Prof Siwan Thomas-Gibson

Consultant Gastroenterologist and Specialist Endoscopist
Profile Photo for Professor Siwan Thomas-Gibson

Professor Siwan Thomas-Gibson is a gastroenterologist and specialist endoscopist at St Mark’s National Bowel Hospital London. She is the Dean of St Mark’s Hospital Academic Institute, Professor of Practice in Gastrointestinal Endoscopy at Imperial College London and Clinical Lead for LC Endoscopy unit.

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Professor Thomas-Gibson specialises in the delivery of high quality and safe colonoscopy; bowel cancer screening and the detection and endoscopic management of early colorectal neoplasia in inflammatory bowel disease and inherited cancer and polyposis syndromes. She has been an accredited bowel cancer screening colonoscopist since 2007.

She manages patients with a variety of gastrointestinal conditions including inflammatory bowel disease, irritable bowel syndrome, indigestion and those with bowel symptoms following cancer treatment.

Her research interests include the development of high quality and safe endoscopy, improving endoscopic training and assessment and developing new ways of investigating and managing bowel problems such as polyps. 

In 2018 she was awarded the prestigious British Society of Gastroenterology Hopkins prize for her achievements in endoscopic research. She was Chair of the Joint Advisory Group for Gastrointestinal Endoscopy 2017-2020 where she launched the JAG Improving Safety and Reducing Error in Endoscopy strategy. 

She is frequently faculty on national and international meetings, performing and teaching live endoscopy. She has supervised a number of PhDs and MDs and has over 100 academic publications including several National Guidelines as well as authorship in several books. She was awarded a Chair at Imperial College London in 2020 becoming a Professor of Practice in Gastrointestinal Endoscopy.

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116 Harley Street
London W1G 7JL

  • Consultant gastroenterologist and specialist endoscopist, Deputy Director Bowel Cancer Screening
    St Mark’s National Bowel Hospital London
  • Dean
    St Mark’s Hospital Academic Institute
  • Professor of Practice in Gastrointestinal Endoscopy
    Imperial College
  • Honorary Senior Lecturer
    Imperial College London
  • Bowel cancer screening (accredited 2007)
  • Detection and prevention of bowel cancer in normal and high risk conditions
  • Diagnosis and management of gastroenterology conditions
  • Diagnosis and management of inflammatory bowel disease
  • Year qualified 1992
  • St Mary's Hospital, Imperial College London 1986
  • MD, Imperial College London 2006

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