Fetal hydrops – A review and a clinical approach to identifying the cause. Esther Dempseya, Tessa Homfrayb, John M Simpsonc, Steve Jefferya, Sahar Mansoura,b, Pia Ostergaarda a Molecular and Clinical Sciences, St George’s University of London, London, UK b SW Thames Regional Genetics Department, St George’s University Hospitals NHS Foundation Trust, London, UK c Department of Congenital Heart Disease, Evelina London Children’s Hospital, Guy’s and St Thomas’ NHS Foundation Trust, London UK Academic qualifications and job titles of all authors: Esther Dempsey: 0000-0002-7653-4653 BSc, MSc, MBBS, MRCPCH. Clinical Research Fellow. Tessa Homfray: 0000-0002-9981-9678. Consultant in Clinical Genetics, FRCP John Simpson: 0000-0002-9773-7441. MD FRCP . Professor of Paediatric and Fetal Cardiology, Evelina London Children’s Hospital. Steve Jeffery: 0000-0003-1369-6951. BSc, MSc, PhD. Emeritus Professor. Sahar Mansour: 0000-0001-6629-4118. Professor of Clinical Genetics, FRCP Pia Ostergaard: 0000-0002-2190-1356. BSc, MSc, PhD. Associate Professor. Corresponding author: Dr Esther Dempsey, Molecular and Clinical Sciences, St. George’s University of London, Cranmer Terrace, London SW17 0RE, UK. email:
[email protected] Article highlights: 1 • Fetal hydrops is the abnormal accumulation of fluid in two or more extravascular fetal compartments. • Fetal hydrops confers a high risk of morbidity and mortality. • Fetal hydrops can be divided into immune (largely materno-fetal alloimmunisation) and non-immune. • Non-immune fetal hydrops can be caused by a multitude of different causes including infection, congenital malformation, chromosome abnormalities and single-gene disorders. • The identification of fetal anaemia from the second trimester is crucial to guiding further investigations.