Zaher Alwafai, Verena M. C. Reichert, Paula Spring, Marek Zygmunt, Günter Köhler

• Background: There are conflicting data regarding the detection rate of high-risk uterine sarcoma (HRUS) by endometrial biopsy. In addition, there are no studies in the literature on its impact on the chosen surgical approach and survival. Methods: This study includes 415 patients with HRUS. Of these, 178 (42.9%) patients had undergone endometrial biopsy. We analyzed the detection rate of endometrial biopsy and its impact on surgical approach and survival data. Results: Correct specific histologic diagnosis was achieved in only 30.0% of LMS and 33.3% of HGESS/UUS. Other uterine sarcoma, unspecified malignant mesenchymal tumor, carcinosarcoma or carcinoma were found in 45% of LMS and 78.2% of HGESS/UUS. As a result of the histologic findings, the rate of inadequate surgery was reduced by up to 19.9%. As tumor morcellation was performed significantly less often with biopsy (32.5% with vs. 55.4% without biopsy, p < 0.001), the locoregional recurrence-free interval remained unaffected between the two groups (p = 0.81). This is obviously an advantage of biopsy, although it does not affect the local recurrence rate in morcellated patients. Conclusions: Indicated endometrial biopsy is an important step in the diagnosis of HRUS, despite its low detection rate. It helps to avoid inappropriate surgical procedures but does not affect OS.