Retraction Note: Oxycodone versus morphine for analgesia after laparoscopic endometriosis resection

Niu et al. BMC Anesthesiology (2021) 21:314 https://doi.org/10.1186/s12871-021-01540-1 RETRACTION NOTE Retraction Note: Oxycodone versus morphine for analgesia after laparoscopic endometriosis resection Lijun Niu1, Lihong Chen2, Yanhua Luo3, Wenkao Huang4 and Yunsheng Li1* © The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecom- mons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Retraction Note: BMC Anesthesiol 21, 194 (2021) https://doi.org/10.1186/s12871-021-01417-3 The Editor has retracted this article because after obtaining approval for this clinical trial from the Insti - tutional Ethical Review Committee for Clinical Trials of The First Affiliated Hospital of Sun Yat-sen University the authors made changes to the protocol without obtain - ing the Committee’s approval. All authors agree to this retraction. Author details 1 Department of Anesthesiology, The First Affiliated Hospital, Sun Yat-sen University, No.58, Zhongshan 2nd Road, Guangzhou 510080, China. 2 Depart- ment of Anesthesiology, The Six Affiliated Hospital, Sun Yat-sen University, No. 26, Erheng Road, Guangzhou 510655, China. 3 Department of Anesthesiology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, No.54 Xianlie South Road, Guangzhou 510060, China. 4 Department of Anesthesiology, Nanfang Hospital, Southern Medical University, 1838 Guangzhou Avenue North, Guangzhou, China. Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in pub- lished maps and institutional affiliations. Open Access The original article can be found online at https:// doi. org/ 10. 1186/ s12871- 021- 01540-1. *Correspondence: [email protected] 1 Department of Anesthesiology, The First Affiliated Hospital, Sun Yat-sen University, No.58, Zhongshan 2nd Road, Guangzhou 510080, China Full list of author information is available at the end of the article