Skip Ribbon Commands
Skip to main content

Clin Asst Prof Vikneswaran N

Clin Asst Prof Vikneswaran N


Senior Consultant

Specialty: Gastroenterology & Hepatology

Sub-specialties: Endoscopic Mucosal Resection (EMR) and Endoscopic Submucosal Dissection (ESD), Irritable Bowel Syndrome and Motility Disorders, Early Gastrointestinal Cancers & Dysplasia, Advanced Endoscopic Imaging, Gastroesophageal Reflux Disease (GERD), Diagnostic and Therapeutic Endoscopy

Conditions Treated by this Doctor:
Abdominal Pain and Bloating, Achalasia, Cirrhosis, Colon Cancer Screening, Colonic Polyps, Complex Colonic Polyps, Constipation, Early Cancer of the Esophagus, Stomach & Colon, GERD, Irritable Bowel Syndrome, Viral Hepatitis.

Clinical Appointments

  • Senior Consultant Gastroenterology & Hepatology Singapore General HospitalSingapore General Hospital

Academic Appointments

  • Clinical Assistant Professor, Duke-NUS Graduate Medical School
  • NUS Yong Loo Lin School of Medicine
  • Clinical Teacher, Lee Kong Chian School of Medicine


​Dr. N. Vikneswaran is Senior Consultant with the Department of Gastroenterology & Hepatology, Singapore General Hospital.  He obtained his medical degree from National University of Singapore in 2000 and his specialist accreditation in Gastroenterology in 2009. He completed an advanced fellowship at Mayo Clinic, Rochester, USA and further attachment at National Cancer Center Hospital, Tokyo, Japan.

His main area of training is in endoscopic resection (EMR and ESD) of early cancers and advanced endoscopic imaging techniques (NBI , chromoendoscopy) for early cancer and polyp detection in the esophagus (Barrett’s esophagus), stomach and colon. His training also encompasses gastroesophageal reflux disease and motility disorders (achalasia, functional dyspepsia and irritable bowel syndrome). He performs pH-impedance testing, Bravo capsule insertion and esophageal manometry for the evaluation of reflux and swallowing disorders and endoscopic dilatation of strictures and achalasia.

He is actively involved in research in therapeutic endoscopy, reflux and motility disorders and colorectal cancer.  He has authored several publications in peer-reviewed international journals and book chapters and has served as reviewers for several GI journals. In addition he has also served as an invited speaker and faculty at several conferences and endoscopy workshops in the region.


  • Training stint in Endoscopic Submucosal Dissection at National Cancer Center Hospital, Tokyo, Japan (2011)
  • Advanced Fellowship in Esophageal Diseases, Mayo Clinic, Rochester, Minnesota, USA (2009-2010)
  • Certificate of Specialist Accreditation (Gastroenterology), Specialist Accreditation Board, MOH, Singapore (2009)
  • Member of Royal College of Physicians (MRCP), UK (2004)
  • Bachelor of Medicine and Surgery (MBBS), National University of Singapore (2000)

Professional Appointments and Committee Memberships


​• Singapore Health Manpower Development Plan (HMDP) Fellowship, Singapore Health Services (2009, 2011)

