Endoluminal anatomy in retrograde ureteroscopy: surgical landmarks and clinical implications.

PURPOSE: To redefine upper urinary tract anatomy from an endoluminal, retrograde perspective and to identify key surgical landmarks and anatomical factors directly relevant to modern ureteroscopic practice, providing practical guidance in the context of evolving endourological technologies. METHODS: A narrative review was conducted using PubMed/MEDLINE to identify relevant literature published from database inception to 2026. Search terms included endoscopic anatomy, ureteroscopy, urinary tract anatomy, renal collecting system, calyceal anatomy, ureteral anatomy, intrarenal pressure, ureterovesical junction, ureteropelvic junction, flexible ureteroscopy, and endourology. Original articles, reviews, classical anatomical references, and selected textbook sources were included based on relevance. Findings were qualitatively synthesized according to a predefined retrograde anatomical framework, from the urethral meatus to the renal papilla. RESULTS: A clinically oriented endoluminal map of the urinary tract was developed, describing the sequential anatomical landmarks encountered during ureteroscopy, including the urethra, bladder neck, trigone, ureteral orifice, ureter, ureteropelvic junction, renal pelvis, calyces, papilla, and fornix. Key anatomical factors (such as zones of resistance, ureteral narrowing, pelvicalyceal variability, perpendicular calyces, lower pole anatomy, infundibulopelvic angle, and anterior-posterior calyceal orientation) were shown to directly influence endoscopic access, scope deflection, working-channel alignment, lithotripsy efficiency, and complication risk. Practical intraoperative concepts, including bubble-guided orientation, stone relocation strategies, and the impact of miniaturized ureteroscopes and suction-enabled access sheaths, were also highlighted. CONCLUSION: This work provides a clinically relevant framework of endoluminal urinary tract anatomy tailored to contemporary ureteroscopy. Integrating functional anatomy with instrument behavior and pressure-related dynamics may improve navigation, enhance procedural efficiency, reduce complications, and support surgical training in modern endourology.