AUTHOR=Tang Mingming , Tian Xingbo , Luo Jianglai , Zhang Xiaohang , Ran Suzhen , Xiong Jiaojiao , Chen Yanlin , Chen Gongli TITLE=Twin-Twin Transfusion Syndrome After Radiofrequency Ablation in Dizygotic Monochorionic Triamniotic Triplet Pregnancy With Sex Discordance: A Case Report JOURNAL=Frontiers in Medicine VOLUME=Volume 9 - 2022 YEAR=2022 URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.924356 DOI=10.3389/fmed.2022.924356 ISSN=2296-858X ABSTRACT=Background: We report a case of dizygotic monochorionic triamniotic triplet pregnancy. Twin-twin transfusion syndrome was subsequently diagnosed combined with sex discordance in the two surviving foetuses after one foetus was reduced, which is extremely rare and has not been previously reported. Case presentation: After reducing one foetus by radiofrequency ablation of a monochorionic triamniotic triplet pregnancy, twin-twin transfusion syndrome was subsequently diagnosed combined with sex discordance in the two surviving foetuses. Amniotic fluid for chromosome analysis showed normal karyotype 46, XY/46, XX of the donor and recipient foetus, and short tandem repeat (STR) analysis revealed dizygotic twins. Conclusions: Through this is an unusual case, we aim to emphasize the importance of accurate diagnosis of chorionicity and zygosity in sex discordant triplet pregnancy, which is the key to appropriate clinical management. Keywords: Dizygotic Triplet Pregnancy; Monochorionic Triamniotic Triplet Pregnancy; Twin-Twin Transfusion Syndrome; Radiofrequency Ablation; Sex Discordance