Perirenal Extravasation After Retrograde Intrarenal Surgery for Renal Stones: A Prospective Study.

Background The incidence and consequences of the perirenal extravasation of the irrigation fluid during retrograde intrarenal surgery (RIRS) are not fully elucidated. The objective of this study was to assess the incidence, risk factors, and complications of perirenal extravasation of irrigation fluid during RIRS. Methods This prospective observational study was conducted in the Department of Urology, Bir Hospital, Kathmandu, Nepal, from January 2020 to March 2021. Patients undergoing RIRS for renal stones less than 2 cm in diameter were included in the study. Irrigation during the procedure was performed using isotonic normal saline under gravity at 50 cm from the symphysis pubis of patients with intermittent manual compression if required. Lithotripsy was performed with 120-Watt Ho:YAG laser using 200-micron laser fiber. Retrograde pyelogram was performed after the completion of lithotripsy to document the presence or absence of extravasation on fluoroscopic images. A double-J stent was placed at the end in all patients. Patients were observed for systemic inflammatory response syndrome (SIRS) features. Postoperative abdominal ultrasonography was performed on the first postoperative day to assess the perirenal collection together with complete blood count. The visual analogue scale (VAS) was used to assess pain in postoperative period. The preoperative patient's and stone characteristics, hydronephrosis, intraoperative characteristics, and postoperative findings were analyzed. Results A total of 71 patients who underwent RIRS during the study period were analyzed. The mean (SD) stone size was 13.19 (3.12) mm. Intraoperative perirenal extravasation of contrast was noted in eight (11.26%) patients; however, no patient had ipsilateral perirenal collection on ultrasonography obtained on the first postoperative day. No significant differences were observed among patients with or without perirenal extravasation in terms of mean stone size, laser settings, operative duration, and lasing duration. Use of ureteral access sheath (UAS) was associated with lower incidence of extravasation; however, it was not significant. SIRS was documented in eight patients overall, with none of the patients with extravasation having features of SIRS. Patients with extravasation experienced more postoperative flank pain (p<0.05). Conclusion Perirenal extravasation was common during RIRS and was associated with higher postoperative pain scores. Stone size, use of UAS, laser settings, operative duration, and lasing duration were not associated with an increased risk of extravasation. Extravasation was not associated with increased postoperative complications.