Background:The Food and Drug Administration recently announced that the use of morcellation may cause fibroids or pelvic dissemination and metastasis of uterine sarcoma;therefore,the use of morcellation is limited in the USA.A large sample study is necessary to assess the proportion of uterine malignant tumors found in patients with laparoscopic myomectomy.Methods:A national multicenter study was performed in China.From 2002 to 2014,33,723 cases were retrospectively selected.We calculated the prevalence and recorded the clinical characteristics of the patients with malignancy after morcellation application.A total of 62 cases were finally pathologically confirmed as malignant postoperatively.Additionally,the medical records of the 62 patients were analyzed in details.Results:The proportion of postoperative malignancy after morcellation application was 0.18％ (62/33,723) for patients who underwent laparoscopic myomectomy.Nearly 62.9％ (39/62) of patients had demonstrated blood flow signals in the uterine fibroids before surgery.And,23 (37.1％) patients showed rapid growth at the final preoperative ultrasound.With respect to the pathological types,38 (61.3％) patients had detectable endometrial stromal sarcoma,13 (21.0％) had detectable uterine leiomyosarcoma,only 3 (3.2％) had detectable carcinosarcoma,and 5 (8.1％) patients with leiomyoma had an undetermined malignant potential.Conclusions:The proportion of malignancy is low after using morcellation in patients who undergo laparoscopic myomectomy.Patients with fast-growing uterine fibroids and abnormal ultrasonic tumor blood flow should be considered for malignant potential,and morcellation should be avoided.