex (and luckily rare) surgical scenario and offers practical recommendations.