Optimizing Use of a Uterine Manipulator for Laparoscopic Hysterectomy: A Cadaveric Study of Distances to the Pelvic Ureter

INTRODUCTION: Use of a uterine manipulator may mitigate the risk of ureteral injury during laparoscopic hysterectomy by distancing the ureter, particularly for critical steps such as uterine artery ligation and colpotomy. However, evidence to reliably support this spatial effect is lacking, and more data is needed to inform optimal manipulator position and technique. OBJECTIVE: To determine distances from key anatomic structures relevant to laparoscopic hysterectomy to the pelvic ureter while varying manipulator use, position, and colpotomy cup size. METHODS: Ureteral anatomy was assessed in nine unembalmed female cadavers with intact uteri. Three anatomic relationships were measured bilaterally: 1) the lateral uterine isthmus to the ureter at its closest point, 2) the lateral vaginal fornix to the ureter at its closest point, and 3) the lateral uterine isthmus to the ureter at its intersection with the uterine artery. Anatomic distances were assessed without a uterine manipulator and with the manipulator (VCare Plus, ConMed, Largo, FL) using both small and large cervical cups while configured in six different positions: neutral, half maximal cephalic elevation, maximal cephalic elevation, then combined maximal cephalic elevation with anteversion (45 degrees from the longitudinal axis), retroversion ( −15 degrees), and contralateral angulation (30 degrees). Distances with and without manipulator were analyzed with Wilcoxon signed-rank test. Pairwise comparisons between manipulator positions were performed using Friedman test post-hoc analysis with Bonferroni correction. P<0.05 was considered significant. RESULTS: Mean±SD donor age was 76.9±9.0 years with uterine length 6.5±1.1 cm (Table 1). Manipulator versus no manipulator: Manipulator use in any of the six positions significantly increased the distance from the lateral uterine isthmus to the closest ureteral segment on the right compared to no manipulator (Figure 1). Findings were similar for the distance from the right lateral vaginal fornix to the ureter, as well as on the left side. The distance from the lateral uterine isthmus to the ureter at the uterine artery intersection only increased with manipulator use in the maximally elevated, anteverted, and angulated positions on the right (Figure 2) with similar findings on the left. Manipulator positions: Compared to manipulator use in neutral position, only anteversion and angulation produced significant increases in the three distances. Distances did not differ by degree of cephalic elevation, with no differences between neutral, half elevation, or maximum elevation. Similarly, there were no differences between maximum elevation, anteversion, or angulation. Cervical cup size: Distances were similar between use of small and large cups, except for a significantly shorter distance from the right lateral uterine isthmus to the closest ureteral segment with the small cup in anteverted position (5.5 cm vs 5.9 cm, p=0.02, Figure 1). CONCLUSIONS: Placement of a uterine manipulator itself increases the distances from uterine and vaginal structures to the pelvic ureters. The furthest distances are achieved by maximal elevation with combined anteversion or angulation, which may increase the safety margin against ureteral injury. As not all manipulator positions confer the same degree of distancing effect, precise manipulator technique may be key to maximizing its protective benefit during laparoscopic hysterectomy.