The learning curve of laparoendoscopic single-site adrenalectomy: an analysis of over 100 cases

Recently, laparoendoscopic single-site adrenalectomy (LESS-A) has been developed as an alternative treatment for adrenal tumors. Although LESS-A is more technically complex than conventional laparoscopic adrenalectomy, its learning curve and the factors associated with poor surgical outcomes are poorly understood. We analyzed the learning curve of LESS-A and attempted to identify risk factors associated with worse surgical outcomes.

We identified 103 patients who underwent LESS-A [performed by the same surgeon (A.M.)] from 2009 to 2015. The learning curve was analyzed using the moving average method (the 10-case moving average), and we assessed potential risk factors for a prolonged pneumoperitoneum time.

The learning curve stabilized at 30 cases. The cases were divided into two groups, the learning stage (LS) (cases 1-29) and master stage (MS) (cases 30-103) groups. The percentage of females and the frequency of previous abdominal surgery were higher in the LS group (p = 0.022 and 0.001, respectively). In the LS group, the mean pneumoperitoneum time was 92 ± 35 min, which was significantly longer than the equivalent value for the MS group (55 ± 18 min, p < 0.001). In the LS group, univariate analysis revealed that tumor size (≥50 mm) and the visceral fat area (VFA)/total fat area (TFA) ratio (≥0.49) were significantly associated with a prolonged pneumoperitoneum time (p = 0.046 and 0.046, respectively). In the multivariate analysis, tumor size and the VFA/TFA ratio were confirmed to be associated with a prolonged pneumoperitoneum time (p = 0.029 and 0.029, odds ratio 20.83 and 20.83, respectively). On the other hand, none of the examined factors were found to be associated with a prolonged pneumoperitoneum time in the MS group.

LESS-A was performed safely in most cases. However, surgeons who are learning the LESS-A procedure need to pay attention to tumor size and visceral obesity.