Research Interests


  • ​Vikneswaran N, Murray JA. Discounting the duration of bolus exposure in impedance testing underestimates acid reflux. BMC Gastroenterol. 2016 Jun 8;16(1):60
  • Singh R, Jayanna M, Wong J, Lim LG, Zhang J, Lv J, Liu D, Lee YC, Han ML, Tseng PH, Namasivayam V, Banerjee R, Uedo N, Chan WK, Ho SH, Chen SY, Bhatia S, Funasaka K, Ando T, Wu J, Lesmana C, Tam W, Wang WL, Chang CY, Jung HY, Jung KW, Bestari MB, Yao K, Chong VH, Sharma P, Ho KY. Narrow-band imaging and white-light endoscopy with optical magnification in the diagnosis of dysplasia in Barrett's esophagus: results of the Asia-Pacific Barrett's Consortium. Endosc Int Open. 2015 Feb;3(1):E14-8.
  • Namasivayam V, Prasad GA, Lutzke LS, Dunagan KT, Borkenhagen LS, Okoro NI, Tomizawa Y, Buttar NS, Michel WL, Wang KK. The risk of endoscopic mucosal resection in the setting of clopidogrel use. ISRN Gastroenterol. 2014 Apr 27;2014
  • Orbelo DM, Enders FT, Romero Y, Francis DL, Achem SR, Dabade TS, Crowell MD, Geno DM, DeJesus RS, Namasivayam V, Adamson SC, Arora AS, Majka AJ, Alexander JA, Murray JA, Lohse M, Diehl NN, Fredericksen M, Jung KW, Houston MS, O'Neil AE, Katzka DA. Once-daily omeprazole/sodium bicarbonate heals severe refractory reflux esophagitis with morning or nighttime dosing. Dig Dis Sci. 2015 Jan;60(1):146-62. 
  • Tamai N, Saito Y, Sakamoto T, Nakajima T, Matsuda T, Vikneswaran N, Tajiri H. Visualization of laterally spreading colorectal tumors by using image-enhanced endoscopy. Gastroenterol Res Pract. 2012;2012:
  • Nelsen EM, Kirihara Y, Takahashi N, Shi Q, Lewis JT, Namasivayam V, Buttar NS, Dunagan KT, Prasad GA. Distribution of body fat and its influence on esophageal inflammation and dysplasia in patients with Barrett's esophagus. Clin Gastroenterol Hepatol. 2012 Jul;10(7):728-34
  • Namasivayam V, Arora AS, Murray JA. Weakly Acidic Reflux. Dis Esophagus 2011 Jan;24(1):56-62
  • Namasivayam V, Wang KK, Prasad GA. Endoscopic Mucosal Resection in the Management of Esophageal Neoplasia: Current Status and Future Directions. Clin Gastroenterol Hepatol 2010 Sep;8(9):743-54.
  • Prasad GA, Namasivayam V. Endoscopic Mucosal Resection. Techniques in Gastrointestinal Endoscopy, Volume 12, Issue 2, April 2010, Pages 108-115
  • Pasha SF, Crowell MD, Alexander JA, Harris LA, Achem SR, Farrugia G, Lee JJ, Thompson DM, Jung KW, Kita H, Ravi K, Namasivayam V, Kim HJ, Fleischer DE,  Sharma VK, Romero Y. Eosinophilic oesophagitis in Adults – A Rising Epidemic. European Gastroenterology and Hepatology Review, 2011; 7(1):14-20
  • Namasivayam V, Wang KK. Translumenal and Endolumenal Treatment of Gastric Tumors. In: Evidence-based Approach to Minimally Invasive Surgery.
  • Romero Y, Namasivayam V, and Jung KW. Barrett Esophagus. In Talley, N.J., DeVault, K.R. & Fleischer D.E. (eds) (2010) Practical Gastroenterology and Hepatology: Esophagus and Stomach. Blackwell Publishing Ltd, Oxford.
  • Namasivayam V, Wang KK. Endoscopic Management of Pre-invasive Esophageal Adenocarcinoma. In Fitzgerald RC. (ed) (2010) Pre-invasive Disease: Pathogenesis and Clinical Management. Springer.
  • Namasivayam V, Lori LS, Prasad GA, et al. Non-Invasive Thermal Imaging of Effects of Endoscopic Cryotherapy in an ex vivo Porcine Model. Gastrointest Endosc 2010; 71 (5): AB315.
  • Namasivayam V, Lori LS, Tomizawa Y, et al. Gastric Lymphatic Mapping With Infra-red Endoscopic Imaging (IRE): Dose Response Study with Indocyanine Green (ICG) in an ex vivo Porcine Model. Gastrointest Endosc 2010; 71(5): AB323-4.
  • Namasivayam V, Lutzke LS, Okoro NI, et al. Endoscopic Transmural Gastric Resection Without Creation of a Defect: Feasibility Study in an ex vivo Porcine Model. Gastrointest Endosc 2010; 71(5): AB239.
  • Namasivayam V, Dierkhising RA, Okoro NI, et al. Hemoclip Retention Following Endoscopic Mucosal Resection (EMR) in Barrett's Esophagus. Gastrointest Endosc 2010; 71(5): AB182.
  • Okoro NI, Prasad  GA, Tomizawa Y, Namasivayam V, et al. Is Biopsy Necessary in Narrow Band Imaging (NBI) Negative Patients? Gastrointest Endosc 2010; 71(5): AB122.
  • Katzka DA, Enders F, Romero Y, Alexander JA, Achem SR, Francis DL, Grothe R, Jung KW, Namasivayam V, et al. Which Chronic Upper Airway Symptoms May Be Due to Acid Reflux?  Gastroenterology 2011, Volume 140(5):S216
  • Tomizawa Y, Prasad GA, Wongkeesong LM, Buttar NS, Okoro NI, Namasivayam V, et al. Should We Still Ablate the Residual Barrett's Mucosa After Successful EMR of a Neoplastic Lesion in Barrett's Esophagus.Gastrointest Endosc 2010; 71(5): AB172.

Research Trials