Objective: To estimate the risk of uterine leiomyosarcoma in patients undergoing gynecological surgery and also to identify groups at risk for unrecognized uterine leiomyosarcoma. Methods: A national cohort study was performed evaluating all uterine leiomyosarcoma (ULMS) diagnosed in The Netherlands between January 2000 and September 2015. Cases were identified and supplied by the nationwide network and registry of histo- and cytopathology in The Netherlands (PALGA). Unexpected and expected ULMS were compared. Approval for this study was granted by the Medical Ethics Committee of all participating hospitals and by the review board of PALGA. Results: 262 original cases were included. The overall incidence of ULMS in our study was 0.25% or 1:400 patients. The incidence of unexpected ULMS was 0.12% or 1:865 patients. Preoperatively, a malignancy was unexpected in 46% of the cases and expected in 54%. Abnormal uterine bleeding constituted most of the symptoms. 90% of women underwent abdominal hysterectomy and/or bilateral salpingo-oophorectomy. Conclusions: Leiomyosarcoma are rare. Women aged 40–50 years with abnormal uterine bleeding are most at risk for unexpected ULMS. In contrast, this risk is low in postmenopausal women. ULMS were highly uncommon in women aged under 40 years.

Background: To assess potential risks of new surgical procedures and devices before their introduction into daily practice, a prospective risk inventory (PRI) is a required step. This study assesses the applicability of the Health Failure Mode and Effects Analysis (HFMEA) as part of a PRI of new technology in minimally invasive gynecologic surgery. Methods: A reference case was defined of a patient with presumed benign leiomyoma undergoing a laparoscopic hysterectomy or myomectomy including in-bag power morcellation; however, pathology defined a stage I uterine leiomyosarcoma. Using in-bag morcellation as a template, a HFMEA was performed. All steps of the in-bag morcellation technique were identified. Next, the possible hazards of these steps were explored and possible measures to control these hazards were discussed. Results: Five main steps of the morcellation process were identified. For retrieval bags without openings to accommodate instruments inside the bag, 120 risks were identified. Of these risks, 67 should be eliminated. For containment bags with openings 131 risks were identified of which 68 should be eliminated. Of the 10 causes most at risk to cause spillage, two can be eliminated by using appropriate bag materials. Myomectomy appears to be more at risk for residual tissue spillage compared to total hysterectomy. Conclusion: The HFMEA has provided important new insights regarding potential weaknesses of the in-bag morcellation technique, particularly with respect to hazardous steps in the morcellation process as well as requirements that bags should meet. As such, this study has shown HFMEA to be a valuable method that identifies and quantifies potential hazards of new technology.