Background <p>The objective is to evaluate the comprehensive complication index (CCI) for the purpose of assessing immediate postoperative complications following radical cystectomy (RC) for urothelial carcinoma with variant histology (VUC). This evaluation aims to quantify the combined surgical morbidity and facilitate a comparison of surgical expertise.</p> Methods <p>From March 2020 to October 2024, we collected clinical data from patients at VUC who underwent RC with urinary diversion. To assess complications occurring within 30 days post RC and their impact on hospital stay duration, the CCI was employed for evaluation purposes. Additionally, our facility utilized cumulative sum control models (CUSUM) to evaluate overall surgical morbidity associated with RC in VUC patients and facilitate intersurgeon comparisons.</p> Results <p>The study involved a total of 80 participants, with 66 individuals (82.5%) experiencing a combined total of 249 complications. The CCI was found to be 22.6, and significant associations were discovered between its increase and factors such as gender, subtype of urinary diversion, procedural approach, and surgeon (<i>p</i> &lt; 0.05). Furthermore, there was an observed correlation between the length of hospital stay and CCI (<i>R</i>² = 0.429). Additionally, the utilization of the CUSUM-CCI model unveiled variations in growth distribution over time among individual surgeons.</p> Conclusions <p>The CCI effectively indicates postoperative complications after VUC with RC, as it exhibits a robust correlation with the duration of hospitalization following surgery. Moreover, the CUSUM-CCI model promptly offers valuable insights into the surgical proficiency of individual surgeons, accurately reflecting their level of expertise.</p>