Optimizing use of a uterine manipulator for laparoscopic hysterectomy: a cadaveric study of distances to the pelvic ureter.

BACKGROUND

Uterine manipulator use may mitigate the risk of ureteral injury during laparoscopic hysterectomy by distancing the ureters, particularly for critical steps such as uterine artery ligation and colpotomy. However, evidence to reliably support this spatial effect is lacking, and more data are needed to inform optimal manipulator position and technique.

OBJECTIVE

To determine distances from key uterovaginal structures relevant during laparoscopic hysterectomy to the pelvic ureter while varying manipulator use, position, and cervical cup size.

STUDY DESIGN

Ureteral anatomy was assessed in 9 unembalmed female cadavers with intact uteri. Three anatomic relationships were measured bilaterally: (1) lateral uterine isthmus to the ureter at its closest point, (2) lateral vaginal fornix to the ureter at its closest point, and (3) lateral uterine isthmus to the ureter at its intersection with the uterine artery. Anatomic distances were assessed without a uterine manipulator and with the VCare Plus manipulator (ConMed, Largo, Florida) configured in 6 different positions using both small and large cervical cups: neutral, half maximal cephalic elevation, maximal cephalic elevation and then combined maximal cephalic elevation with anteversion, retroversion, or contralateral angulation. Distances with and without the manipulator were analyzed with Wilcoxon signed-rank test. Pairwise comparisons between manipulator positions were performed using Friedman test post-hoc analysis with Bonferroni correction.

RESULTS

Mean±standard deviation donor age was 76.9±9.0 years with uterine length 6.5±1.1 cm. Manipulator vs no manipulator: Compared to without a manipulator, manipulator use significantly increased the distance from the lateral uterine isthmus to the closest ureteral segment bilaterally regardless of specific manipulator position (no manipulator: 1.8-1.9 cm; manipulator all positions: 2.9-6.2 cm; right: neutral, P=.017 half elevation, P=.008, max elevation, P=.007, anteversion, P=.008, retroversion, P=.008, angulation, P=.008; left: neutral, P=.008, half elevation, P=.008, max elevation, P=.008, anteversion, P=.008, retroversion, P=.012, angulation, P=.008). Findings were similar for the distance from the lateral vaginal fornix to the ureter bilaterally (no manipulator: 1.4 cm; manipulator all positions: 2.2-5.1 cm; right: neutral, P=.018, half elevation, P=.011, max elevation, P=.008, anteversion, P=.008, retroversion, P=.008, angulation, P=.008; left: neutral, P=.008, half elevation, P=.008, max elevation, P=.008, anteversion, P=.008, retroversion, P=.008, angulation, P=.008). The distance from the lateral uterine isthmus to the ureter at the uterine artery intersection only increased with manipulator use in the maximally elevated (right, P=.035; left, P=.013), anteverted (right, P=.013; left, P=.011), and angulated (right, P=.008; left, P=.008) positions bilaterally (3.7-5.8 cm) vs no manipulator (2.6-2.9 cm). Manipulator positions: Compared to manipulator use in the neutral position, only anteversion and angulation significantly increased any of the 3 distances (manipulator neutral: 2.2-3.7 cm; manipulator anteversion: 3.9-5.9 cm; right isthmus to ureter, P=.001, left isthmus to ureter, P=.003, right fornix to ureter, P<.001, left fornix to ureter, P=.013, right isthmus to intersection, P=.046, and manipulator angulation: 5.0-6.2 cm, right isthmus to ureter, P<.001, left isthmus to ureter, P<.001, right fornix to ureter, P<.001, left fornix to ureter, P<.001, right isthmus to intersection, P=.013, left isthmus to intersection, P=.002), with contralateral angulation most consistently producing farther measurements for all distances bilaterally. Half elevation, maximum elevation, and retroversion did not significantly differ from the neutral manipulator position for any distance. Cervical cup size: Distances were similar between use of small and large cups, except for a significantly farther distance from the right lateral uterine isthmus to the closest ureteral segment with the large cup in anteverted position (5.9 cm vs 5.5 cm, P=.02).

CONCLUSION

Placement of a uterine manipulator itself increases the distances from uterine and vaginal structures to the pelvic ureters. The farthest distances are achieved by maximal elevation with combined anteversion or contralateral 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.