Searching for the Lost Ostium: A Morphometric Analysis of the Ureteral Ostia Distribution in Normal and Thickened Bladders and Its Applications in Endourology

Introduction: The ureteral ostia may not be easily identified in urological endoscopic procedures, leading to an incomplete diagnosis of urinary tract diseases or a predisposition to iatrogenic lesions. The purpose of our study is to evaluate the anatomical distribution of ureteralostia in normal bladders and those with thickened walls. Materials and Methods: We dissected 30 vesical-prostate blocks from human cadavers and identified the ostia of the bladder trigone. A computerized morphometric analysis was performed to measure the thickness of the detrusor muscle, the distances between the ureteral ostia themselves and the distances between each ureteral ostium (left—LUO and right—RUO) and the internal urethral ostium (IUO). The angle formed between the IUO and LUO/RUO was also recorded as well as the volume of the prostates. Results: Fifteen bladders with a non-thickened detrusor (<5 mm) as well as 15 bladders with muscular thickening (>6 mm) were identified. The average prostatic volume of the dissected blocks was 23.7 cm. The distance between ureteral ostia, the distance from IUO to LUO, the distance from IUO to RUO and the angle formed between IUO and LUO/RUO in normal and thickened bladder were, respectively, 1.9 cm/2.2 cm (p = 0.09), 1.6 cm/1.6 cm (p = 0.82), 1.6 cm/1.7 cm (p = 0.79) and 77/91 (p = 0.17). Conclusions: Our study shows that there is no significant difference in the position of bladder ostia in healthy and thickened bladders. We believe that our findings may facilitate locating the ureteral orifices in situations where endoscopic identification is difficult.