Gastroenterologist Staff

Gastroenterologist Newport Beach, CA

All of the medical professionals at our practice maintain the highest levels of accreditation and pursue ongoing education to stay abreast of the latest trends in gastroenterology.

Glenn D. Madokoro, M.D., FACG

Newport Beach, CA Physician

Newport Beach, CA Gastroenterologist Dr. Madokoro welcomes you to this site and hopes it provides you with the information you need to make a thoughtful decision about your care.

Dr. Madokoro majored in chemistry at Stanford, where he was elected to Phi Beta Kappa and graduated with great distinction. He received all his post-graduate training at UCLA, including attending medical school, and training as an intern, resident, and fellow.

He has twice served as chairman of gastroenterology at Hoag Hospital Newport Beach.

He was recognized by Greater Newport Physicians, an IPA that currently includes over 900 physicians, who voted Dr. Madokoro the best specialist in the organization. Each year only one specialist in Greater Newport Physicians is chosen as the best. All specialists in every specialty compete for the distinction.

Every gastroenterologist likes to think that they are doing the best job in their profession, but our professional societies, the ASGE and the ACG, as well as the Mayo Clinic, all stated in print in 2015 that there is one measurement that best objectively rates the performance of all gastroenterologists. That measurement is the adenoma detection rate (ADR), which is the rate at which doctors find pre-cancerous growths (adenomas) in the colon during a colonoscopy.

If adenomas are not found and removed, then colon cancer can still occur after a colonoscopy, a problem of growing magnitude in the US and throughout the world.

It has also been discovered that the rate that gastroenterologists find pre-cancerous polyps varies up to 28 fold. That variation has been shown to be determined primarily by the amount of time the physician spends looking for polyps during each colonoscopy. This wide variation in quality has been documented even at the Mayo Clinic and the Cleveland Clinic. You can see a graph of the variation of accuracy versus time published in the New England Journal of Medicine, our premiere journal of internal medicine, and reprinted in the New York Times below:

New York Times Study on Gastroenterology Dr. Madokoro spends the most time searching for polyps of any gastroenterologist in Newport Beach and was documented to find the most polyps per patient of any gastroenterologist at Hoag Hospital by a wide margin.  The same variation in the accuracy of colonoscopies was found among gastroenterologists at Hoag as in16 published studies from the US and Europe.

The accuracy of Dr. Madokoro’s colonoscopic examinations has also been confirmed independently by the national GI database and benchingmarking site, GIQuic, which was established by the American College of Gastroenterology and the American Society of Gastrointestinal Endoscopy.

Dr. Madokoro devotes equal attention to all his patients’ care, and is known to spend more time listening to his patients’ symptoms, concerns, and priorities than any other gastroenterologist in the community.

We also know that convenience is a factor in your selection of a gastroenterologist, and on this site you will find information about our location, maps, directions, hours, and appointment scheduling. Please feel free to contact us for further questions or to schedule an appointment.

Contact Us

Send us an email if you have any interests or concerns

Our Location

PERMANENTLY CLOSED 2901 W Cst Hwy ste 200, Newp Bch, CA 92663

Office Hours


8:30 am-12:30 pm


8:30 am-3:00 pm




8:30 am-12:00 pm


8:30 am-12:00 pm