Greater Houston Gastroenterology

Isaac Raijman, MD

Isaac Raijman, MD, Dang M. Nguyen, MD, and H. Chami Amaratunge, MD

Together, Dr. Isaac Raijman, Dr. Dang M. Nguyen, Dr. H. Chami Amaratunge, and Andrea Washington, FNP-C, form Greater Houston Gastroenterology in their Texas Medical Center Houston office. This practice is designed to provide compassionate care and a comprehensive diagnosis in an atmosphere of comfort and trust for their patients. Greater Houston Gastroenterology is the largest full-service gastroenterology group in the Houston metro. This network of highly skilled physicians works together in the diagnosis, treatment, and care of people with gastrointestinal symptoms and diseases.

A gastroenterologist is a highly trained physician who treats all aspects of the digestive system, including the esophagus, stomach, small intestine, large intestine, rectum, liver and gallbladder, and pancreas. As these organs work together in a healthy body, they are easy to ignore. A properly functioning digestive tract, after all, is easy to take for granted. Yet when problems arise due to diet, obesity, smoking, cancer, and disease, choosing the right gastroenterologist is one of the most important decisions you can make.

Why see a Specialist?

Many people who suffer from problems with their digestive system suffer in silence, often waiting until the symptoms are unbearable before seeking a physician’s help. These sufferers believe that they’re alone in their discomfort and trouble, and blame the pain and dysfunction on old age or other factors rather than seeking the help they need. In fact, studies show that more than 34 million Americans suffer from digestive disease, and an estimated 22 percent of annual cancer deaths can be attributed to cancers of the digestive tract. Millions of people suffer each year from some form of digestive disorder, from diverticulitis to liver disease to acid reflux.

The good news is that you don’t have to suffer alone. Treatments are available, and the right gastroenterologist can help bring together your causes of discomfort with your symptoms in order to choose the best treatment plan for you going forward.

By choosing a specialist, you can trust that you are choosing the most experienced, skill, and best trained physician in their field. Board certified in both internal medicine and gastroenterology, Drs. Raijman, Nguyen, and Amaratunge have the training and experience that you need.

Treatment Mean Results. Results Mean a Healthier You.

Preventive measures such as colon cancer screening are paramount in keeping you healthy. Many of the GI tract disorders are common and treatable. Often times simple measures such as dietary changes and life style modifications. Conditions such as gastroesophageal reflux disease, gastritis and ulcer disease and functional bowel disease require additional medications. Other conditions such as inflammatory bowel disease including Crohn’s disease and ulcerative colitis require a more specialized approach and a higher level of management. More difficult processes such as those involving the bile duct and pancreas, as well as tumors of the digestive tract often require a highly specialized endoscopic intervention and a multi-disciplinary approach. Dr. Isaac Raijman, Dr. Dang Nguyen and Dr. Chami Amaratunge are highly trained in all aspects of digestive tract pathology and surround themselves with highly trained physicians in all subspecialties including nutritionist to provide comprehensive management. In addition, alternative medicine approach to Western medical care is provided, including medical foods, supplements and acupuncture.

Meet the Doctors

Isaac Raijman, MD, FASGE, AGAF, FACG, isn’t just a clinician with 20 years experience in gastroenterology and endoscopy, he’s also Chief of Gastroenterology at CHI Baylor St. Luke’s Hospital. As a leader in endoscopy, he’s actively involved with clinical research, as a presenter in national and international conferences, in training other physicians, and in writing manuscripts, book chapters, and peer-reviewed journals. Board certified in both internal medicine and gastroenterology,
Dr. Raijman is considered the doctor of doctors. Dr. Raijman is trained in advanced endoscopic procedures and has developed techniques and tools used by others in the field. He is regarded as the “go to doctor” when others can’t solve the problem. He specializes in management of pancreatic and biliary disorders, resection of tumors and difficult lesions, ablative therapies, management of gastroesophageal reflux disease and Barrett’s, Zenker’s diverticulum and in patients with complications of bariatric surgery. He performs all endoscopies, ERCP, endoscopic ultrasound, laser and radiofrequency ablations, placement of prosthesis and in endoscopic management of obesity.

H. Chami Amaratunge, MD and Dang M. Nguyen, MD

Dang M. Nguyen, MD, is board certified in internal medicine and gastroenterology. He completed his medical degree, internship, residency, and fellowship at Baylor College of Medicine. Dr. Nguyen is an interventional gastroenterologist—his clinical expertise lies in the screening and surveillance of gastrointestinal cancer, the management of pancreatic diseases, and advanced endoscopy, including endoscopic ultrasound, balloon-assisted small bowel enteroscopy, and endoscopic management of obesity. He’s a member of the American College of Gastroenterology, the American Gastroenterological Association, the American Society for Gastrointestinal Endoscopy, and the Harris County Medical Society. He works in both the main office at 4100 South Shepherd Drive and the satellite office at 2430 North Fry Road, Suite 100, in Houston.

H. Chami Amaratunge, MD

Board certified in both internal medicine and gastroenterology, Dr. Amaratunge received her bachelor’s degree from Houston Baptist University and her medical degree from the University of Texas Medical Branch Galveston. She completed her internship, residency, and fellowship from Baylor College of Medicine. A member of the American College of Gastroenterology, the American Gastroenterology Association, and the Harris County Medical Association, she specializes in screenings and surveillance of gastrointestinal cancers (colonoscopy) and diagnosis and management of motility disorders of the upper digestive tract including comprehensive reflux testing for GERD. She also has special interest in IBD and women’s health.

Andrea Washington, FNP-C

Andrea Washington, FNP-C

Andrea Washington is a native Houstonian and is a certified family nurse practitioner through the American Association of Nurse Practitioners. She received her bachelor’s of science in nursing from the University of Texas-Arlington and completed her master’s of science in nursing from Prairie View A&M. She is a member of multiple professional organizations such as the American Academy of Nurse Practitioners, the Houston Area Nurse Practitioners, and the Texas Nurse Practitioners. She has worked as an endoscopic nurse since 2012.

Patient Testimonial

“Dr. Raijman has treated my husband for approximately five years now for acute/chronic pancreatitis. Each and every time we are admitted to the hospital I always feel relief when I see Dr. Raijman walk in the door. He always takes the time to sit and talk to me after each procedure and explains the pros and cons of my husband’s treatment. He is so very kind and I love the twinkle in his eye.” – A thankful wife of one of Dr. Raijman’s patients

Greater Houston Gastroenterology Serves Patients by Providing:

  • Colonoscopy
  • Upper GI Endoscopy
  • Liver Biopsy
  • Infusion Treatment
  • ERCP
  • Ideal Protein Weight Loss Program
  • Orbera Weight Loss System
  • Endoscopic Ultrasound
  • Hemorrhoid banding
  • Capsule Endoscopy
  • Esophageal Motility
  • Reflux testing


4100 South Shepherd Drive

Houston, Texas 77098

(713) 795-4444


Photography by MM Photography

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