Preoperative Uterine Weight Estimation Using UroNav in Robot-Assisted Total Laparoscopic Hysterectomy: An Exploratory Study

Objective: The accuracy of uterine weight estimation using the UroNav MR/Ultrasound Fusion Biopsy System, originally developed for prostate imaging and intervention, has not been investigated in gynecologic surgery. We evaluated the accuracy of UroNav-based three-dimensional uterine volume measurement for preoperative estimation of uterine weight in patients undergoing robot-assisted total laparoscopic hysterectomy (RA-TLH). Subjects and Methods: We evaluated 51 patients who underwent RA-TLH for benign uterine tumors and who had not received preoperative gonadotropin-releasing hormone agonists or antagonists. Uterine volume was measured using three-dimensional reconstructions generated from MRI obtained within 3 months before surgery. Predicted uterine weight was calculated assuming a tissue density of 1.0 g/mL. Agreement between UroNav-predicted and retrieved uterine weight (RUW) was assessed. The caliper technique was also evaluated for comparison. Results: The mean RUW was 676 g, and the mean UroNav-predicted weight was 668 g, with a mean difference of −8.0 g. Forty-two of 51 cases (82.4%) had prediction errors within ±10% of the RUW, and the mean absolute percentage error (MAPE) was 6.82%. The RUW was strongly associated with the UroNav-predicted weight (R² = 0.9903). In comparison, the caliper technique yielded a mean predicted weight of 617 g, a MAPE of 15.25%, and prediction errors within ±10% in 16 of 51 cases (31.4%). Conclusion: UroNav-based three-dimensional reconstruction showed good agreement with RUW and provided more accurate weight estimation than the caliper technique. This novel application of an MR/ultrasound fusion platform may assist in preoperative selection of specimen retrieval strategies during RA-TLH.