The size of parapelvic cyst may affect the effect of ureteroscopic laser incision and internal drainage.

Background: To evaluate the efficacy and the safety of flexible ureteroscopic laser incision and internal drainage in the treatment of parapelvic cysts and investigate the key variables affecting the collapse effect after cyst surgery.

Methods: A retrospective analysis was conducted on the clinical data of 45 patients diagnosed with parapelvic cysts and treated with laser incision and internal drainage at West China Hospital of Sichuan University from January 2018 to December 2024. The reduction ratio of the maximum transverse diameter of the cysts pre- and post-operation was utilized as the criterion for assessing therapeutic efficacy. Scatter plots illustrating the postoperative reduction ratio and the preoperative maximum transverse diameter of the cysts, along with the receiver operating characteristic (ROC) curve, were constructed. The postoperative collapse of the cysts and the reduction ratio of their maximum transverse diameter were statistically described. Univariate and multivariate logistic regression analyses were employed to identify the variables affecting the efficacy of incision and internal drainage in cysts post-operation.

Results: A cohort of 45 patients was monitored over a median duration of 12 months. These patients were categorized into two groups based on a postoperative reduction threshold of 50%: 9 patients were classified into the ineffective operation group, while 36 patients were classified into the successful operation group. At the 3-month follow-up, the success rate was determined to be 80%, with no cases of recurrence at 12 months. Univariate and multivariate analyses identified the maximum transverse diameter of the preoperative cyst as an independent predictor of surgical success (OR = 9.41, 95% CI 1.33-66.83, P = 0.025). Further regression analysis indicated that when the preoperative cyst's maximum transverse diameter exceeded 6 cm, the reduction ratio of the cyst's transverse diameter progressively decreased following internal drainage. Sensitivity, specificity, and area under the curve (AUC) of the ROC curve cutoff point were 77.8%, 72.2%, and 0.75, respectively.

Conclusion: The maximum transverse diameter of the cyst prior to surgery may serve as an independent factor influencing the efficacy of laser incision and internal drainage treatment for parapelvic cysts. This factor exhibits a negative correlation with the postoperative success rate. Specifically, when the cyst's diameter exceeds 6 cm, the likelihood of cyst collapse diminishes progressively.